Magnetospheres of the Outer Planets

2018 Conference

July 8 - 13, 2018

University of Colorado Boulder Boulder, Colorado, USA

Sponsored by:

European Space Agency

Laboratory for Atmospheric and Space Physics

Southwest Research Institute

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We thank sponsors of 2018 Magnetospheres of the Outer Planets Conference:

Laboratory for Atmospheric & Space Physics, University of Colorado European Space Agency

Southwest Research Institute, Boulder Colorado We thank the following for making the meeting happen: MOP2018 Scientific Organizing Committee Fran Bagenal, Chair Carol Paty Tomoki Kimura Emmanual Chane Tamas Gombosi Masaki Fujimoto Frank Crary Joachim Saur Xianzhe Jia Chihiro Tao Joe Westlake Olivier Witasse John Clarke Tom Stallard Philippe Zarka Norbert Krupp MOP2018 Local Organizing Committee Fran Bagenal – The Boss Rob Wilson Andrew Steffl LASP Event Staff Anca Kokinakos Anastasia Bailey Louise Krieger Chris Crouch MOP2018 Student Helpers – The MOPsters Grace Marshall Jon Lutz Amanda Swain Parker Hinton Eddie Nerney

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Agenda

Sunday, July 8th

6:00-9:00p Reception Rayback Collective: 2775 Valmont Rd, Boulder, CO 80304

Monday, July 9thInvited Talks: 25 minutes Contributed Talks: 15 minutes Abstract Page #

9:00 IntroductionChair: Michele Dougherty

9:10 Thomsen, M.F. Magnetospheric Structure and Dynamics at Saturn (and maybe Jupiter) 1019:35 Connerney, J.E.P. A Degree 10 Spherical Harmonic Model of Jupiter’s Magnetic Field

from the Juno Magnetometer Investigation 299:50 Cao, H Saturn’s Internal Magnetic Field Revealed by Cassini Grand Finale 2310:05 Khurana, K.K. Discovery of Atmospheric-Wind-Driven Electric Currents in Saturn’s

Magnetosphere in the Gap between Saturn and its Rings 5610:30 Break

Chair: Carol Paty11:00 Masters, A. The magnetospheres of Uranus and Neptune 7011:25 Griton, L. A Uranus-like magnetosphere in a magnetized Solar Wind: solstice and

equinox configurations 3811:40 Kivelson, M.G. Mass transport at Jupiter and Saturn 5812:05 Delamere, P.A. Entropy constraints on radial transport in the giant planet magnetospheres 3212:30 Lunch

Chair: Peter Delamere2:00 Vasyliunas, V.M. Outflow of plasma without removal of magnetic flux: What is the real

magnetic topology? 1032:15 Badman, S.V. Saturn’s auroral processes: insights from the Cassini Grand Finale 152:40 Burkholder, B.L. Quantifying Kelvin-Helmholtz driven variability of plasma conditions

near Saturn's magnetopause boundary 222:55 Kinrade, J. Analysing Cassini UVIS & INCA imagery during injection events at Saturn:

an inverse problem 573:15 Break

Chair: Abi Rymer4:00 Southwood, D.J. Saturnian planetary period oscillations, angular momentum transfer and

plasma sub-corotation 97Given by: Hunt, G.J.

4:15 Bradley, T.J. Planetary period modulations of reconnection events in Saturn’s magnetotail 204:30 Provan, G. Will we ever know the time on Saturn? Saturn’s Planetary Period

Oscillations observed throughout the Cassini mission. 854:45 Azari, A. R. Are Saturn’s Interchange Injections Organized by Rotation Longitude? 14

Tuesday, July 10th8:55 Announcements

Chair: Nick Achilleos9:00 Yates, J.N. 3D Jovian Magnetosphere - Ionosphere - Thermosphere (MIT) 1089:15 O'Donoghue, J. The atmospheric consequences of mid-latitude magnetosphere-ionosphere

coupling at Saturn 809:30 Allen, R.C. Internal versus external sources of plasma at Saturn: Overview from

MIMI/CHEMS data 129:45 Mitchell, D.G. D-Ring Dust Falling into Saturn’s Equatorial Upper Atmosphere 7310:00 Hsu, H.-W. Cosmic Dust Analyzer onboard Cassini Collects Material from Saturn’s

Main Rings 4710:15 Hadid, L. Z. Saturn’s ionosphere: Electron density altitude profiles and ring

shadowing effects from the Cassini Grand Finale 4010:30 Break

Chair: Barry Mauk11:00 Cravens, T. E. The Ion Composition and Dynamics of Saturn’s Equatorial Ionosphere

as Observed by Cassini 30

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11:15 Cassidy, T.M. Comparative Modeling of the Magnetosphere of Saturn and Jupiter 2511:30 Becker, H.N. Jupiter’s high energy particle environment at high latitudes: observations

from Juno’s Radiation Monitoring Investigation 1711:55 Santos-Costa, D. Results from 2 years of high time-space sampling of Jupiter’s radiation

with JUNO/MWR 9112:10 Haggerty, D. K. Charged particle injections at high Jovian latitudes 4012:30 Lunch

Chair: Gabby Provan2:00 Kollmann, P. The ion radiation belts of Jupiter and Saturn 612:25 Kim, T.K. Ion Properties of Jupiter's Plasma Sheet: Juno JADE-I Observations 562:40 Lamy, L. A brief overview of auroral processes on Uranus and Neptune 643:05 Smith, H.T. Confirming and constraining the presence of a Europa-generated neutral

(asymmetric) torus 953:20 Break

Posters: Session APoster # Author Title

1 Arridge, C.S. Neutral tori in Neptune’s magnetosphere 142 Bergman, J. Radio & Plasma Wave Investigation (RPWI) for JUpiter ICy moons

Explorer (JUICE) – Langmuir probe investigations 183 Ebert, R. W. JUpiter MagnetosPheric boundary ExploreR (JUMPER) 354 Imai, K. CubeSat project for Jupiter's radio science 495 Kasaba, Y. High Frequency part in Radio & Plasma Wave Investigation (RPWI)

aboard JUICE: Toward the investigation of Jupiter and Icy Moons System 556 Bagenal, F. Is Jupiter a colossal comet? Will Juno decide? 168 Huscher, Ezra Plasma sheet properties observed by Juno at Jupiter 489 Krupp, N. Future Jovian Magnetospheric science with JUICE 63

10 Lee-Payne, Z Correcting Galileo’s Energetic Particle Detector (EPD) data; Methodology and Implications. 65

11 Lorch, C An investigation into radial and azimuthal currents in Jupiter's Magnetodisc 6612 Manners, H. Standing Alfvén waves in Jupiter's magnetosphere as a source of ~10-60

minute quasi-periodic pulsations 6913 Nakamura, Y. Study of the Jovian magnetosphere-ionosphere coupling using an

ionospheric potential solver: Contributions of H+ and meteoric ions to ionospheric conductivity 77

14 Ranquist, D.A. Properties of Jupiter's Dawn Magnetosheath as Measured by Juno and New Estimate of the Polar Flattening of Jupiter's Magnetosphere 86

15 Sarkango, Y. Response of Jupiter's magnetosphere to varying solar wind conditions: Insights from global MHD simulations 92

16 Valek, P. W. The Jovian Ionospheric ion population observed by Juno's JADE instrument 10317 Vogt, M. F. Juno Observations of Magnetotail Reconnection at Jupiter 10418 Wilson, R.J. Forward Modeling Multiple Heavy Ion Species in JADE Data 10719 Yoshioka, K. Plasma and energy transport in Jupiter’s inner magnetosphere as deduced

from Hisaki observation 10920 Alexeev, I.I. Contributions of the Ionospheric Hall Currents to the Jupiter's and Saturn's

Magnetic Field 1121 Horanyi, M. Charged Dust Dynamics at Jupiter and Saturn 4522 Kivelson, M. G. Heating Jupiter’s plasma torus (Saturn’s too) through interchange 5923 Guio, P. Effects of the Size Scale on the Dynamics of Trapped Charged Particles

in Gas Giant Magnetospheres 3924 Masters, A. A more viscous-like solar wind interaction with all the giant planets? 7125 Pontius, D.H. Consequences of non-conformal magnetic field mapping 8426 Sakanoi, T. Planetary and exoplanetary observations with the Haleakala telescopes

and a future 1.8-m off-axis telescope project PLANETS 9127 Agiwal, O. Modelling the structure of Saturn's nightside current sheet during

Cassini's F-ring apoapsis passes 1128 Andrews, D.J. Equatorial magnetic field oscillations observed over the Cassini mission 1329 Bader, A. Statistical planetary period oscillation signatures in Saturn’s UV auroras 1530 Bunce, E.J. Observations of Saturn’s Ring Current during the Cassini Grand Finale Orbits 2131 Chané, E. Global MHD simulations of Saturn's magnetosphere 2632 Davies, E.H. Transient Configurations of Saturn’s Dayside High Latitude Magnetic Field 3133 Farrell, W.M. Saturn’s Plasma Density Depletions Along Magnetic Field Lines Connected

to the Main Rings 36

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34 Hamil, O.Q. The significance of Saturn ring-ice in Cassini proximal observations. 4135 Hardy, F. Towards a self-regulating magnetopause model with application to Saturn 4136 Hendrix, A. R. Cassini UVIS detects energetic electrons and dust in the Saturn system 4237 Hunt, G. J Field-aligned currents from the F-ring orbits of Cassini 48

38a Jasinski, J. M. Plasma observations at Saturn’s high-latitude magnetosphere and cusp 5138b Jasinski, J. M. Suvery of Electron measurements at Saturn's Magnetosphere using

CAPS-ELS 5239 Jia, X. Coupled Fluid-kinetic Global Simulations of Saturn's Magnetopause Dynamics 5240 Kane, M. Cassini Mission-wide Analysis of Hot Ions Detected by the INCA and

CHEMS Instruments in the Magnetosphere of Saturn 5441 Martin, C. J. Current density in Saturn’s Equatorial Current Sheet 6942 Menietti, J. D. Anomalous Plasma Waves Observed During Cassini's Ring-grazing Orbits 7243 Misawa, H. Identification of Jupiter's hectometric radiation associated with reconnection

in the magnesphere 7244 Morooka, M.W. Saturn’s Dusty Ionosphere 7445 Neupane, B. Transport and Turbulent Heating in Saturn’s Magnetosphere. 7946 Parunakian, D.A. Open and partially closed models of solar wind interaction with Saturn's

magnetosphere 8147 Perry, M. E. Relative fractions of water-group ions in Saturn’s inner magnetosphere 8248 Píša, D. Electrostatic solitary waves observed during Cassini's ring-grazing and

Grand Finale orbits 8349 Ponce, I.D. Rotation of the Interplanetary Magnetic Field in Saturn's Magnetosheath 8350 Roussos, E. Sources, sinks and transport of energetic electrons near Saturn's main rings 8951 Sawyer, R.P. An Investigation of Suppression of Magnetic Reconnection at Saturn’s

Magnetopause 9352 Sergis, N. Distribution of hot ion plasma in Saturn’s middle magnetosphere, from

>13 years of Cassini orbits 9453 Sorba, A. M. Investigating how the large-scale structure of Saturn’s magnetosphere

varies with local time using a combined data and modeling approach 9654 Staniland, N.R. Quantifying the stress of Saturn's magnetosphere during the entire

Cassini mission 9855 Stephens, G.K. A new empirical magnetic field model for Saturn's magnetosphere 9956 Vriesema, J. W. Electrodynamics in Saturn's Thermosphere 10457 Wahlund, J.-E. On the Characteristics of Charged Dust in Saturn’s Equatorial Ionosphere –

Implications from Cassini RPWS/LP data 10558 Woodfield, E.E. The effect of wave particle interactions on electrons close to Saturn 10859 Cao, X. Diurnal and Seasonal Variability of Ice Giant Magnetospheres under

Different IMF Conditions 2360 Wang, L. Self-consistent modeling of planetary electron dynamics 10561 Carlton, A.K. Using the Galileo Solid-State Imaging Instrument as a Sensor of Jovian

Energetic Electrons 2462 Collier, M.R. A K-means Clustering Approach to the Number of States of the Jovian

and Terrestrial Magnetopauses 2863 Kammer, J.A. Juno-UVS Measurements of High-Energy Radiation at Jupiter 5364 Nenon, Q. What has been learnt about the radiation belts of Jupiter with the physical

model Salammbô 7865 Soto-Chavez, R. Generation of ULF waves by the Drift-Mirror Plasma Instability 97

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Wednesday, July 11th8.55 Announcements9:00 Next Meeting

Chair: Marissa Vogt9:25 Palmaerts, B. Auroral storm and polar arcs at Saturn – Final Cassini/UVIS auroral

observations 809:40 Murakami, G. Response of Jupiter's inner magnetosphere to solar wind derived from

Hisaki and Juno/JADE observations 7610:05 Gladstone, G.R. Jupiter's Ultraviolet Auroras 3810:30 Break

Chair: Emma Bunce11:00 Grodent, D. Jupiter’s mesmerizing auroral show; HST ultraviolet observations near

and far from Juno perijoves 3911:15 Nichols, J. D. Jupiter’s mesmerizing auroral show; HST ultraviolet observations near

and far from Juno perijoves 7911:30 Bonfond, B. The polar region of Jupiter’s aurora : barcode noise, conjugate flares

and more… 2011:45 Kita, H. EUV aurora’s response to solar wind measured with Hisaki & Juno 5812:10 Clarke, J.T. Thoughts on the Production of Jupiter’s Aurora 2712:30 Lunch

2:00 Free Time

6:00-9:00 Banquet

Thursday, July 12th8:55 Announcements

Chair: Licia Ray9:00 Mura, A. Juno/JIRAM observations of Jupiter’s main aurorae and satellite footprints. 759:25 Clark, G Megavolt potentials over Jupiter’s polar cap region 269:40 Cecconi, B. Physics and Observations of auroral radio emissions at Jupiter and Saturn 2510:05 Elliott, S.S. A two-step mechanism for accelerating up-going electrons throughout

Jupiter’s polar cap region via interactions with up-going whistler-mode waves 3610:30 Break

Chair: Jamey Szalay11:00 Dunn, W. R. Jupiter’s X-ray Aurora Spectra 2016-2017 3311:25 Rymer, A.M. Juno observations of energetic charged particles associated with

Jupiter’s aurora. 9011:40 Ebert, R. W. Comparing Electron Energetics and UV Brightness in Jupiter’s Polar

Auroral Region 3511:55 Mauk, B. H. Auroral acceleration at Jupiter and its possible role in creating Jupiter’s

uniquely energetic radiation belts 7112:30 Lunch

Chair: Joe Westlake2:00 Allegrini, F. Energy flux of precipitating electrons over Jupiter’s main auroral emission 122:15 Damiano, P.A. Kinetic simulations of electron acceleration by dispersive scale Alfven

waves in the Jupiter magnetosphere 312:30 Saur, J. Wave-Particle Interaction in Jupiter's Magnetosphere: Auroral and

Magnetospheric Particle Acceleration 922:45 Lysak, R. L. Alfvenic Aurora at Earth and Jupiter 683:00 Kurth, W.S. Novel Electron Distribution Functions Associated with a Source of

Broadband Kilometric Radiation at Jupiter 633:30 Break

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Posters: Session BPoster # Author Title

1 Dunn, W. R. Jupiter's X-ray Aurora During Solar Minimum 342 Higgins, C. Radio Jove Citizen Science Partnerships 433 Higgins, C. LWA1 Observations of Jupiter’s Left-Hand Polarized Decametric Emission 444 Houston, S.J. Modeling of Jovian Auroral Polar Ion and Proton Precipitation 465 Hue, V. Juno-UVS observation of the Io footprint 47

6Imai, K. Frequency dependence on the beaming angle of Jupiter's decametric

radio emissions 50

7Imai, M. Stereoscopic observations of Jovian decametric radio arcs associated

with ultraviolet auroras 50

8Gérard, J.-C. Combined Juno observations and modeling of the Jovian auroral electron

interaction with the Jovian upper atmosphere 37

9Jackman, C.M. Assessing quasi-periodicities in Jovian X-ray emissions: techniques and

heritage survey 51

10Kimura, T. Response of Jupiter's Aurora to Plasma Mass Loading Rate Monitored

by the Hisaki Satellite During Volcanic Eruptions at Io 57

11Louarn, P. On the saturation mechanisms of the cyclotron maser instability - An

investigation with Juno 6712 Louis, C. Jupiter auroral emissions : statistical distibution of radio sources 6713 Magalhaes, F.P. Long-term variations and correlations of Jovian radio components 6814 Ray, L.C. Characterising Jupiter's Auroral Acceleration Region 87

15Rutala, M.J. Characterizing Local and Interplanetary Control of Jupiter's Auroral

Dawn Storms using HST and Juno 90

16Sinclair, J. A. Gemini-TEXES mid-infrared spectral observations of Jupiter’s auroral

regions: comparison with ultraviolet and near-infrared observations 9517 Song, Y. Towards Unified Theory of Auroral Particle Acceleration at Earth and Jupiter 96

18Tao, C. Volcanic Control of Jupiter's Aurora and Middle Magnetosphere Dynamics

Observed by Hisaki/EXCEED and Analysis Improvements by Juno 10119 Trafton, L.M. Auroral Excitation Along Open Jovian Magnetospheric Field Lines 102

20Watanabe, H. Pulsation characteristics of Jovian infrared polar aurora observed by

Subaru IRCS with adaptive optics during Juno’s solar wind campaign 10621 Fischer, G. SKR: A rotating radio source that appears clock-like 3722 Lamy, L. The low frequency source of Saturn’s Kilometric Radiation 64

23Nakamura, Y. Long-term variation of the North–South asymmetry in the intensity of

Saturn Kilometric Radiation (SKR) in 2004-2017 76

24Prangé, R. Saturn’s northern aurorae at solstice from HST observations coordinated

with Cassini’s Grand Finale 8525 Pryor, W.R. Cassini UVIS Observations of Saturn's Auroras and Polar Haze 86

26Ye, S.-Y. An SLS5 longitude system based on the rotational modulation of Saturn

radio emissions 109

27Berland, C Analysis of HST, VLT and Gemini recent observations of Uranus at

UV/IR wavelengths 1828 Roth, L. HST Lyman-alpha observations of Uranus 8929 Liuzzo, L. Energetic ion dynamics near Callisto 65

30Liuzzo, L. A comprehensive picture of Callisto's magnetic and cold plasma

environment during the Galileo era: Implications for JUICE 6631 Crary, F. J. Energetci neutrals from the Europa interaction: Finite gyroradius effects 29

32Heuer, S.V. Investigating Deflection of Jovian Bulk Plasma by Europa’s Ionosphere

using Galileo Plasma Data 4333 Huybrighs, H.L.F. Signatures of Europa’s atmosphere in Galileo EPD data during the E12 flyby 4934 Korth, H. Fields and Particles Investigations by the Europa Clipper Mission 6235 Spencer, J. R. Spatial Distribution of Condensed Oxygen on Europa 9836 Bard, C. Simulating Ganymede's Magnetosphere with Graphics Processing Units 17

37Carnielli, G. Constraining Ganymede’s neutral and plasma environment through

numerical simulations of its ionosphere 24

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Collinson, G.A. New results from Galileo's first flyby of Ganymede: Reconnection driven flows at the low-latitude magnetopause boundary, crossing the cusp, and icy ionospheric escape 28

39Zhou, H. Magnetopause Dynamics from 3D Hall MHD-EPIC Simulations of

Ganymede`s Magnetosphere 110

40Arakawa, R. Longitudinal variations of the sulfur ions in the Io plasma torus observed

by the HISAKI/EXCEED 1341 Coffin, D. A. The effect of subcorotation on Jupiter's System IV periodicity 27

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42Hikida, R. Variation in composition and temperature of plasmas in the Io plasma

torus confirmed by the Hisaki/EXCEED observation 4443 Hinton, P. A 4D Model of the Io Plasma Torus 45

44Koga, R. Spatial distribution of atomic oxygen emissions around Io's orbit during

volcanically quiet and active periods 60

45Morgenthaler, J.P. Observations of the Jovian sodium nebula and Io plasma torus with the

Io Input/Output Facility (IoIO) 73

46Nerney, E.G. Constraining Plasma Conditions of the IPT via Spectral Analysis of UV

& Visible Emissions and Comparing with a Physical Chemistry Model 7847 Phipps, P.H. Io plasma torus geometry from Juno radio occultations 8248 Rathbun, J. A. Io Volcano Monitoring from the IRTF in Support of Juno and Hisaki 8749 Schmidt, C.A. Visible Wavelength Spectroscopy of the Io Torus During the Hisaki Mission 9350 Schneider, N.M A Search for Ion Scale Height Variability in Hisaki Io Torus Observations 94

51Wannawichian, S. Angular Size of Io Magnetic Footprint’s Main Alfvèn Wing Spot: In

Corresponding to Satellite’s Locations 10652 Dols, V. Atmospheric loss at Io, Europa; massloading and ion cyclotron waves production 3253 Bagenal, F. Flow of Mass and Energy Through the Io-Europa Space Environment 1654 Travnicek, P. Multi-species hybrid modeling of plasma interactions at Galilean moons 10256 Crary, F. J. Magnetic induction signatures from an ocean within Triton 3057 Paty, C. The magnetospheric interaction between Neptune and Triton 81

58Katoh, Y. Software-type Wave-Particle Interaction Analyzer (S-WPIA) by RPWI

for JUICE 55

59Munoz, J., Jr. Obstruction of Low Energy Electron Trajectories to JADE-E Due to

Jupiter’s Strong Magnetic Field and its Effect on Pitch Angle Measurements 7460 Brown, L.E. Visualizing Data from Cassini, JUNO, and More Using HAPI, Autoplot, and MIDL 2161 Burton, M.E. Cassini Magnetospheric Science Discipline End-of-Mission PDS Data Products 2262 Koskinen, T.T. Saturn’s thermosphere from Cassini/UVIS Grand Finale stellar occultations 62

Friday, July 13th8:55 Announcements

Chair: Amanda Hendrix9:00 Sulaiman, A.H. Auroral hiss emissions during Cassini’s Grand Finale: Diverse

electrodynamic coupling between Saturn, its rings, and Enceladus 1009:15 Hospodarsky, G.B. Juno Observations of Plasma Waves Associated with the Io Footprint Tail 469:30 Szalay, J. R. Juno Observations Connected to the Io Footprint Tail Aurora 1009:45 Roth, L. Io and Europa: Influence of volcanic outbursts, moon-footprint

connections and plume activity. 8810:10 Retherford, K.D. HST Mid-Cycle 25 Europa Campaigns: New Approaches to Constrain

Plume Abundance, Composition, and Variability 8810:30 Break

Chair: Melissa McGrath11:00 Jia, X. Evidence of a Plume on Europa from Galileo Magnetic Field and

Plasma Wave Signatures 5311:15 Blöcker, A. Alfvén winglets due to plumes on Europa and Io 1911:30 Harris, C.D.K. Quantifying the access of Jupiter’s magnetospheric plasma to Europa’s

surface through a multi-fluid MHD model 4211:45 Poppe, A.R. Thermal and energetic ion dynamics in Ganymede's magnetosphere 8412:00 Liuzzo, L. Energetic ion dynamics near Callisto 6512:15 Zarka, P. Jupiter radio emission induced by Ganymede and consequences for

the radio detection of exoplanets 11012:30 Lunch

Chair: Frank Crary2:00 Bertucci, C. Titan's plasma interaction 192:25 Martin, C.J. Statistical Analysis of Flux Ropes in Titan’s Ionosphere: A comparison

of force-free and non-force-free methods 702:40 Westlake, J.H. A Compendium of the Saturn-Titan Interaction as Observed with

Energetic Neutral Atoms (ENAs) from Cassini MIMI-INCA 1073:00 Break

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Abstracts

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ModellingthestructureofSaturn'snightsidecurrentsheetduringCassini'sF-ringapoapsispassesAgiwal,O.,ImperialCollegeLondonDougherty,M.K.,Hunt,G.J.,Provan,G.,Cowley,S.W.H.

TheCassinispacecraftconducted20F-ringorbitsduringnorthernsummeratSaturn.Theorbits’apoapsispassescorrespondtothespacecraftcrossingSaturn’snightsidecurrentsheet.Thecrossingofthecurrentsheetisidentifiedbyareversalintheradialcomponentofthemagneticfield.Observationsshowthatthenatureofthisreversaldiffersfromorbittoorbit,despitetheirsimilartrajectories.CrossingsareobservedatarangeofpositionsaboveandbelowtheexpectedmagneticequatorinSaturn’smagnetotail,withsomecasesevenshowingmultiplereversalsduringthesameorbit.Weconsideramodelwhichcombinestheperturbationeffectsofthenorthernandsouthernplanetaryperiodoscillation(PPO)systemsonSaturn’shingedmagnetotailcurrentsheet.Dependingontherelativephasebetweenthetwosystems,thecurrentsheetundergoesacombinationofthicknessmodulationsandnorth-southdisplacements.For12F-ringorbits,themodeloffersaplausibledescriptionforthedifferenttypesofcrossingsobservedinthemagneticfielddata.ItalsoconfirmsthatthesecrossingsoccurinaregimewherethenorthernPPOsystemdominatesthesouthern,aswouldbeexpectedfornorthernsummeratSaturn.ContributionsofionosphericHallcurrentstoJupiter’sandSaturn’smagneticfieldAlexeev,I.I.,FederalStateBudgetEducationalInstitutionofHigherEducationM.V.LomonosovMoscowStateUniversity,SkobeltsynInstituteofNuclearPhysics,RussianFederationLavruchin,A.S.,ParunakianD.A.

Magnetosphere-ionosphereinteractionsincaseofrapidlyrotatingplanetswithanadditionalsourceofinter-magnetosphericplasma(JupiterandSaturn)resultsintothemagnetosphericplasmabeingunabletorigidlycorotatewiththeplanet.Slippingofthemagnetosphericplasmaresultsintogenerationoftheequatorialplasmamagnetodiscwithembeddedstrongazimuthalcurrents.IncaseofJupiterthismechanismresultsintoaneffectiveplanetarydipoleenhancementbyafactorofabout2-3.Thesameprocessresultsintogenerationofapotentialdropalongmagneticfieldlines,aswellaselectronsbeamaccelerationandpowerfulauroraemissionsintheupperatmosphere.Theveryhighfield-alignedconductivityrequiresmagneticfieldlinestobeequipotential(parallelelectricfieldmustbezero)andangularvelocitytobethesameattheionosphereandintheequatorialplane,butbeyondtheAlfvenicradiusmagneticfieldcannotcontroltheplasmaflowinthemagnetosphere,andaspecific3Dcurrentsystemisgenerated.Theionosphericpartofthetotalcurrentsystemresultsinaspecificdistortionoftheplanetarymagneticfield.WedescribeallthetoroidalandpoloidalcurrentsconnectedtoeachotherthroughtheratioofthePedersenandHallionosphericconductivitiesaspartsofthetotalcurrentsystem.

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EnergyfluxofprecipitatingelectronsoverJupiter’smainauroralemissionAllegrini,F.,SouthwestResearchInstituteMauk,B.,Gladstone,G.R.,Bagenal,F.,Bolton,S.,Clark,G.,Connerney,J.E.P.,Ebert,R.W.,Greathouse,T.,Hue,V.,Hospodarsky,G.B.,Kurth,W.S.,Levin,S.,Louarn,P.,McComas,D.J.,Pollock,C.,Ranquist,D.,Thomsen,M.F.,Valek,P.W.,Wilson,R.J.

Jupiter’saurorae,themostpowerfulinthesolarsystem,arecausedbyenergeticelectronsprecipitatingfromthemagnetosphereintotheatmospherewheretheyexcitethemolecularhydrogen.TheJovianAuroralDistributionsExperiment(JADE)andJupiterEnergeticparticleDetectorInstrument(JEDI)onJunomeasuretheenergyandpitchangledistributionsoftheseelectronsandhelpusunderstandhowtheseaurorae,imagedbyJuno’sUltravioletSpectrograph(UVS),arecreatedandpowered.Mono-andbi-directionalfield-alignedelectronbeamsareobservedoverthepolarregionandmainemission,withbroadandpeakedenergyspectra.Whenflyingoverthemainemissionfromhighertolowerlatitudes,Junoobserveshigherenergyelectronsfirst(10sto100skeV)thatgraduallytransitiontolowerenergyelectrons(fewkeVtolessthan100eV).Theenergyfluxoftheprecipitatingelectronsisaproxyofhowmuchenergyisdepositedintotheatmosphereand,thus,canbecomparedwiththephotonintensityoftheaurora.Lookingattheenergyflux,thereseemstobeapatternwherethemainemissioncouldbepoweredbyhigherenergyelectrons(10sto100skeV)andthediffuseauroraequatorwardofthemainemissionbylowerenergyelectrons(lessthanafewkeV).Inthispresentation,weshowhowtheenergyfluxmapstotheauroralemissionsand,inparticular,howthecontributionsfromthedifferentenergyrangescontributetothedifferentemissions.

InternalversusexternalsourcesofplasmaatSaturn:OverviewfromMIMI/CHEMSdataAllen,R.C.,JohnsHopkinsAppliedPhysicsLabMitchell,D.G.,Paranicas,C.P.,Hamilton,D.C.,Clark,G.,Rymer,A.M.,Vines,S.K.,Roelof,E.C.,Krimigis,S.M.,Vandegriff,J.

Plasmacompositionobservationsprovideausefulmechanismforinvestigatingplasmasourcesandsubsequentevolutionwithinplanetarymagnetospheres.WhileHe++isthesecondmostabundantionspeciesinthesolarwind,therearenoknownsourcesofHe++ionswithinthemagnetosphereofSaturn,allowingHe++toserveasatracerofsolarwindionswithintheKronianmagnetosphere.Meanwhile,W+andH2

+,knowntooriginatewithinthemagnetosphereofSaturn,serveasatracerofinternallyionizedplasma.Inthispresentation,weinvestigatetherelativeabundancesandpropertiesofenergetic(32-220keV)ionspeciesoriginatingfromsourceswithinthemagnetosphereandfromthesolarwind.Solarwind-originatingionsareobservedtohavesignificantfractionalabundance(upto~0.05)inthemidnight,dawn,andnoonlocaltimequadrantsathighradialdistances(~40,~45,and~20RSrespectively).Severalpossibleentryprocesses,suchasreconnectionandKelvin-Helmholtzinstabilities,areoutlinedinthispresentationaswellasadiscussionofsubsequenttransport.

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EquatorialmagneticfieldoscillationsobservedovertheCassinimissionAndrews,D.J.,SwedishInstituteofSpacePhysicsCowley,S.W.H;Hadid,L.Z.;Hunt,G.;Morooka,M;Provan,G.;Wahlund,J.-E.

Wepresentacompleteanalysisoftheequatorialstructureoftheplanetaryperiodoscillationmagneticfield,asmeasuredbyCassinioverthecompletemission.Incontrasttopreviousrelatedwork,wenowfullyaccountfortheactionofthetwoindependentmodulationsassociatedwiththeauroralcurrentsystemsinthenorthern(N)andsouthern(S)hemispheres.Up-to-datephasemodelsareemployedtoorganisethedata,accountingforslowdriftsinoscillationperiods.WhilelimitedsomewhatbytheseasonalandspatialcoverageaffordedbyCassini’strajectoryaboutSaturn,weneverthelessobtain‘maps’oftheequatorialoscillationsforbothNandSsystemsindependently.Inaddition,usingpredeterminedvaluesfortheseasonallyshiftingamplituderatiobetweentheNandSsystems,weproduceasimilarmapoftheequatorialmagneticfieldusingallavailabledata,makingtheassumptionthatthespatialstructureoftheoscillatingfieldiscommontobothNandSsystems.Field-alignedcurrentdensitiesarethencomputedandcomparedtopreviouswork.LongitudinalvariationsofthesulfurionsintheIoplasmatorusobservedbytheHISAKI/EXCEEDArakawa,R.,TohokuUniversityTsuchiya,F.,Misawa,H.,Kagitani,M.,Suzuki,Reina,H.,F.,Yoshioka,K.,Kimura,T.,Murakami,G.,Yoshikawa,I.,Yamazaki,A.

WeanalyzedtimevariationsinintensitiesofEUVemissionsfromtheIoplasmatoruswithlongtermdatasetobtainedbytheHISAKI/EXCEEDtoderivetheSystemIVperiodicity,whichislongerthantheSystemIIIperiod(9.925h),duringtheHISAKIeraandfoundforthefirsttimethattheSystemIVperiodhasshortenedaftertheIovolcanicevent.ThedatausedinthisstudywasobtainedforNov.2014–May2015includingtheIovolcaniceventstartedinthemiddleofJan.,2015[Yonedaetal.,Icarus,2015].TofindtheSystemIVperiod,temporalvariationsintheSystemIIIlongitudeatthepeakofEUVintensitywerederivedbyasinusoidalfittothelightcurvesofsulfurions.TheSystemIVperiodsofS+(76.5nm)beforeandaftertheIo’svolcaniceventwere10.046±0.001hand9.989±0.001h,respectively.Ontheotherhands,theSystemIVperiodduringtheIo’svolcaniceventwas9.937±0.014h.ThetimingwhentheSystemIVperiodshortenedcorrespondstothetimingwhentransientauroraactivitiesenhanced.ThephaseofthelongitudinalmodulationofS3+(65.7nm)alsochangedabruptlyatthattimingintheorderfromtheoutertotheinnerpartofthetorus.ThesefactssuggestchangeinSystemIVperiodicitywasrelatedwiththeinjectionofhotplasma.WeexaminedtheeffectofthegradientBdriftoftheinjectedhotelectronandthecollisionrelaxationtimescaleoftheinjectedhotelectronwiththethermalelectronandproposethattheshortSystemIVperiodjustaftertheinjectionwasproducedbythegradientBdriftoftheinjectedhotelectronwhoseenergywasinafewkeVtoafewtenkeV.However,theoriginofthenormalSystemIVperiod,thatistheperiodicitybeforetheIovolcanicevent,isnotstillresolved.

13

NeutraltoriinNeptune’smagnetosphereArridge,C.S.,LancasterUniversityRay,L.C.;Higgins,P.M.

NitrogenandhydrogenionsarethoughttobethemainionspeciesintheneptunianmagnetosphereandarethoughttoderivemainlyfromthelargesatelliteTriton.OthersourcesofneutralspotentiallyincludeNeptune’sexosphereandtherings.InthisworkweuseanewDirectSimulationMonteCarlo(DSMC)modelforneutraltoriinNeptune’smagnetospheretoinvestigateneutralsourcesatNeptuneandtheeffectsofplasma-neutralasymmetries.Themodelincludesincludeneutral-neutralandneutral-ioncollisions,photolysis,electronimpactionisation/dissociationandrecombination,andchargeexchangereactions(includingchemistry).Reactionsinvolvingionsandelectronsaremodelledusingasimplifiedplasmamodel,basedonVoyager2observations,whichincludesthelatitudinaldistributionforionsandelectrons.WealsoincludeawatergroupneutralsourcefromringarcsintheinnermagnetospheretoinvestigatethepresenceofadenseionsourceclosetoNeptune.AreSaturn’sInterchangeInjectionsOrganizedbyRotationLongitude?Azari,A.R.,UniversityofMichigan,ClimateandSpaceSciencesandEngineeringJia,X.,Liemohn,M.W.,Provan,G.,Ye,S.-Y.,Cowley,S.W.H.,Hospodarsky,G.B.,Paranicas,P.,Rymer,A.M.,Mitchell,D.G.,Sergis,N.,andThomsen,M.F.

Saturn’smagneticandplasmaenvironmenthasbeenextensivelystudiedoverthepastdecadeandahalfwiththerecentconclusionoftheCassinimission.PeriodicitiesintheplasmapropertiesandmagneticfieldhavebeenobservedatperiodscloselyrelatedtothoseoftheemissionpowerofSaturnKilometricRadiation(SKR),leadingtothehypothesisthattheprocesscontrollingSKRmodulationalsocontrolsaspectsofmagnetosphericphysics.Here,webuildonpreviousworkidentifyinginterchangeinjectionsfromhigh-energy(3-22keV)H+intensificationstoinvestigatewhetherinterchangeinjectionsdisplayperiodicitiessimilartoeitherSKRmodulationorotherphenomena.

InterchangeinjectionsareRayleigh-TaylorlikeplasmainstabilitiesandaprimarysourceofmasstransportinSaturn'smiddlemagnetosphere.Ourpreviousworkfoundthatenergeticprotoninjectionsarestronglyorganizedbylocaltimeandradialdistance.Here,weconsidertheorganizationbyseveraldifferentperiodicfluctuation-basedlongitudesystems.Iforganizedbyplanetaryoscillationphase,theninterchangewouldassistincommunicatingtheseperiodicitiesbetweentheinnerandoutermagnetosphereofSaturn.Wetakeadvantageoftherecentlyupdatedandnear-continuousdefinedSaturnlongitudesystem(SLS-5),whichisbasedonthemodulationphaseofSKR,alongwiththeplanetary–periodoscillationslongitudesystem(PPO),whichisbasedonmagnetosphericmagneticfieldmeasurements.Weanalyzethephasesystemdistributionforequatoriallyobservedinterchangein2005–2016andcomparethistopreviousstudies.

WecanreproduceapreviousfindinglinkinginjectionstotheSLSlongitudesystem,butonlyifthetimeinterval,spatialrange,andinjectionintensitylevelistightlyrestricted.Examinationsofthisrelationshipoverlongertimeintervalsandawiderrangeofinjectionamplitudes,however,revealnostrongconnectionwitheithertheSLS-5orPPOlongitudesystems.

14

StatisticalplanetaryperiodoscillationsignaturesinSaturn’sUVaurorasBader,A.,LancasterUniversityBadman,S.V.andKinrade,J.andCowley,S.W.H.andProvan,G.andPryor,W.

Saturn'sauroralemissionsprovidegoodgroundsforinvestigatingfield-alignedcurrent(FAC)systemsintheplanet'smagnetosphericenvironment.Previousstudiesbasedonmagneticfielddatahaveidentifiedcurrentsystemsrotatingwiththeplanetaryperiodoscillations(PPOs)inbothhemispheres[e.g.,Hunt2014,2015],superimposedontothelocaltime-invariantcurrentsystemproducingthemainauroralemission.InthisstudyweanalyzethestatisticalbehaviourofSaturn'sUVauroralemissionsoverthefullCassinimissionusingallsuitablepubliclyavailableCassini-UVISimages.Wecalculateaccuratestatisticalboundariesandcenterlocationsoftheauroraloval.UsingPPOphaseanglesdeterminedby[Provan2016],weexamineauroralintensitiesandboundariesinareferenceframerotatingwiththePPOsystemineachhemisphere.StrongstatisticalintensificationsareobservedclosetotheexpectedlocationsofupwardFACsinmagneticlongitude,clearlysupportingthemainassumptionsofthecurrenttheoreticalmodel[e.g.,Provan2016].However,ananalysisofseparatetimeperiodswithdifferentrelativerotationratesandstrengthsofthenorthernandsouthernPPOsystemsindicatessomesortofinterhemisphericcouplingofthetwo,asthestatisticalvariationsinauroralintensityareobservedatshiftingmagneticlongitudes.Similarly,thepreviouslyobservedellipticmotionoftheauroraloval'scenters[e.g.,Nichols2015]isfoundtodependontherotationofbothPPOsystemsandtheirinteraction.

Saturn’sauroralprocesses:insightsfromtheCassiniGrandFinaleBadman,S.V.,LancasterUniversityBader,A.,Kinrade,J.,Pryor,W.,Esposito,L.,Radioti,A.,Grodent,D.,Yao,Z.,Palmaerts,B.,Lamy,L.,Brown,R.H.,Baines,K.,Buratti,B.,Clark,R.,Nicholson,P.,Sotin,C.,Melin,H.,Stallard,T.

Saturn’sauroralemissionsdisplayavarietyoffeaturesreflectingdifferentregionsofthemagnetosphere.The‘main’auroraisusuallydominatedbyadawnarcmappingtoouter,closedfieldlines.Itcanbecomplementedbyarcsandspots,sometimespulsating,athighlatitudes,likelyoccurringonfieldlinesopentothesolarwind.Diffusepatchesorarcsarealsodetectedatlowerlatitudescorrespondingtoparticlesprecipitatingfromtheinnerregions.Thedawnarcitselfhasahighlyvariableintensityandstructure,modulatedbyrotatingfeaturesandstorm-likeexpansions.WereviewSaturn’sauroralfeaturesandthedrivingmechanismsinlightofthemeasurementsmadeduringthehighlatitude,lowaltitudeGrandFinaleorbits.Wefocusontheintensityandpositionvariabilityobservedonsmallspatialscalesandhowtheunderlyingmechanismscancontributetotheglobalmagnetosphericdynamics.

15

IsJupiteracolossalcomet?WillJunodecide?Bagenal,F.,UniversityofColoradoDelamere,P.A.

Jupiter’smagnetosphereisthelargeststructureinthesolarsystem,averagingabout150timesthewidthoftheplanet.ThesolarwindstreamspastJupiter,stretchingtheplanet’smagnetosphereintoalongtailthatcanreachpasttheorbitofSaturn.The0.5ton/siogenicplasmaisultimatelyejecteddownthetailandlosttothesolarwind.ThenatureofthesolarwindinteractionwiththemagnetospheremaybeverydifferentfromthatatEarth-morelikeacomet.Juno’sorbitoverJupiter’spolesisdesignedtoallowthespacecrafttomapJupiter’sgravityandmagneticfieldsandtheamountofwaterinitsatmosphere,butthepolarvantagepointalsoaffordsJunoaperfectopportunitytostudythiscompletelyunexploredregionofmagnetosphere.Someofthechargedparticlesinthemagnetospherearefunneledintothepolaratmospheretocreateintenseauroralemissions,whichJunoobserveswithunprecedentedresolution.Juno'sstretchedoutorbitaroundJupiterwillalsoenableittosampledifferentportionsofthemagnetosphereoverthecourseofthemission,buildingamorecompletepictureoftheaurorasandprocessesthatcontrolthem.Instrumentsonthespacecraftmeasurefluxesofparticlesthatinteractwiththeatmospheretogeneratetheauroras.Ultravioletandinfraredimagesprovidevisualcontextfordatafromthemagnetometer,plasmaandradio-waveinstruments,whichelucidatehowchargedparticlesareacceleratedto10sofkeVenergiesinJupiter'smagnetosphere.Inthisposterweillustratewaysthatmass,momentumandenergycouldbetransferredthroughthemagnetosphereandpresentideas,tobetestedbyJuno,aboutthemagnetictopologythatresemblesacometaryinteractionwiththesolarwind.ModelingtheFlowofMassThroughtheIo-EuropaSpaceEnvironmentBagenal,F.,UniversityofColoradoDols,V.,Cassidy,T.,Nerney,E.

Ground-basedobservationsinthe60sand70sindicatedIowaspeculiar.TheVoyager1flybyin1979discoveredvolcanismonIo,foundstrongUVemissionsfromanionizedtorus,andmeasuredthetorusplasmainsitu.OnitswaytoSaturntheCassiniUVISprovidedmonthsofhigh-qualityobservationsofthetorusemissions,tellingustheplasmacompositionandhowthetoruschangedafteravolcaniceruption.TheGalileospacecraftmeasuredmagneticandparticleperturbationsnearIoonseveralpasses.WhenThomas+2004wrotethepost-GalileoreviewofIo’sneutralcloudsandplasmatorusintheJupiterbookwethoughtthemainphenomenawereexplained–about1ton/sofsulfurandoxygenescapesIo,becomesionizedandtrappedinJupiter’smagneticfield,movesouttofillthevastmagnetosphere.Inthemeantime,newobservationsandmodelshaveemerged,andthereisimportantscienceintheunexplaineddetails.(i)Modelssuggest~90%oftheplasmamovesoutwardsfromIo(e.g.Delamere+2005)butweseethepeakdensityina“ribbon”extendinginsideIo’sorbit.

(ii)Ground-basedobservationsandVoyagerinsitudataindicatesthere’saphysicalgapbetweenthe“ribbon”andthecolddiscoftheinnertorus(Herbert+2008).

(iii)AddingtoknownneutralcloudsofatomicOandS,GalileoobservationsandmodelsshowmolecularSO2andSOarealsokey(Russell+2003;Dols+2008,2012).

(iv)JAXA’sHisakisatellitehasmonitored>3yearsofIotorusspatialandtemporalvariations.(v)ReanalysisofVoyagerSO2

+ionsquantifiesthedistributioninsideIo’sorbit.(vi)FocusonEuroparaisedideasofiogenicspeciesdeliveringusefulchemicalstothesurface.(vii)Europaisunlikelyamajorplasmasource,buttheescapingneutralsabsorbenergetic

particlesmovinginwardsfromtheoutermagnetosphere.

16

SimulatingGanymede'sMagnetospherewithGraphicsProcessingUnitsBard,C.,NPPFellow,NASAGoddardSpaceFlightCenterDorelli,J.C.;Collinson,G.;Paterson,B.

Theresolutionrequiredtoresolvecurrentsheetswithinsimulationsofplanetarymagnetospheresresultingridsizesapproachingseveralhundredmillioncells.Runningtheseproblemsarefeasibleonlyforthelargestsupercomputers;however,graphicsprocessingunits(GPUs)provideanalternativemeansofquickeningcomputationalMHDsolvers.OneGPUcandotheworkofroughly80-100cores,allowingmodestGPUclusters(~8GPUs)tosimulateGanymedewithinreasonabletimescales.Wereportourprogressindevelopingathree-dimensionalHallMHDcodeoptimizedtorunonmultipleGPUsandbenchmarkitwiththeGanymedeG8flyby,reproducingpreviousresultsdemonstratingthataddingtheHalltermtotheidealOhm'slawchangestheglobalconvectionpatternwithinthemagnetosphere.WepresentnewresultsfortheGalileoG1flybyanddemonstratethataddingasimpleisotropicelectronpressuretermtoOhm'slawcausesadditionalchangestotheglobalmagnetosphericbehavior.Jupiter’shighenergyparticleenvironmentathighlatitudes:observationsfromJuno’sRadiationMonitoringInvestigationBecker,H.N.,JetPropulsionLaboratory,CaliforniaInstituteofTechnologyAlexander,J.W.,Brennan,M.J.,Guillaume,A.,Adumitroaie,V.,Perry,K.L.,Jorgensen,J.L.,Denver,T.,Gladstone,R.,Greathouse,T.K.,Hue,V.,Versteeg,M.H.,Adriani,A.,Mura,A.,Cicchetti,A.,Noschese,R.,Sordini,R.,Connerney,J.E.P.,Mauk,B.H.,Bolton,S.J.,Levin,S.M

TheJunospacecraft’snovelpolarorbittraverseshighmagneticlatitudes,andtheinneredgesofJupiter’srelativisticelectronbelt,passingwithin3400km(1.05Rj)ofthecloudtops.JunoisthefirstspacecrafttoorbitthisclosetoJupiterandthefirsttosampletheinnerradiationbeltsandpolarregionsextensively(plannedscienceorbitsachieveamappingwith<12degreelongitudespacingattheequator).Juno’sRadiationMonitoring(RM)InvestigationmeasuresMeVelectronfluxesatJupiterbyusingionizationsignaturesfrompenetratinghigh-energyparticles(usuallyconsidered“noise”byinstruments)astheinsituobservable.AcquisitionofimagesandhousekeepingdatafromseveralofJuno’sheavilyshieldedinstrumentsarecoordinatedforthepurposeofobservingpenetratingradiationencounteredduringeachscienceorbit.Thedataareanalyzedtoextractthecharacteristicsignaturesofpenetratinghigh-energyelectrons(>5MeVand>10MeV)andions(>100MeV)andderivecountrateswhicharethenusedtoinferexternalelectronfluxlevels.Sincearrivalin2016JunohasreturnedbountifuldatasetsandnewsurprisesaboutJupiter’sradiationenvironmentathighlatitudes.Encounterswiththehighlatitudelobesofthesynchrotronemissionregionrevealedrelativisticelectronintensitiesanorderofmagnitudelowerthananticipatedpriortoarrival.Apopulationofhighenergyheavyions(>100MeV/nucleon)wasanothersurprisingdiscoveryinthisregion.WepresenthighlightsoftheRMobservationstodate.

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Radio&PlasmaWaveInvestigation(RPWI)forJUpiterICymoonsExplorer(JUICE)–LangmuirprobeinvestigationsBergman,J.,SwedishInstituteofSpacePhysics(IRF)Wahlund,J.-E.,Eriksson,A.I.E.,Edberg,N.J.T.,Khotyaintsev,Y.,Morooka,M.W.,Santolik,O.,Retino,A.,andtheRPWIteam

TheRadio&PlasmaWaveInvestigation(RPWI)providesanelaboratesetofstate-of-the-artelectromagneticfieldsandcoldplasmainstruments,whereseveraldifferenttypesofsensorswillsamplethethermalplasma,DCelectricfields,electricandmagneticsignalsfromradio,plasmawaves,andmicrometeoriteimpacts.ThecapabilityoffourLangmuirprobes,ondedicatedbooms,tomeasuretheelectricfieldvectorfromDCto1.6MHz,andplasmaconvection(ExBdrift)allowsfordetailedinvestigationsofplasmaelectrodynamicsintheJoviansystemand,inparticular,howtheionospheresandsubsurfaceoceansoftheicyGalileanmoonscoupleelectrodynamicallytothehighlyvariableJovianmagnetosphere.Thecapabilityofatriaxialsearchcoilmagnetometer,togetherwiththeLangmuirprobes’capabilities,allowformeasurementsofthemagneticandelectricvectorfieldssimultaneouslybelow20kHz,toidentifyAlfvénandwhistlerwaves,filamentarycurrents,fluxropes,andelectrostaticstructuresinvolvedinthetransferofenergyandmomentumbetweendifferentparticlepopulationsintheinteractionbetweentheJovianmagnetosphereandtheionizedexospheresaroundtheicymoons.TheRPWIhasasignificantlyenhancedcapabilityofusingbothpassiveandactivemethodstoinferthecold(<100eV)plasmacharacteristicsandinferthebulkiondriftvelocityvector.Forinstance,thisallowsforin-situmeasurementsofthepartiallyionizedgasexhaustedbywaterrichplumesaboveactivesurfaceregionsontheicymoons.TheLangmuirprobeswillalsobeusedtomonitorelectricallychargeddustimpactsandidentifyanydust-plasmainteractions.Suchmeasurementsonopenvs.closedmagneticfieldlinesatGanymede,combinedwithmeasurementsoftheelectricfieldacceleratingtheseparticlestowardthesurface,willgiveinsightintosputteringprocessesandtheireffectsontheatmosphereandtheicysurfaceofthemoon.AnalysisofHST,VLTandGeminirecentobservationsofUranusatUV/IRwavelengthsBerland,C.,LESIA,ObservatoiredeParisL.Lamy,N.André,R.Prangé,T.Fouchet,T.Encrenaz,E.Gendron,X.Haubois

Late2014,HSTremotelyobservedtheUranus’magnetosphereduringstrongwindshocksinteractionswiththeSTISandCOSinstrumentsintheFar-UV.ACOShighresolutionspectrumwastakenjustafterSTISimagedlocalizedsouthernaurorae,afew10kRbrightintheH2bands,on2Nov.2014.TheanalysisofthissinglespectrumrevealstransientH2auroralemissions,providesafirstmeasurementofthediscalbedobeyond170nm(upto210nm)andbringsnewconstraintsonatmospherichydrocarbonsresponsibleforabsorptionofthesolarreflectedspectrumatlongwavelengths.AsimilarobservingcampaignofUranusinvolvingmulti-spectralobservationsatFar-UV,Near-IRandX-raywavelengthsduringactivesolarwindconditionswasexecutedlate2017,whentheplanetreachedanintermediateconfigurationbetweensolsticeandequinox.WewillpresenttheNIRimagesoftheplanettakenwithVLT/NACOusingadaptiveopticsandGemini/NIRIwhichdisplayextendedH3

+emissionregions.

18

Titan'splasmainteractionBertucci,C.,InstitutodeAstronomíayFísicadelEspacio(UBA/CONICET)

Titanistheepitomeofamultivariateplasmainteractionbetweenadenseatmosphereandawindofplasma.LocatedintheconfinesofSaturn'srotatingmagnetosphere,Titan'susuallyinteractssubsonicallywiththeflappingmagnetodiskofitsparentplanet.Thisinteractionisunlikeanyotheratmosphericbodyofthesolarsystemasthedirectionsoftheincomingflowandthesolarphotonsvaryasafunctionofthemoon'sorbitalphase.Therearetimes,however,whenthesolarwindpressureisstrongenoughtoleaveTitanintheshockedandeveninthesupersonicsolarwind,whereacolissionlessbowshockwasdetected.Inthesecases,theenrichmentoftheexternalplasmawithTitan'scoldandsometimesheavyionsleadstocomplexmagneticfieldmorphologiesfromwhichthehistoryofitsmagneticenvironmentcanbereconstructed.Thiseffect,negligibleatMarsandVenus,isanotheressentialcharacteristicofTitan'splasmainteraction.InthistalkwewillreviewtheseandotherresultsfromtheCassinispacecraftaroundTitanandidentifysomeopenquestionsthatcouldbeaddressedinthenearfuture.AlfvénwingletsduetoplumesonEuropaandIoBlöcker,A.,UniversityofCologneSaur,J.,Roth,L.,Strobel,D.F.

OnIo,volcanicplumesarecommonandrecentobservationssuggestedthatEuropaalsopossessesplumeactivity.Weapplya3DmagnetohydrodynamicmodeltoanalyzetheeffectsofvolcanicplumesonIoandwatervaporplumesonEuropaonthemoons'plasmaenvironmentandtheirAlfvénwings.Plumesproducelocallyenhancedatmosphericdensities,andconsequentlyenhancedandlocalionosphericconductivities.Theseconductivitiescreatealocalionosphericelectriccurrentsystem.Includinglocalplumesinthemoons'atmospheres,weshowthatsuchlocaldensityenhancementsinfluencetheplasmainteractionlocallygeneratinganAlfvénwingletwithintheAlfvénwing.SinceEuropa'satmosphericcolumndensityisaboutafactorof100smallerthanIo’satmosphericcolumndensitywedemonstratethatdenseatmosphericinhomogeneitiesonEuropaaffecttheAlfvénicfar-fieldmuchstrongercomparedtoIo.Ourworkprovidesideasonhowtodetectplumesinfutureplasmaandfieldobservations.

19

ThepolarregionofJupiter’saurora:barcodenoise,conjugateflaresandmore…Bonfond,B.,STARInstitute,UniversitédeLiège,BelgiumGrodent,D.,Gladstone,R.,Yao,Z.,Gérard,J.-C.,Greathouse,T.,Hue,V.,Versteeg,M.,Kammer,J.,Davis,M.,Radioti,A.,Paranicas,C.,Becker,H.,Bolton,S.,ConnerneyJ.,Levin,S.

Juno’sunprecedentedpolarorbitsaroundJupiterallowforuniqueobservationsofthepolarauroraeandrelatedphenomena.HerewemakeuseofJuno-UVS,theUVimagingspectrographoperatinginthe60-200nmrange,toexplorethepolarphysicsintwoverydifferentways.Inthefirstpartofthispresentation,wewillanalyzetherapidvariationsofthebackgroundnoisecausedby>10MeVelectronspenetratingtheinstrument.InUVimages,thisrapidlyvaryingsignaltakestheformofabarcode-likepattern.Wewilldiscussthemapping,thealtitudeandthecharacteristictimescaleofthe“barcodeevents”inordertoconstrainthemechanismsgivingrisetothem.Inthesecondpart,wewillcomparesimultaneousobservationsoftheauroraefromthetwohemispheres.OnedatasetcomesfromJuno-UVSwhiletheothercomesfromtheHubbleSpaceTelescopeSTISinstrument.Wewillshowthatmostauroralfeaturesinonehemispherehaveaclearcounterpartintheotherone.Amongotherexamples,wewillshowevidenceofconjugateflaresintheactiveregionofthetwohemispheres.However,otherstrongbrightnessenhancementsonlyshowupinonehemisphere,withoutanyechointheotherone.PlanetaryperiodmodulationsofreconnectioneventsinSaturn’smagnetotailBradley,T.J.,UniversityofLeicesterCowley,S.W.H.,Bunce,E.J.,Provan,G.,Palmaerts,B.,Smith,A.W.,Jackman,C.M.,Kurth,W.S.,Roussos,E.,Krupp,N.,Dougherty,M.K.

WenewlyanalyzemagneticfielddatafromthefinalorbitoftheCassinispacecraftinrelationtoalargeauroralstormobservedintheUVISdataset.Afielddipolarizationobservedat~9hUTonthe14September2017ataradialdistance~15RSinthenear-midnightnortherntailindicatesalargescalemagnetotailreconnectionevent,assupportedbyobservationoftheonsetofalowfrequencyintensificationofSaturnkilometricradiation(SKR)observedinRPWSdata,andasubsequentinjectionofhotplasmaobservedbyLEMMS.WithanelevatedradialcomponentofthemagneticfieldinSaturn’smagnetotailobservedpriortotheevent,weproposethestormisassociatedwithaninitialcompressionofthemagnetosphereviaasolarwindshock,andisthentriggeredundernear-optimumplanetaryperiodoscillation(PPO)conditionsassociatedwithathinnedtailcurrentsheetatalocalnorthernPPOphaseof~0°andalocalsouthernPPOphaseof~180°,inconformitywiththemodelofCowleyetal.[JGR-Space,2015JA023367,2017].Wesupportthisconclusionwithastatisticalanalysisof2094reconnection-relatedeventsinSaturn’smagnetotailidentifiedbySmithetal.[JGR-Space,2015JA022005,2016]usingCassinimagnetometertaildatafromintervalsduring2006and2009-10,whichwealsoorganizebyPPOphase.Theresultsshowclearmodulationoftheevents,withmostoccurringpreferentiallyattheabovelocalnorthernandsouthernphasesatwhichthetailcurrentsheetisthinnest.However,organizationoftheseeventsbythelocalPPOphaserotatingacrossthetailfromdusktodawnsuggestsamorelocalorigin,ratherthanthedominanceoflarge-scaleeventsthatsimultaneouslyaffectmuchofthetailwidth.WealsodiscusstherelationbetweentheseresultsandtheapparentlycontradictoryfindingsconcerningthemagneticPPOphasedependencyofmaximainSKRemissionsfromtheprincipalpost-dawnsources,whichoccurunderapproximateantiphasePPOconditions.

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VisualizingDatafromCassini,JUNO,andMoreUsingHAPI,Autoplot,andMIDLBrown,L.E.,JohnsHopkinsAppliedPhysicsLabVandegriff,J.D.,Faden,J.B.,Mitchell,D.G.,Kurth,W.S.

WepresentawaytovisualizeHeliophysicsdatafromCassiniandJUNO(andothermissions/datacenters)inacommontool.AnewaccessmechanismcalledtheHeliophysicsApplicationProgrammer'sInterface(HAPI)isbeingadoptedatmanydatacentersacrossHeliophysicsandplanetarysciencefortheservingoftimeseriesdata.TwoexistingtoolsarealsobeingenhancedtoreadfromHAPIservers,namelyAutoplotfromtheUniversityofIowaandMIDL(MissionIndependentDataLayer)fromTheJohnsHopkinsAppliedPhysicsLab.BothtoolswillbeabletoaccessdatafromRPWS,MAG,CAPS,MIMI,JEDI,andWaves.Inadditiontobeingabletoaccessdatafromeachother'sinstitutions,thesetoolswillbeabletoreadfromallthenewdatasetsexpectedtocomeonlineusingtheHAPIstandardinthenearfuture.ThePDSplanstouseHAPIforalltheholdingsatthePlanetaryandPlasmaInteractions(PPI)node,asdoesCDAWebatGoddardSpaceFlightCenter.WewilldescribethenewHAPIdataservermechanismanddemonstratethevisualizationandanalysistools.ObservationsofSaturn’sRingCurrentduringtheCassiniGrandFinaleOrbitsBunce,E.J.,UniversityofLeicesterProvan,G.,Cowley,S.W.H.,Achilleos,N.,Cao,H.,Dougherty,M.K.,andHunt,G.J.

Saturn’sringcurrentflowsintheequatorialmagnetosphereeastwardaroundtheplanetextendingthefieldlinesradiallyoutward.Earlynear-equatorialCassiniorbitswereusedtodeterminethestrengthandradialextentofthecurrent,showingthatthisvariesstronglywiththesizeofthemagnetospheredependentonthedynamicpressureofthesolarwind[Bunceetal.,2007].Theinneredgeofthecurrentliesatanequatorialradialdistanceof~7RS,whiletheradiusoftheouteredgevariesbetween~15RSwhenthemagnetosphereiscompressedto~22RSwhenitisexpanded.WhendatafromthefirsthighlyinclinedCassiniorbitsbecameavailable,thefirstmeasurementsofthenorth-souththicknessofthecurrentsheetweremade,withvaluesbeingtypically~3RSonthedayside,and~1to~5RSonthenightside[Kellettetal.,2009].Hereweinvestigatethefirstsystematicobservationsofringcurrentperturbationsintheresidualmagnetosphericfield(followingsubtractionoftheinternalmagneticfieldmodel)insidethemaincurrentcarryingregionduringtheGrandFinaleorbits.ThesecylindricalfieldcomponentsarecomparedwiththeSaturnmagnetodiscmodel[Connerneyetal.,1981;Edwardsetal.2001].Duringthistimethespacecraftcrossednorthtosouthinsidetheinneredgeofthecurrentcarryingregion,between~1.05RSand~2.5RS.WefindthattheBρ fieldassociatedwiththeringcurrentinthisregionisnear-zero,andthemainringcurrentobservableisthenorth-southcomponentofthefield,Bz.Followingpreviouswork,wecaninferthevalueoftheringcurrent‘amplitude’µI0(nT)fromthestrengthoftheaxialBzfieldatthecentreofthering(equivalentlySaturn’s‘Dst’),assumingaconstantvaluefortheringcurrentthickness.WecomparethevariabilityofthisparameterduringtheGrandFinaleorbitswiththatfrompreviousequatorialobservations,anddiscusstheimplicationsforthedynamicsoftheringcurrentingeneralterms.

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QuantifyingKelvin-HelmholtzdrivenvariabilityofplasmaconditionsnearSaturn'smagnetopauseboundaryBurkholder,B.L.,GeophysicalInstitute-UniversityofAlaskaFairbanksDelamere,P.A.

TheauroralformsthatJunoisobservingmakeitclearthatthesolarwindinteractionforagiantmagnetosphereisfundamentallydifferentfromEarth's.Thelargedifferenceinthescaleofthesystem,aswellasacontinuouslyreplenishedinternalsourceofplasmawhichsubcorotatesouttothemagnetopauseboundary,couplesthesolarwindtothemagnetospheresofJupiterandSaturninawaythatisperhapsstrongerthantheterrestrialcase.IncontrasttoattemptstoquantifyaDungeycycleforthegiantmagnetospheres,aviscous-likeinteractionproposedbyAxfordandHines[1961]canbeinvokedintheformoftheKelvin-Helmoltzinstabilityactingonthemagnetopauseboundary.Cassiniplasmadatahaveshownthattheasymmetricflowshearatthemagnetopausewithrespecttolocaltimeresultsinanasymmetryinthemagnetosheathflowvelocity.WebuildontheseresultsbyexaminingthedatafortheportionofthemagnetosphericplasmathatCassinitraverseswithin100minutes(0.25-0.5Saturnradii)ofthemagnetopause.Further,usingthemagnetometerdata,wehaveidentifiedabimodaldistributionofactiveandquietmagneticfieldfluctuationsinthemagnetosphere.SomeactiveeventsnearthemagnetopausemaybeassociatedwiththeturbulentheatingfoundinactivelygrowingKHvortices.ThedataanalysisiscomparedwithresultsfromahybridsimulationofaKHunstableportionofthemagnetopauseboundary.WeusestresstensoranalysistoquantifythetransportofmomentumacrossthemagnetopauseasaresultofMaxwellandReynoldsstresses,andwecalculateheatingratesfromthesimulatedmagneticfieldfluctuations.Wealsoconductsimulationsinwhichthemagnetosphericsideoftheboundarycontainsheavyionsand/orasuperthermalvelocitydistributionasisthecaseatSaturn.CassiniMagnetosphericScienceDisciplineEnd-of-MissionPDSDataProductsBurton,M.E.,JetPropulsionLaboratory

TheCassinispacecraftmadeitsfinalplungeintotheinteriorofSaturninmid-September,2017.Sincethattime,theCassiniprojecthascontinuedandthemainfocushasbeentocapturetherichlegacyofthatlong-livedmission.Eachofthe12scientificinstrumentsandthevariousscientificdisciplines,includingtheMagnetosphericSciencedisciplinehaveidentifiedandarchiveddataproductsatthePlanetaryDataSystem(PDS)thatarelikelytobeusefultofuturescientists.Thoseproductsinclude:higherorderdataproducts,updatedinstrumentdataUserGuides,detailedspacecrafttrajectoryinformation,eventidentificationlists(eg.,magnetopause,bowshockcrossings)andspacecraftobservationlists(eg.,Cassiniremotesensingauroralobservations).ThisposterprovidesanoverviewofthedataproductsthatwillbemadeavailableatthePDStofuturescientistinterestedinstudyingSaturn’smagnetosphere.

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Saturn’sInternalMagneticFieldRevealedbyCassiniGrandFinaleCao,H,HarvardUniversityDougherty,M.K.,Khurana,K.K.,Hunt,G.J.,Provan,G.,Kellock,S.,Burton,M.E.,Burk,T.A.,Bunce,E.J.,Cowley,S.W.H.,Kivelson,M.G.,Russell,C.T.,Southwood,D.J.

Saturn’sinternalmagneticfieldcontinuestooffersurprisessincethefirstin-situmeasurementsduringthePioneer11Saturnflyby.TheCassinispacecraftenteredtheGrandFinalephaseinApril2017,duringwhichtimethespacecraftdivedthroughthegapbetweenSaturn’satmosphereandtheinneredgeoftheD-ring22timesbeforedescendingintothedeepatmosphereofSaturnonSep.15th2017.TheunprecedentedproximitytoSaturn(reaching~2550+/-1290kmabovetheclouddeck)andthehighlyinclinednatureoftheGrandFinaleorbitsprovidedanidealopportunitytodecodeSaturn’sinternalmagneticfield.ThefluxgatemagnetometeronboardCassinimadeprecisein-situvectormagneticfieldmeasurementsduringtheGrandFinalephase.MagneticsignalsfromtheinterioroftheplanetandvariousmagnetosphericcurrentswereobservedduringtheGrandFinalephase.HerewewillreportnewfeaturesofSaturn’sinternalmagneticfieldrevealedbymeasurementsfromtheCassiniGrandFinalephase.WewillshowthedirectlydeterminednorthwardoffsetofSaturn’smagneticequatoranditvariations.Small-scaleyethighlyconsistentmagneticstructuresweredetectedalongeveryGrandFinaleorbits.Whenexpressedinspectralspace,intrinsicmagneticmomentsuptoatleastdegree9areneededtodescribethesemagneticstructures.ImplicationsforthedeepinteriorofSaturnwillbediscussed.DiurnalandSeasonalVariabilityofIceGiantMagnetospheresunderDifferentIMFConditionsCao,Xin,GeorgiaInstituteofTechnologyCarolPaty

Inordertostudythedynamicandasymmetricstructureoficegiantmagnetopauses,weproposeaquantitativeapproachtomeasuretheasymmetriesofthemagnetosphericboundaries.First,weuseanumericalmodel(multifluidMHD)tosimulatetheglobalmagnetosphereofUranus,whichhasanextremelydynamicandasymmetricmagnetosphereduetoitshighobliquityanditsseverelytiltedandoffcentereddipolemoment.WeinvestigatethemagnetosphericinteractionwiththesolarwindforarangeofInterplanetaryMagneticField(IMF)orientationsandstrengthsforbothequinoxandsolsticeseasons.Basedontheresultsofoursimulations,weuseapreviouslydevelopedanalyticalmodelfortheshapeofthemagnetopausetofitthemagnetopauseboundaryofUranusandanalyzethecharacteristicsofthemagnetopausesuchasthevariationoftheflaringparameterandthecuspindentation.Inthisway,wecandeterminetheinfluenceofseasonalityandsolarwindconditions(externaldrivers)aswellastheintrinsicfieldgeometry(internal)onthemagnetosphericasymmetry.TheresultsofthisinvestigationillustratethecomplexinteractionofUranus'magnetosphere;thatitisstronglyinfluencedbothbyseasonalityandIMForientation,butthatunderlyingandpredictablesignaturesexistduetotherotationofsuchanasymmetricintrinsicfield.WeapplythesesamemethodstotheinvestigationofNeptune'smagnetosphere,andpresentpreliminaryresultsinthecontextofcomparativeplanetologywithUranus.Thisstudymayproveusefulforpredictingthemagnetopauseboundarydetectioninfuturespacemissionstoicegiantsaswellasforindicatingwhatconditionsmaygenerateenhancedcuspsandthepotentialforcuspaurora.

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UsingtheGalileoSolid-StateImagingInstrumentasaSensorofJovianEnergeticElectronsCarlton,A.K.,MassachusettsInstituteofTechnology,DepartmentofAeronauticsandAstronauticsdeSoria-SantacruzPich,M.,Kim,W.,Jun,I.,andCahoy,K.

Dedicatedinstrumentstomonitorthehigh-energyradiationenvironmentarenotalwaysincludedonspacecraftduetoresourcelimitations;however,high-energyelectronsinJupiter’smagnetosphereaffecttheoperation,performance,andlifetimeofspacecraftandtheirinstruments.Wedevelopatechniquetoquantitativelycharacterizethehigh-energyelectronenvironmentusingtheGalileospacecraftSolid-StateImaging(SSI)instrumentandparticletransportsimulationsinGeant4.Wepost-processrawSSIimagestoobtainframeswithonlytheradiationcontribution.Thecamerasettings(gainstate,filter,etc.)areusedtocomputetheenergydepositedineachpixel,whichcorrespondstotheintensityoftheobservedradiationhits.TheenergydepositedintheSSIpixelsbyincidentparticlesfromprocessedSSIimagesiscomparedwiththeresultsfrom3DMonteCarlotransportsimulationsoftheSSIusingGeant4.SimulatingtheresponseoftheSSIinstrumenttomono-energeticelectronenvironments,wefindthattheSSIiscapableofdetecting>10MeVelectrons(90%confidence).UsinggeometricscalingfactorsfortheSSI,wecomputetheenvironmentparticlefluxgivenanumberofpixelswithradiationhits.WecomparetheSSIresultstomeasurementsfromtheGalileoEnergeticParticleDetector(EPD),examiningtheelectronfluxesfromthe>11MeVintegralfluxchannel.WefindagreementwiththeEPDdatawithinthe3-sigmadeviationoftheEPDdatafor40outof43(92.03%)oftheSSIimagesevaluated.Thisapproachcanbeappliedtoothersetsofimagingdatainenergeticelectronenvironments,suchasfromstartrackersingeostationaryEarthorbit.ConstrainingGanymede’sneutralandplasmaenvironmentthroughnumericalsimulationsofitsionosphereCarnielli,G.,ImperialCollegeLondon,UKGaland,M.;Modolo,R.;Leblanc,F.;Leclercq,L.;Beth,A.;Huybrighs,H.L.F.;Jia,X.

Ganymede’sionospherehasbeenpartiallycharacterizedbyfewin-situobservationsbytheGalileospacecraft.Manyofitsproperties,suchascomposition,dynamics,andinteractionwiththemoon’sownmagneticfield,remainpoorlyunderstood.GanymedeisalsothekeymoontargetedbytheJUICEmission.Inthiscontext,wehavedevelopedacomprehensive,ionosphericmodelforGanymedewhichaimstobeausefultoolinpreparationtothemission.Itwouldbeessentialtointerpretdata,suchasenergydistributionandmomentsfortheenergeticionsandneutralsfromPEP,ionosphericdensitiesfromRPWI,andtodisentangledifferentcontributionstothemagneticfield.

Ourmodelisbasedon3Dmulti-speciestestparticleMonteCarlosimulationswithtwokey,fixedinputs:theexosphereandelectromagneticfieldconfigurationsaroundthemoon.Theionosphereisgeneratedfromionizationoftheneutralexosphereviatwomechanisms:photoionizationinthedaysideandelectron-impactionizationintheregionsofopenmagneticfieldlines.Theoutputsofthesimulationincludeindividualtestparticletrajectoriesand3Dmapsofnumberdensity,bulkvelocityandtemperaturefordifferentionspecies.

Wefindthattheionosphereishighlynon-uniform,reflectingthecomplexstructureofGanymede’smagnetosphere.ThedominantionspeciesisfoundtobeO2

+.UnlikeJovianmagnetosphericions,ionosphericionsarefoundtoconcentrateandimpactthesurfaceintheequatorialregionovertheorbitalleadinghemisphere.BycomparingtheresultsofoursimulationwithobservationsfromGalileoduringtheG2flyby,wefindthattheionosphericnumberdensityisunderestimatedbyatleastoneorderofmagnitude,whiletheenergydistributionsmatchremarkablywell.Weattributethediscrepancyintheionosphericdensitytotheneutralexosphere,which,weargue,isunderestimated,especiallyneartheboundarybetweenopenandclosemagneticfieldlines.

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ComparativeModelingoftheMagnetosphereofSaturnandJupiterCassidy,T.M.,LaboratoryforAtmosphericandSpacePhysics,Univ.ofCO,Boulder

GiventhesimilaritiesbetweenIoandEnceladus,botharelargegassourcesintherapidlyspinninginnermagnetospheresofgiantplanets,thedifferencesinmagnetosphericchemistrybetweenJupiterandSaturnaresurprising.Saturnissurroundedbyaneutralcloudwithasmallfractionofionizedspeciesanditsenergyoutputisdominatedenergeticneutralatomescape.PlasmadominatesatJupiteranditlosesenergyprimarilybyUVradiation.

WeusedthechemistrymodeldevelopedbyFleshmanetal.toexplorethereasonsforthesedifferences.Thisrequiredtheadditionsofphysicalprocessesignoredintheearlierwork.Themostimportantforthisstudyincludeenergylossbyelectronexcitationofwatermoleculesandchargeexchangebetweenmolecularionsandatomicneutrals.Wealsocorrectedanerrorinthecalculatedcrosssectionofhydroniumionproduction.Fleshmanetal.usedacrosssectionappropriateforlow-energy(300K)reactions,andsooverestimatedthehydroniumproductionratebytwoordersofmagnitude.Withthatcorrection,themodeledhydroniumdensityisnegligiblecomparedtootherwatergroupions.

WiththesecorrectionsimplementedwealteredtheinputparameterstoseewhatwouldberequiredtopushSaturn’smagnetosphereintoajovian-likestate.Themostimportantdifferenceistheexternalenergyinputfromelectronsinthe10sto1000sofeV.ExternalenergyinputmakeslittledifferenceatSaturn.Butthisalonedoesnotresultintheobservediontoneutralratio>>1.Thatrequiresanatomicsource(OandHforthismodel)ratherthanH2O,whichisextremelyefficientatquenchingelectronenergy.ThehigherpickupionenergyatIoalsocontributes,butislessimportantforwaterchemistrythanthemuchheavierSandOchemistryatJupiter.

PhysicsandObservationsofauroralradioemissionsatJupiterandSaturnCecconi,B.,LESIA,ObservatoiredeParis

Auroralradioemissionsareintenseelectromagneticwavesproducedbynonthermalplasmainstabilitiesinplanetaryauroralregions.ThepresentationpresentsthecurrentknowledgeonthephysicsofauroralradioemissionsatJupiterandSaturn,introducingtheradiosourceemissionprocesses,namelytheCyclotronMaserInstability,aswellasitsassociatedphenomenology.Theinstrumentsusedtoobservethem(fromspaceandfromground)arealsodescribed,andrecentresultsfromtheCassiniandtheJunomissionarepresented.

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GlobalMHDsimulationsofSaturn'smagnetosphereChané,E.,UniversityofLeuven

Inthiswork,wehaveadaptedourglobalmodelofJupiter'smagnetospheretoSaturn.UsingthecodeMPI-AMRVAC,wemodelinthreedimensionstheinteractionsbetweentheKronianmagnetosphereandthesolarwind.TheMHDequationsaresolvedonasphericalnon-uniformmeshrangingfrom3Rs(innerboundary)to200Rs(outerboundary).Thecouplingwiththeionosphereisintroducedbyaddingion-neutralcollisionstotheMHDequationsinanregionjustabovetheinnerboundary.Thesecollisionsacceleratetheplasmaintheionosphericregion(whichinitiatestherotationofthemagnetosphere)andmakeelectricalcurrentclosurepossibleintheionosphericregion(becausetheion-neutralcollisionsgeneratefinitePedersenandHallconductivities).WeassumethattheneutralparticlesintheionospherearerigidlycorotatingwithSaturn.Themass-loadingassociatedwithEnceladusisincludedasanaxisymmetrictoruscenteredat5.5Rs.Wecomparetheoutputofthesimulationswithinsitumeasurements,remotesensingobservationsandanalyticalmodels.Inaddition,weinvestigatehowvariationsinthesolarwindaffectthemagnetosphere.MegavoltpotentialsoverJupiter’spolarcapregionClark,G.,JHU/APLMauk,B.H.,Paranicas,C.,Kollmann,P.,Haggerty,D.,Rymer,A.,Mitchell,D.G.,Saur,J.,Bolton,S.,Connerney,J.E.P.,Levin,S.

OneofmanysurprisesfromJuno’sexplorationofJupiter’spolarmagnetosphereisthediscoveryofprecipitatingionswithMaxwellian-likeenergydistributionsashighasseveralmega-electronvolts(MeV).ThecasestudyanalysisofPerijove(PJ)3observationsrevealedthattheseionsaremagnetosphericinoriginandtheirreminiscentinverted-Vspatial/temporalprofilecanlastaslongas10minutesorseveraldegreesinlatitude–indicatingverylargescalepotentialstructures.Inaddition,thestudybyClarketal.[2017]hypothesizedthatthesestructureswereassociatedwithadownwardcurrentregioninJupiter’smiddle-to-outermagnetosphereandthelargepotentialswereaconsequenceofsparsecurrentcarriersinthehigh-latitudepolarregion(basedofftheideasfromterrestrialstudies[e.g.,TemerinandCarlson,1998]).InthispresentationwepresentnewandmorerecentJunoobservationsoftheselarge-scale,peakedMeViondistributioninJupiter’spolarcap.Severalopenquestionsremainabouttheirexistence,suchas:1)howaremegavoltpotentialsformedinJupiter’spolarcap;2)dotheymapoutlargescalepotentialstructuresofadownwardcurrentregion?;3)aretheseionsconnectedtothegenerationofX-rayemissions?;4)aretheseionscausallyconnectedtotheupwardMeVelectronsobservedbyMauketal.,2017andParanicasetal.,[2018]?Definiteanswerstothesequestionsarenotexpectedinthispresentation,butanalysisoftheseeventsandmodelingofthecurrent-voltagerelationshipsinJupiter’sdownwardcurrentregionareexpectedtoprovideclues.

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ThoughtsontheProductionofJupiter’sAuroraClarke,J.T.,BostonUniversity

RecentmeasurementsofauroralemissionsandrelatedmagnetosphericprocessesatJupiterfromtheJUNOmissionhaveprovidednewinsightsintohowtheauroraareproduced.HighresolutionimagesofbothIRandUVauroralemissionsprovidekeyinformationabouttheproductionoftheaurora,complementedbymapsoftheUVauroralcolorratio.Theexistenceofnear-simultaneousdataonfield-alignedpopulationswiththebrightnessdistributionoftheauroralemissionsatthebaseofthesamefluxtubesiskey,andhascomewithsurprisescomparedwiththeoreticalexpectations.ThistalkwillemphasizethatwhileweoftenthinkaboutJupiterinthecontextofourunderstandingoftheEarth’saurora,theconditionsaresodifferentatJupiterthatthisisadangerousapproach.Wearenowapproaching40yearsofobservationsofJupiter’saurora,andmaybejuststartingtounderstandhowdifferenttheyarefromthoseattheEarth.InthistalkspecificexampleswillbepresentedalongwithsuggestionsfornewwaysofthinkingaboutJupiter.

TheeffectofsubcorotationonJupiter'sSystemIVperiodicityCoffin,D.A.,UniversityofAlaskaFairbanksDelamere,P.A.

JupiterexhibitsafundamentalrotationalperiodicityknownasSystemIVthathasnowidely-acceptedexplanation.ThisSystemIVperiodicityisparticularlyobservedinultravioletemissionfromtheIoplasmatorus.ToattackthisproblemwemodeltheresponseoftheIoplasmatorustosuperthermalelectronmodulationandvolcaniceruptionsusingatwo-dimensionalphysicalchemistrymodel(Copperetal.,2016).Themodelincludesradialandazimuthaltransport,latitudinally-averagedphysicalchemistry,andprescribedSystemIIIsuperthermalelectronmodulationfollowingSteffletal.,[2008].VolcaniceruptionsaremodelledasatemporalGaussianenhancement(e.g.,2x)oftheneutralsourcerateandhotelectronfraction(e.g.,<1%).However,weadoptanalternativeapproachfortheSteffletal.,[2008]SystemIVelectronmodulation.Couplinghotelectronstoradialtransport,themodulationisdeterminedbytheradialfluxtubecontentgradient.Radially-dependentsubcorotationisprescribed,consistentwithobservations[Brown,1994;Thomasetal.,2001].WeshowthattheSystemIV-likeperiodicityisdeterminedbyaninterplaybetweenphysicalchemistry,radialtransport,andaradiallydependentsubcorotationprofile.OurmodelusesaGaussiansubcorotationprofiledependentonamplitudeofsubcorotation,L-shelllocationofthepeakamplitude,andthewidthoftheGaussianprofile.WedemonstratethatvariationofthisprofileissufficienttoexplainobservedshiftsbyafactoroftwooftheSystemIVperiod[Ryoetal.,2017].

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AK-meansClusteringApproachtotheNumberofStatesoftheJovianandTerrestrialMagnetopausesCollier,M.R.,NASA/GSFCGruesbeck,J.R.;Connerney,J.E.P.;Joy,S.P.;Hospodarsky,G.B.;Roberts,A.;Sibeck,D.G.;andRoelof,E.C.

Previousstudies[e.g.,Joyetal.(2002),ProbabalisticmodelsoftheJovianmagnetopauseandbowshocklocations,J.Geophys.Res.,107,A10,doi:10.1029/2001JA009146;Walkeretal.(2005),ThelocationsandshapesofJupiter’sbowshockandmagnetopause,AIPConf.Proc.781,95,doi:10.1063/1.2032681]havesuggestedthattheJovianmagnetopausepositionhasabimodaldistributionimplyingthattheJovianmagnetopauseisatwo-statesystem.Weappliedak-meansclusteringanalysismodifiedtoaccommodatecurve-fittingtoboththeJovianandterrestrialmagnetopausecrossings.Thetraditionalk-meansapproachisadaptedtocurvefittingbysubstitutingaleast-squarescurvefittingtoaclusterofpointsinplaceofcalculatingthemeanofthepointsandsubstitutingthedistancefromeachpointtothefittedcurveinplaceofthedistancefromeachpointintheclustertothemeanpositionoftheclusterpoints.OurresultsindicatethattheJovianmagnetopauseisbest-describedasatwo-statesystemwhereastheterrestrialmagnetopausehasonlyonestateindicatingthatthebehavioroftheJovianmagnetopauseisfundamentallydifferentthanthatoftheterrestrialmagnetopause.Theoriginofthiscontrastingbehaviormaybethedisparatesourcestrengthssupplyingthetwomagnetospheres.WhereastheJoviansatelliteIosuppliesaboutametrictonofheavyionspersecondtotheJovianmagnetosphere,theterrestrialsource,Earth’sionosphere,isovertwoordersofmagnitudeweaker[e.g.,Bagenal,F.(1992),Giantplanetmagnetospheres,Annu.Rev.EarthPlanet.Sci.,20,289-328].

NewresultsfromGalileo'sfirstflybyofGanymede:Reconnectiondrivenflowsatthelow-latitudemagnetopauseboundary,crossingthecusp,andicyionosphericescapeCollinson,G.A.,NASAGoddardSpaceFlightCenterPaterson,B.,Bard,C.,Dorelli,J.,Glocer,A.,Sarantos,M.,WIlson,R.J.

Onthe27thofJune1996,theNASAGalileospacecraftmadehumanity'sfirstflybyofJupiter'slargestmoon,Ganymede,discoveringthatitistheonlymoonknowntopossessaninternallygeneratedmagneticfield.ResurrectingtheoriginalGalileoPlasmaSubsystem(PLS)dataanalysissoftware,weprocessedtherawPLSdatafromG01,andforthefirsttimepresentthepropertiesofplasmasencountered.EntryintothemagnetosphereofGanymedeoccurredneartheconfluenceofthemagnetopauseandplasmasheet.Reconnection-drivenplasmaflowswereobserved(consistentwithanEarth-likeDungeycycle),whichmaybearesultofreconnectionintheplasmasheet,magnetopause,ormightbeGanymede'sequivalentofaLow-LatitudeBoundaryLayer.DropoutsinplasmadensitycombinedwithvelocityperturbationsafterwardssuggestthatGalileobrieflycrossedthecuspsintoclosedmagneticfieldlines.Galileothencrossedthecusps,wherefield-alignedprecipitatingionswereobservedflowingdownintothesurface,atalocationconsistentwithobservationsbytheHubbleSpaceTelescope.ThedensityofplasmaoutflowingfromGanymedejumpedanorderofmagnitudearoundclosestapproachoverthenorthpolarcap.Theabruptincreasemaybearesultofcrossingthecusp,ormayrepresentanaltitude-dependentboundarysuchasanionopause.Morediffuse,warmerfield-alignedoutflowswereobservedinthelobes.Fluxesofparticlesnearthemoononthenightsideweresignificantlylowerthanonthedayside,possiblyresultingfromadiurnalcycleoftheionosphereand/orneutralatmosphere.

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ADegree10SphericalHarmonicModelofJupiter’sMagneticFieldfromtheJunoMagnetometerInvestigationConnerney,J.E.P.,SpaceResearchCorporationOliversen,R.J.,Espley,J.R.,Kotsiaros,S.,Joergensen,J.L.,Joergensen,P.S.,Merayo,J.M.G.,Herceg,M.,Bloxham,J.,Moore,K.M.,Bolton,S.J.,Levin,S.M.

CharacterizingtheplanetarymagneticfieldofJupiterisoneoftheprimaryscienceobjectivesoftheJunoMission.Juno’s53.5-daycaptureorbittrajectorycarriesherscienceinstrumentsfrompoletopoleinapproximately2hours,withaclosestapproachtowithin1.06Rjofthecenteroftheplanet(oneRj=71,492km),justafewthousandkmabovetheclouds.Observationsacquiredduring8ofJuno’sfirst9orbitsprovidethefirsttrulyglobalcoverageofJupiter’smagneticfieldwithacoarselongitudinalseparationof~45degreesbetweenperijoves.Observationsacquiredwithin~7RjofJupiterduringthefirst9polarpassesareusedtocharacterizetheplanetarymagneticfieldwithextraordinaryspatialresolution.Themagneticfieldisrepresentedwithadegree20sphericalharmonicmodelfortheplanetaryfield,combinedwithanexplicitmodelofthemagnetodisc.Partialsolutionoftheunderdeterminedinverseproblemusinggeneralizedinversetechniquesyieldsamodel(“JRM09”)oftheplanetarymagneticfieldwithsphericalharmoniccoefficientsdeterminedthroughdegreeandorder10,providingthefirstdetailedviewofaplanetarydynamobeyondEarth’s.TheJovianmagneticfieldisunlikeanythingpreviouslyimagined,evidencingacomplexitythatportendsgreatinsightintothedynamoprocessingeneralandthedynamicsofJupiter’sinteriorinparticular.Wepresentadegree10sphericalharmonicmodeloftheJovianmagneticfieldandillustrateitscharacteristicsviaasetofmapsofthesurfacefield,andconsiderimplicationsforparticlemotion,auroralemissions,andthedynamo.

EnergeticneutralsfromtheEuropainteraction:FinitegyroradiuseffectsCrary,F.J.,UniversityofColorado,Boulder,LASP

TheinteractionbetweenEuropageneratesenergeticneutrals,asthebackgroundionschargeexchangewithmolecularoxygeninEuropa'satmosphere.Thissourceofenergeticneutrals,andnon-so-energeticneutrals,mayimpactthesurfaceandproduceenhancedsputtering,mayremaingravitationallyboundtoEuropaandproduceanextendedcorona,mayescapetojovianorbitandproduceanneutralcloudorbesufficientlyenergetictoescapethesystementirely.Inthelatercase,theenergeticneutralfluxwouldbeobservablebyspacecraftatasignificantdistancefromEuropa.

Dolsetal.,2016,foundthatmostoftheseenergeticneutralswouldnotbeadirectproductofchargeexchangebetweenbackgroundionsandtheatmosphere.Instead,theinitialchargeexchangewouldproduceanO2

+ioninaringdistributionandthisionwouldsubsequentlychargeexchangewithanotheratmosphericneutral,producinganenergeticneutralandanewioninaringdistribution,whichthenmightexperienceyetanotherchargeexchange,etc.

Thisringdistributionsourceproducesaenergeticneutralwithcharacteristicenergyandangulardistribution,andthisdistributionismodifiedbythefactthatboththeatmosphericdensityandconvectionelectricfieldvaryonscalescomparabletothepickupgyroradius.Inthispresentation,Ishowaanalyticformforthisenergeticneutralsourcefunction,accountingforthesefinitegyroradiuseffects.

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MagneticinductionsignaturesfromanoceanwithinTritonCrary,F.J.,UniversityofColorado,Boulder,LASPBrain,D.A.andCaldwell,C.A.

Thesubsurface(ormediterranean)oceanwithinEuropawasdetectedthroughitsinducedmagneticdipole.ThisisgeneratedbythechangingbackgroundmagneticfieldfromJupiter,whichrotateswitha11.2hour(synodic)period.Thissignatureshowsthatthereisanelectricallyconductivelayerwithinthebody,butitdoesnotuniquelydeterminethedepth,thicknessorconductivityoftheocean.Todorequiresvariationsinthebackgroundfieldondifferenttimescales.SuggestedtimescalesaretheorbitalperiodofEuropa(sincethecurrentsheetvarieswithlocaltime)andharmonicsofthesynodicperiod(sincethefieldisnotperfectlysinusoidalinSystemIIIlongitude.)Howeverthereoscillationsareveryweakcomparedtothemain,11.2hourdrivingfield.

ItispossiblethatNeptune'smoon,Triton,alsocontainsanocean[RoadmapstoOceanWorlds,May2017.Archivedat:http://www.lpi.usra.edu/opag/ROW.Andreferencestherein.]ThepossibilityofobservingsuchanoceanhasbeenmentionedbySaur,etal.2010,andexaminedinmoredetailbyCaldwelletal.,submittedtoGRL,2017.ThemagneticsignaturediffersfromthatofEuropaintworespects.First,itisdrivenatalargenumberoffrequencies.TheinternalfieldofNeptuneiscomplex,withstrongquadrupoleandoctupoleterms,andtheorbitofTritonisinclined.Thisproducesvariationsinthebackgroundatthesynodicperiod,theorbitalperiod,harmonicsofthetwoandbeatfrequenciesofthetwo.Second,unlikeEuropa,theconductivityofTriton'satmosphereissignificantcomparedtothatoftheocean.Asaresult,Triton'sinducedfieldinvolvestwo,concentricconductinglayers.Inthisposter,weexaminethedetectabilityofsuchanocean,howpresenceofmultipleexcitingfrequenciesenhancesandcomplicatesstudiesoftheocean,andhowtheionosphereaffectssuchstudies.TheIonCompositionandDynamicsofSaturn’sEquatorialIonosphereasObservedbyCassiniCravens,T.E.,UniversityofKansasRenzaglia,A.R.,Moore,L.,Waite,Jr.,J.H.,Perryman,R.,Perry,M.,Wahlund,J.-E.,Persoon,A.,Kurth,W.S.

TheCassiniOrbitermadethefirstinsitumeasurementsoftheupperatmosphereandionosphereofSaturnduring2017.MeasurementsmadebytheIonandNeutralMassSpectrometer(INMS)foundmolecularhydrogenandheliumaswellasminorspeciesincludingwater,methane,ammonia,andorganics.TheINMSmeasuredseverallightionspecies(H+,H2

+,H3+,He+)andtheRadio

andPlasmaWaveScience(RPWS)instrumentmeasuredionosphericelectrondensities.Thecurrentpaperpresentsmeasurementsofthedaysideionosphericcompositionandaphotochemicalanalysisofthisdata.WeshowthatquantitativelyexplainingthemeasuredH+andH3

+densitiesrequiresheavymolecularspecieswitha.0001mixingratio,consistentwithINMSneutralcompositionmeasurements.Anempiricalphotochemicalanalysis,basedonINMSandRPWSmeasurements,suggeststhatthemajorionspecies(orsetofspecies)isheavyandmolecularwithashortchemicallifetimeneartheionosphericpeak.WealsopresentINMSdatafortheoneproximalorbitduringwhichanH+energyscanwasmade.Someionflowinformationwasobtainedandwecomparetheseresultswithasimpledynamicalmodelappropriateforhigheraltitudes.

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KineticsimulationsofelectronaccelerationbydispersivescaleAlfvenwavesintheJupitermagnetosphereDamiano,P.A.,GeophysicalInstitute,UniversityofAlaskaFairbanksDelamere,P.A.andStauffer,B.H.

RecentobservationsoftheJunosatellitehaveillustratedalargelybroadbandenergizedelectronsignatureathighlatitudes(e.g.Mauketal.,2017;Allegrinietal.,2017).Intheterrestrialmagnetosphere,signaturesofthisnaturearegenerallyattributedtoelectronenergizationbydispersivescaleAlfvenwaves(Alfvenwaveswithperpendicularscalelengthsontheorderoftheelectroninertial,ionacousticoriongyroradiusscalelengths).IntheJupitercontext,AlfvenwaveenergygeneratedintheIointeraction,orfromtransportmechanismsinthemagneto-disc,probablyreachesthesekineticscalelengthsviaaturbulentcascade.Inthispresentation,weuseahybridgyrofluid-kineticelectronsimulationmodelinadipolartopology(Damianoetal.,2007;2015)toinvestigateelectronenergizationbythesewavesatJupiter.Specifically,weconsiderthepropagationofdispersivescaleAlfvenwaves,sourcedintheIoplasmatorus,tohighlatitudesandhighlighttheresultingenergizedelectronsignatures-whicharealsobroadbandinnature.Weadditionallyinvestigatehowthedetailsofthisenergizationvarieswiththesteepnessofthetorusdensitygradientandthemagnitudeoftheion-to-electrontemperatureratio.TransientConfigurationsofSaturn’sDaysideHighLatitudeMagneticFieldDavies,E.H.,ImperialCollegeLondonMasters,A.;Hunt,G.J.;Sergis,N.;Dougherty,M.K.

AnoverviewoftheazimuthalstructureofSaturn’sdaysidemagneticfieldathighlatitudesispresented.DatafromtheentireCassiniMissionareusedtoillustratetheconfigurationofthefieldbeyondtheco-rotationlimit.Variabilityofthisconfigurationinbothspaceandtimeisdiscussed.TheconfigurationisshowntovarywithSaturnlocaltime,withdeviationofmagneticfieldfrommeridionalplanegreatesttowardstheduskanddawn.Inbothcases,thefieldisshowntosweeptowardsthetail,asweptbackconfigurationatdawnandasweptforwardconfigurationatdusk.Nosignificantvariationisfoundoverthedurationofthemission.Twocasestudiesarepresented,inthepre-duskandpost-dawnsectorsrespectively.Thefieldconfigurationisshowntoexhibittransientbehaviourinbothcases,withseveralexamplesofasuddensweepforwardshown.Atduskitissuggestedthatthesetransienteventsmayresultfromcompressionofthemagnetospherefollowingshocksinthesolarwind,usingdatafromtheMichiganSolarWindModel.Atdawnthesesignaturesareattributedtoreturnflowplasmafromtailreconnection,usingmagneticfieldandplasmadata.

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EntropyconstraintsonradialtransportinthegiantplanetmagnetospheresDelamere,P.,UniversityofAlaskaFairbanksX.Ma,B.Neupane,andB.Burkholder

Radialtransportinthegiantplanetmagnetodiscsisatwo-wayprocessthatresultsinnetmassoutflow.Itisgenerallyacceptedthatanegativeradialgradientinfluxtubemasscontentleadstoacentrifugally-drivenfluxtubeinterchangeinstability.However,thephysicaltransportmechanismscannotbeunderstoodwithoutconsideringmagneticfluxandinternalenergy(i.e.,entropy)transport.Magneticfluxmustbebalancedandapositivefluxtubeentropyprofilemustbemaintainedtoensurelong-termconvectivestability(justasaninvertedatmospherictemperatureprofileisconvectivelystable).Usingthermalplasmamoments[Thomsenetal.,2010],weexaminelocal(specific)andfluxtubeintegratedentropy,incombinationwitha2-Daxisymmetricmagnetodiscequilibriummodel[i.e.,Caudal,1986]toconstrainradialtransportprocesses.InidealMHD,specificandfluxtubeentropyareconservedquantities.Variationsindicate,forexample,non-adiabaticheatingand/orchangesinfluxtubeentropycontentviamagneticreconnection.AtSaturn,wefindthatspecificentropyincreasesfrom4Rstoroughly20Rs(whereRs=Saturn’sradius),suggestingnon-adiabaticheating.Beyond20Rsthemeanprofileisconstant,indicatingthatthetransportmechanismsmaybefundamentallydifferent.The2-Dmodelconfirmstheexpectedpositiveradialfluxtubeentropygradientnecessaryforstability.However,iffluxtubeinterchangemotioninvolvestheentirefluxtube(equipotentialmagneticfieldlines),thenentropywillbetransportedradiallyinward.Fromtheperspectiveoflong-termstabilitythiscannothappen.Insteadwesuggestthattransportlikelyinvolvespartialfluxtubeinterchangethroughadoublereconnectionprocess(non-equipotentialmagneticfieldlines)firstsuggestedbyMaetal.,[2016]fortheRayleigh-Taylor(RT)instability.Resultsfrom3-DRThybridsimulationswillalsobepresented.AtmosphericlossatIo,Europa;massloadingandioncyclotronwavesproductionDols,V.,LASPCUBoulderBagenal,F.;Crary.F

AtIoandEuropa,theinteractionoftheJovianplasmawiththemoonatmosphereleadstomassloadingofnewionsandsignificantlossesofneutralstospace.

Dependingontheirvelocity,someneutralswillbeejectedoutoftheJoviansystem;otherswillformextendedneutralcloudsalongtheorbitofthemoons.TheseextendedneutralcloudsareprobablythemainsourceofplasmafortheJovianmagnetosphere.Theyaredifficulttoobservedirectlythustheircompositionanddensityarestillpoorlyconstrained.Afuturemodelingoftheformationoftheseextendedcloudsrequiresanestimateoftheiratmosphericsources.

WeestimatetheatmosphericlossesatIoandEuropaforeachlossprocess(dissociationandcollisions)withamulti-specieschemistrymodel,usingaprescribedatmosphericdistributionconsistentwiththeobservations.

Wealsoestimatetheproductionofnewmolecularions(massloading),whicharepickedupbytheflowinaring-beamdistribution.ThisdistributionisthesourceofElectroMagneticIonCyclotron(EMIC)waves,whichhavebeendetectedclosetoIoandEuropabytheGalileospacecraft.ThisproductionrateisimplementedinaplasmahybridcodethatsimulatestheproductionofEMICwavealongflowlinesinteractingwiththemoon’sneutralatmosphere.

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Jupiter’sX-rayAuroraSpectra2016-2017Dunn,W.R.,UniversityCollegeLondonBranduardi-Raymont,G.;Ness,J-U.;Ray,L.C.;Gladstone,G.R.;Jackman,C.M.;Achilleos,N.;Gray,R.;Elsner,R.F.;Rae,I.J.;Yao,Z.;Grodent,D.;Bonfond,B.;Nichols,J.;Kraft,R.P.;Ford,P.G.;Rodriguez,P.

PolewardofJupiter’smainauroralemission,therearediversedynamicmulti-wavebandaurorae.ThemostenergeticphotonsobservedfromthisregionareX-rays.MostoftheseX-raysareproducedwhenhigh-energy(~10sMeV)ionscollidewithJupiter’satmosphere[Gladstoneetal.2002;Elsneretal.2005;Branduardi-Raymontetal.2007;2008].TheseX-rayemissionstypicallypulseandchangemorphology,intensityandprecipitatingparticlepopulationsfromobservationtoobservationandpoletopole[Kimuraetal.2016;Dunnetal.2016;2017;Jackmanetal.,inreview].Theaccelerationprocess/esthatallowJupitertoproduceX-raysremaintobeconfirmed,butprobablyinvolveacombinationofoutermagnetosphereprocessesandlocalaccelerationatthepole[Cravensetal.2003;Bunceetal.2004;Clarketal.2017;Paranicasetal.2018].Wepresentanoverviewof~100hoursofXMM-NewtonobservationsofJupiterfrom2016-17andfocusona40-hourcontinuousobservationfromJuly10-12th2017,duringJunoPJ7.Atthistime,weobservesignificantchangesintheX-rayaurorafromJupiterrotationtorotation.Amongstthesechanges,weobservetime-varyingauroralpulsationrates,whichchangefromanon-regularintervaltoregular10-13-min(40-45-min)Northern(Southern)auroralpulses.Wealsoobservetime-varyingaccelerations,withatransientpossiblesulphurXVlinesuggestingthattheionsmaysometimesprecipitatewithenergiesinexcessof64MeV[Kharchenkoetal.2008].Alongsidearangeofauroralsulphurandoxygenlinesthathavepreviouslybeenobserved[Elsneretal.2005;Branduardi-Raymontetal.2007;Dunnetal.2016],wealsofindspectrallinesthatarenotcataloguedasoxygenorsulphurlines,butareatknownwavelengthsforcarbonand/ornitrogenandmagnesium,suggestingthatthespeciesandabundancesoftheprecipitatingionpopulationsmaychangewithtimeand/orspace.Wefinishbytryingtoplacetheseresultsinthecontextofotherwavebandsandtheirpossiblephysicaldrivers.

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Jupiter'sX-rayAuroraDuringSolarMinimumDunn,W.R.,UniversityCollegeLondonW.R.Dunn,Branduardi-Raymont,G.;Elsner,R.;Gray,R.;FordP.;Gladstone,G.R.;Ray,L.;Jackman,C.;Achilleos,N.;Guio,P.;Nichols,J.;Ebert,R.;McComas,D.;Elliott,H.;Rae,I.J.;YaoZ.;Badman,S.;Kraft,R.

Jupiter’sNorthernandSouthernX-rayauroraeareeachdominatedbyaflaringpolarspot[Gladstoneetal.2002;Elsneretal.2005;Branduardi-Raymontetal.2004;2007a;Dunnetal.2016;2017].X-rayemissionlinespectrashowthatthesehotspotsareproducedbytheprecipitationofhigh-energy(~MeV/amu)ions.SlightlyequatorwardofeachhotspotthereisatransientauroralovalofhardX-raysthatareproducedwhenthoseprecipitatingelectronsthatalsogeneratetheUVmainemissionhavesufficientenergytoemitX-raybremsstrahlung(typicallywhentheyarerelativistic)[Branduardi-Raymontetal.2008].Thesolarminimumfrom2007-2009isthedeepestandlongestofthespaceage.Here,wepresentX-rayobservationsofJupiterduringFebruaryandMarch2007,whentheNewHorizonsspacecraftwasapproachingtheplanetandconductingin-situobservationsofthesolarwind.WefindthattheX-rayemissionfromJupiter'sequatorialregionsisexceptionallydimrelativetonon-solarminimumX-rayobservations.Thisisexpected,sincethelowsolarX-rayfluxwouldproducelowerlevelsofscatteredorfluorescedX-rays[e.g.Branduardi-Raymontetal.2007b].WealsofindthatduringthistimetheX-rayauroraisgenerallyverydim,butbrightens/dimsbyafactorof2fromobservation-to-observation.Duringthese6Chandraobservationsand4XMM-Newtonobservations,NewHorizonsmeasuredmultipleapproachesbytwoCorotatingInteractionRegions.Here,wecomparetheX-rayobservationswithboththeupstreamsolarwindmeasurementsfromNewHorizonsandthecontemporaneousHubbleSpaceTelescopeUVobservations[Nicholsetal.2009].Wefindcertainauroralemissionsappeartobetriggeredbysolarwindcompressionswhileothersseemindependent.WealsoconnectpulsatingUVpolaraurorawithsimilarX-rayemissions.

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ComparingElectronEnergeticsandUVBrightnessinJupiter'sPolarAuroralRegionEbert,R.W.,SouthwestResearchInstituteGreathouse,T.K.,Clark,G.,Allegrini,F.,Bagenal,F.,Bolton,S.J.,Gladstone,G.R.,Hue,V.,Levin,S.,Louarn,P.,Mauk,B.H.,McComas,D.J.,Paranicas,C.,Szalay,J.R.,Thomsen,M.F.,andWilson,R.J.

Todate,studiesofelectronobservationsfromJunoinJupiter’spolarauroralregion,theregionpolewardofJupiter’smainaurora,haveidentifiedmagneticfieldalignedelectronbeamsmovingawayfromtheplanet(upward)withnarrowenergydistributionsandmono-energeticpeaksbetween20keVand400keV[Ebertetal.,2017;Clarketal.2017],upwardelectronbeamswithMeVenergies[Mauketal.2017;Beckeretal.2017;Paranicasetal.2018]andbi-directional(upwardanddownward)electronbeamswithbroadenergydistributionsthatroll-overbetween~2–5keVandhaveapowerlawtailthatextenduptoatleast~100keV[Ebertetal.2017].Thedownwardbeamsassociatedwiththesebroadinenergyelectrondistributionsappeartorelatetoaprimarysourceofprecipitatingelectronsinthepolarauroralregion.PreliminaryanalysisbyEbertetal.2017showedthattheenergyfluxassociatedwiththesedownwardbeamsrangedfrom~0.1–5mWm-2,whichisexpectedtoproducebetween1–50kilorayleighs(kR)ofUVemissions.Thequestionofwhetherthesebeamscouldproducethebrighter(100sofkR)UVemissionsobservedinJupiter’spolarauroralregionremainsunanswered.Inanattempttoaddressthis,wepresentaquantitativecomparisonbetweentheelectronenergyfluxandtheUVbrightnessobservedneartheJunomagneticfootprintinJupiter’snorthernpolarauroralregionpriortoperijove5.WeuseobservationsfromtheJovianAuroralDistributionsExperimentElectronsensor(JADE-E;McComasetal.2017,JupiterEnergeticparticleDetectorInstrument(JEDI;Mauketal.2017)investigationandtheUltravioletSpectrograph(UVS;Gladstoneetal.2017)onJuno.WealsopresentastatisticalanalysisoftheenergyfluxassociatedwiththesebroadinenergydistributionsofdownwardelectronstoestimatetherangeinUVbrightnesstheyareexpectedtoproduce.

JUMPER:JUpiterMagnetosPhericboundaryExploreREbert,R.W.,SouthwestResearchInstituteAllegrini,F.,Bagenal,F.,Beebe,C.,Dayeh,M.A.,Desai,M.I.,George,D.,Hanley,J.,Mokashi,P.,Murphy,N.,Valek,P.W.,Wenkert,D.,Wolf,A.,andYen,C.-w.L.

TheSouthwestResearchInstitute(SwRI),incollaborationwithNASA’sJetPropulsionLaboratory(JPL)andtheUniversityofColorado’sLaboratoryforAtmosphericandSpacePhysics(CU/LASP),hasdevelopedtheJUpiterMagnetosPhericboundaryExploreR,orJUMPER,missionconcept.JUMPER’sscienceobjectivesfocuson(1)howthesolarwindinfluencestheglobalstructureanddynamicswithinthemagnetosphereand(2)interactswithJupiter’smagnetosphericboundaries,and(3)determiningthecontributionofenergeticneutralatoms(ENAs)tomasslossfromtheJovianspaceenvironment.Thesescienceobjectivesaremetwithaninstrumentpayloadconsistingofaplasmasensor,amagnetometer,andaneutralatomimager.MeasurementsfromtheseinstrumentswillcomplementsimultaneousobservationsofJupiter’smagnetosphere,radioemissions,and/oraurorafromaJupiter-orbitingspacecraftand/orEarth-basedobservatories,providingsimultaneous,multi-pointobservationstostudythissystem.SupplementalscienceopportunitiesassociatedwithflybysofGalileansatellitesGanymedeandCallistoandmulti-pointobservationsinsideJupiter’smagnetospherearealsopossible.JUMPERwasselectedforfullmissionconceptdevelopmentthroughNASA’sPSDS3program.Thispresentationwilldiscussessomeofthedetailsofthismissionconceptstudy,focusingonJUMPER’sscienceinvestigation,scienceimplementationandinstrumentcomplement,missiondesign,spacecraftconcept,conceptofoperationsandtechnicalchallenges.

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Atwo-stepmechanismforacceleratingup-goingelectronsthroughoutJupiter’spolarcapregionviainteractionswithup-goingwhistler-modewavesElliott,S.S.,UniversityofIowaGurnett,D.A.,Kurth,W.S.,Mauk,B.H.,Valek,P.,Allegrini,F.,Connerney,J.E.P.,Bolton,S.J.

Electronsoverarangeofenergies(fromtensofkeVtoaboveoneMeVwithapproximatepowerlaw-likedistributions)havebeenobservedinassociationwithintenseup-goingwhistler-modewavesthroughouttheJovianpolarregions.Boththeelectronsandthewavesaretravelingupwardsandarestronglycorrelatedwithoneanother,indicativeofwave-particleinteraction.Theenergyfluxofthewhistler-modewavesiscomparabletotheenergyfluxoftheenergeticelectrons(upto0.24W/m^2inthepolarcap).Thissuggeststhatthewhistler-modewavesinteractwiththeelectrons,providingacandidateaccelerationmechanism.Weproposethatthismechanisminvolvesatwo-stepprocess.First,acurrent-drivenparallelelectricfieldiscreatedinregionsoflowdensityandconvergingmagneticfieldlines,wheretheplasmacannotcarrythedownwardcurrent,therebygeneratinganelectronbeam(i.e.aninverted-V).Thisbeamdrivesanelectron-beam-plasmainstability,generatinglarge-amplitudewhistler-modewavesoverabroadfrequencyrange.Second,thesewavesarethendampedastheymovetohigheraltitudes,acceleratingtheelectronsandleadingtoabroadrangeofelectronenergiesviaastochasticprocess.Byanalyzingabeamdistributionfunction,thegrowthrate(gamma)isshowntoswitchfrombeingpositive(wavegrowth)tonegative(wavedamping,electronacceleration)whenthephasevelocityofthewaveexceedstheelectronbeamvelocity.Wethereforeproposethatwavesaregeneratedatlowaltitudesandmovetohigheraltitudes,increasingtheirphasevelocityandexceedingthebeamvelocity,dampingthewavesandacceleratingtheelectrons.Saturn’sPlasmaDensityDepletionsAlongMagneticFieldLinesConnectedtotheMainRingsFarrell,W.M.,NASA/GoddardSFCHadid,L.Z.,Morooka,M.W.,Kurth,W.S.,Wahlund,J.-E.,MacDowall,R.J.,Sulaiman,A.H.,Persoon,A.M.,andGurnett,D.A.

WereportonasetofclearandabruptdecreasesinthehighfrequencyboundaryofwhistlermodeemissionsdetectedbyCassiniathighlatitudes(about+/-40o)duringthelowaltitudeproximalflybysofSaturn.TheseabruptdecreasesordropoutshavestartandstoplocationsthatcorrespondtoL-shellsattheedgesoftheAandBring.Langmuirprobemeasurementscanconfirm,insomecases,thattheabruptdecreaseinthehighfrequencywhistlermodeboundaryisassociatedwithacorrespondingabruptelectrondensitydropoutoverevacuatedfieldlinesconnectedtotheAandBrings.Widebanddataalsorevealelectronplasmaoscillationsandwhistlermodecutoffsconsistentwithalowdensityplasmaintheregion.Theobservationoftheelectrondensitydropoutalongring-connectingfieldlinessuggeststhatstrongambipolarforcesareoperating,drawingcoldionosphericionsoutwardtofillthefluxtubes.Thereisananalogwiththerefillingoffluxtubesintheterrestrialplasmasphere.Wesuggestthering-connectedelectrondensitydropoutsobservedbetween1.1and1.3RsareconnectedtothelowdensityringplasmacavityobservedovertoptheA-Bringduringthe2004Saturnorbitalinsertionpass.

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SKR:Arotatingradiosourcethatappearsclock-likeFischer,G.,AustrianAcademyofSciencesYe,S.-Y.

TheclassicalpictureofSaturnKilometricRadiation(SKR)fromtheVoyagereraisthatofaclock-likeradiosourcewhosephaseisindependentofthepositionoftheobserver.ThispicturehasbeenmodifiedintheCassiniera:Theexistenceofrotatingmagneticfieldperturbationsimpliestheexistenceoftworotatingcurrentsystems(oneforeachhemisphere),suggestingthatthesecurrentsystemsalsocauserotatingmodulationsinthenorthernandsouthernSKRemissions.RotatingSKRsourceshavebeenshowntoexist,butthedominanceoftheintenseSKRsourcesinthemidmorningsectorgivesrisetoaclock-likemodulationoveracertainlocaltimerangeoftheobservingspacecraft.ItisthisdominancethatmakesmostSKRappearclock-like.

Adistinctionbetweenclock-likemodulationandarotatingsourcecanbemadewhentheobservingspacecrafttraversesoveralargeregioninlocaltimewithinashorttime,i.e.duringperiapsispasses.InthispresentationwewilllookattheCassiniperiapsispasses(takingplaceatvariouslocaltimes)andplottheSKRintensityasafunctionofsub-solarlongitudeandasafunctionofsub-spacecraftlongitudetoseewhichkindoflongitudesystemorganizestheSKRdatainabetterway.

CombinedJunoobservationsandmodelingoftheJovianauroralelectroninteractionwiththeJovianupperatmosphereGérard,J.-C.,UniversitédeLiègeB.Bonfond,G.R.Gladstone,F.Allegrini,D.Grodent,T.K.Greathouse,V.Hue,M.H.Versteeg,S.Bolton,J.E.P.Connerney,S.M.Levin

TheJunomissionprovidesauniqueopportunityduringeachperijovepasstosamplethedownwardelectronfluxatspacecraftaltitudewhileobservingfarultravioletH2andinfraredH3

+emissionsatJuno’smagneticfootprint.Inaddition,theratiooftheH2spectralbandabsorbedbyhydrocarbonstotheunabsorbedportionofthespectrum(FUVcolorratio)isoftenusedasaproxyforthedepthofthepenetrationofenergeticelectrons(relativetothehydrocarbonhomopause).TherelationshipbetweenthecolorratioandtheelectronpenetrationhasbeensimulatedwithaMonteCarlomodelsolvingtheBoltzmanntransportequation.AnalysisofconcurrentFUVandIRimagesobtainedduringthefirstperijove(PJ1)suggeststhattheratioofH3

+radiancetoH2unabsorbedemissionismaximalinregionswithlowFUVcolorratio.ThisresultsuggeststhatpartoftheH3

+columnislostinreactionswithmethanewhichconvertsH3

+intoheavierions.WealsoexaminetheobservedrelationshipbetweenthedetailedmorphologyoftheultravioletstructuresandoftheassociatedUVcolorratio,thetotaldownwardelectronenergyfluxanditsspectralcharacteristics.

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Jupiter'sUltravioletAurorasGladstone,G.R.,SwRI

Ashortreviewoffar-ultraviolet(FUV,100-200nm)observationsandmodelsoftheJovianauroraispresented.AlthoughJupiter’sFUVaurorawasunambiguouslydiscoveredbytheultravioletspectrometer(UVS)onVoyager1in1979,sub-orbitalFUVrocketspectrahadhintedataurorasadecadeearlier.Detailedphysicalmodelsoftheexpectedemissionswerepresentedasearlyas1973.Sincethosetimesourobservationalandmodelingcapabilitieshavedevelopedremarkably,althoughourunderstandinglagsfarbehind.Aswithmostgreatimprovementsindata,therecentastonishingobservationsbyJunohelpsolveafewlongstandingproblemswhilepresentingseveralnewones.AUranus-likemagnetosphereinamagnetizedSolarWind:solsticeandequinoxconfigurationsGriton,L.,LESIA-ObservatoiredeParisPantellini,F.

WepresentMHDsimulationsofafastrotatingplanetarymagnetospherereminiscentoftheplanetUranusatsolstice,i.e.withthespinaxispointingtotheSun,andatequinox.WeimposeatentimesfasterrotationthanforUranus,inordertoemphasizetheeffectsofrotationonthemagnetospherictailwithouttheneedofanexcessivelylargesimulationdomainwhilekeepingthequalitativeaspectsofasupersonicmagnetizedsolarwindinteractingwithafastrotatingmagnetosphere.WefindthatacomplexhelicalAlfvénicstructurepropagatesdownstreamatavelocityexceedingtheplasmavelocityinthemagnetosheath.Similarly,thereconnectionregions,whichmediatetheinteractionoftheplanetarymagneticfieldandtheinterplanetarymagneticfield(IMF),doalsoformahelicalstructurewiththesamedowntailvelocitybutatwotimeslargerpitch.WespeculatethatthemagneticfieldofthehelicalstructureconnectedtotheIMFasymptoticallyreducethephasevelocityofthehelicalstructuretowardsthetailwardplasmavelocityinthemagnetosheath.WecompareoursimulationresultswithpreviousstudiesofUranus'magnetosphere,bothforthesolsticeandequinoxconfigurations.

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Jupiter’smesmerizingauroralshow;HSTultravioletobservationsnearandfarfromJunoperijovesGrodent,D.,UniversitédeLiège,STARInstitute,LPAPYao,Z.,Bonfond,B.,Palmaerts,B.,Dumont,M.,Gérard,J.C.,Radioti,A.,Gladstone,G.R.,Mauk,B.,Connerney,J.E.P.,Nichols,J.D.,Bunce,E.J.,Roth,L.,Saur,J.,Kimura,T.,OrtonG.S.,Badman,S.V.,McComas,D.,Kurth,S.K.,Adriani,A.,Valek,P.W.,Delamere,P.,Bagenal,F.

Aftera6-monthperiodduringwhichtheseparationanglebetweentheSunandJupiterwastoosmalltopermitobservationswithEarthorbittelescopes,operationoftheHubbleSpaceTelescope,supportingtheJunomission,wasresumed(almost)intimeforPJ11.WebrieflyreviewthemainresultsofthepreviouspartofthisHSTcampaign,coveringPJ03toPJ07.WethenpresentthenewestresultsobtainedduringPJ11,PJ12andPJ13.MostoftheobservingtimeallocatedtothisHSTcampaignwasusedduringthefirstpartofthecampaignandallowedustosampleJupiter’saurora,notonlynearJuno’sperijoves,butalsoduringtheweekbeforeandtheweekaftereachperijove.Duringthesetimesawayfromperijove,HST-STISwasthesoleinstrumentabletoprovidehighspatialandhightemporalresolutiondynamicimagesofJupiter’sFUVaurora,whichcanbecomparedwithmeasurementsfromJuno’sinsituinstruments.Insteadofpresentingastatisticaloverviewofthedata,wehaveamoredetailedlookatsomespecificfeaturesrevealedbytheasyetunsurpassedSTIScamera.Inparticular,weidentifydistinctiveauroralphenomena,likeexplosivebrighteningspolewardofthemainauroralemission.Wepresentonesuchevent,whichwelinktoastrongperturbationofthemagneticfieldandoftheenergydistributionoftheplasmaparticlesconcurrentlyobservedwithJuno.Wesuggestthatthecharacteristicsandthetimingofthisperturbationandofitsassociatedauroralsignatureareconsistentwithareconnectionevent.

EffectsoftheSizeScaleontheDynamicsofTrappedChargedParticlesinGasGiantMagnetospheresGuio,P.,PhysicsandAstronomy/UCL/UnitedKingdomAchilleos,N.andArridge,C.

Thespatialandtimecharacteristicsoftrappedchargedparticletrajectoriesinmagnetosphereshavebeenextensivelystudiedusingdipolemagneticfieldstructures.Werecentlyextendedthesecalculationsforchargedparticletrappedina'disc-like'fieldstructureassociatedwiththegasgiantrotation-dominatedmagnetosphereasdescribedbytheUCL/Achilleos-Guio-Arridge(UCL/AGA)magnetodiscmodel.

Inthisstudy,wepresentcalculationsforappropriaterangeofsizescalesforobservedgiantplanetmagnetospheres,characterisedprimarilybythedistanceofthemagnetopauseboundarytotheplanet,or`standoffdistance'ausefulproxyfortheoverallsystemsize.Wediscusstheeffectsofthesizescaleofthemagnetosphereonvariousparticleparameters,andcomparewithotherfieldmodelsforsuchmagnetodiscdominatedmagnetospheres.

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Saturn’sionosphere:ElectrondensityaltitudeprofilesandringshadowingeffectsfromtheCassiniGrandFinaleHadid,L.Z.,SwedishInstituteofSpacePhysics,Box537,SE-75121Uppsala,SwedenMorooka,M.W.,Wahlund,J.E.,PersoonA.M.,Andrews,D.J.,Shebanits,O.,Kurth,W.S.,Edberg,N.J.T.,Vigren,E.,NagyA.F.,Moore,L.,Cravens,T.E.,Hedman,M.M.,Farrell,W.M.,Eriksson,A.I.

WepresenttheelectrondensityaltitudeprofilesofSaturn’sionosphereatequatoriallatitudes(−15o≤φ≤15o)andtheringshadowingeffectsfromallthe23proximalpassesofCassini’sGrandFinale.ThedataarecollectedbytheLangmuirprobe(LP)andforsomecasesfromtheplasmawavefrequencycharacteristicsoftheRadioandPlasmaWaveScience(RPWS)investigation.Ahighdegreeofvariabilityintheelectrondensityprofilesisobserved.However,organizingthembyconsecutivealtituderangesrevealedcleardifferencesbetweenthesouthern(winter)andnorthern(summer)hemispheres.WeshowalayeredelectrondensityaltitudeprofilewithevidenceinthesouthernhemisphereofanelectrodynamictypeofinteractionwiththeplanetsinnermostDring.SimilarlayerswereobservedduringtheFinalPlungeofCassini,wherethemainionosphericpeakiscrossedat~1550kmaltitude[Hadidetal.submitted,2018a].

Moreover,fromtheringshadowsignaturesonthetotalioncurrentcollectedbytheLP,wereproducetheAandBringboundariesandconfirmthattheyareopticallythickerthantheinnerCandDringsandtheCassiniDivisiontothesolarextremeultravioletradiation.Furthermore,observedvariationswithrespecttotheinneredgeoftheBringshadowimplyadelayedresponseoftheionosphericH+becauseofitslonglifetimeand/orsuggestthepresenceofring-derivedplasmafromtheCandDringsreducingtheshadowingsignatures[Hadidetal.submitted,2018b].ChargedparticleinjectionsathighJovianlatitudesHaggerty,D.K.,JohnsHopkinsUniversityAppliedPhysicsLabB.H.Mauk,C.Paranicas.Clark,P.Kollmann,A.Rymer,S.Bolton,J.E.P.Connerney,S.Levin

ChargedparticleinjectionsarecommonlyobservedinJupiter'smagnetosphere.LowenergyparticlesarecarriedinwardtowardJupiter,whilemoreenergeticparticlescandriftlongitudinallyoutoftheinjecteddistribution.Iondriftinthesamedirectionasplasmacorotationandelectronsdriftintheoppositedirection.Becauseofthegradient-curvaturedrift,aspacecraftmeasuringthesedistributionswilloftenseeavelocitydispersiveeventwithhigherenergyionsfirst,followedbylowerenergyions,thenlowerenergyelectrons,andfinallyhigherenergyelectrons.TheJunospacecraftprovidesauniqueopportunityasthefirstpolarorbiterofJupitertostudyinjectioneventsfromhighlatitude.WhileinjectionshavebeenobservedinmultipleplacesalongtheJunoorbit,thestrongestandbestresolvedregionofinjectionsisinthenorthernradiationbeltpriortothenorthpolarpass.Inthisreportwedescribetheobservations,showhowtheyevolveasafunctionofdecreasingradialdistance,andreportonasimplemodeltodescribetheevents.

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ThesignificanceofSaturnring-iceinCassiniproximalobservations.Hamil,O.Q.,UniversityofKansasCravens,T.E.,Sakai,S.,Reedy,N.L.

TheringsofSaturncancontributebothmaterial(i.e.water),andenergytoitsupperatmosphereandionosphere.Ionosphericmodelsrequirethepresenceofmolecularspeciessuchaswaterthatcanchemicallyremoveionosphericprotons,whichareotherwiseassociatedwithelectrondensitiesthatgreatlyexceedthosefromobservation.Thesemodelsadopttopsidefluxesofwatermolecules.OthermodelshaveshownthaticegrainsfromSaturn'sringscanimpacttheatmosphere.Inthecurrentwork,weexaminethemechanicsofwaterandenergydepositiontotheupperatmosphere.Specifically,wemodelhowicegrainsdepositbothmaterialandenergyinSaturn'supperatmosphereasafunctionofgrainsize,initialvelocity(atthe"top"oftheatmosphere,definedatanaltitudeabovethecloud-topsof3000km),andincidentangle.Typicalgrainspeedsareexpectedtoberoughly10-20km/s.Grainswithradiiontheorderof1-10nmdepositmostoftheirenergyinthealtituderangeof1200-1500km,andcanvaporize,contributingwatervaportotheupperatmosphere.

DatafromCassiniindicatethepresenceoficegrainsontheorderof40,000amu.Grainsofthissizedonotablateinourmodel,butweexploretheirenergydepositionandterminalvelocityasafunctionofgraindensitiesspanningarangerepresentativeoftightlypackedsphericalgrains,downtolooselyconfinedsnowflaketypeobjects.Further,wemodelvolatileorganicgrains,representedherebymethane/CO2,todeterminetheinitialgrainparametersrequiredtoaccountforobservationsofthesespeciesintheupperatmosphere.Towardsaself-regulatingmagnetopausemodelwithapplicationtoSaturnHardy,F.,UniversityCollegeLondonAchilleos,N.,Guio,P.

Wereportworkinprogressontheconstructionofanumericalmodelforamagnetopauseboundaryusingthelocalpressurebalancebetweenthesolar-winddynamicpressureandthemagneticpressureduetotheplanetaryfield.WewillapplythismethodtoSaturninordertoillustratethefollowingpoints:

-awell-posedformulationoftheproblemcanbeusedtosolvethepressurebalanceinthenoon-midnightmeridianplane.Thisapproachshedslightonthenatureofthecharacteristicpolarcusp;itspositioncanbefoundaccuratelyandisconsistentwithMeadandBeard’s(1964)numericalresults.

-discretisationtechniquescoupledwithaNewton-Raphsonmethodcanbeusedtomapanon-axisymmetricsurfaceonwhichthemaximumerrorfromexactforcebalanceliesaround5percent.

-theintroductionofinternalplasmapressure‘regularises’theproblemandleadstoamagnetopausesurfacewithlocalresidualsnogreaterthanafewpercent.

WewillalsodiscussthefutureprospectsofthisstudyanditspotentialapplicationstotheconstructionofacomprehensivemodelforSaturn’smagnetopause.

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QuantifyingtheaccessofJupiter’smagnetosphericplasmatoEuropa’ssurfacethroughamulti-fluidMHDmodelHarris,C.D.K.,UniversityofMichiganJia,X.;Slavin,J.A.;Toth,G.;Rubin,M.

Europa’sspaceenvironmentiscontrolledbythewobblingofJupiter’smagneticfield,themagneticresponsetothiswobblinginducedintheconductingsubsurfaceocean,andtheinteractionofJupiter’smagnetospherewithEuropa’sionosphereandextendedexosphere.Wehavedevelopedamulti-fluidMHDmodelforEuropa’splasmainteractionwhichself-consistentlysolvesforthebulkpropertiesof3ionfluids(magnetosphericO+andionosphericO+,O2

+)andtheelectromagneticfieldsinthevicinityofthemoon.Tovalidateourmodel,wehavesimulatedtheGalileoE4andE17Flybysusingtheobservedplasmaandmagneticfieldconditions.OurmodelhasreproducedGalileomagnetometerobservationsandprovidesfull3Ddensityandvelocityfieldsfortheionfluidsduringeachflyby.Basedonthethree-ion-fluidMHDmodel,wehavemappedthedistributionofthemagnetosphericplasmathatwasabletopenetratetheplasmainteractiontoreachEuropa’ssurface.Wefindthatwhilethemajorityofdownwardfluximpingesontheupstreamhemisphere,thesurfaceimpactbytheambientmagnetosphericO+ionsexhibitsaslightpreferencetowardstheanti-jovianhemisphereduetotheinfluenceoftheconvectionalelectricfield.UndertheE4flybyconditions,justafractionoftheavailableupstreamO+ionsprecipitatetoEuropa’ssurface.Mostoftheambientplasmaisinsteaddivertedaroundthemoonduetotheplasmainteractionwiththeionosphere.ThisprecipitationrepresentsthecontributionofthermalplasmatothesputteringinteractionwithEuropa’sicysurfacewhichreplenishestheO2exosphere.CassiniUVISdetectsenergeticelectronsanddustintheSaturnsystemHendrix,AmandaR.,PlanetaryScienceInstituteEsposito,L.W.,Brooks,S.,Hansen,C.J.,Colwell,J.E.,Pryor,W.,McClintock,W.E.,Holsclaw,G.M.,Roussos,E.,Paranicas,C.,Kollmann,P.,Ye,S.

ThroughouttheCassinitouroftheSaturnsystem(2004-2017),theUltravioletImagingSpectrograph(UVIS)observationsoftheplanet,ringsandmoonswereaffectedtovaryingdegreesby“background”signal(noise)inboththeEUVandFUVchannels.Thisnoisewasgenerallysubtractedoffinordertostudythetargetsofprimaryinterest.Now,weinvestigatethisbackgroundandutilizeittounderstandmagnetosphericaspectsoftheSaturnsystem.Weassessthebackgroundnoiseanditsvariationsthroughoutthetour:wecomparewithheightabovetheringplane,withdistancefromSaturn,andwithtimeofdaytounderstandthesourcesofthenoise.WefindthatthemostdominanttrendisbackgroundlevelwithdistancefromSaturn:withinSaturn’sintenseradiationbelts,between~5-6Rsand~2.7-2.8RsUVISobservesanincreaseinbackgroundwithdecreasingRs;closetothemainrings,inwardof~2.7Rsthebackgrounddrops.ThistrendisconsistentwithMIMIobservationsofenergeticparticlesintheradiationbeltsandappearstobemoreconsistentwithMeVelectronsthanprotons.EvenforradiationinstrumentslikeMIMIitcanbechallengingtodisentanglethecontributionfromdifferentspeciesandenergiestoinstrumentcountrates.AddinginformationfromtheUVISbackgroundsthereforemayhelptounderstandtheaveragestateandtimeevolutionofSaturn’selectronradiationbelt.Insomeconfigurations,dustalsocontributestotheUVISbackground,superimposedontheelectronsignatures,asindicatedbycomparisonswithRPWSdata,sensitiveto~1microndustgrains.WeconcludethatMeVelectronspenetratethewallsoftheUVISinstrument,andthatdustenterstheinstrumentapertureinsomegeometries,impingingonthedetectorandcreatingaphoton-likesignal.TheUVISthusprovides,inadditiontotheinsituinstrumentsonCassini,afurthermeasurementofenergeticelectronsanddustintheSaturnsystem.

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InvestigatingDeflectionofJovianBulkPlasmabyEuropa’sIonosphereusingGalileoPlasmaDataHeuer,S.V.,JohnsHopkinsAppliedPhysicsLaboratoryRymer,A.M.,Westlake,J.H

ElectrodynamicinteractionsbetweenEuropa’sionosphereandJupiter’sco-rotatingplasmadecelerateanddeflectthebulkplasma,whichsubsequentlyacceleratesinthewakeofthemoon[Sauretal.,1998].ThedeflectionhasbeenmeasuredinsitubytheGalileoPlasmaScienceInstrument(PLS)[Patersonetal.,1999].WehaveproducedGalileoPLSionsensorenergyspectrogramsforallEuropaflybys(includingseveralpreviouslyunpublished)fromthefullresolutionplasmadatavolumeavailableonPDS.OuranalysishasrevealedsubstantialdeflectionofthebulkplasmawhichcouldpotentiallybeusedtoimprovebestestimatesforconstraintsoncertainpropertiesofEuropa’sexosphereandimproveinputstoMHDsimulationsofEuropa’sinteractionwiththeJovianmagnetosphereandplasmatorus.RadioJoveCitizenSciencePartnershipsHiggins,C.,MiddleTennesseeStateUniversityFung,S.,Thieman,J.,Garcia.L.

TheRadioJoveProject(radiojove.gsfc.nasa.gov)hasbeenoperatingasaneducationalactivityfor20yearstopromoteradioastronomytostudents,teachers,andthegeneralpublic.RadioJovehasrecentlypartneredwiththeNASASpaceScienceEducationConsortium(NSSEC)toworkwithinterestedamateursandpartnerinstitutionstoestablishradiospectrograph(15-30MHz)andsingle-frequency(20MHz)stationsforcitizenexplorationandscienceprojects.Thesestationswillhelpbuildalargeramateurradiosciencenetworkandincreasethespatialcoverageoflong-wavelengthradioobservationsacrosstheUS.

WewilloverviewthepartnershipsanddisplaycitizenobservationsofJupiterdecameteremission,theAugust2017solareclipse,ionosphericscintillationoftheCas-Aradiosource,andinterestingterrestriallightningevents.Inmanycasestheseobservationscompareverywellwithprofessionalradioobservatories.RadioJovealsosupportstheJunoMissionradiowavesinstrumentatJupiterbyusingcitizenscienceground-baseddataforcomparison.ThesedataarebeingarchivedatthePlanetaryDataSystem(PDS)archiveandthroughtheVirtualEuropeanSolarandPlanetaryAccess(VESPA)archiveforusebytheamateurandprofessionalradiosciencecommunity.

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LWA1ObservationsofJupiter’sLeft-HandPolarizedDecametricEmissionHiggins,C.,MiddleTennesseeStateUniversityClarke,T.E.,Imai,K.,Imai,M.,Reyes,F.,Thieman,J.

TheLongWavelengthArrayStation1(LWA1)inSocorro,NM,USA,providesfullStokesparametersand5kHzspectraland0.21mstemporalresolutionofJupiter’sdecametricradioemissionsoverthebandwidthof10-40MHz.LWA1observationsofJupiterfrom2012-2016wereusedtoshownewdetailsregardingJupiter’semissionstructure(Clarkeetal.,2014,2017),modulationlanestructures(K.Imaietal.,2017),and,inpart,thebeamconethickness(M.Imaietal.,2016).

JupiterhasmanyIo-relateddecameterradioemissionsources,andaccordingtotheoreticalmodels,thewell-knownsourcesIo-AandIo-Bemitfromthenorthernhemispherewithright-hand(RH)circularlypolarizedsignatures,andIo-CandIo-Demitfromthesouthernhemispherewithleft-hand(LH)polarization.InadditiontotheotherLWA1results,Higginsetal.(PRE8Proceedings,2017)showedthattheIo-Dradiosourcehassomepreviouslyunknownmorphologyandfinespectralstructures.RecentstudiesoftheIo-CsourceshowsimilarandinterestingLHspectralsignaturessuchasS-bursts,narrowbandN-events,S-Neventinteractions,andspectralarcsplitting.WehighlighttheIo-CobservationsandcomparethemwithIo-DeventstobetterunderstandmagneticinteractionsintheJoviansouthernhemisphere.VariationincompositionandtemperatureofplasmasintheIoplasmatorusconfirmedbytheHisaki/EXCEEDobservationHikida,R.,UniversityofTokyoYoshioka,K.,Murakami,G.,Kimura,T.,Tsuchiya,F.,andYoshikawa,I.

Previousobservations,conductedbyground-basedtelescopesandspacecraftsuchasVoyagerandCassini,haveshownthatcomposition,temperature,anddensityofthecoreplasmasintheIoplasmatorus(IPT)varyinaccordancewiththesurroundingenvironment,suchasvolcanicactivityonIoandmagnetosphericcondition.However,thetimevariationindensityofhotelectrons(~100eV)hasnotbeeninvestigated,althoughtheyplayanimportantroleinenergybudgetoftheIPT.Thisstudyprovidesthefluctuationofhotelectroncomponent.WeappliedthespectraldiagnosismethodtotheEUVspectraobtainedbyEXCEEDonHisakisatellite.ThedatasetfromJan.2014toApr.2014,fromNov.2014toMay.2015,andfromDec.2015toAug.2016wereused.Thefollowingtworesultswereobtained.First,theincreaseinhotelectrondensityinaccordancewiththeincreaseinvolcanicactivitywasconfirmed.WhileHisaki/EXCEEDobservedtheIPT,severalexplosionsofvolcanoesoccurredin2015and2016.TheincreaseinhotelectrondensityisconsistentwiththeactivationofinterchangemotionswhichcanbeassociatedwiththeincreaseingassupplyamounttotheIPT.Second,wefoundthatsometransientbrighteningsoftheIPTwhichfollowtheauroralbrightenings wereduetotheincreaseinhotelectrondensity.ThisresultindicatestheexistenceoftheinwardflowofhotelectronstowardtheIPTfromthedistantregion(magneticallyconnectedtothepolarregion).

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A4DModeloftheIoPlasmaTorusHinton,P.,UniversityofColoradoBagenal,F.

Jupiter’smoonIovolcanicallyoutgassesroughly1000kg/sofneutralatomsthat,throughvariousionizationmechanisms,endupasplasmainJupiter’smagnetosphere.Thisplasmathenbecomesdistributedalongmagneticfieldlinesandassumesanoveralltoroidalstructure.WeuseadiffusiveequilibriummodeltoquantifythestructureoftheIoplasmatorus(IPT).ThedifferentsectionsoftheIPTincludethecoldinnertorus(disk),aportionbetweenthediskandtheorbitofIo(ductorsometimescalledtheribbon),andtheremainingwarmeroutertorus(donut).Thediskexistsfromapproximately4-5.6RJ,theductexistsfrom5.6-6RJ,andthedonutportionextendsfrom6-10RJ,whereRJistheradiusofJupiter(1RJequals71,492km).Inadditiontogeneratingamodelthatcapturesthesedimensions,ourmodelalsoaccountsforlocaltimevariation,mostlyincomposition,observedbyCassini.This4Dmodelincludesvariousparametersthatcanbeadjustedinordertogainfurtherinsightintotheplasmatorus.Suchparametersincludeionandelectrontemperatures,densities,anddistributions,aswellasJupiter’smagneticfield.UsingthismodelwecalculatehowfastAlfvenwavestravelthroughtheIPT.WemakepredictionsaboutthelocationoftheIoauroralfootprint(IFT)whichwillultimatelybecomparedwithJuno’sobservations.Additionally,wecalculateandanalyzetheAlfvenpowergeneratedbyIoasitorbitsinJupiter’smagneticfield.

ChargedDustDynamicsatJupiterandSaturnHoranyi,Mihaly,LASPandPhysics,U.ofColorado

Themotionofchargeddustparticlescanbestronglyinfluencedbymagnetosphericelectricandmagneticfields.ThereareseveralobservationsbothatJupiterandSaturnthatcanbebestexplainedbyrecognizingthisstronginteractionbetweenmagnetosphericfieldsandplasmas,andfaintdustrings.ThistalkwillfocusonrecentobservationsbyJuno,asitrepeatedlycrossedJupiter’sringplane,theCassini’sobservationsofthevariousmoonsembeddedintheE-ringofSaturn,andconcludewithpredictionsforthedustobservationsbytheupcomingClippermissiontoJupiter.

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JunoObservationsofPlasmaWavesAssociatedwiththeIoFootprintTailHospodarsky,G.B.,UniversityofIowaKurth,W.S.,Elliott,S.S.,Gurnett,D.A.,Averkamp,T.F.,Szalay,J.R.,Allegrini,F.,Bonfond,B.,Clark,G.,Connerney,J.E.P.,Ebert,R.W.,Gladstone,G.R.,Bolton,S.J.,Levin,S.M.,Mauk,B.H.andValek,P.

TheJunospacecrafthascrossedmagneticfluxtubesassociatedwiththeIoauroralfootprinttailatavarietyofdowntaildistancesfromtheIofootprintspot.TheJunoradioandplasmawaveinstrument(Waves)detectslargeamplitudeelectromagneticwavesduringmanyofthesecrossings.TheseemissionsareusuallydetectedforjustafewsecondstotensofsecondsandhighresolutionWaveburstdatashowthatpeakamplitudesofthesewavescanreachabout1V/mfortheelectricfieldandafewnTforthemagneticfield.However,ontherecentperijove12northerncrossing,theWavesinstrumentdetectedanintensefunnelshapedemissionlastingformanyminuteswithintenselowerfrequencyemissionatthefunnelapex.InitialanalysisoftheseemissionssuggestthatthesewavesarepropagatingupwardfromJupiter.Theemissionfrequenciesarewellbelowtheelectroncyclotronfrequencyandtheupperfrequencyappearstobecutoffattheelectronplasmafrequency,withanadditionalchangeinintensityalsoobservedattheprotoncyclotronfrequency.Wewilldiscussthedetailsofthesewavesandexaminepossiblewavemodes.ModelingofJovianAuroralPolarIonandProtonPrecipitationHouston,S.J.,DepartmentofPhysicsandAstronomy,UniversityofKansas,Lawrence,Kansas,USA.Cravens,T.E.,Schultz,D.R.,Mauk,B.H.,Haggerty,D.K.

Auroralparticleprecipitationdominatesthechemicalandphysicalenvironmentoftheupperatmospheresandionospheresoftheouterplanets.PrecipitationofenergeticelectronsfromthemiddlemagnetosphereisresponsibleforthemainauroralovalatJupiter,butenergeticelectron,proton,andionprecipitationtakeplaceinthepolarcaps.AtleastsomeoftheionprecipitationisassociatedwithsoftX-rayemission.EnergeticionmeasurementsfromNASA’sspacecraft,Juno,haveyettomeasureionfluxescapableofproducingtheobservedX-rays.WepresentamodelofthetransportofmagnetosphericoxygenionsastheyprecipitateintoJupiter’spolaratmosphere,indicatingthatX-rayemissionbeginsoccurringaslowas0.2MeV/u.WehaverevisedandupdatedthehybridMonteCarlomodeloriginallydevelopedbyOzaketal.,2010andfurtherimprovedbyHoustonetal.,2018tomodeltheJovianaurora.Wenowsimulateawiderrangeofincidentoxygenionenergies(10keV/u-25MeV/u)andupdatethecollisioncross-sectionstomodeltheionizationoftheatmosphericneutrals.Thepolarcaplocationoftheemissionindicatetheassociatedfield-alignedcurrentsmustoriginatenearthemagnetopauseorperhapsthedistanttail.Secondaryelectronsproducedintheupperatmospherebyionprecipitationcouldbeacceleratedupwardtorelativisticenergiesduetothesamefield-alignedpotentialsresponsibleforthedownwardionacceleration.Tofurtherexplorethis,wesimulatetheeffectofthesecondaryelectronsgeneratedfromtheheavyionprecipitation.Weuseatwo-streamtransportmodelthatcomputesthesecondaryelectronfluxes,theirescapefromtheatmosphere,andcharacterizationoftheH2Lyman-Wernerbandemission,includingapredictedobservablespectrumwiththeassociatedcolorratio.Moreover,weperformsomepreliminarycalculationsoftheeffectofprotonprecipitationintothepolaratmosphereanditscontributionstotheauroraldynamics.

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CosmicDustAnalyzeronboardCassiniCollectsMaterialfromSaturn’sMainRingsHsu,H.-W.,LASP,UniversityofColoradoBoulderSchmidt,J.,Kempf,S.,Postberg,F.,Moragas-Klostermeyer,G.,Seiss,M.,Hoffmann,H.,Burton,M.E.,Ye,S.Y.,Kurth,W.S.,Horanyi,M.,Khawaja,N.,Spahn,F.,Schirdewahn,D.,O'Donoghue,J.,Moore,L.,Cuzzi,J.,Jones,G.,Srama,R.

TheregioninsideofSaturn'sDringsampledduringtheCassini'sGrandFinaleMissionispredominantlypopulatedbygrains10snminradii,whosedynamicsisconsistentwithimpactejectafromSaturn'smainrings.Electromagneticforcesleadtoafasttransportoftiny,chargedejectagrains(<hours),whichcomprisesaringmasslosspathway(100-1,000kg/s).About20%ofthemfallintoSaturn,mainlyintheequatorialregionandthesouthernhemisphere,andleadtotheobservedH3

+ionosphericsignature,i.e.,the"RingRain"effect.Twograincompositiontypeswereidentifiedfrom~25%ofrecordedmassspectra-watericeandsilicates,withaicefractiondecreasingfromaround80-100%neartheringplanetowardshighlatitudes.Wefindnoindicationofgrainswithpureorganicsoriron-oxidecompositions.Juno-UVSobservationoftheIofootprintHue,V.,SouthwestResearchInstituteGreathouse,T.K.,BonfondB.,Gladstone,G.R.,Davis,M.W.,Gérard,J.-C.,Grodent,D.C.,Kammer,J.,Roth,L.,Saur,J.,Versteeg,M.,Bolton,S.J.,Connerney,J.E.P,Levin,S.

TheperijoveobservationsperformedbyJuno-UVSnominallyrangefrom-5hoursupto+5hoursaboutperijove,duringwhichJuno’sdistancetoJupiterrangesfrom7RJdownto1.05RJ.TheIofootprintsareacharacterizationofthecomplexelectrodynamicinteractiongeneratedatIoandmodulatedbytheinnermagnetosphereofJupiter.PreviousobservationswiththeHubbleSpaceTelescopeallowedthecharacterizationofthefootprintsasafunctionofIo’scentrifugallatitude,despiteobservationalbiasthatEarth-basedobserversaresubjectto.Juno’suniquevantagepointintheJoviansystemremovesthesebiasesallowingUVSaccesstothefullrangeofcentrifugallatitudesandallpossiblelocaltimegeometries.WewillpresentourinvestigationofthelocaltimevariabilityinIo’sfootprintemittedpowerandcolorratio,includingobservationsofthefootprintswhileIowasineclipse.

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Field-alignedcurrentsfromtheF-ringorbitsofCassiniHunt,G.J,ImperialCollegeLondonProvan,G.,Bunce,E.J.,Cowley,S.W.H.,Dougherty,M.K.,Southwood,D.J.

Weinvestigatetheazimuthalmagneticfieldsignaturesassociatedwithhigh-latitudefield-alignedcurrentsobservedduringCassini’sF-ringorbits(October2016–April2017).Therearedistinctdifferencesbetweenthe2016-2017periodandapreviousopportunitytostudythefield-alignedcurrentprofilesin2008,mostnotablyintheregionspolarwardandequatorwardofthefield-alignedcurrents.Wediscussthesedifferencesintermsoftheseasonalchangebetweendatasetsandlocaltime(LT)differences.TheF-ringfield-alignedcurrentstypicallydohavethesimilarfourcurrentsheetstructurelikethosein2008.Onceagain,wecanshowthatthefield-alignedcurrentsinahemisphereareacentralpartofthathemisphere’s“planetaryperiodoscillation”(PPO)systems.WeseparatethePPO-independentandPPO-relatedcurrentsinbothhemispheresusingtheiroppositesymmetry.TheaveragePPO-independentcurrentspeakat~1.5MArad-1justequatorwardoftheopenclosedfieldlineboundary,similartothe2008observations.However,thePPO-relatedcurrentsinbothhemispheresarereducedby~50%to~0.4MArad-1.ThismaybeevidenceofreducedPPOamplitudes,similartothepreviouslyobservedweakerequatorialoscillationsatsimilardaysideLTs.WecannotdetectthePPOcurrentsystems’interhemisphericcomponent,likelyaresultoftheweakerPPO-relatedcurrentsandtheirclosurewithinthemagnetosphere.Wealsodonotdetectpreviouslyproposedlowerlatitudediscretefield-alignedcurrentsthatwouldacttoshieldthePPOsfrominvariantlatitudesinsideEnceladusorbit.However,wewillshowevidenceofthedistributedPPOfield-alignedcurrentsuptotheedgeoftheF-ring.PlasmasheetpropertiesobservedbyJunoatJupiterHuscher,E.,UniversityofColoradoBagenal,F.,Wilson,R.J.,Valek,P.,Allegrini,F.

UsingJuno’sfirstsciencepassesthroughthejoviansystem,wecombinemeasurementsfromthefieldsandparticlesinstrumentsontheJunospacecrafttomakeapreliminarymapofthepropertiesintheplasmadisk.Juno’sorbitisparticularlyusefulforexploringthevariationinpropertieswithlatitudeaswellasradialdistance(beyond~10RJ).Wecomparebasicplasmaproperties(flow,density,temperature,composition,magneticfieldstrength)aswellasderivedquantities(pressure,plasmabeta,Alfvenspeed)withthosefrompreviousobservations(specificallyVoyagerandGalileo)andestimatetheflowofmassandenergythroughthesystem.

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SignaturesofEuropa’satmosphereinGalileoEPDdataduringtheE12flybyHuybrighs,H.L.F.,MaxPlanckInstituteforSolarSystemResearchRoussos,E.,Krupp,N.,Fraenz,M.,Futaana,Y.,Barabash,S.,Glassmeier,K.-H.

Jupiter’smoonEuropaisthoughttobesurroundedbyatenuousatmosphereofneutralparticles.ObservationsofthisatmospherearelimitedtoremotesensingobservationsbytheHubblespacetelescope(e.g.Rothetal.,2014orSparksetal.,2016).However,currentlylackingarein-situdetectionsoftheatmosphere.Inthiswork,inordertoassesstheexistenceofsuchatenuousatmosphere,weinvestigateaseriesofenergeticiondepletionfeaturesfoundindatacollectedbyGalileo’sEnergeticParticleDetector(EPD)duringtheE12flyby.

EnergeticiondepletionscanbecausedbytheprecipitationoftheseparticlesontoEuropa’ssurface.Additionally,suchlossescanoccurwhentheenergeticionschargeexchangewithneutralparticlessurroundingEuropa.Therefore,aMonteCarloparticletracingcodehasbeendevelopedtosimulatethedepletionfeaturesunderdifferentscenariosincludingthosewithandwithoutanatmosphere.Theatmosphericmodelassumesanexponentiallydecayingdensityandisfullydeterminedbyasurfacedensityandscaleheight.

ThesimulationwithouttheatmospherecouldnotreproducethedepletionfeaturesintheEPDdata.ThisdiscrepancysuggeststhattheobserveddepletionfeaturescannotbesolelyattributedtointeractionoftheparticleswithEuropa’ssurface,andthatEuropathereforepossesanatmosphere.Severalsimulationrunswithanatmosphereforcertainrangesofsurfacedensityandscaleheighthavebeenconducted.BycomparingthesimulationresultswiththeEPDdeletiondata,wesuggestconstraintsonthesurfacedensityandscaleheightofEuropa'satmosphere.

CubeSatprojectforJupiter'sradioscienceImai,Kazumasa,NationalInstituteofTechnology,KochiCollegeNobutoHirakoso,KentarouKitamura,TakuTakada,KOSEN-Space-RenkeiGroup,CharlesA.Higgins,JamesR.Thieman,NASARadioJOVETeam

SincethediscoveryofJupiter'sdecametricradioemissionsin1955,importantdetailsofitsradiationmechanismhavenotyetbeenelucidated.InordertoinvestigatethebeamingstructureofJupiter'sradioemissiontoclarifyaspectsoftheemissionmechanism,weplantolauncha2U-sizeCubeSatforobservationofJupiter'sradiowavesandobservesimultaneouslyinouterspaceandontheground.Thepurposeofthisprojectistomeasuretheemissiondelaytimebyusingacorrelationanalysismethod.ThedelaytimecanbemeasuredbythecorrelationanalysisofwaveformdataobtainedbysimultaneousobservationsofJupiter'sradioSburstsbetweenthissatelliteandtheground.IfthebeamofJupiter'sradioSburstsismovingtogetherwiththerotationofJupiter,wecancalculateatimedifferenceofabout70millisecondsatthebaselinelengthof8000km.UsingtheproposedsimultaneousobservationsitispossibletotestwhethertheJovianSburstsareemittedlikea'beacon',rotatingwithJupiter'smagneticfieldandsweepingbytheEarth,orlikea'flashlight',aninstantaneousemissionwitha0millisecondtimedelay.ThisresultisveryimportantinformationtodeterminethenatureoftheJupiter'sradioemissionmechanism.ThisCubeSatisbeingconsideredtobelaunchedfromtheInternationalSpaceStation(ISS).Thedurationofthepossibleobservationisestimatedtobemorethan50days.Theworldwideground-basedobservationswillbesupportedbytheNASARadioJOVEproject,aneducationandoutreachprogramforplanetaryradioastronomy.ThisprojectissupportedbytheCoordinationFundsforPromotingAeroSpaceUtilizationtheMinistryofEducation,Culture,Sports,ScienceandTechnology(MEXT),JAPAN.

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FrequencydependenceonthebeamingangleofJupiter'sdecametricradioemissionsImai,Kazumasa,NationalInstituteofTechnology,KochiCollegeCharlesA.Higgins,MasafumiImai,TracyClarke

ThebeamingangleofJupiter'sdecametricradioemissionsisveryimportanttoelucidatetheemissionmechanismofJupiter'sdecametricradioemissions.Thisbeaminganglecanbeestimatedbythemodulationlanemethod[Imaietal.,2017].ThemodulationlanemethodisbasedonthemeasurementsoftheslopeofmodulationlanesonthedynamicspectrumofJupiter'sdecametricradioemissions.Weusuallymeasuretheslopewitha1MHzbandwidthanddeterminethemostprobablevalueoftheleadangletofitthevalueoftheslope.Thelongitudinallocationofthemagneticfieldlineoftheradioemittingsourcescanbecalculatedbytheleadangle.Oncethelocationofthesourceisfound,wedeterminethebeamingangle(so-calledconehalf-angle)astheanglebetweenthedirectiontangenttothemagneticfieldlineatthesourceandthedirectiontotheEarthasseenfromthesource.

TheLongWavelengthArraystation1(LWA1)isalow-frequencyradiotelescopedesignedtoproducehigh-sensitivity,high-resolutionspectrainthefrequencyrangeof10-88MHz.ThesensitivityoftheLWA1,combinedwiththelowradiofrequencyinterferenceenvironment,allowsustoobservethewidebandmodulationlanesofJupiter'sdecametricradioemissions[Clarkeetal.,2014].WehaveanalyzedthedataincludingthewidebandIo-BmodulationlanesobservedbyLWA1.Wefoundauniqueeventshowingcurvedmodulationlanesovera22MHzfrequencybandwidthfrom12MHzto34MHz.Byusingourmodulationlanemethodwecalculatedbeaminganglesof57degreesfor12MHzand63degreesfor34MHz.Thedifferenceofthebeaminganglesis6degreesovera22MHzfrequencyrange.Thismeansthevalueofbeamingangleisgraduallyincreasingtowardthehigheremittingfrequency.WewilldiscussthisfrequencydependenceonthebeamingangleofJupiter'sdecametricradioemissionsbasedonthearchivedLWA1data.StereoscopicobservationsofJoviandecametricradioarcsassociatedwithultravioletaurorasImai,M.,UniversityofIowaKurth,W.S.,Bonfond,B.,Grodent,D.,Hospodarsky,G.B.,Bolton,S.J.,Connerney,J.E.P.,Levin,S.M.,Lecacheux,A.,Lamy,L.,Zarka,P.,Clarke,T.E.,Higgins,C.A.,Cecconi,B.

AurorasinJupiter’spolarregionsshowcomplexactivityoverabroadrangeofelectromagneticwavelengths.Oneoftheauroralradiocomponents,decametricradiation(DAM),dominatesthefrequencyrangefromafewto40MHzandisproducedatafrequencyveryclosetothelocalelectroncyclotronfrequency.SinceJunofirstbegandetectingsporadicDAMarcsonMay5,2016,duringtheapproachtoJupiter,theDAMradioarcshavebeenmonitoredinafrequencyrangeof3.5to40.5MHzbyseveralobservatories.TheseincludeJunoatJupiter,CassiniatSaturn,STEREOAat1AU,WINDatEarth,andEarth-basedradioobservatories(LongWavelengthArrayStationOne(LWA1)inNewMexico,USA,andNançayDecameterArray(NDA)inFrance).WehavecarriedoutavisualsurveyofthespectraldatatoidentifyconcurrentDAMradioarcs,fromMay5,2016,throughSeptember,2017(Cassini’send-of-mission).Wefoundsixeventsforwhichtwoormoreobserversclearlycapturedthesamegroupofarcs.InoneoftheeventsonDecember3,2016,JunofirstcapturedagroupoftheDAMarcsaround4:00UTandtwointensearcswerelaterrecordedinNDAspectrogramsat6:30and7:45UT.Onthesamedayfrom13:44to14:24UT,theHubbleSpaceTelescope(HST)observedabrightauroralarcatultravioletwavelengthswithanemittedpowerof20to25GW,suggestingapossiblelinktotheconcurrentlyobservedDAMarcs.Inthispaper,weshowresultsfromthestereoscopicDAMradioobservationsandcomparewiththeultravioletaurorascapturedbyHST.

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Assessingquasi-periodicitiesinJovianX-rayemissions:techniquesandheritagesurveyJackman,C.M.,UniversityofSouthamptonKnigge,C.,Altamirano,D.,Gladstone,R.,Dunn,W.,Elsner,R.,Kraft,R.,Branduardi-Raymont,G.,Ford,P.

WearecurrentlyinanexcitingeraforjoviansciencewiththeJunospacecraftinorbitaroundJupiterandseveralEarth-basedandspace-basedobservatoriesstudyingJupiterinmultiplewavelengths.Jupiter’sauroralX-raysarerathermysterious,withanunknowndriver,andseveralpreviousreportsofindividualcasesofquasi-periodicemission.InthisworkwerevisitheritageX-raydatasetsfromthe1990sto2015andapplysignificancetestingofemergingquasi-periodicities,seekingtounderstandtherobustnessandregularityofpreviouslyreportedquasi-periodicemissions.OuranalysisincorporatestheuseoftheRayleightestasanalternativetoLomb-Scargleanalysis,whereRayleighisparticularlysuitedtoatime-taggeddatasetofsparsecountssuchasiscommonforjovianX-raydata.Furthermore,theanalysistechniquesthatwepresent(includingRayleighandMonte-Carlosimulation)canbeappliedtoanytime-taggeddataset.Wefindfiveinstancesofquasi-periodswithsingletrialsignificancesabovethe99thpercentilefromJupiter’snorthernauroralregion,withperiodsrangingfrom~8.1to47.6minutes,andthreeinstancesfromthesouth,withperiodsof~11,24and42minutes.Theselectionofarestrictivehotspotsourceregionseemstobecriticalfordetectingquasi-periodicemission.PeriodsvaryfromoneJupiterrotationtothenextinonelongobservation,andthenorthandsouthareshowntopulseindependentlyinanotherconjugateobservation.TheseresultshaveimportantimplicationsforunderstandingthedriverofjovianX-rayemission.PlasmaobservationsatSaturn’shigh-latitudemagnetosphereandcuspJasinski,J.M.,NASA-JetPropulsionLaboratoryMurphy,N.

Thehigh-latitudepolarmagnetosphereatSaturnislocatedonopenfieldlineswhicharelargelydevoidofplasmadenseenoughtobemeasuredbytheCassiniPlasmaSpectrometer.However,embeddedwithinthislargely“empty”polarmagnetosphereareunexplainedobservationsofsporadicburstsoftenousplasma,whichwepresenthere.Additionally,weshowrecentanalysisplasmacomposition,structureandvariabilityinSaturn’scusps.

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SurveyofElectronmeasurementsatSaturn'sMagnetosphereusingCAPS-ELSJasinski,J.M.,NASA-JetPropulsionLaboratoryMurphy,N.,Coates,A.J.

UsingallthedatafromCassini'sElectronSpectrometer(ELS)wecomposeasurveyofSaturn'smagnetosphere.Wefocusonmeasureingtheregionswherethereisnoplasmaobserved.Thisletsusidentifywheretheopen-closedfieldlineboundaryisinthehigh-latitudesandwherethereconnectionx-lineisinthenightsidetailatlowlatitudes.Fromthisweestimateaveragemagneticfluxesintheopenpolarcaps.Wealsofindadawn-duskasymmetryintheouterequatorialmagnetosphere.CoupledFluid-kineticGlobalSimulationsofSaturn'sMagnetopauseDynamicsJia,X.,UniversityofMichiganChen,Yuxi;Toth,Gabor;Slavin,James.A.;Kivelson,MargaretG.;Gombosi,TamasI.

Thegiantplanets,JupiterandSaturn,arerapidrotatorswithstronginternalsourcesofplasmaarisingfromtheirmoons.Theroleofsolarwind-driventransportattheseplanetshasbeenatopicofintenseinterest.BothmagneticreconnectionandKelvin-Helmholtz(K-H)instabilityhavebeensuggestedtoplayanimportantroleincouplingthesolarwindwiththemagnetosphere.TodeterminetheimpactofreconnectionandK-Hinstabilityonthegiantplanetmagnetospheres,wehaveadaptedacoupledfluid-kineticglobalmodeltothegiantplanetsbasedontheMHDwithembeddedparticle-in-cell(MHD-EPIC)codeoriginallydevelopedforEarthandGanymede.TheMHDcode(BATSRUS)isemployedoverthefullsimulationdomain,whilethefullykineticcode(iPIC3D)coversregionswherekineticphysicsisimportant.Thetwo-waycoupledMHD-EPICprovidesauniquecapabilityofsimulatingreconnectionatkineticscaleswhilesimultaneouslycapturinglarge-scaleeffectsofreconnectiononaglobalmagnetosphere.Inthispresentation,wereportonfirstresultsfromourMHD-EPICsimulationsofthesolarwindinteractionwithSaturn'smagnetopause.OurSaturnMHD-EPICmodelhasbeenrunwithvariousIMFconditions(northward,southward,spiralconfigurations)todeterminethemainprocessthroughwhichthesolarwindiscoupledtothemagnetosphere.WehavealsoperformedpurelyMHDsimulationsforthesameupstreamandinternalconditionsasusedinMHD-EPICtoidentifyhowtheeffectsofboundaryprocessesdifferinthetwomodels.ThesecomparisonsallowustodeterminewhenandwherereconnectionorK-Hlikeinstabilitiesoccurundertheexternalandinternalconditionspertinenttothegiantplanetmagnetospheres.Asaquantitativemeasureoftheglobalcouplingefficiency,weanalyzetherateatwhichopenmagneticfluxisbeingaddedtothepolarcapandhowitvarieswiththeIMForientation,andcomparetheresultsbetweenMHD-EPICandMHDsimulations.

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EvidenceofaPlumeonEuropafromGalileoMagneticFieldandPlasmaWaveSignaturesJia,X.,UniversityofMichiganKivelson,MargaretG.;Khurana,KrishanK.;Kurth,WilliamS.

TheicysurfaceofJupiter’smoon,Europa,isthoughttolieontopofaglobalocean.SignaturesinsomeHubbleSpaceTelescopeimageshavebeenassociatedwithputativewaterplumesrisingaboveEuropa’ssurface.PlumesthusfaridentifiedfromHubbleimagesaresimilarinspatialscale,appearingtorise~200kmabovethediskofEuropa’ssolidbody.TheonesneartheequatorarelocatedonEuropa’strailinghemispheresouthoftheequatorinaregionofcomparativelyhighsurfacetemperature.However,alltelescopicdetectionsreportedweremadeatthelimitofsensitivityofthedata,therebycallingforasearchforplumesignaturesinin-situmeasurements.Herewereportin-situevidenceofaplumeonEuropafromthemagneticfieldandplasmawaveobservationsacquiredonGalileo’sclosestencounter(E12)withthemoon.Onthisflybythatdroppedbelow400kmaltitude,themagnetometerrecordeda~1000kmscalefieldrotationandadecreaseofover200nTinfieldmagnitudeandthePlasmaWaveSpectrometerregisteredintenselocalizedwaveemissionsindicativeofabriefbutsubstantialincreaseinplasmadensity.WehavemodeledtheE12flybyusinga3Dmulti-fluidmagnetohydrodynamic(MHD)modelthatincorporatesaplumewithpropertiesconsistentwiththoseinferredfromtheHubbleobservations.Weshowthatthelocation,duration,andvariationofthemagneticfieldandplasmawavesignaturesareentirelyconsistentwiththeinteractionofJupiter’scorotatingplasmawithEuropaifaplumewithcharacteristicsinferredfromHubbleimageswaseruptingfromtheregionofEuropa’sthermalanomalies.OurresultsprovidestrongindependentevidenceofthepresenceofplumesatEuropa.Juno-UVSMeasurementsofHigh-EnergyRadiationatJupiterKammer,J.A.,SouthwestResearchInstituteGladstone,G.R.,Greathouse,T.K.,Versteeg,M.H.,Hue,V.,Davis,M.W.,Becker,H.N.,Bolton,S.J.,Connerney,J.E.P.,Levin,S.M.

Juno-UVSisanultravioletspectrographthatprimarilyobservesJupiter’sauroralemissions,buttheinstrumentisalsosensitivetopenetratinghigh-energyradiation(generally>10MeVelectrons),whicheffectivelyactsaswhitenoiseduringUVobservations.Instudyingthisradiationbackgroundnoise,wefindthatthelevelofmaximumbackgroundradiationobservedbyJuno-UVSvariesonatimescaleofhours,and-basedontheoutputofmagneticfieldmodels-theinstrumentcountrateduetohighradiationreachesitsmaximumincertainregionsaroundJupiterdependingonrho,thespacecraftdistancefromthemagneticdipoleaxis,andz,thespacecraftdistanceabovethemagneticequator.WeusethisempiricalrelationshiptopredictthelevelsofradiationseenbyJuno-UVSforfutureperijoves.Wealsofindthatmeasuredlevelsofradiationvaryonshorter(~30second)timescalesduetothespinningofthespacecraft,andhavedevelopedmodelstoexplainthisvariationasafunctionofspinphase.WepresentcomparisonsoftheJuno-UVSdatafromeachoftheperijovepassessofar,anddiscusswhatfutureperijovesmightrevealaboutthenatureandextentofhigh-energyradiationaroundJupiter.

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CassiniMission-wideAnalysisofHotIonsDetectedbytheINCAandCHEMSInstrumentsintheMagnetosphereofSaturnKane,M.,HRIMitchell,D.G.,Hill,M.E.,Carbary,J.F.,Krimigis,S.M.

AnextensiveanalysisofCassiniINCAandCHEMSmeasurementsof5-149keVionsacquiredduringselectedperiodsofnearlyallmissionorbitshasbeencompleted.Inadditiontoselectedperiodswithinnearlyallequatorialorbits,dataacquiredwhenthespacecraftwaswithin~20degreeslatitude,whereconditionspermitted,formostnon-equatorialorbitswasalsoanalyzed.Thecoveragespansalllocaltimesandrangesfrom~6Rstothemagnetopauseinthedaysideandto~70Rsonthenightside.Usingaconvectedkappadistributionasthemodelforthehotionpopulations,thedensity,temperature,3componentvelocity,andspectralindexwerecalculatedfromabestfittotheCHEMSandINCAinstrumentdata.ForINCA,oxygenionswereanalyzedseparately.SpinandstarespacecraftmodeswereanalyzedforbothINCAandCHEMS.ThecomputedplasmafractionalcorotationspeeddecreasessharplywithincreasingdistancefromSaturn.Theoxygenionprofilefollowsthehydrogeniontrend.Thepolarconvectionspeedisthesmallestofthe3velocitycomponents,andiscenteredaboutzero,buttheradialspeedhasasignificantoutwardradialcomponentandisenhancedinthepre-dawnsector.ThehydrogenandoxygentemperaturesincreasewithdecreasingdistancetoSaturn.Thecalculatedpatternofconvectionisconsistentwithanempiricalmodelofplasmaconvectionthatincludesoutwardradialtransportandescapeofplasmainadawnsideboundarylayerofplasmaentrainedbythedawnmagnetosheathflow.However,CHEMSanalysisoftheinnerregionsinthenightsideindicateaninwardcomponenttothevelocity,possiblyanindicationoftheexistenceofhotioninjections.Whenthemodelconvectionpatternisscaledtothesub-solarmagnetopausedistanceandtothesizesofJupiterandSaturn,thepatternagreeswiththatderivedfromanalysisofhotionsdetectedbytheLECPdetectoronVoyagerandtheEPDinstrumentonGalileo.

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HighFrequencypartinRadio&PlasmaWaveInvestigation(RPWI)aboardJUICE:TowardtheinvestigationofJupiterandIcyMoonsSystemKasaba,Y.,TohokuUniversityCecconi,B.,Misawa,H.,Tsuchiya,F.,Kumamoto,A.,Kimura,T.,Kita,H.,Nakamura,Y.,Miyoshi,Y.,Kasahara,Y.,Kojima,H.,Jarzynka,S.,Palma,P.,Tokarz,M.,Wiśniewski,Ł.,Puccio,W.,Bergman,J.,Wahlund,J.-E.

In2018wedeveloptheQM/PFM/FMofRadio&PlasmaWaveInvestigation(RPWI)aboardESAJUICE.RPWIprovidesanelaboratesuiteforelectromagneticfieldsandplasmaenvironmentaroundJupiterandicymoons,with4Langmuirprobes(LP-PWI;3-axisE-field-1.6MHz,andcoldplasmas),asearchcoilmagnetometer(SCM;3-axisB-field-20kHz),andatri-dipoleantennasystem(RWI;3-axisE-field0.08-45MHz,2.5-mtip-to-tiplength).

RWIwithHighFrequencyReceiver(HF)providethehighestsensitivityreachingthegalacticbackgroundforthehighly-resolvedJovianradioemissionsfrommagnetosphere(auroraetc.),atmosphere(lightning),andicymoons.Itsdirectionandpolarizationcapabilitiesenableustoidentifythesourcelocationsandcharacteristics.TheirdevelopmentsareunderthecollaborationofJapan,France,PolandandSweden,basedontheH/WandS/WdesignsofKaguya-LRS/BepiColombo-PWI/Arase-PWEandCassini-RPWS.Inthispaper,weintroducekeyactionstakeninrecentyearstoachievethebestperformancesandquietenvironmentwithenoughtoleranceforwidetemperaturerangearoundVenus-Jupiterandharshplasmaenvironment(charging&intenseradiation).

Asabyproduct,wetrythepassivesubsurfaceradar(PSSR)tosoundtheicycrustsofGalileansatellites,bythereflectionsofJovianHOM/DAM.Forcontinuousandcoherentwaves,reflectorinformationisdeterminedbyspectrumpatternscausedbytheinterferenceamongthedirectwave,reflectedonefromsurface,andscatteredonebysubsurface.Forburstwaves,thereflectioncomponentisdeterminedbycross-correlationofthewaveformsfor~msecslength.Althoughitisnoteasytoreachthetopofsubsurfaceoceanbystrongattenuationoftheiceclosetoitsmeltingtemperature(>50dB/km),wearelookingforwardtoseerealdataandsupportthesubsurfacestudiesexecutedbyRIME(activeradarsounder)andmanypayloadteamswhohavemuchinteresttothistopic.Software-typeWave-ParticleInteractionAnalyzer(S-WPIA)byRPWIforJUICEKatoh,Y.,TohokuUniversity,JapanH.Kojima,K.Asamura,Y.Kasaba,F.Tsuchiya,Y.Kasahara,T.Imachi,H.Misawa,A.Kumamoto,S.Yagitani,K.Ishisaka,T.Kimura,M.Hikishima,Y.Miyoshi,M.Shoji,M.Kitahara,O.Santolik,J.Soucek,J.Bergman,W.Puccio,R.Gill,M.Wieser,W.Schmidt,S.Barabash,andJ.-E.Wahlund

Software-typeWave-ParticleInteractionAnalyzer(S-WPIA)willberealizedasasoftwarefunctionofrunningontheDPUofRPWI(RadioandPlasmaWavesInvestigation)fortheESAJUICEmission.S-WPIAconductsonboardcomputationsofphysicalquantitiesindicatingtheenergyexchangebetweenplasmawavesandenergeticions.Onboardinter-instrumentscommunicationsarenecessarytorealizeS-WPIA,whichwillbeimplementedbyeffortsofRPWI,PEP(ParticleEnvironmentPackage)andJ-MAG(JUICEMagnetometer).TheprimetargetofS-WPIAinJUICEisioncyclotronwavesandrelatedwave-particleinteractionsoccurringintheregionclosetoGanymedeandotherJoviansatellites.Low-Frequencyreceiver(LF)andLangmuirProbes(LP)datawillbeusedforelectromagneticwaveformofioncyclotronwavesinthefrequencyrangeofafewHz.Fortheparticledata,S-WPIAusesparticlecountsdetectedbyJovianplasmaDynamicsandComposition(JDC)ofPEPintheenergyrangefrom1eV/qto25keV/q.ByprovidingthedirectevidenceofionenergizationprocessesbyplasmawavesaroundJoviansatellites,S-WPIAincreasesthescientificoutputofJUICEwhilekeepingitsimpactonthetelemetrydatasizetoaminimum.

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DiscoveryofAtmospheric-Wind-DrivenElectricCurrentsinSaturn’sMagnetosphereintheGapbetweenSaturnanditsRingsKhurana,K.K.,Dept.ofEarth,PlanetaryandSpaceSciences,UniversityofCalifornia,LosAngeles,CA,90095DoughertyM.K.,ProvanG.,HuntG.J.,KivelsonM.G.,CowleyS.W.H.,SouthwoodD.JandRussellC.T.

AsCassinirepeatedlytraversedthegapbetweenSaturn’satmosphereanditsDringduringtheproximalorbits,theazimuthalcomponentofthemagneticfieldshowedaconsistentpositiveperturbationwithastrengthof15-25nTneartheclosestapproach.TheclosestapproacheswereneartheequatorialplaneofSaturnandweredistributednarrowlyaroundthelocalnoonandbroughtthespacecrafttowithin2550kmofSaturn’scloudtops.Modelingofthefieldintermsofsphericalharmonicsshowsthattheperturbationisnotofinternaloriginbutisproducedbyexternalcurrentsthatcouplethelow-latitudenorthernionospheretothelow-latitudesouthernionosphere.Theazimuthalperturbationsdiminishathigherlatitudesonfieldlinesthatconnecttothering.TheconsistentpositiveazimuthalperturbationobservedbyCassinineartheequatorialplanesuggeststhatthespacecraftpassedinbetweentwoshellsofoppositelydirectedcurrentslinkedintheionosphere.TheoutershellwascrossedbyCassinitwiceandiscomposedoffield-alignedcurrentsthatareflowinginthesouthwarddirection.TheinnershellwasnotcrossedbyCassini.Weshowthatthestrengthofthiscurrentsystemis~1MA/radian,i.e.comparableinstrengthtotheplanetary-period-oscillationrelatedcurrentsystemsobservedintheauroralzone.WeshowthattheLorentzforceintheionosphereextractsmomentumfromthefastermovingequatorialzonalbeltanddeliversittothenorthernionosphere.Wefurthershowthatelectriccurrentsaregeneratedwhenthetwoendsofafieldlinesareembeddedinzonalflowswithdifferingwindspeedsinthelow-latitudethermosphere.Thewind-generatedcurrentsdissipate2×10^11Wofthermalpower,similartotheinputfromthesolarEUVfluxinthisregion.IonPropertiesofJupiter'sPlasmaSheet:JunoJADE-IObservationsKim,T.K.,DepartmentofPhysicsandAstronomy,UniversityofTexasatSanAntonio,SanAntonio,TX,USAValek,P.W.,McComas,D.J.,Allegrini,F.,Bagenal,F.,Clark,G.,Connerney,J.E.P.,Ebert,R.W.,Kollman,P.,Livadiotis,G.,Mauk,B.H.,Thomsen,M.F.,Wilson,R.J.,Levin,S.,Bolton,S.

WepresentobservationsofJovianplasmasheetionsasmeasuredbytheJovianAuroralDistributionsExperimentIonsensor(JADE-I)ontheJunospacecraft.JADE-Imeasuresanion’senergy-per-charge(E/Q)from0.01-46.2keV/qandmass-per-charge(M/Q)from1-64amu/q.ThisextendedE/QandM/QinformationpermitsdetailedobservationsofJupiter’splasmasheet.WepresentbulkionplasmapropertiesforH+,O+,O2

+,O3+,Na+,S+,S2+,andS3+obtainedfromaforwardmodel.Theforward

modelutilizessimulatedinstrumentresponsefunctions(fullraytracingsimulationwithcarbon-foil-effects)toreproducethe2-dimensionalE/Qandtime-of-flightmeasurementsoftheplasmasheetionsbasedonaconvectedkappadistribution.Maxwell-Boltzmanndistributionsaretypicallyusedtodescribesystemsinthermalequilibrium.Butspaceplasmasaremostlyconsideredascollisionlessandarenotalwaysinthermalequilibrium.Oftentimes,suchsystemshavedistributionsextendingtohigherenergies(highenergytail)andcanbebetterdescribedwithkappadistributions.Inourforwardmodelweassumeallionshaveacommonflowspeed(alongtheco-rotationdirection)andisotropicdistributionswithdifferenttemperatureandkappaindexforprotonandheavyions(i.e.,M/Q>5).Wefindthattheplasmatemperaturesanddensitiesarehigherthanpreviouslyreported.

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ResponseofJupiter'sAuroratoPlasmaMassLoadingRateMonitoredbytheHisakiSatelliteDuringVolcanicEruptionsatIoKimura,T.,TohokuUniversityHiraki,Y.,Tao,C.,Tsuchiya,F.,Delamere,P.,Yoshioka,K.,Murakami,G.,Yamazaki,A.,Kita,H.,Badman,S.V.,Fukazawa,K.,Yoshikawa,I.,Fujimoto,M.

Theproductionandtransportofplasmamassareessentialprocessesinthedynamicsofplanetarymagnetospheres.AtJupiter,itishypothesizedthatIo’svolcanicplasmacarriedoutoftheplasmatorusistransportedradiallyoutwardintherotatingmagnetosphereandisrecurrentlyejectedasplasmoidviatailreconnection.Theplasmoidejectionislikelyassociatedwithparticleenergization,radialplasmaflow,andtransientauroralemissions.However,ithasnotbeendemonstratedthatplasmoidejectionissensitivetomassloadingbecauseofthelackofsimultaneousobservationsofbothprocesses.WereporttheresponseofplasmoidejectiontomassloadingduringlargevolcaniceruptionsatIoin2015.ResponseofthetransientauroratothemassloadingratewasinvestigatedbasedonacombinationofHisakisatellitemonitoringandanewly-developedanalyticmodel.Wefoundthetransientaurorafrequentlyrecurredata2–6-dayperiodinresponsetoamassloadingincreasefrom0.3to0.5ton/s.Ingeneraltherecurrenceofthetransientaurorawasnotsignificantlycorrelatedwiththesolarwindalthoughtherewasanexceptionaleventwithamaximumemissionpowerof~10TWafterthesolarwindshockarrival.Therecurrenceofplasmoidejectionrequiresthepreconditionthatamountcomparabletothetotalmassofmagnetosphere,~1.5Mton,isaccumulatedinthemagnetosphere.Aplasmoidmassofmorethan0.1Mtonisnecessaryincasethattheplasmoidejectionistheonlyprocessformassrelease.AnalysingCassiniUVIS&INCAimageryduringinjectioneventsatSaturn:aninverseproblemKinrade,J.,LancasterUniversityBadman,S.V.,Gray,R.L.,Mitchell,D.G.,Paranicas,C.,Arridge,C.S.,Ray,L.C.,A.Bader,Pryor,W.R.

Large-scaleinjectioneventsfromSaturn’smagnetotailproducerotatingsignaturesinboththeplanet’sauroralemissionandmagnetospherichotplasmapopulation.Previouslythesesignatureshavebeenobservedtotrackthroughsimilarlocaltimes,whichsuggestsacausallinkbetweenanauroralsourceregioninthemagnetosphereandanultimatesinkintheionosphere,likelyconnectedviafieldalignedcurrents.Thephysicsdrivingthiscurrentsystemandrotatingauroralemissionarenotfullyunderstood.Dopressuregradientsassociatedwithinjectionflowchannelsdrivecurrentsthatproducetheauroralsignature?Doesgradient-curvaturedriftrestrictauroralcurrentstotheedgesofinjectionregionsaschargeseparationisolatestheenergeticionsandelectrons?Doestheionosphereimpedemotionoftheinjectedplasma?

TheCassiniUltravioletImagingSpectrograph(UVIS)capturesSaturn’smostintenseUVauroralemissions,whicharetheoptical,ionosphericfingerprintofhotplasmainthemagnetosphere.ImagingofEnergeticNeutralAtoms(ENAs)usingCassini’sIon-NeutralCamera(INCA)providesaglobalviewofthemagnetosphere’shotplasmapopulation.Herewediscusshowthesetwoimagesetsmaybecomparedintheframeofaninverseproblem,torevealthedynamicsoftheauroralsourceregionanddrivingcurrentsduringlarge-scaleinjectionevents.Toresolveradialandazimuthalmotions,wetranslatetheauroralandENAimagerytoacommonmagnetosphericgrid,andautomaticallytrackauroralenhancementsusingadynamicintensitythreshold.WetesthowtheFUVintensityandspectraprovidedbyUVISateachpixellocationmayberelatedtotheINCAENAfluxinacommonauroralsourceregionparameterspace.ThisproblemisconstrainedherebyassimilatingsimultaneousobservationsfromUVISandINCA,togetherwithmodelestimatesforneutraldensity,energeticparticledriftrates,atmosphericabsorption,andmagneticfluxequivalencemapping.

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EUVaurora’sresponsetosolarwindmeasuredwithHisaki&JunoKita,H.,TohokuUniv./ISASJAXAKimura,T.,Tao,C.,Tsuchiya,F.,Murakami,G.,Yamazaki,A.,Yoshioka,K.,Ebert,R.W.,Wilson,R.J.,Valek,P.W.,Clark,G.,Connerney,J.E.P.,Gladstone,R.,Kasaba,Y.,Yoshikawa,I.,Fujimoto,M.

WhiletheJovianmagnetosphereisknowntobedominatedbytheinternalsourceofplasmaandenergy,italsohasaninfluencefromthesolarwind.ThistalkmainlyfocussesonthesolarwindresponseofJupiter’saurora,whichisachievedbyHisakiandJuno.HisakiisanEUV/UVspacetelescopelaunchedin2013.ItsspectrometerEXCEED(ExtremeUltravioletSpectroscopeforExosphericDynamics)begancontinuousmonitoringofJupiterfromDec.2013.

WemadeastatisticalanalysisofthetotalpowervariationofJovianUVauroraobtainedfromHisaki.WecomparedthetotalUVauroralpowerin90-148nmwiththesolarwindmodel.PreviousobservationssuchasthosebytheHubbleSpaceTelescopeshowedthattheUVauroraandsolarwinddynamicpressurehad,attimes,apositivecorrelation.Fromthedataobtainedin2014-2015,theauroraltotalpowershowedapositivecorrelationtothedurationofaquiescentintervalofthesolarwindbeforetheenhancementsofthedynamicpressure.Itislargerthanthecorrelationtotheamplitudeofdynamicpressureenhancement.Asimilartrendwasidentifiedagainin2016whenHisakiobservedJupiterwithJunointheupstreamsolarwind.In-situsolarwindplasmameasurementbyJunowasusedforApril-June.Ontheotherhand,thedynamicpressurewasestimatedfromJuno-MAGdataforJan-Mar.WecalculatedcorrelationsbetweenJuno-MAGandthesolarwinddynamicpressureandusedtherelationshipwhensolarwindplasmadatawasnotavailable.

Onepossiblescenariotoexplaintheseresultsisthatthemagnetosphericplasmacontentcontrolstheauroraresponsetothesolarwindvariation.LongquiescentintervalwouldmeanthatthemagnetosphericplasmasuppliedfromIoismoreaccumulatedinthemagnetosphere.Thesolarwindcompressionofthemagnetosphereshiftstheplasmainwardandincreasestheplasmatemperatureanddensitybyadiabaticheating,whichleadstoanenhancementoftheauroralfield-alignedcurrentdensity.MasstransportatJupiterandSaturnKivelson,M.G.,Earth,Planetary,andSpaceSciences,UCLA,LosAngeles,CA90095-1567,USA

Themagnetospheresofthegasgiantplanets,JupiterandSaturn,owemanyoftheiruniquepropertiestotheneutralvaporsspewedoutofmoonsintheirdeepinteriors:IoatJupiter,EnceladusatSaturn.Theneutralsareionizedinthenear-equatorialmagnetosphereatandsomewhatbeyondtheorbitsofthemoons.Bothmagnetospheresdevelopquasi-steadystructurethatimpliesthattherateofplasmalossisonaveragethesameastherateofplasmainput.Itiswidelyagreedthatthewarmplasmaoftheinnermagnetospherediffusesoutwardataslowrate.Magneticfluxconservationrequiresthatasmuchfluxmoveinwardasoutwardanditislikelythattheinwardtransportofrapidlymovingdepletedfluxtubesprovidestherequiredbalance,buttheobservationssupportingthispicturequantitativelyareincomplete.Oncetransportedfromtheinnertotheoutermagnetosphere,theplasmamustbelostcompletelyfromthesystem,buthereagainquantitativeconfirmationofthelossmechanismisabsent.Candidateremovalmechanismsincludeplasmoidsthatcarryplasmadowntailoroutthemorning-sideboundaryand“drizzle”downthedusksideflank.Kelvin-Helmholtzvorticesontheflanksmayalsotransportplasmaoutofthedawnandduskflanks.Studiesofplasmoidssuggestthattheydonotaccountfortherequiredmasstransportratebutsimulationscallintoquestiontheadequacyofcoverageofthemeasurements.Drizzleispostulatedtooccurinregionsnotexploredbyspacecraft,andKelvin-Helmholtzobservationsremainincomplete.Thistalkwillconsiderwhatwedoanddon’tknowaboutthetransportprocess.

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HeatingJupiter’splasmatorus(Saturn’stoo)throughinterchangeKivelson,M.G.,EPSS,UCLA,LosAngeles,CA90095-1567Khurana,K.K.,andRamer,K.M.(deceased)

In1988,Smithetal.notedthatinJupiter’sequatorialmagnetosphereoutsideoftheorbitofIoobservedUVandEUVradiationcannotbemaintainedsolelythroughenergyinputbyionpickup,alludingtothisproblemasthe“energycrisis”oftheIoplasmatorus.Furthermore,thetemperatureofthetorusplasmaincreaseswithequatorialradialdistance(LRJ)(BagenalandDelamere,2011),eventhoughadiabaticheatingwouldleadtoadecreaseoftemperaturewithL.Smithetal.suggestedthatthemissingenergyis“carriedintothetorusbyinwardradialdiffusionoflow-density,hot[energiesgreaterthan300eV]ions,”throughwhattodaywewouldcallinterchange,estimatingthat1TWofpowerisavailablefromthisprocess.Returningtothisproblemandrequiringconservationofmagneticfluxtoestablishtransportrates,weusethepressureoftheenergeticplasmareportedbyBagenalandDelameretoestimatetherateofheattransportthroughtheIotorus.Wefindthatinterchangecanaccountforasmuchas15TWofpoweratJupiter,soinprinciplethemechanismcanwork.Perspicaciously,Smithetal.stated:“itiscrucialthat[theenergeticparticle]energy-losstimescalebeshorterthanorcomparabletotheirlifetimeagainstchargeexchangeiftheyaretoprovidetheneededenergy.”Furthermore,toheatthethermalplasmaoverarangeofradialdistances,theenergeticparticlesmustdriftoffthefluxtubesata“Goldilocks”rate,rapidlyenoughtodepositsomeenergyatL-valuesjustinsidetheirsourceregionandslowlyenoughthatanenergysourceremainsontheinward-movingfluxtubewhenitapproachesIo’sorbit.Onceonambientfluxtubes,thehotplasmaparticlesmusttransferenergytothewarmplasmabeforetheyarelostthroughchargeexchangeorotherprocesses.WewillprovideestimatesshowingthatthismechanismcanplausiblyaccountforpropertiesofthetorusplasmaandthatitalsoappliestoheatingofSaturn’sequatorialplasma.

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SpatialdistributionofatomicoxygenemissionsaroundIo'sorbitduringvolcanicallyquietandactiveperiodsKoga,R.,TohokuuniversityTsuchiya,F.,Kagitani,M.,Sakanoi,T.,Kimura,T.,Yoshikawa,I.,Yoshioka,K.,Yamazaki,A.,Murakami,G.,Smith,H.T.

Io’satmosphereismainlydominatedbysulfuroxidesthatoriginatedfromvolcanoes.TheyaredissociatedandsomeofoxygenandsulfuratomsescapefromIo’sgravitybyatmosphericsputtering,andcreateIo’sneutralcloudaroundIo’sorbit.ThespatialdistributionofIo’soxygenandsulfurneutralcloudhasnotbeenobservedbecausetheiremissionsarefaint(severalRayleighs(R)).ThankstothecontinuousobservationsofIoplasmatorusbyHisaki,wesucceedtoderivethespatialdistributionofatomicoxygenemissionsat130.4nmaroundIo’sorbit.

First,weanalyzedtheIophaseangle(IPA)dependenceandradialdistributionofatomicoxygenemissionduringavolcanicallyquietperiod(fromNovembertoDecember,2014).TheresultsshowIo’sneutraloxygencloudconsistsoftwocomponents,aleadingcloudthatspreadsinsideIo’sorbit(called“bananacloud”)andalongitudinallyuniform,diffuseregiondistributedalongIo’sorbit.Wealsofindthecloudspreadsatleast7.6RJfromJupiter.Weestimatedatomicoxygennumberdensity(40-80cm-3)andoxygenplasmasourcerate(410kg/s)fromlongitudinallyaveragedradialprofileofOIemissions.TheestimationisconsistentwithpreviousmodelstudiesbasedonthespectraldiagnosisofemissionionsobservedbyCassiniandHisaki.

WeobservedtheenhancementofatomicoxygenemissionsaroundIointhespringof2015.Inthesameperiods,theenhancementofinfraredemissionfromIo’svolcanoandextendedsodiumnebulaemissionwerealsoobserved.ThisshowsthevolcanicactivityincreasesneutralgasesoriginatedfromIo.WeanalyzedtimevariationsofIPAdependenceofOIemissionsevery10daysandfindboththebananacloudandthediffuseregionincreaseinthesamerate.ThisshowsoxygenatomsescapefromIospreaddiffuseregionfasterthan10days.TheresultisconsistentwithIo’sescapevelocity(2.6km/s).

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TheionradiationbeltsofJupiterandSaturnKollmann,P.,JHU/APLRoussos,E.;Kotova,A.;Regoli,L.;Paranicas,C.;Clark,G.;Nenon,Q.;Mauk,B.;Krupp,N.;Mitchell,D.G.;Haggerty,D.;Rymer,A.M.;Carbary,J.;Connerney,J.E.P.

Planetaryradiationbeltsareregionsofquasi-stablytrappedchargedparticlesfromthehundredsofkeVprobablyintothehundredsofMeV.Even60yearsafterthediscoveryofEarth’sradiationbelts,whichwasthefirstdiscoveryofthespaceage,wearenotdonediscovering:WithinthelasttwoyearstheJunoandCassinimissionsfoundentirelynewradiationbeltsclosetotheatmospheresoftheseplanets.TheoriginandphysicalprocessesinthesenewbeltsareasfundamentallydifferentfromthepreviouslyknownbeltsaroundtheseplanetsassomeoftheirbeltsdifferfromwhatweknewfromEarth.

EvenduringitsfirstsciencepassaroundJupiter,Juno’sJEDIinstrumentdiscoveredanewionradiationbeltinwardofthebeltsthatweremeasuredbytheGalileoProbeathigherenergies.ThemorerecentJunoorbitsreachdowntosufficientlylowlatitudestodetectalsotheradiationbeltsinwardofabout3RJ.ThenewJunomeasurementsareatlowerenergiesthantheGalileoProbeandhaveaclearionspeciesidentification,whichcanprovideinsightsintotheoriginoftheseradiationbelts.

Duringtheproximalphaseofitsmission,Cassini’sMIMIinstrumentdiscoveredanothernewradiationbeltlocatedinwardofthemainrings.Thein-situmeasurementsshowedMeVandGeVprotonsindicatingthatthekeVionsdetectedremotelyearlieroriginatefromloweraltitudesthanwerereachedbyCassini.

InthistalkwewillprovideanintroductionintothephysicalmechanismsthatsupplyMeVionstothegiantplanetradiationbeltsandareresponsiblefortheirevolution.Wewillillustrateourdiscussionwithdatafrommissionstotheseplanets.

ThisintroductionwillleadtorecentresultsonJupiter’sinnerionbelts,asdeterminedfromthecombinationofmission-longJuno/JEDImeasurementswitharecenthigher-ordermagneticfieldmodel.WewillalsoprovideanupdatetoouranalysisonSaturn’sinnermostradiationbeltfoundduringthelastCassiniorbits.

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FieldsandParticlesInvestigationsbytheEuropaClipperMissionKorth,H.,JohnsHopkinsUniversityAppliedPhysicsLaboratoryPappalardo,R.T.,Senske,D.A.,Kempf,S.,Raymond,C.A.,Waite,J.H.,Westlake,J.H.,EuropaClipperScienceTeam

TheEuropaClippermissionwillexploreJupiter’sicysatelliteEuropatoinvestigateitshabitability.Themission’sscienceobjectiveswillbeaccomplishedusingasuiteofremote-sensingandin-situinstruments,thelatterprovidingobservationsofthemagneticfieldandparticleenvironmentsnearEuropaand,forcomparison,throughoutthesampledregionoftheJovianmagnetosphere.TheInteriorCharacterizationofEuropausingMagnetometry(ICEMAG)investigationwillmeasuremagneticfieldsgeneratedbycurrentsinducedinEuropa’ssubsurfaceocean,ionizedmaterialejectedfromanyplumes,andelectromagneticcouplingofthemoontoJupiter.ThePlasmaInstrumentforMagneticSounding(PIMS)willmeasureionsandelectronsinEuropa’satmospheretoinferthecontributionstothemagneticfieldfromplasmacurrentsandtounderstandtheinteractionandcouplingoftheplasmawiththemoon’ssurfaceandwithJupiter.TheMAssSpectrometerforPlanetaryExploration(MASPEX)measurestraceneutralspeciestodeterminethecompositioninEuropa’ssputter-producedexosphereandpotentialplumes.Finally,theSUrfaceDustAnalyzer(SUDA)willmapthechemicalcompositionofparticlesejectedfromEuropa’ssurfaceandidentifythemakeupofpotentialplumesbydirectlysamplingmicroscopicparticlesoriginatingfromthesurface,entrainedintheplumes,ordeliveredfromelsewherewithinoroutsidetheJoviansystem.Themissionplanimplementsasynergisticsetofobservationsamongtheseinstrumentstocharacterizetheice-shellthickness,oceanthicknessandsalinity,compositionofmaterialsmakingupEuropa’ssurfaceanditssubsurfaceocean,andanycurrentplumeactivity.Wepresentthesuiteofin-situinstrumentsandthemissionplanthatimplementsthemeasurementsrequiredtomeetthescienceobjectivesoftheEuropaClippermission.

Saturn’sthermospherefromCassini/UVISGrandFinalestellaroccultationsKoskinen,T.T.,LPL,UniveristyofArizonaBrown,Z.L.,West,R.A.,Jouchoux,A.,Esposito,L.W.

AglobalpictureofSaturn'supperatmosphereisnecessarytounderstandthedynamics,energybalanceandminorspeciescompositioninthethermosphere.OccultationdatafromVoyager/UVSandCassini/UVIShavebeenusedtostudythispoorlyknownregionoftheatmosphere.Thepreviousdata,however,arelargelyconcentratedatlowtomid-latitudesandwereobtainedsporadicallyatdifferenttimes,complicatingtheseparationoftemporalandspatialtrends.TheGrandFinaleoccultationsovercometheselimitationsasmostofthedatawereobtainedwithinsixweeksinthesummerof2017.Togetherwiththeobservationsfrom2016,theyprovideavitalnewlookatmeridionaltrendsinSaturn'sthermosphere.Wepresenttemperatureanddensityprofilesretrievedfromtheseoccultations,includingourfirstlookatthepolarthermosphere.

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FutureJovianMagnetosphericsciencewithJUICEKrupp,N.,MaxPlanckInstituteforSolarSystemResearchMasters,A.;Witasse,O.;Barabash,S.;Wahlund,J.-E.;Dougherty,M.K.;Gladstone,R.

JUICEisthefirstlargemissionintheESACosmicVisionprogram.Thespacecraftwillbelaunchedin2022andwillarriveatJupiterin2029.ItwillspendthreeyearscharacterizingtheJoviansystem,theplanetitself,itsgiantmagnetosphere,andtheicymoonsGanymede,Callisto,andEuropa.JUICEwillthenorbitGanymedeasthefirstspacecraftinhistoryforalmostayear.

Themaingoalofthemissionistoexploretheemergenceofhabitableworldsaroundgasgiants.WhileGanymedeisinthefocusoftheJUICE-missionalsothemagnetosphereofJupiterwillbestudiedingreatdetail.Thelong-termmagnetosphericsciencewillpushsignificantlybeyondthecapabilitiesofpreviousmissions.JUICEwillexploreJupiter’sequatorialmagnetospherecoveringawiderangeoflocaltimesandradialdistancestostudytheglobalandlocalmagnetosphericparameters,butthespacecraftwillalsostudyhigherlatitudesupto30degreestoexploretheregionsaboveandbelowthemagnetodisc,studyremotelytheringcurrentandtheJovianaurora.

WewillshowhowJUICEwillcarryoutitsmagnetosphericsciencegoaltocharacterizetheJovianenvironmentbystudyingthemagnetosphereasafastrotatorandagiantacceleratoraswellastryingtounderstandthemoonsassourcesandsinksofmagnetosphericplasma.Inaddition,wewillelaboratethesecondmagnetosphericsciencegoalofJUICEtocharacterizethemagnetosphereofGanymedeinunprecedenteddetailsincludingtheinteractionbetweenbothmagnetospheres.NovelElectronDistributionFunctionsAssociatedwithaSourceofBroadbandKilometricRadiationatJupiterKurth,W.S.,UniversityofIowaLouarn,P.,Imai,M.,Hospodarsky,G.B.,Allegrini,F.,Valek,P.,Connerney,J.E.P.,Kotsiaros,S.,Gladstone,G.R.,Adriani,A.,Mauk,B.H.,Louis,C.,Zarka,P.,andBolton,S.J.

Juno'spolarorbitmakesinsituobservationsofJovianauroralradioemissionsourcespossible.Whileitisgenerallyagreedthattheseradioemissionsaregeneratedviathecyclotronmaserinstability,itisimportanttounderstandthenatureoftheunstableelectrondistributionsforcomparisonswiththoseatEarthandasextraterrestrialexamplesofacommonastrophysicalradiosourcemechanism.DuringJuno'seleventhperijove(PJ11)on7February(Day038)2018,Junocrossedasourceofbroadbandkilometricradiationatabout80kHzduringanapproachtothesouthernmainauroraloval.Identificationofthesourcecomesfromnotingthatthelow-frequencylimitoftheradioemissionat18:12:58isnearly2%belowtheelectroncyclotronfrequency.Duringthisevent,therewasadearthoflowenergyplasma,suggestingaplasmacavity.Nearby,aringdistributionofelectronsaboveafewkeVwasmeasuredbytheJunoAuroralDistributionsExperiment.Thiselectrondistributionwascertainlyhighlyunstableandpossiblysimilartoso-calledhorseshoedistributionsinEarth'sauroralradiosources.Theradiosourceisalsocoincidentwithadeflectioninthemagneticfieldconsistentwithanauroralcurrentsystem.

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AbriefoverviewofauroralprocessesonUranusandNeptuneLamy,L.,LESIA,ObservatoiredeParis

OurcurrentknowledgeofauroralprocessesprevailingonthemagnetictwinsUranusandNeptune,andoftheunderlyingsolarwind-magnetosphere-ionosphereinteraction,stillmostlyreliesonVoyager2radio/UVandinsituobservationsobtainedduringtheflybyofeachplanet,respectivelyin1986andin1989.Theseobservationswereadditionallyacquiredatepochscorrespondingtospecificsolarwind/magnetosphereconfigurations,expectedtovarysignificantlyforbothplanetsalongtheirrevolutionaroundtheSun.Fortunately,whilewaitingforfutureindepthexplorationmissionsoficegiantplanets,someadditionalclueswerein-betweenobtainedfromremotelong-termEarth-basedUV/IRobservationswhichsampleddifferentseasons.TheaimofthispresentationistostartfromtheVoyager2originalpicturebeforetointroducemorerecentresultsuptothelatestmulti-spectralobservingcampaignsexecutedatbothplanetslate2017.ThelowfrequencysourceofSaturn’sKilometricRadiationLamy,L.,LESIA,ObservatoiredeParisP.Zarka,B.Cecconi,R.Prangé,W.Kurth,G.Hospodarsky,A.Persoon,M.Morooka,J.-E.WahlundandG.Hunt

Understandingthegenerationofplanetaryauroralradioemissions,thepowerfulnon-thermalradiationsproducedbyallthemagnetizedplanetsexploredsofar,andactivelysearchedfromexoplanetsandmoremassiveobjects,requiresinsitumeasurementsfromwithintheirsourceregion.Duringthering-grazinghigh-inclinationorbitsspanninglate2016toearly2017,theCassinispacecraftsampledatthreeoccasionsthetopofSaturn’sKilometricRadiation(SKR)emissionregion,whoseintensificationshavelongbeenusedasasensitiveproxyoflarge-scalemagnetosphericdynamics.Thenarrow-bandedradiosourceswerecrossedatfrequenciesof10-20kHz,allinthenortherndawn-sidesector.Theyhostedextraordinarymodeemission,radiatedquasi-perpendicularlytothelocalmagneticfieldfrom6-12keVelectron-beamsconsistentwiththeCyclotronMasterInstabilityandembeddedwithinregionsofupwardcurrentsthemselvescoincidentwiththemainauroraloval.Overall,theSKRlowfrequencysourcesappeartobestronglycontrolledbytime-variableelectrondensities.

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CorrectingGalileo’sEnergeticParticleDetector(EPD)data;MethodologyandImplications.Lee-Payne,Z,AberystwythUniversityGrannde,M

Overthecourseofits8-yearmissiontheEnergeticParticleDetectorontheGalileosatellite,launchedin1989,tookdataontheJovianParticleenvironment.Inthehighradiationenvironment,theEPD’sCompositionMeasurementSystem(CMS)degradedovertime;highermassparticles,specificallyoxygenandsulphur,readatfarlowerenergiesandcountratesatlaterepochsinthemissions.Byconsideringthenon-steadyaccumulationofdamageinthedetector,aswellastheoperationoftheprioritychanneldatarecordingsysteminplaceontheEPD,acorrectioncanbemade.Amodelofdeadlayerbuild-upinsemiconductor-detectorsisbuilt,basedonSRIMresults,andthenusedtoreversetheeffectsofthebuild-up.Theresultassignsanestimationofdead-layerdepthduringthemissiondatarecordings,andisusedtoproduceacorrectedversionofboththehighratedataandrealtimecountratesofallchannels.Theinferredsulphurabundancesareincreased.EnergeticiondynamicsnearCallistoLiuzzo,L.,GeorgiaInstituteofTechnologySimon,S.

WeexaminethedynamicsofmagnetosphericenergeticionsinthehighlyperturbedandasymmetricelectromagneticenvironmentoftheJovianmoonCallisto.TheAlfvenicinteractionofthe(nearly)corotatingmagnetosphericplasmawithCallisto'sionosphereandinduceddipolefieldgenerateselectromagneticfieldperturbationsnearthemoon,thestructureofwhichvariesasafunctionofCallisto'sorbitalposition.Forthisstudy,theseperturbationsareobtainedfromtheAIKEFhybridmodel(kineticions,fluidelectrons)whichhasalreadybeensuccessfullyappliedtoCallisto'slocalplasmaenvironment(Liuzzoetal.,2015,2016,2017).ToisolatetheinfluenceofCallisto'sionosphereandinduceddipolefieldonenergeticiondynamics,weanalyzethetrajectoriesofenergeticH+,O++,andS+++ionsforvariousconfigurationsofthelocalelectromagneticfields.WepresentspatiallyresolvedsurfacemapsthatdisplayaccessibilityoftheseionpopulationstoCallistoatselectenergiesfrom1keVto5000keV.TheAlfvenicinteractionwith(i)Callisto'sionosphere,(ii)Callisto'sinducedfield,and(iii)thecombinationofboth,allleavedistinctimprintsintheseaccessibilitypatterns.ThemagnetosphericfieldlinedrapingaroundCallisto'sionospherepartiallyshieldsthemoon'strailinghemispherefromenergeticionimpacts,andtheinducedfieldtendstofocusenergeticionimpactsnearCallisto'sJupiter-facingandJupiter-avertedapices.DependingonthenatureofCallisto'sAlfvenicplasmainteraction,theaccessibilityofitssurfacetoenergeticprotonsmayevolvenon-monotonicallywithincreasingenergy.Additionally,wecalculatemapsofenergeticionaccessibilityandtheresultingenergydepositionontoCallistoatthetimeoftheGalileoC3,C9,andC10flybys.

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AcomprehensivepictureofCallisto'smagneticandcoldplasmaenvironmentduringtheGalileoera:ImplicationsforJUICELiuzzo,L.,GeorgiaInstituteofTechnologySimon,S.

WeapplydataanalysistechniquesandhybridmodelingtostudyCallisto’sinteractionwithJupiter’smagnetosphere.MagnetometerdatafromtheC3andC9Galileoflybyshadbeenexplainedwithapureinductionmodel,astheplasmainteractionwasweak.Weexpandthisanalysistoincludetheremainingfiveflybys(C10,C21,C22,C23,C30)wheretheplasmainteractionwasnon-negligible.WethereforeconsidercontributionstoCallisto’smagneticenvironmentgeneratedbyinductionaswellastheplasmainteraction.Wehaveidentifiedaquasi-dipolar“coreregion”nearCallisto’swakesidesurface,dominatedbyinductionandpartiallyshieldedfromtheplasmainteraction.Outsideofthisregion,Callisto’smagneticenvironmentischaracterizedbyfieldlinedraping.FutureflybysduringtheupcomingJUICEmissionmaysamplethewakeside“coreregion”tobetterconstraintheconductivity,thickness,anddepthofCallisto’ssubsurfaceocean.Ouranalysisalsoshowsthatevenduringasingleflyby,variousnon-stationaritiesintheupstreamenvironmentmaybepresentnearCallisto,whichmaypartiallyobscurethemagneticsignatureofthemoon’ssubsurfaceocean.Overall,ourstudyprovidesacompletethree-dimensionalpictureofCallisto’smagneticenvironmentduringtheGalileoera,basedonallavailablemagnetometerdatafromtheGalileoflybys.WeapplyourunderstandingtothefutureJUICEflybysofCallistotodeterminewhichencounterswillbebesttoidentifyCallisto’sinductiveresponseinmagnetometerdata.AninvestigationintoradialandazimuthalcurrentsinJupiter'sMagnetodiscLorch,C,UniversityofLancaster,UKRay,L.C.Arridge,C.Martin,C.Bader,A

Jupiter’smagnetosphereandatmospherearecoupledviafield-alignedcurrentsthatflowalongtheplanetarymagneticfield,moveradiallyoutwardthroughthemagnetodiscandreturnbacktotheplanet,finallyclosingintheionosphere.Magnetosphere-ionosphere(MI)couplingisaffectedbylocaltimevariationsinthemagnetosphericcurrentswithinthemagnetodiscas∇·J=0.ProducingamapofthevariationsinthesecurrentsisimportantforunderstandingthemechanismswhichinfluencethemainauroralfeaturesobservedatJupiter.Khurana[2001]determinedtheradialandazimuthalcurrentswithinthemagnetodiscusingallavailablemagnetometerdatafromVoyager1&2,Pioneer10&11,Ulysses,andGalileothroughtoMay31st,2000.HereweextendupontheKhurana[2001]analysistoincludeallavailableGalileomagnetometerdatainordertoproduceamorecompletemapoftheradialandazimuthalcurrentsforallavailablelocaltimes.WeusetheVIP4modeloftheinternalmagneticfield(Connerneyetal.[1998])andaJupitercenteredlocalcurrentsheetreferenceframetoinvestigatethemagnetodisccurrents.Furthermore,wemakeacom-parisonbetweentheresultsobtainedusingtheKhurana[2001]currentsheetmodelandthemorerecentKhurana&Schwarzl[2005]currentsheetmodel,whichallowsthecurrentsheettobecomeparalleltothesolarwindatlargedistances.

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Onthesaturationmechanismsofthecyclotronmaserinstability-AninvestigationwithJunoLouarn,P.,IRAP/CNRSKurth,W.S.,Allegrini,F.,McComas,D.J.,Valek,P.W.,André,A.,Bagenal,F.,Bolton,S.,Connerney,J.,Ebert,R.W.,Imai,M.,Levin,S.,Szalay,J.R.,Wilson,R.J.

Junoplasma,waveandmagneticfieldobservations(JADE,WavesandMAGinstruments)haveconfirmedthatthecyclotronmaserinstabilityisthegenerationmechanismofthejovianauroralradioemissions,from10skHzto10sMhz.Afundamentalquestionconcernsitssaturationmechanism.Howis,infine,theintensityoftheradiowavesdetermined?Bywhatphysicalprocesses?Answeringthesequestionsisakeystepinprogresstowardsaquantitativetheoryoftheradioemissiongeneration.WeshowthatJunoobservationsofferasplendidopportunityforbetterunderstandingthesaturationmechanisms.UsingtheelectrondistributionfunctionsmeasuredbyJADE,onecanindeedusethecyclotronmasertheorytocalculatethenormalizedgrowthrate(theratiobetweenthegrowthandthegyrofrequency).Typicalvaluesof10-3areobtainedmeaningthatthetruegrowthratesvarybyalmost3ordersofmagnitude,fromafew100sHzto100kHz,dependingoftheradiodomains(deca,hectoandkilometric).Thesehugedifferencesshouldcorrespondtovarioustypesofsaturationmechanisms,includingsimpleconvectionoutofthesourceregion,quasi-linearrelaxationorthenon-lineartrappingtheory.Thesepossibilitiesareinvestigatedandcomparedwithwaveandparticleobservations.

Jupiterauroralemissions:statisticaldistibutionofradiosourcesLouis,C.,LESIA,ObservatoiredeParisP.Zarka,L.Lamy,S.Hess,R.Prangé,M.Imai,W.Kurth

InthisstudyweareinterestedinthepositionofthesourcesproducingtheJupiter'sauroralradioemissions.WehavepickupallthesourcescrossedfortheperijovesdoneyetbyJuno.Thisallowedustomaptheradiosources,aswellasassociatedmagneticfieldlines,overtheentirefrequencyrangecoveredbyJuno/Waves(50Hz-40MHz).ThecomparisonwithmagneticfieldmodelsandUVimages(Juno/UVSandHubble/STIS)revealedacorrelationbetweentheUVemissionofthemainovalandtheidentifiedradiosources(kilometric,hectometricanddecametric).

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AlfvenicAuroraatEarthandJupiterLysak,R.L.,UniversityofMinnesotaSong,Y.

ObservationsfromJunohaveyieldedunprecedentednewdetailabouttheacceleratedplasmapopulationsthatproduceJupiter’saurora.ManyofthesefeaturesarefamiliartothoseatEarth;however,therearealsomajordifferences.Bothinverted-Vandbroadbandtypeaccelerationmechanismsareobserved,althoughthebroadbandprecipitationseemstobemoredominantatJupiter.AtEarth,suchbroadbandaccelerationofparticlesisgenerallyassociatedwithtime-dependentaccelerationinkineticAlfvenwaves,whichdevelopaparallelelectricfieldinlow-betaplasmasduetoelectroninertiaandinthemoderatebetaregimeduetoelectronpressureandLandaudamping.Thus,theauroralemissionsassociatedwiththisbroadbandprecipitationareoftencalledtheAlfvenicaurora.GiventhedynamicnatureoftheauroraasobservedbyJuno,itislikelythatsimilarmechanismstakeplaceatJupiter.Anotherquestionistherelationshipbetweenbroadbandandinverted-Vprecipitation.AtEarthitappearsthattheAlfvenicauroraoccursintransitionregionssuchastheplasmasheetboundarylayerandduringsubstormonset,anditisreasonabletosupposethatthisisatransitionalstateandcanevolveintoamorestaticinverted-VtypeofaccelerationwhenasteadysupplyofPoyntingfluxcanbemaintained.However,atJupiter,theredoesnotappeartobethetypeoflarge-scalesteadycurrentsystemsthatappearatEarth,whichmayberelatedtotherelativelackofinverted-Vpopulations.Thelackofalarge-scalesystemassociatedwiththebreakdownofco-rotation,andthepatchynatureoftheaurorainthemainoval,suggeststhatthisregionoflargevelocityshearmaybeunstabletoinstabilitiesoftheinterchangetype.PotentialcandidatesforthisinstabilitywillbeinvestigatedandtheirpotentialforunderstandingtheJovianaurorawillbeassessed.Long-termvariationsandcorrelationsofJovianradiocomponentsMagalhaes,F.P.,NationalInstituteofSpaceResearch(INPE/Brazil)Magalhaes,F.P.;Echer,E.;Zarka,P.;Marques,M.S.;Dabidin,;Cecconi,B.;Louis,C;Lamy,L.;Kurthetal.

Jupiterhasastrongmagneticfieldandacomplexmagnetosphere.Asaconsequence,ithasverydiversezooofintenseradioemissions.Thehighlatitudeemissionsextendfromkilometrictodecametricwavelengths(bKOM,HOMandDAMcomponents).TheDAMcomponentisitselfsplitinemissionsthatarecontrolledbysatellite-Jupiterinteraction(Io,Europa,Ganymede)andauroralemissions.Moreover,nKOMemissionhasitsoriginintheIoplasmatorus.Inspiteofseveraldecadesofsatelliteobservations,therelationbetweenthesecomponents,andtheirlinktomagnetosphericdisturbances(internal,i.e.essentiallyIorelated,orexternal,i.e.solarwindrelated),isnotfullyunderstood.WehaveconductedadetailedanalysisofRPWSdatarecordedduringtheCassini-Jupiterflyby(fromOct.1st,2000toApril1st,2001).Thedatawerereduced,calibratedanddetrended(fordistance-relatedvariations),andacatalogofalloccurrencesofallradiocomponents(theaboveJovianonesandsolarTypeIIIbursts)wascreatedfromameticulousvisualselectionbasedontheirwellknowntime-frequencymorphology.Basedonthisselection,robustcorrelationsbetweencomponents(evenwhentheysharethesamefrequencyrange),spectralanalysesoftheirtimeseries,andstackedlongitude-frequencydynamicspectrawereperformed.CorrelationstudiesallowustoaddresstherelationbetweentheIotorusactivity(nKOM,Io-DAM)andtheauroralactivity(bKOM,HOM,DAM).SpectralanalysesallowustoaddressperiodicitiesrelatedtoSystemIIIversusSystemIVmodulations,aswellaslongerperiodsrelatedtoIo'svolcanismorthesolarwind.Stackeddynamicspectraprovide"signatures"ofeachradiocomponent,thatweattempstointerpretintermsofsourcelocationandbeamingproperties,inrelationwithmagnetosphericdynamics.Cassini-RPWSdataarefurthercorrelatedwiththeNancaylongtermDAMdatabase,andacomplementaryanalysishasstartedbasedonJuno-Wavesdata.

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StandingAlfvénwavesinJupiter'smagnetosphereasasourceof~10-60minutequasi-periodicpulsationsManners,H.,ImperialCollegeLondonMasters,A.

Jupiter’sgiantmagnetosphereexhibitsmanyphenomenathataredifficulttoexplain,andquasi-periodic(QP)pulsationsintheultra-low-frequency(ULF)bandhaveprovenespeciallymysterious.SincetheVoyagerera,alargebodyofULFmeasurementshasemergedwithperiodicities10-60minutes,spanningmagnetic,X-Ray,radioandplasmawaveperturbations.

PreviouspublicationsproposedtreatingULFmagneticperturbationsasstandingAlfvénwavesonJupiter’smagneticfieldlines.Inthisproposal,pulsationsareproducedwhencompressionalperturbationscoupletotransversemodes.Thesetransversewavesarereflectedbytheionosphere,therebyestablishingresonantfieldlineharmonics.Theresonantfieldlinesthenmodulatevariousprocessestoproducetheobservedpulsations.

WhetherallULFpulsationsaretheresultofthesamephenomenonhasbeenthesubjectofdebate.Furtherinvestigationintohowthedynamicsofthemagnetosphereaffecttheeigenperiodsofresonantfieldlinesisrequiredtoexplaintherangeofperiodicityinthereportedpulsations.

WehaveusedamagnetosphericboxmodeltocomputethenaturalperiodsoftheJovianmagnetosphereforvaryingequatorialplasmasheetconditions.Largeuncertaintiesinthespatialextentandplasmadensityoftheplasmasheetproduceabroadrangeofnaturalperiods.Theseuncertaintiesalsomeancontributionsfromeachharmonicareindistinguishableinouranalysis.Excludingthefundamentalmode,thefirsthalf-dozen(andpotentiallymore)harmonicshaveeigenperiodsof10-60minutes.WesuggestthatallsuchJovianULFphenomenamaybetheresultofstandingAlfvénwavesonJupiter'smagneticfieldlines.CurrentdensityinSaturn’sEquatorialCurrentSheetMartin,C.J.,PhysicsDepartment,LancasterUniversity,Lancaster,UKArridge,C.S.

Saturn’sequatorialcurrentsheetexhibitsanumberofperiodicmovementsassociatedwiththeseasonsandtheplanetaryrotationrate,alongwithaperiodicmovementsofacurrentlyunknownorigin.TheseaperiodicmovementsofthemagnetodiscareutilisedtocalculatetheheightintegratedcurrentdensityofthecurrentsheetusingamodifiedHarrissheetdeformedbyaGaussianwavefunction.Wefindalargeasymmetryintheradialheightintegratedcurrentdensityattributedtosweptforwardandsweptbackwardsfieldintheduskanddawnsectorsrespectively.WenotethatthisrelationshipisverysimilartowhatisseenatJupiterandcommentonthespatialversustemporaldifferencesinthecurrentdensityatSaturn.Additionally,acomparisonofSaturn,JupiterandEarth’sazimuthalandradialequatorialcurrentsarediscussed,andwefindthatSaturnexhibitssimilaritieswithboth.

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StatisticalAnalysisofFluxRopesinTitan’sIonosphere:Acomparisonofforce-freeandnon-force-freemethodsMartin,C.J.,PhysicsDepartment,LancasterUniversity,Lancaster,UKArridge,C.S.,Badman,S.V.,Wei,H.Y.,Russell,C.T.,Dougherty,M.K.

Fluxropesareacommonfeatureinmagnetisedplasmaregimesalloverthesolarsystem.85fluxropesareidentifiedusingtheCassinimagnetometerduringallofCassini’sTitanflybys.Weutiliseaforce-freefluxropemodeltoextractvaluesforthecorefieldofthefluxropeandtheradii,andcomparethesevaluesandthegoodnessoffittoanon-force-freemodelthatallowsthecurrentsgeneratedinthefluxropetobeanalysed.BothmethodsfitthefluxropesfoundinTitan’sionosphere,howeverthenon-force-freefluxropealongwithit’sassumptionsshowamuchimprovedfittoTitan’sfluxropesthantheforce-freemethod.Wediscussthephysicalmechanismsassociatedwiththeproductionandmaturationofthesefluxropesandcommentontheirvariability,alongwiththevariabilityofSaturn’smagnetosphericenvironmentatTitan’sorbit.ThemagnetospheresofUranusandNeptuneMasters,A.,ImperialCollegeLondon

ThemysteriousmagnetospheresofUranusandNeptunehavebarelybeenexploredbyspacecraft,yettheyaredistinctfromallothersolarsystemmagnetospheresinmanyrespects.Understandingthephysicsofthesemagnetospheresiscentraltounderstandinghowenergyflowsthrougheachglobal,coupledplanetarysystem.Hereweintroducethesehighlyasymmetricanddynamicicegiantmagnetospheres.WereviewwhatwelearnedfromthesnapshotofeachsystembyVoyager2inthe1980sandwhatwehavelearnedsince,focusingonthekeyopenquestionsthatwemustanswerinordertodeterminehoweachofthesemagnetosphericsystemsworks.Wewillconcludewithadiscussionofongoingpreparationandlobbyingforafuturemissiontooneofthesedistantplanets,wheremagnetosphericsciencemustbeamajordriver.

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Amoreviscous-likesolarwindinteractionwithallthegiantplanets?Masters,A.,ImperialCollegeLondon

Identifyingandquantifyingthedifferentdriversofenergyflowthroughaplanetarymagnetosphereiscrucialforunderstandinghoweachcoupledplanetarysystemworks.Themagnetosphereofourownplanetisdrivenexternallybythesolarwindviaglobalmagneticreconnection,aswellasthroughaviscous-likeinteractionunderpinnedbygrowthoftheKelvin-Helmholtzinstabilityasasecondaryeffect.Hereweshowthattherelativeimportanceofexternaldrivingbyaviscous-likeinteractionisexpectedtobegreateratthegiantplanetarymagnetospheresintheouterSolarSystem.WedemonstratethatthisresultsfromcombiningpresentunderstandingofthefundamentalprocessesinvolvedwiththeestablishedscalingoftypicalsolarwindparameterswithdistancefromtheSun.Ourresultssupportthepossibilityofaprimarilyviscous-likeinteractionbetweenthesolarwindandthegiantplanetmagnetospheres,asproposedbypreviousauthorsandincontrastwiththesolarwind-magnetosphereinteractionatEarth.AuroralaccelerationatJupiteranditspossibleroleincreatingJupiter’suniquelyenergeticradiationbeltsMauk,B.H.,TheJohnsHopkinsUniversityAppliedPhysicsLaboratoryHaggerty,D.K.,Paranicas,C.P.,Clark,G.B.,Kollmann,P.,Rymer,A.M.,Bolton,S.J.Levin,S.M.,Adriani,A.,Allegrini,F.,Bagenal,F.,Becker,H.N.,Bonfond,B.,Connerney,J.E.P.,Ebert,R.W.,Elliott,S.S.,Gladstone,G.R.,Kurth,W.S.,McComas,D.J.,Ranquist,D.,Valek,P.W.

TheelectronaccelerationprocessesthatgenerateJupiter’suniquelypowerfulauroraareunexpectedlydiverse.Broadbandacceleration,likelystochastic,providesthegreatestdownwardelectronenergyfluxesoverJupiter’smainauroralregions.Butelectricpotentialsalongthemainauroralfieldlinesaresometimespresent,attimesexceeding400kVineithertheupwardordownwarddirections.Hugedownwardelectronenergyfluxesareunexpectedlyobservedontheverysamefieldlineswherehugeelectricpotentialsarealsoacceleratingdownwardenergybeamsofprotons.Usingthemagneticfield-alignedpotentialdirectionalityasaproxyforthedirectionalityofmagneticfield-alignedelectriccurrents,themagnitudeofthedownwardelectronenergyfluxessurprisinglydoesnotseemtocareaboutthedirectionalityoftheelectriccurrents.Butthedirectionalityoftheelectricpotentialsdoesseemtoplayaroleindeterminingthecharacterofthebroadbandaccelerationprocessesandparticularlyintheup-downasymmetriesintheaccelerationprocesses.Surprisingly,evenoververyintenseUVaurora,theupwardaccelerationofelectronscanbecomparableandevengreaterthanthedownwardacceleration.Andmoresurprisingstill,theintensityoftheupwardlyacceleratedelectronsatMeVenergiescanbeasmuchas2ordersofmagnitudegreaterthantheintensityofJupiter’sradiationbelts.Basedonthatfinding,weexploreherethepossibilitythat,atJupiter,auroralaccelerationrepresentsthefirstaccelerationstepinthegenerationofJupiter’suniquelyenergeticradiationbelts.

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AnomalousPlasmaWavesObservedDuringCassini'sRing-grazingOrbitsMenietti,J.D.,UniversityofIowaPisa,D.,Sulaiman,A.H.,Averkamp,T.F.,Kurth,W.S.

InthefinalperiodoftheCassinimissionthespacecrafttrajectoryincluded20highinclinationring-grazingorbits.TheseorbitstraversedtheinneredgeoftheEnceladustorus,aregionofintenseZ-modeandnarrowbandemissionaswellasintenseupperhybridresonanceemission.Thelattersometimeshaveanomalousappearance,andcanbeassociatedwithsourcesofintenseelectromagneticemission.WehavesingledoutsimilaranomalousemissionwhichoccurredoccasionallyonpreviousCassiniorbitsthatlieclosetotheregiontraversedbythering-grazingorbits.ThesepreviousorbitsareimportantbecausewehaveaccesstoCassinielectronphasespacedistributionsforwhichwecanperformdispersionanalysistobetterunderstandthefreeenergysourceandinstabilityoftheanomalousemission.Webelievethisemissionmaysometimesbeassociatedwithdensityanomaliesandstrongdensitygradientsneartheringplane.Inthispaperwediscussourinitialresults.IdentificationofJupiter'shectometricradiationassociatedwithreconnectioninthemagnesphereMisawa,H.,GraduateSchoolofScience,TohokuUniversityTsuchiya,F.,Mizuguchi,T.

ItisknownthatJupiter'sradioemissioninthehectometricwaverange(HOM)showstwotypeoccurrencecomponents.Oneisacomponentrelatingtosolarwindvariations(sw-HOM)appearingaroundCML(CentralMeliansystemIIILongitudeofanobserver)=180degwhensolarwindpressureenhances.Anotheroneisgenerallymoreintensethansw-HOMandhasnoorweakrelationwithsolarwindvariations(nsw-HOM)appearingaroundCML=110degand280degasthetwomajorcomponentswhenDe(Jovicentricdeclinationofanobserver)=-1deg(Nakagawa,2003).Thensw-HOMisthoughttobegeneratedbysomeinternalprocessesinitiatedbytherapidplanetaryrotationandmassiveplasma,howeverprecisesourceprocessesandlocationshavenotbeenclarifiedyet.

WehavereanalyzedoccurrencecharacteristicsofHOMusingtheWIND/WAVESdatatoinvestigatepreciserelationbetweenoccurrenceofnsw-HOMandJupiter'smagnetosphericvariationsobservedbytheGalileoJupiterorbiter.Asaresult,wefoundthatHOMhasthe3rdnsw-HOMcomponentappearingfrom340degto+20deginCMLwhichgenerallyappearsquasiperiodicallywiththetimescaleofafewtoseveraldaysandalsoshowslong-termoccurrencevariationswithseeminglycapricioustimescales.Acomparisonstudybetweentheoccurrencetimingofthe3rdnsw-HOMandmagnetosphericeventsfortheGalileoeraindicatesthatmostofthe3rdnsw-HOMappearedwhenmagneticreconfigurationeventsoccurredinthemagnetotailregion.Theresultsuggeststhatthe3rdnsw-HOMshallbeoneofgoodremoteproxiesindicatingoccurrenceofJupiter'sinternalglobalvariations.

Acknowledgement:TheWIND/WAVESdatawereobtainedfromtheNASAWIND/WAVESteampage.WewouldliketothankM.L.KaiserandtheWIND/WAVESteamforprovidingthedata.

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D-RingDustFallingintoSaturn’sEquatorialUpperAtmosphereMitchell,D.G.,JHU/APLPerry,M.E.,Hamilton,D.C.,Westlake,J.H.,Kollmann,P.,Smith,H.T.,Carbary,J.F.,Waite,Jr.,J.H.,Perryman,R.,Hsu,H.-W.,Wahlund,J.-E.,Morooka,M.W.,Hadid,L.Z.,Persoon,A.M.,KurthW.S.

WepresentdirectmeasurementsoftheentryofdustfromSaturn’sinnermostring(theD-ring)intoSaturn’sequatorialatmosphere.BasedonmeasurementsbytheCassinimagnetosphericimaginginstrument,measurementsthatwerenotanticipatedbefore-handandrepresentingaresponsetohypervelocitydustthatwasnotcalibrated,thedataneverthelesspresentclearevidenceforthedirectentryofnanometersizeddustgrainsasatmosphericdrag(collisionswithexospherichydrogenatoms)reducestheirorbitalvelocitiesandcausesthemtode-orbitinlessthanonerevolutionabouttheplanet.ThisrepresentsanewmechanismforthedepositionofringmaterialintoSaturn’satmosphere,uniquetotheD-ring(althoughsimilartooneproposedbyBroadfootetal.,1986atUranus).Unlikethemuchdiscussed‘ringrain’,thismechanismdoesnotinvolvedustchargingandelectromagneticinteractions(althoughthoseeffectsdoaltertheobserveddistributions),butratheradirectkineticinteractionbetweenSaturn’sexosphereanditsinnermostring.Aninterestingpredictionthatarisesfromtheanalysisofthisphenomenonisthattheinteractionshouldalsoproduceanadditional,veryhighaltitude(uptomanySaturnradii),veryanisotropic(nearequatorial)componenttoSaturn’shydrogenexosphere,aseachgrain-Hcollisionwillresultinaveryhigh-speedHatom,biasedstronglyinthedirectionofthegrainorbitalmotion.EachprecipitatinggraincanpotentiallyproducehundredsoftheseenergeticHatoms.ThismechanismmayexplainthehydrogenplumeobservedbytheCassiniUVISinstrument,asdescribedinShemanksyetal.,2009D.E.Shemansky,X.Liu,andH.Melin,Planet.SpaceSci.,57,1659(2009).A.L.Broadfootetal.ScienceVol.233,Issue4759,pp.74DOI:10.1126/science.233.4759.74(1986)ObservationsoftheJoviansodiumnebulaandIoplasmatoruswiththeIoInput/OutputFacility(IoIO)Morgenthaler,J.P.,PlanetaryScienceInstitute

TheIoplasmatorusisacollectionofionstrappedinJupiter'smagneticfieldnearIo'sorbitalradius.Basedonestimatesandmodelingoftheinterchangeinstability,theresidencetimeoftorusionsshouldbe~10hours.Theobservedresidencetimesare20--80days.Whatphysicalmechanismisimpedingradialdiffusionfromthetorus?A35cmroboticcoronagraph,theIoInput/OutputFacility(IoIO)hasbeenconstructedtohelpanswerthisquestion.IoIOhasoperatedforover130nightssinceMarch2017,recordingover2600observationsofthetorusandover700observationsoftheinnerJoviansodiumnebula.Thesodiumimagesextendtoadistanceof>80Rjandshowthedetailedstructureofthe"banana"and"stream"emissions.Theseimagescanbeusedtomeasurevariationinvolcanicactivityandconstrainmodelsoftheflowofneutralmaterialintheinnermagnetosphere.Thetorusimagescanbeusedtoestablishthetimehistoryof[SII]6731Aemissionsandvariationsinthemagnitudeofthedawn-duskelectricfield.Together,thesedataprovideachronologyofthematerialflowingintoandoutoftheplasmatorusandcanbeusedtohelpdeterminethephysicalmechanismwhichimpedesradialdiffusionfromthetorus.ThisprojectissupportedbyNSFgrantAST1616928tothePlanetaryScienceInstitute.

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Saturn’sDustyIonosphereMorooka,M.W.,IRF(SwedishInstituteofSpacePhysics),UppsalaWahlund,J.-E.

Wepresentobservationsofelectronandiondensities,thecharacteristicionmass,aswellastheelectrontemperatureobtainedbytheLangmuirProbeonboardCassiniduringtheGrandFinalorbits.Athighaltitudesabove2,500km,weidentifiedmostofthetimethattheplasmaisdominantinH+,however,someorbitsshowedanincreaseofcharacteristicionmassandelectrondensitydepletionaroundtheequator,thatindicatesthepresenceofnegativelychargeddust.Atlowaltitudesbelow2,500km,plasmadensitiesincreaserapidlyandiondensity(Ni)increasesfasterthantheelectrondensity(Ne).ThesmallNe/Niratioindicatesthepresenceofadustyplasma,aplasmathatcontainsnegativelychargedheavyparticlespredominantly.ComparisonwiththelightiondensitiesobtainedbytheIonandNeutralMassSpectrometer(INMS)indicatesthepresenceofheavyions.Apositivefloatingpotentialoftheprobehasalsobeenobservedwhentheiondensitiesareinexcessoftheelectrondensities.ElectrontemperatureenhancementshavealsofoundinthesmallNe/Niregion.TheobservationssuggestthattheplasmaofSaturn’sionosphereconsistsofbothnegativelyandpositivelychargedheavyclusterions.ObstructionofLowEnergyElectronTrajectoriestoJADE-EDuetoJupiter’sStrongMagneticFieldanditsEffectonPitchAngleMeasurementsMunoz,J.,Jr.,UniversityofTexasatSanAntonioAllegrini,F.,Valek,P.W.,Ebert,R.W.,Bagenal,F.,Kim,T.K.,Louarn,P.,McComas,D.J.,Wilson,R.J.

TheJovianAuroralDistributionExperiment-Electronsensors(JADE-E)onJunomeasureelectronsfrom0.1to100keVwithafield-of-view(FOV)of240degreesby3-5degreesthatcanbeorientedtotrackthedirectionofthemagneticfield.Intheabsenceofamagneticfield,theFOVisun-obstructed.However,inJupiter’sstrongmagneticfield,lowenergyelectronsmayhitotherspacecraftstructuresandneverreachJADE-Eduetotheirsmallgyro-radius.Preliminarystudieshaveshownthatlowenergyelectronshavingpitchanglesnear90degreesareaffectedanddonotmakeittotheinstrumentaperture.Inthisproject,wemodelelectrontrajectoriesaroundtheJunospacecrafttoquantifytheobstructiontoJADE-E’sFOVasafunctionofpitchangleandenergy.Todothis,weutilizetheionopticssoftwareSIMION8.1tosimulateelectronsflyingbackwardintimeleavingtheJADE-Esensorsoutward.Weaccountforspinphaseforeachofthe64energysteps.Iftheelectronshitastructureontheirway,thentheSIMIONsoftwareassignsthemanumberdesignatingthemtoablindspot.ThissimulationtoolrunsonesecondatatimeandcanbeusedtoevaluateFOVobstructionsaffectingflightdata.

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Juno/JIRAMobservationsofJupiter’smainauroraeandsatellitefootprints.Mura,A.,INAFAdriani,A.;Altieri,F.;Bagenal,F.;Bolton,S.;Bonfond,B.;Connerney,J.;DinelliB.M.;GérardJ-C.;Grodent,D.;Greathouse,T.K.;Levin,S.;Mauk,B.;Moriconi,M.;Plainaki,C.;Saur,J.;Waite,H.

JIRAM(JovianInfraredAuroralMapper)onboardJunoisanimager/spectrometerinthe2-5umrange.OneimagerchannelsisdesignedtostudytheJovianH3

+auroralemissions.Itshighangularresolution,combinedwiththeuniquevantagepointprovidedbyJuno,allowsJIRAMtoobservetheauroraewithunprecedenteddetails.

Herewepresenttheresultsof~2yearsofauroralobservations,withparticularemphasisontheauroralfootprintsoftheGalileanmoons.Thesearebrightspots(withassociatedtail)thatappearinJupiter’sionosphereatthebaseofthemagneticfieldlinesthatsweeppastIo,Europa,andGanymede.ThemoonsareobstaclesinthepathofJupiter’srapidlyrotatingmagnetosphericplasmaandtheresultingelectromagneticinteractionlaunchesAlfvénwavesalongthemagneticfieldtowardsJupiter,whereintenseelectronbombardmentofthehydrogenatmospherecausesittoglow.

RecentobservationsrevealforthefirsttimethatthefootprintofIoiscomprisedofaregularlyspacedarrayofemissionfeatures,extendingdownstreamoftheleadingfootprint,resemblingarepeatingpatternofswirlingvortices(vonKármánvortexstreet)shedbyacylinderinthepathofaflowingfluid.ContrarytothelargerspotsseenintheUV,thesmallscaleofthesemultiplefeatures(~100km)isincompatiblewiththesimpleparadigmofmultipleAlfvénwavereflections.Additionally,observationsofIo’strailingtailwelldownstreamofthemainfootprintrevealapairofcloselyspacedparallelarc,previouslyunresolved.

Thetemperaturesofthemainspotandtail,retrievedwiththespectrometer,arelowerthanthemainauroraloval.Thiscouldindicatethattheemissionislocatedatadeeperlevel,possiblycausedbyhigherenergyelectrons.

BothofGanymede’sfootprintspots(mainandsecondary)appearasapairofemissionfeaturesthatevidentlyprovidesaremotemeasureofGanymede’smagnetosphere,mappedfromitsdistantorbitontoJupiter’sionosphere.

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ResponseofJupiter'sinnermagnetospheretosolarwindderivedfromHisakiandJuno/JADEobservationsMurakami,G.,JapanAerospaceExplorationAgencyKita,H.,Ebert,R.W.,Kimura,T.,Tao,C.,Tsuchiya,F.,Yoshioka,K.,Yamazaki,A.,Wilson,R.J.,Valek,P.W.,Allegrini,F.,Clark,G.,Smith,T.,Suzuki,F.,Hikida,R.,Yoshikawa,I.,andFujimoto,M.

BecauseJupiter’smagnetosphereishugeandisrotationallydominated,solarwindinfluenceonitsinnerparthasbeenthoughttobenegligible.Meanwhile,dawn-duskasymmetricfeaturesofthisregionhavebeenreported.Presenceofadawn-to-duskelectricfieldisoneoftheleadingexplanationsoftheasymmetry;however,thephysicalprocessofgeneratingsuchanintenseelectricfieldstillremainsunclear.UsinglongandcontinuousmonitoringoftheextremeultravioletemissionsfromtheIoplasmatorus(IPT)inJupiter’sinnermagnetospherebytheHisakisatellitebetweenDecember2013andMarch2014,itwasrevealedthatthedusk/dawnbrightnessratiooftheIPTclearlyrespondstorapidincreasesofthesolarwinddynamicpressure.Theobservationsindicatethatdawn-to-duskelectricfieldintheinnermagnetosphereisenhancedundercompressedconditions.Inordertounderstandthephysicalprocessbetweenthesolarwindandthedawn-to-duskelectricfield,thetimescaleoftheresponseisakeyparameter.NASA’sJunospacecraftmeasuredthesolarwindduringitsapproachphasetoJupiter.WecomparedthesolarwinddynamicpressuremeasuredbyJuno/JADEandthedawn-duskasymmetryofIoplasmatorusobservedbyHisakifrom16May2016to25June2016.WefoundthreecleareventsoftheIPTresponsetosolarwinddynamicpressurevariationsandtheaverageresponsetimeis~13hours.Thistimescalecanbeanimportantconstrainttohelpidentifythephysicalmechanismofsolarwindinfluence.Long-termvariationoftheNorth–SouthasymmetryintheintensityofSaturnKilometricRadiation(SKR)in2004-2017Nakamura,Y.,DepartmentofGeophysics,GraduateSchoolofScience,TohokuUniversityKasaba,Y.,Kimura,T.,Lamy,L.,Cecconi,B.,Fischer,G.,Sasaki,A.,Tao,C.,Tsuchiya,F.,Misawa,H.,Kumamoto,A.,Morioka,A.

Thisstudyinvestigatesthelong-termvariationofSaturnKilometricRadiation(SKR)intensityobservedbytheRadioandPlasmaWaveScience(RPWS)instrumentonboardtheCassinispacecraftfrom2004(southernsummer)to2017(northernsummer).

Kimuraetal.[2013]studiedthelong-termvariationofSKRintensityinthesouthernsummerseasonfrom2004to2010andshowedthatSKRwasbrighteronthesummersidethanonthewinterside.WeextendedthisstudyuptoSeptember2017,takingadvantageofradioobservationsacquiredoverthewholeCassinimission.

Inthelong-termvariations,thetotalnorthernSKRfluxdidnotlargelychangefrom2004to2017,whilethetotalsouthernSKRfluxbecame100timessmalleratnorthernsummerthanatsouthernsummer.Astheresult,theintensityratioofsouthernSKRtonorthernSKRevolvedfrom~10aroundmidsouthernsummer(2004),reducedto~1aroundequinox(2009),andto~0.1inmidnorthernsummer(2015).Theseresultsshowthat(1)SKRisbrighterinthesummerhemisphere,inagreementwithKimuraetal.[2013],(2)thereversalintheintensityratiowasmainlycausedbythelong-termreductionofthesouthernSKRintensity,and(3)thelong-termvariationoftheintensityratiowasnotclearlysynchronizedtothatofnorthernandsouthernSKRrotationalperiods.WedidnotfindacorrelationbetweentheSKRintensitiesandthesolarEUVflux.WethusconcludethattheseasonalvariationofsolarEUVilluminationofSaturn’sionospheredonotsimplycausetheSKRintensityvariations.

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StudyoftheJovianmagnetosphere-ionospherecouplingusinganionosphericpotentialsolver:ContributionsofH+andmeteoricionstoionosphericconductivityNakamura,Y.,DepartmentofGeophysics,GraduateSchoolofScience,TohokuUniversityTerada,K.,Tao,C.,Terada,N.,Kasaba,Y.,Kita,H.,Nakamizo,A.,Yoshikawa,A.,Ohtani,S.,Tsuchiya,F.,Kagitani,M.,Sakanoi,T.,Murakami,Go.,Yoshioka,K.,Kimura,T.,Yamazaki,A.,Yoshikawa,I.

ThecorotationofJovianmagnetosphericplasmadominatestheconvectionintheJovianinnermagnetosphere.Therefore,thesolarwindhardlyinfluencestheplasmaconvectionthere.However,theHisakisatelliteshowedthatthebrightnessintensityoftheIoplasmatorus(IPT)changedasymmetricallybetweenthedawnandthedusksidesandthischangecoincidedwitharapidincreaseinthesolarwinddynamicpressure.Suchchangecanbeexplainedbytheexistenceofadawn-to-duskelectricfieldof~4-9mV/maroundIo’sorbit.Thedawn-to-duskelectricfieldshiftsthepositionofIPTtowarddawnsideby~0.1-0.3RJandtheplasmaintheIPTisadiabaticallyheatedatduskandcooledatdawn,whichmakesthedawn-duskbrightnessasymmetry.Thefollowingprocesseshavebeensuggestedasapossiblecauseofthedawn-to-duskelectricfield.First,theJovianmagnetosphereiscompressedbyanincreaseinthesolarwinddynamicpressure.Then,theM-Icurrentsystemismodified,andtheFACconnectedtothehigh-latitudeionosphereincreases.Asaresult,theionosphericelectricpotentialincreasesandpenetratestolowerlatitudes.Itismappedtotheequatorialplaneoftheinnermagnetospherealongmagneticfieldlines,andthedawn-to-duskelectricfieldiscreatedaroundIo’sorbit.

Inordertodemonstratethisscenarioquantitatively,weconstructeda2-Dionosphericpotentialsolver,whichwascomposedofaphotochemicalmodel,aheight-integratedconductivitymodel,andaPoissonequationsolver.Wecalculatedtheionosphericpotentialandtheresultingdawn-to-duskelectricfieldatIo’sorbitusingFACsestimatedfromGalileoobservations.Thecalculateddawn-to-duskelectricfieldmarginallyagreedwiththeHisakiobservationsonlywhenweaddedH+andmeteoricionstoourphotochemicalmodel.OurresultssuggestthattheH+andmeteoricionsplayamajorroleindeterminingtheionosphericconductivityandtheelectricfieldintheJovianinnermagnetosphere.

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WhathasbeenlearntabouttheradiationbeltsofJupiterwiththephysicalmodelSalammbôNenon,Q.,ONERASicard,A.Kollmann,P.Garrett,H.B.

Thedistributioninkineticenergy,latitudeandradialdistanceofthehigh-energyparticlefluxesencounteredintheradiationbeltsofJupiterisdrivenbythevariousphysicalprocessesactingonthetrappedparticles.Eventhoughthesebeltshavebeenobservedremotelysince1959andin-situsince1973,disentanglingthephysicalmechanismsattheoriginoftheobservedfluxesonlyfromtheobservationsremainsdifficult,sothatamodelingeffortisneeded.Forinstance,whatdoesremove99%ofMeVprotonsnearIo’sorbit,asobservedbyPioneer10-11,Voyager1,GalileoandJuno?Isitanabsorptioneffectofthevolcanicmoon,chargeexchangewithitsneutraltorus,Coulombcollisionswiththeplasmatorusorpitch-anglescatteringbyEMICwaves?

Ononehand,in-situobservationsarecarefullyselectedanddiscussedinthispresentation.Forinstance,GalileoProbeprotonmeasurementsfrom1.8Rjto2.3RjfromthecenterofJupiterarenotanevidenceforaprotonsourcenearthegiantplanet(CRAND)butarecontaminatedbyheavyions.

Ontheotherhand,allthephysicalprocessesabletoshapetheradiationbeltsaremodeledintheglobalphysics-basedmodelnamedSalammbô,developedsince1998atONERAandrecentlyrevisited.

ThispresentationwillshowhowthecomparisonbetweenthefluxespredictedbytheSalammbômodelandtheobservationsenablestodeterminethedominantmechanismsatworkintheradiationbelts.

Themainresultsofourstudywillbediscussed.Inparticular,wewillpointoutthatpitch-anglescatteringbyEMICwavesobservedbyGalileo-MAGandHiss-likewavesobservedbyGalileo-PWSseverelylimitstheintensityofMeVprotonsandelectronsnearIo’sorbit.Ifwave-particleinteractionwasnotefficientinthemagnetodisc,theinnermostradiationbeltsofJupiterwouldbe20to50timesharsherthanwhatisobserved.ConstrainingPlasmaConditionsoftheIPTviaSpectralAnalysisofUV&VisibleEmissionsandComparingwithaPhysicalChemistryModelNerney,E.G.,LASP,UniversityofColorado,BoulderBagenal,F.

Ioemitsvolcanicgasesintospaceatarateofaboutatonpersecond.ThegasesbecomeionizedandtrappedinJupiter’sstrongmagneticfield,formingatorusofplasmathatemits2terawattsofUVemissions.Inrecentworkre-analyzingUVemissionsobservedbyVoyager,Galileo,&Cassini,wefoundplasmaconditionsconsistentwithaphysicalchemistrymodelwithaneutralsourceofdissociatedsulfurdioxidefromIo(Nerneyetal.,2017).InfurtheranalysisofUVobservationsfromJAXA’sHisakimission(usingourspectralemissionmodel)weconstrainthetoruscompositionwithgroundbasedobservations.Thephysicalchemistrymodel(adaptedfromDelamereetal.,2005)isthenusedtomatchderivedplasmaconditions.Wecorrelatetheoxygentosulfurratiooftheneutralsourcewithvolcaniceruptionstounderstandthechangeinmagnetosphericplasmaconditions.OurgoalistobetterunderstandandconstrainboththetemporalandspatialvariabilityoftheflowofmassandenergyfromIo’svolcanicatmospheretoJupiter’sdynamicmagnetosphere.

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TransportandTurbulentHeatinginSaturn’sMagnetosphere.Neupane,Bishwa,UniversityofAlaskaFairbanksPeterDelamere,BrandonBurkholder,C.-S.Ng

Saturn'smagnetodiscisrapidlyrotatingwithaninternalplasmasource.Radialtransportoccursbyacentrifugally-driveninterchangeinstability,determinedbyradialgradientoffluxtubecontentandfluxtubeentropy.Plasmaproducedintheinnermagnetospheremustbetransportedradiallyoutward.Theoutwardmotionoftheplasmastretchesthemagneticfieldlines,leadingtoamagnetodiscconfiguration.Reconnectionallowsmagneticfluxtocirculatebacktotheinnermagnetosphere.Saturn'smagnetodisccanbecategorizedasactiveorquiet.Theactiveperiodisdefinedwherewehavesignificantvariationinallthreecomponentsofmagneticfield(andwhereweseeanumberofcurrentsheetcrossings).However,inthequietperiod,theexpectedstructureofthemagnetodiscispresent(i.e.positiveBθwithradialandazimuthalcomponentspresentbutnocurrentsheetcrossings).Wehavefoundthatroughly1%ofthetimethemagnetodisccanbecategorizedas"active".Duringtheactiveperiod,itissuggestedthatturbulenceisthesourceofplasmaheating.Therequiredheatingratedensity(BagenalandDelamere,2011)ofthewholemagnetosphereiscomparablewiththeheatingintheactiveregions.Wehaveobservedactiveeventsnotonlyattheequatorialplanebutalsoathigherlatitude(greaterthan10degree).Thedwelltimenormalizationofactiveeventshowsthatmostoftheeventshappenbetween10degreeto20degreelatitude.Wewilldiscussthespotheatingandtransportassociatedwiththeactiveregionsofthemagnetosphere.Goings-oninJupiter'sauroras:PeriodicemissionwithinJupiter’smainauroralovalandshorttimescalevariationsinthemotionoftheGanymedefootprintNichols,J.D.,UniversityofLeicesterBonfond,B.,Bunce,E.J.,Chowdhury,M.N.,Cowley,S.W.H.,Robinson,T.R.,Yeoman,T.K.

InthispresentationwediscusssomeresultsfromaprogrammeofHubbleSpaceTelescopeobservationsofJupiter’sFUVaurorasobtainedduring2016.Inparticular,wehavediscoveredpulsatingemissionwithinJupiter’smainauroraloval,providingevidenceoftheauroralsignatureofJovianULFwaveprocesses.Theformcomprisesa1O×2Ospotlocateddirectlyonthemainemission,whoseintensityoscillateswithaperiodof~10minthroughoutthe45minobservation.Thefeatureappearsontheduskwardedgeofthediscontinuity,mapsto~13–14hLTand~20–50RJ,androtatesataroundahalfofrigidcorotation.WeshowthattheperiodoftheoscillationissimilartotheexpectedAlfvéntraveltimebetweentheionosphereandtheupperedgeoftheequatorialplasmasheetinthemiddlemagnetosphere,andwethussuggestthatthepulsatingauroraisdrivenbyamodeconfinedtothelow-densityregionoutsidetheplasmasheet.Wealsodiscussthediscoveryofshort(10min)timescalevariationsinthelocationoftheGanymedeauroralfootprint,whichpossiblyindicatechangesintheambientplasmadensitynearGanymede.

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Theatmosphericconsequencesofmid-latitudemagnetosphere-ionospherecouplingatSaturnO'Donoghue,James,NASAGoddardSpaceFlightCenterMoore,L.,Connerney,J.E.P.,Melin,H.,Stallard,T.,Miller,S.,Baines,K.H.

Weperformedanewanalysisofground-basedobservationsthatweretakenon17April2011usingthe10-metreKecktelescopeonMaunaKea,Hawaii.H3

+emissionswerepreviouslyanalyzedfromtheseobservations,indicatingthatpeaksinemissionatspecificlatitudeswereduetoaninfluxofchargedwaterproductsfromtheringsknownas'ringrain'.SubsequentmodelingshowedthatthesepeaksinemissionarelikelydrivenbyanincreaseinH3

+density,ratherthantemperature,asalocalreductioninelectrondensity(duetochargeexchangewithwater)lengthensthelifetimeofH3

+.However,missinguntilnowwasadirectderivationoftheH3

+parameterstemperature,densityandradiance,whicharerequiredtoconfirmandexpandonexistingmodelsandtheory.HerewepresentmeasurementsoftheseH3

+parametersforthefirsttimeinthenon-auroralregionsofSaturn.Weconfirmthatindeed,H3

+densityisenhancedneartheexpected'ringrain'planetocentriclatitudesof45Nand39S.Inaddition,theH3

+densityisremarkablyhighat39S,likelyduetothesouthward-inclinedmagneticfieldinthevicinityoftheringplane,whichleadstochargedgrainsbeingimmediatelydrawnsouthwardsduetogravitationalforcesinthatregion.Ananti-correlationbetweenH3

+temperatureanddensitywasalsoobservedat39S,potentiallyindicatingthatmostchangetotheionosphereduetoringrainisinthedeepionosphere.Finally,Saturn'sicymoonEnceladusappearstobrightenH3

+at61S,perhapsduetoawaterinfluxbutwithanunknowntransportmechanism.AuroralstormandpolararcsatSaturn–FinalCassini/UVISauroralobservationsPalmaerts,B.,LPAP,UniversityofLiegeRadioti,A.,Grodent,D.,Yao,Z.H.,Bradley,T.J.,Roussos,E.,Lamy,L.,Bunce,E.J.,Cowley,S.W.H.,Krupp,N.,Kurth,W.S.,Gérard,J.-C.andPryor,W.R.

On15September2017theCassinispacecraftplungedintoSaturn'satmosphereafter13yearsofsuccessfulexplorationoftheSaturniansystem.Thedaybefore,theUltravioletImagingSpectrograph(UVIS)onboardCassiniobservedSaturn'snorthernauroraforabout14h.InthisfinalUVISsequence,severalauroralstructuresappear,revealingprocessesoccurringsimultaneouslyinSaturn'smagnetosphere.Apolewardexpansionandabrighteningofthemainemissiondawnarc,aphenomenonknownasanauroralstorm,suggeststhatanintensefluxclosureprocesstookplaceinthemagnetotailthroughmagneticreconnection.Thismagnetotailreconnectionandtheassociatedfielddipolarizationgeneratedsignaturesintheauroral,magneticfield,andplasmawavedata.TheenhancedmagnetotailreconnectionislikelycausedbyacompressionofthemagnetosphereinducedbythearrivalatSaturnofaninterplanetarycoronalmassejection.Inadditiontotheauroralstorm,apolararcobservedonthedusksidewastrackedforthefirsttimefromthestartofitsgrowthphaseuntilitsquasidisappearance,providingevidenceofitsformationprocess.Thispolararcisaproxyforthelocationofreconnectionsitesonthedaysidemagnetosphereandfortheorientationoftheinterplanetarymagneticfield.Finally,theatypicalobservationofoneofthemostpolarauroralarcseverreportedatSaturnsupportsthescenarioofaninterplanetaryshockarrivingatSaturnattheendoftheCassinimission.Inthatrespect,theultimateUVISauroralsequenceallowedustocapturedynamicalaspectsofSaturn’smagnetospherenotfrequentlyorevenneverobservedinthepast.

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OpenandpartiallyclosedmodelsofsolarwindinteractionwithSaturn'smagnetosphereParunakian,D.A.,MoscowStateUniversityBelenkayaE.S.,CowleyS.W.H.,AlexeevI.I.,KalegaevV.V.,PensionerovI.A.,BlokhinaM.S.

InthisworkweexaminetheissueofreconnectionefficiencyinSaturn'smagnetosphereforcasesofnorthwardandsouthwardIMFusingtheparaboloidmagnetospheremodelfittedtodataacquiredbytheCassinimagnetometer,andimagesofSaturn'sUVauroraacquiredbytheHST.

ThereconnectionefficiencyisinvolvedinacomplexinterplayofvariousimportantfactorsaffectingtheinteractionofthesolarwindandSaturn'smagnetosphere,butcurrentlyaclearunderstandingofthispictureislacking.Themagnetosheathpropertiesareconnectedwiththereconnectionrate.FromaverylowreconnectionefficiencyazerodegreeofIMFpermeabilityintothemagnetospherewouldfollow.

Wecomparetheopen-closedboundarylayoutandfieldlinestructureoftwomodelvariants:anopenmodelwithapenetratingIMF,andapartiallyclosedmodelinwhichfieldlinesfromtheionosphereextendtothedistanttailandinteractwiththesolarwindatitsremoteend.WeshowthattheresultsproducedbytheopenmodelmatchHSTauroraobservationsbetter.ThemagnetosphericinteractionbetweenNeptuneandTritonPaty,C.,GeorgiaTech/UniversityofOregonCao,X.

Tritonprovidesanexcitingicymoon-magnetosphereinteraction,andonethathasyettobeexploredbyinsituspacecraftotherthanfromadistanceof~40,000kmbyVoyager2.TheobservationsfromthatbriefencounterrevealedTritontobeaninterestingtargetoffuturestudy;ahigh-densityicymoonwithactivegeysersofnitrogengasanddarkparticles,adiffuseatmosphere,andaretrogradeorbitindicativeoforiginsbeyondNeptune.Thegeologyrevealsahistoryofresurfacingandthepotentialfortidalheatingprocessesinthesubsurface,likelytheresultofTriton’scaptureandorbitalevolution.InthisposterweexaminethenatureofTriton’sinteractionwithNeptune’smagnetosphere,includingthevariablemagneticenvironmentexperiencedduringTriton’s5.88-dayorbitwhichmayprovideadriverforaninducedmagneticfield.OurstudywillincludeasuiteofsimulationsofTriton’snearspaceenvironmentbasedonthesimpleassumptionsofthepresence(orlack)ofasubsurfaceoceancapableofsustaininganinducedmagneticfield.

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Relativefractionsofwater-groupionsinSaturn’sinnermagnetospherePerry,M.E.,JohnsHopkinsApplitedPhysicsLabCravens,T.E.,Tokar,R.,Smith,H.T.,Waite,J.H.Jr.,McNutt,R.L.Jr.

Attwodozentimesovertenyears,theCassiniIonNeutralMassSpectrometer(INMS)measuredtherelativefractionsofwater-groupionsintheinnermagnetosphereofSaturnneartheequatorialplanebetween3.8and6.5Saturnradii(Rs).Unlikeenergy-sortinginstruments,eachINMSmeasurementdeterminestheabundanceofasingleion,withnoambiguityinidentifyingtheparticularionwithinthewatergroup.EachINMSmeasurementcoversasmallportionofvelocityspace,sovelocity-dependentfractionsarepossibleifthemultipledependentparametersandtemporalvariationscanbede-convolved.Densitiesandcountratesarelow,sometimesrequiringbinning10,000countstoachievea2-sigmaresult.Takentogether,INMSionmeasurementsspannedabroadrangeofvelocityspace,fromthecoreofthedistributiontomultiplesofthepick-upvelocity.

ThedatashowthatH2O+comprisesthebulkoftheionsnear4.0Rs,andthattheH2O+fractiondecreaseswithincreasingdistancefrom4.0Rs,thesourceofneutralwateratEnceladus.At4.0Rs,thefractionofH2O+rangesfrom60%to100%,withthewater-groupionsthatareclosesttothepick-upvelocityhavingthehighestfractionofH2O+.At6.5Rs,thethreemainwater-groupconstituents,H2O+,OH+,andO+,arenearlyequal.H3O+,whichdominatesthewater-groupionfractionsintheEnceladusplume,is10%orlessinSaturn’smagnetosphereoutsidetheplume.Othervariationsintherelativeionfractionsdonotshowclearlinkstoparameterssuchasvelocity,density,andtheorbitphaseofEnceladus.IoplasmatorusgeometryfromJunoradiooccultationsPhipps,P.H.,DepartmentofAstronomy,BostonUniversityWithers,P.,Buccino,D.R.,Yang,Y.-M.,Hinton,P.C.,Bagenal,F.

Io’svolcanicactivity,thedominantsourceofplasmaatJupiter,releasesmaterialintoIo’satmospherewhichislosttoJupiter’smagnetospherenearIo.ThismaterialisthenionizedandtrappedbythemagneticfieldtoformatorusofplasmaaroundJupiter,calledtheIoplasmatorus.Thisplasmacanbedetectedbyradiooccultationsinwhichtheplasma’stotalelectroncontentaffectspropertiesofaspacecraft’sradiosignalasitpropagatesthroughtheplasmaonthewaytothereceiver.ThetotalelectroncontentoftheIoplasmatorusisderivedfromthedualfrequency(KaandX-band)gravitymeasurementsfromtheJunospacecraftduringPerijove1.Thetimeforthepeakofthedistributionisfoundtobedeterminedbythelocationofthecentrifugalequatorialplane.Wepresenttheeffectofdifferentfieldlinemodelsonthetotalelectroncontentprofiles.Preliminaryresultsfromsubsequentperijovesarealsopresented.

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ElectrostaticsolitarywavesobservedduringCassini'sring-grazingandGrandFinaleorbitsPíša,D.,IAPCAS,Prague,CzechiaPickett,J.S.,Sulaiman,A.H.,Souček,J.,Ye,S.-Y.,Kurth,W.S.,Gurnett,D.A.,Santolík,O.

AttheendofNovember2016,Cassinistartedasetof20highlyinclinedring-grazingorbitstoexploreregionattheouteredgeofSaturn’smainrings.StartinginApril2017,thespacecraftmade22highlyinclinedorbitsatunprecedentedproximitytotheplanet.ThesephasesofCassini'smissionofferedanewinsightintounexploredterritoryofSaturnandtheplanet'sconnectionwithitsringsystem.TheWidebandReceiver(WBR),apartoftheRadioandPlasmaWaveScienceinstrument,oftendetectedstrikingmono-,bi-ortri-polarstructuresinwaveformsnapshots.Thesestructurescanbetheresultofelectrostaticsolitarywaves(ESWs)ordustimpacts.Forproperidentification,eventshavetobeoftenvisuallyinspected.TypicalexamplesofESWsanddustimpactsareprovidedtoshowtheirpropertiesanddifferences.UsingalmostfivemillionWBRwaveformsnapshots,wecarryoutasurveyofbipolarelectrostaticsolitarywavesdetectedduringthelastphasesofCassini'smissionatSaturn.Wediscusstheirpropertiesandpossiblegenerationprocesses.

RotationoftheInterplanetaryMagneticFieldinSaturn'sMagnetosheathPonce,I.D.,OglethorpeUniversityMeier,M.J.

ThemagnetospheresofJupiterandSaturnbothcontainplasmasheetsduetointernalsourcesofplasma,primarilyIoatJupiterandEnceladusatSaturn.Theeffectoftheseplasmasheetsonthemagnetopauseboundaryistoinflatethemagnetopauseintheequatorialregion,withtheresultthatthemagnetopauseisnotaxisymmetric,asshownintheoreticalmodeling(EngleandBeard,JGR85,1980;Staharaetal,JGR94,1989)anddata(Slavinetal,JGR90,1985).Theasymmetryofthemagnetopauseboundaryissensitivetothesolarwinddynamicpressure(Joyetal,JGR107,2002;Arridgeetal,JGR111,2006),withhigherdynamicpressurecorrespondingtoagreaterdegreeofasymmetry.

MHDsimulationsofsolarwindflowaroundanonaxisymmetricboundaryhaveshownthattheinterplanetarymagneticfieldisexpectedtorotateasthesolarwindapproachestheboundary(Erkaevetal,JGR101,1996;Farrugiaetal,Planet.Space.Sci.46,1998).Themagnetosheathmagneticfieldattheseplanetsisthereforeexpectedtobeorientedclosetoperpendicularwiththeequatorialplanenearthesubsolarpointandintheequatorialregionalongtheflanks,leadingtoconditionsthatarefavorableforthedevelopmentoftheKelvin-Helmholtzinstability(Desrocheetal.,JGR118,2013;Desrocheetal.,JGR117,2012).

AninitialstudyofthemagneticfieldrotationinJupiter’smagnetosheath(Ponce&Meier,AGUFallMeeting2017)wasunabletofindaconsistentsignatureofthepredictedmagneticfieldrotation.Inthepreviousstudy,twocrossingsoftheJovianmagnetosheathwereanalyzed–onefromPioneer10andtheotherfromUlysses.Inthisstudy,weextendthepreviousworktolookforrotationofthemagneticfieldinSaturn’smagnetosheath,usingtheCassinimagnetometerdata.

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Consequencesofnon-conformalmagneticfieldmappingPontius,D.H.,Birmingham-SouthernCollegeFernanzez,C.,Brooks,E.L.

Analytictreatmentsofmagnetospheric-ionosphericcouplingtypicallyassumethattheplanetarymagneticfieldisnorth-southsymmetric.Thatimpliesthattheionosphericfootprintsofanymagneticfluxtubeareidenticalinthetwohemispheres.Forconstantionosphericconductivityandperfectlyconductingmagneticfieldlines,whenfield-alignedelectriccurrentsfromtheplasmasheetareinjectedintotheionospheresalongtheboundaryofafluxtube,thecurrentscancloseentirelywithineachhemisphere.However,inarealisticrepresentationofafieldsuchasJupiter's,themappingisnon-conformalandLaplace'sequationcannotbesatisfiedsimultaneouslyinbothhemispheres.Wetreatasimplesituationwhereafluxtubeofsmallcrosssectionismappednon-conformallybetweentheionospheres.Twosituationsareconsidered:(i)onefootprintisstretchedoutalongoneaxisandcompressedalongtheother,withtheoppositemappingintheotherhemisphere,and(ii)thefootprintsexperiencecomplementarynon-orthogonalmappings.Inadditiontothecurrentsontheedgeofthefluxtube,therearenowcurrentsonfieldlinesoutsidethefluxtubethatpassentirelyfromonehemispheretotheother.Dependingonthedegreeofdistortion,thetotalmagnitudeofthoseauxiliarycurrentscanbecomparabletotheoriginalfluxtubecurrent.ThermalandenergeticiondynamicsinGanymede'smagnetospherePoppe,A.R.,SpaceSciencesLab.,U.C.BerkeleyFatemi,S.;Khurana,K.K.

Ganymedeisthesolarsystem'sonlyknownmoonwithanintrinsic,globalmagneticfield.Thisfieldisstrongenoughtostandofftheincidentjovianmagnetosphericflowandformsasmall,yetcomplexmagnetospherearoundthesatellite.Ganymede'smagnetosphereisthoughttoberesponsibleforvariablesurfaceweatheringpatterns,theproductionofaneutralexosphere,andthegenerationofUVauroraenearGanymede'sopen-closedfieldlineboundaries;however,theexactdetailsandunderlyingmechanismsarenotfullyunderstood.Here,weuseresultsfrompreviousthree-dimensionalhybridmodelsofGanymede'smagnetosphereandathree-dimensionalparticle-tracingmodeltoquantifythedynamicsofthermalandenergeticjovianionsastheyinteractwithGanymede'smagnetosphereandprecipitatetothesurface.Weidentifytheformationofquasi-trappedionicradiationbeltsinthemodel,similartothatobservedbytheGalileoEnergeticParticleDetector,andvariablesurfaceweathering,correspondingtoVoyagerandGalileoobservationsoftheganymedeansurface.WefindthatmostoftheparticleprecipitationoccursinGanymede'spolarcaps,yetenergeticionscanalsoprecipitatetoGanymede'sequatorialregioninsomewhatlesseramountsthaninthepolarregionsduetoparticleshadowingofquasi-trappedionsinGanymede'sionicradiationbelts.ModelresultspredictthatforconditionswithinJupiter'scentralplasmasheet,totalionfluxestoGanymede'spolar,leading,andtrailinghemispheresare50e6cm-2s-1,10e6cm-2s-1,and0.06e6cm-2s-1,respectively.Finally,convolutionofincidentionfluxeswithexperimentallymeasuredneutralsputteringyieldsforicybodiespredictsneutralsputteredfluxesinGanymede'spolar,leading,andtrailinghemispheresof1.3e9,4.8e8,and1.2e8neutralscm-2s-1,respectively.

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Saturn’snorthernauroraeatsolsticefromHSTobservationscoordinatedwithCassini’sGrandFinalePrangé,Renée,LESIA,ObservatoiredeParisL.Lamy,C.Tao,T.Kim,S.Badman,P.Zarka,B.Cecconi,W.S.Kurth,W.Pryor,E.BunceandA.Radioti,

Saturn'snorthernfar-ultravioletauroraehavebeenregularlyobservedthroughout2017withtheSpaceTelescopeImagingSpectrograph(STIS)oftheHubbleSpaceTelescope(HST),duringnorthernsummersolstice.TheseconditionsprovidedthebestachievableviewingofthenorthernkronianauroralregionforanEarth-basedtelescopeandamaximalsolarillumination,expectedtomaximizethemagnetosphere-ionospherecoupling.TheHSTobservationswerecoordinatedwithinsitumeasurementsalongthepathoftheCassinispacecraftacrossauroralfieldlinesduringtheGrandFinale.Inthisstudy,weanalyze24STISimagesconcurrentlywithquasi-continuousCassini/RPWSmeasurementsofSaturn'sKilometricRadiationandsolarwindparametersderivedfromnumericalMHDmodels.Theobservednorthernauroraedisplayhighlyvariableauroralcomponents,withatotalpowerrangingfrom7to124GW.Theyincludeaprominentmainovalabove72°latitudeswhichbearsclearsignaturesofthesolarwindandplanetaryrotationcontrol,frequentcuspemissionsnearnoon,withanunusuallybrighteventwhichradiated13GW,andadaysideweaksecondaryovalaround70°latitude.Inaverage,thenorthernauroraedisplayastrongLTdependencewithtwomaximaatdawnandpre-midnight,thelatterbeingattributedtoregularnightsideinjectionspossiblyassociatedwithsolsticeconditions,butnoobviousrotationaldynamics.TheseresultsprovideareferencebasistoanalyzeCassiniinsituand/orremotemeasurements,whethersimultaneousornot.WillweeverknowthetimeonSaturn?Saturn’sPlanetaryPeriodOscillationsobservedthroughouttheCassinimission.Provan,G,UniversityofLeicesterCowley,S.W.H.,Bradley,T.J.,Bunce,E.J.,Hunt,G.J.,Lamy,L.,Dougherty,M.K.

WereportonaseriesofstudiesdeterminingpropertiesofSaturn’splanetaryperiodoscillations(PPOs)fromCassinimagneticmeasurementsthroughouttheCassinimission,beginningunderpost-solsticesouthernsummerconditionsin2004,extendingthroughvernalequinox,andfinishingafternorthernsummersolsticeatendofmission.WediscusstheseasonalevolutionofPPObehavior,comparingourresultswiththosederivedfromanalysisofSaturnkilometricradiationemissionsfromtheVoyager,Ulysses,andCassinimissions.Thephasesderivedfromthemagneticdataprovideasuitableframeworkwithinwhichtoorganizeothermission-longmagnetosphericdata,andarefreelyavailabletothecommunity.

WefurtherpayparticularattentiontoPPOobservationsontheCassiniFringandproximalorbits,whichallowuniquehigh-cadencemeasurementsofthephaseandamplitudeofthePPOsneartheopen-closedfieldboundaryinthenear-midnightmagnetictail.Thesedatanewlyrevealthepresenceofdualmodulatedoscillationsvaryingatthe~42daybeatperiodofthenorthernandsouthernsystemsonthesepolarfieldlines.WediscussapossibletheoreticalscenariowherebyPPOsinonehemispherearecommunicatedviafieldalignedcurrentsonclosedfieldlinestotheoppositehemisphere,wheretheydrivevorticalflowswhichextendontopolaropenfieldlines.Theproximalorbitsalsonewlyprovideaccesstofieldregionsthreadingthroughandinsidetheplanetaryringsystem.Wedescribeinitialanalysesofthefielddataonsuchfieldlines,andshowthatPPOoscillationsareingeneralpresentthroughouttheseregions.

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CassiniUVISObservationsofSaturn'sAurorasandPolarHazePryor,W.R.,CentralArizonaCollegeEsposito,L.W.,West,R.A.,Jouchoux,A.,Grodent,D.,Gerard,J.-C.,Gustin,J.,Radioti,A.,Lamy,L.,Koskinen,T.

In2016and2017,theCassiniSaturnOrbiterexecutedafinalseriesofhighinclination,low-periapsisorbitsidealforstudyingSaturn'spolarregions.TheCassiniUltravioletImagingSpectrograph(UVIS)obtainedanextensivesetofauroralimagesofbothpoles,someatthehighestspatialresolutionobtainedduringCassini'slongorbitalmission(2004-2017).Insomecases,twoorthreespacecraftslewsatrightanglestothelongslitofthespectrographwererequiredtocovertheentireauroralregiontoformimagesofauroralH2andHemission.

ThelongwavelengthpartofthenorthernUVISpolarimagescontainsasignalfromreflectedsunlightwithabsorptionsignaturesofacetyleneandotherSaturnhydrocarbons.Saturn'sUV-darkpolarhexagonisnowseeninthenewUVISlong-wavelengthdata,surroundedbyacircularcollarthatislessdark.ThereisadefinitespatialrelationshipbetweentheUV-brightaurorasandthedarkmaterial,withthedarkmaterialconcentratedunderorjustinsideofthemainauroraloval.Theouterdarkcollarroughlycorrespondswiththepreviouslyreportedweakerouterauroraloval(Grodentetal.,2011;Lamyetal.,2013).Timevariationsinthedarkmaterialareseen.Thespectroscopyofthedifferentregionswillbediscussed.AshasbeenpreviouslydiscussedusingVoyagerdata(Laneetal.,1982,Westetal.,1983,PryorandHord,1991),Hubbledata(BenJaffeletal.,1995;Gerardetal.,1995)andCassinidata(Sayanagietal.,2018),Saturn'saurorasappeartobegenerating,throughbothneutralandionchemistry,UV-darkmaterialthatisprobablycomposedofcomplexhydrocarbons.PropertiesofJupiter'sDawnMagnetosheathasMeasuredbyJunoandNewEstimateofthePolarFlatteningofJupiter'sMagnetosphereRanquist,D.A.,UniversityofColorado-Boulder(LASP)Bagenal,F.,Wilson,R.J.,Hospodarsky,G.B.,Valek,P.W.,Connerney,J.E.P.,Kurth,W.S.

Juno's53-dayorbit,withitsapojoveat112RJ,hasspentasubstantialamountoftimeinthemagnetosheathonthedawnsideofJupiterandcrossedthemagnetopauseboundarymorethanahundredtimes.JunofirstenteredthemagnetosheathonJune24,2016andthelastrecordedmagnetosheathcrossingoccurredonJanuary6,2018.ItisincreasinglyunlikelythatJunowillre-enterthemagnetosheathuntilafterorbit30(November2020).UsingtheJovianAuroralDistributionsExperiment(JADE),theMagneticFieldInvestigation(MAG)andtheWavesInvestigation(Waves),wepresentthestatisticalplasmapropertiesofJupiter'sdawnmagnetosheath,includingmagneticfieldstrengthanddirections,densities,plasmaflowvelocities,pressures,Alfvénspeeds,andplasmabetas.CharacterizingJupiter'smagnetosheathpropertiesisimportanttounderstandthefrequencyandefficienciesofmagneticreconnectionandtheKelvin-Helmholtzinstabilityatthemagnetopauseboundary.Inaddition,wepresentanewmethodofusingthedrapingofthemagneticfieldinthemagnetosheathtoestimatethepolarflatteningofJupiter'smagnetosphere.

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IoVolcanoMonitoringfromtheIRTFinSupportofJunoandHisakiRathbun,J.A.,PlanetaryScienceInstituteSpencer,John.R.

Sinceearly2016wehaveimagedIo's2.2-4.8micronvolcanicthermalemissiononnearly80dates,inparttoprovideconstraintsonIo'svolcanicinputtoJupiter'smagnetosphereinsupportoftheJunoandHisakimissions.WehaveusedtheNASAIRTF,andtheguidecamerasfortheSPEXandISHELLspectrographs,forthiswork.WeimageIoinsunlight,Jupitereclipse,andduringJupiteroccultations,constraininglocationsandbrightnessesofvolcanosbothviadirectimagingandJupiteroccultationtiming.DuringthisperiodwehaveobservedoneoftheLokivolcano'sremarkableperiodicbrightenings,fromFebruary-July2016.WehavenotobservedanymajoroutburstsanywhereonIo,thoughgapsintemporallongitudecoveragedonotruleouttheoccurenceofshort-livedoutburstsduringthisperiod.CharacterisingJupiter'sAuroralAccelerationRegionRay,L.C.,LancasterUniversityArridge,C.S.

AtJupiterandothermagnetizedplanets,auroralemissionsaresignaturesofparticleaccelerationabovetheplanetaryatmosphere.PriortothearrivalofJuno,itwasexpectedthatquasi-staticfield-alignedpotentialswoulddominateJupiter’sauroralaccelerationregion(AAR),similartothoseatEarth.Surprisingly,insitudatasuggeststhatstochasticaccelerationismorewidelypresentinJupiter’sAAR.WeusetwomethodstodescribeparticleaccelerationatJupiter.Inthefirst,weconsiderquasi-staticfieldalignedpotentials,usingHSTimagesofJupiter’sauroracombinedwiththeKnightRelationandBayesiananalysistoinferthecharacteristicsofJupiter’sauroralaccelerationregioni.e.initialenergyanddensityofprecipitatingelectrons,andthelocationofaccelerationregion.ThesecondmethodconsiderstheaccelerationoftrappedelectronsbykineticAlfvénwavestopredicttheprecipitatingauroralenergyfluxes.WecomparetheinferredAARpropertiesfrombotheventstoJunomeasurements.

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HSTMid-Cycle25EuropaCampaigns:NewApproachestoConstrainPlumeAbundance,Composition,andVariabilityRetherford,K.D.,SouthwestResearchInstituteL.Roth,J.Saur,D.F.Strobel,P.D.Feldman,N.Ivchenko,T.M.Becker,D.C.Grodent,L.Paganini,A.Bloecker,M.Ackland,P.M.Molyneux,K.R.deKleer

WereportearlyresultfromourlatestsetofEuropaplumesearchingobservationsobtainedaspartofHubble’sMid-Cycle25EuropaCampaigns.Wehaveplannedasetof55orbitswith22visitsduringtheJupiterobservingseasonstartingonMarch28,2018andspreadintoJuly.InadditiontocontinuedSpaceTelescopeImagingSpectrograph(STIS)instrumentlong-slitfar-UVauroralLyman-alphaandoxygenlineemissionandLyman-alphatransitspectraldatasetsreportedpreviously,wewilldescribeourobservationsusingthreenewmodes:i)STIS/NUVG230Lspectroscopy,off-limb,ii)STIS/CCDG750Mspectroscopyineclipse,andiii)WFC3/UVISimagingineclipse.TheseHSTGOprogram15419observationscomplementtwootherHubbleprogramsfocusedonFUVtransits(30orbits)andvisibleeclipses(10orbits),withatotalof95orbitsplannedfortheEuropacampaigns.ThefullprogramusesthreedifferentSTISspectralmodesandtwoWFC3narrowbandfilterstogloballyconstrainfar-UV,near-UVandvisibleauroralemissionsaswellasLyman-alphaabsorptionfromplumesinsunlight,eclipseandJupitertransit.EachvisitwillbecarriedoutduringoptimizedobservingconditionstomaximizethesensitivityofHSTtoplumesignals.We’lldiscussourearlyassessmentsofthesuccessfulnessofthevarioustechniques,includingcomparisonswithprevioustestsofotherlesssuitablemodes.Startingjustbeforethetimeofabstractsubmission,the~6monthprogramwillbe~2/3rdscompletedatthetimeoftheMOPmeeting.AdditionalconfirmationofandinformationregardingwatervaporplumesatEuropaisneeded.IoandEuropa:Influenceofvolcanicoutbursts,moon-footprintconnectionsandplumeactivity.Roth,L.,KTHRoyalInstituteofTechnology

WereviewselectedcharacteristicsofthemoonsIoandEuropaandtheirinteractionswiththeJovianmagnetosphereandshowsomerecentresultsfromongoingobservationstudiesonthereviewedtopics.ForIo,wediscussthelinesofevidencethatstochasticallychangingvolcanicactivitycausestransient,aperiodicchangesintheneutralenvironmentandmagnetosphere.In2017,wehaveobtainedsub-mmobservationswiththeIRAM/NOEMAinterferometerover5monthstomonitorsuddenchangesinIo'sbulkSO2atmosphereduetovolcanicoutbursts;preliminaryresultsarepresented.Inaddition,wediscusstherelationofIo'slocalUVaurorabrightnesstotheUVbrightnessofthemoon’sauroralfootprintonJupiter.ForEuropa,wereviewandcomparetheHSTandGalileoobservationsthatwererelatedtoplumeactivityandgiveanoverviewoverournew2018HSTplumeobservingcampaign.

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HSTLyman-αobservationsofUranusRoth,L.,KTHRoyalInstituteofTechnologyLamy,L.;Strobel,D.F.

SpectralandimagingultravioletobservationsofUranuswereobtainedbytheHubbleSpaceTelescope(HST)withinsixobservationcampaignsbetween1998and2017.WefocusonthespectralobservationsandanalyzethehydrogenLyman-α(HI1216Å)signalinthesedataaddressingafewunansweredquestionsregardingUranus'Lyman-αemission:WhatistheradialprofileofUranus'Hcorona?HowmuchoftheemissionsissolarfluorescenceandthusdirectlycorrelatedtothesolarLyman-αflux?WefurthermoresearchforlocalizedbrightnesssurplusesthatcanberelatedtoauroraandcomparepotentialauroralocationstoUranus'updatedrotationalmagneticfieldgeometry.Sources,sinksandtransportofenergeticelectronsnearSaturn'smainringsRoussos,E.,MaxPlanckInstituteforSolarSystemResearchKollmann,P.,Krupp,N.,Paranicas,C.,Dialynas,K.,Jones,G.H.,Mitchell,D.G.,Krimigis,S.M.,Cooper,J.F.

WepresentthefirststatisticalinvestigationthatfocusesonthetransitionregionbetweenSaturn'selectronradiationbeltsandtheplanet'smainringsusingMIMI/LEMMSmeasurementsfromCassini'sProximalorbits.Saturn'sdenseA-ringpresentsanimpermeableobstacleevenforthehighestenergyelectronsthatcanbemeasuredwithLEMMSsoitwasnaturallyexpectedtoobserveasharpdropoutofenergeticelectronfluxesatthatrings'outeredge(~2.27Rs).Despitethat,thisinnerboundaryoftheelectronbeltswasfoundconsistentlybetween1200and6000kmawayfromtheA-ringfor41outofthe45crossingsofthisregionbyCassini.Theboundary'saveragelocationmapswellwithinSaturn'sF-ring(~2.32Rs),anarrow,dynamicandlongitudinallyasymmetricringofSaturn,suggestingthattheF-ringmaycontributetothegloballossesofelectronsbeforethesegettransportedontotheA-ring.Morelikely,however,isthecasethattheinnerboundaryoftheelectronbeltswasdisplacedbyconvectiveflowstoitsobservedlocation.Thislocation'sdistancefromtheringswasfoundtooscillatewithacharacteristicsolarperiodicity,revealingtheinfluenceofsolarwindverydeepintoSaturn'smagnetosphere.Theeffectsoftheseconvectiveflowsbecomenoticeablealsothroughaseriesoflocaltimeasymmetriesobservedatthebelts-ringstransition.ThemoststrikingasymmetryidentifiedwasthatoflocalizedMeVelectronintensityenhancements("microbelts")centeredwithintheF-ringandonlyinthepost-noonsectoroftheelectronradiationbelts.WeproposethatthesemicrobeltscontainenergeticelectronsinneardriftresonancewithcorotationthatarelocallyproducedbyGalacticCosmicRaycollisionswiththeF-ringandgettrappedinlocal-timeconfinedtrajectoriesduetothepresenceoftheaforementionedconvectiveflows.

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CharacterizingLocalandInterplanetaryControlofJupiter'sAuroralDawnStormsusingHSTandJunoRutala,M.J.,BostonUniversityClarke,J.T.

ThedegreetowhichJupiter'sauroraarebrightenedbyvariousinterplanetaryprocessesandsolarconditionsisacomplexquestion,compoundedbythepresenceofthreedistinctauroralzones:thebrightauroraloval,footprintemissioncausedbytheGalileanmoons,anddiffusepolaremission.Recentresearchhasfocusedontheresponseofthebrighteningofthewell-definedauroralovaltointerplanetaryandlocalprocesses;thespecificresponseofthediffusepolaremissiontothesamestimuliremainsanopenquestion.Ourinterestliesinacomponentofthispolaremissionknownasdawnstorms:relativelybrightemissionwhichremainsfixedatmagneticlocaldawn.BycouplingobservationsofJupiter'sdawnstormsfromarecentHSTcampaignrunningfrom2015through2017within-situmeasurementstakenbyJuno,weintendtocharacterizehowthedawnstormsform.Specifically,wecomparethemorphologyandintensityoftheaurorainalargersetofHSTobservationsthanhavepreviouslybeenavailabletoconcurrentinterplanetarymeasurementsinordertoshowwhichconditionsarenecessaryfordawnstormstoformandbrighten.JunoobservationsofenergeticchargedparticlesassociatedwithJupiter’saurora.Rymer,A.M.,JHUAPLMauk,B.;Kollmann,P.;Haggerty,D.;Clarke,G.;Paranica,C.

JunohasbeeninhighinclinationorbitatJupitersinceAugust2016.OfthenumeroussurprisesaffordedbytheexcellentinstrumentsuitefromthisuniquevantagepointhavebeenconsistentobservationsofupwardelectronsapparentlyassociatedwithJuno’scrossingofJupiter’sauroraloval–thisinitselfisnotnecessarilyunexpectedbutoncomputingtheenergyfluxassociatedwiththeplanetwardversusanti-planetwardelectronbeamsweoftenfindthat–inregionsthataremostobviouslyassociatedwiththemainauroraloval-thefluxofanti-planetwardelectronsexceedsthatofthosegoingdownward[Mauketal.,2017].HereweextendtheworktoincludeallJunocrossingstodatetopresentthemostrecentcontextoftheseobservationsatJupiter.

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PlanetaryandexoplanetaryobservationswiththeHaleakalatelescopesandafuture1.8-moff-axistelescopeprojectPLANETSSakanoi,T.,TohokuUniversityKagitani,M.,Nakagawa,H.,Kuhn,J.R.,Berdyugina,S.V.,Emilio,M.,Obara,T.,Kasaba,Y.,Scholl,I.F.,Okano,S.,Kita,H.,Kimura,T.,Yoshikawa,I.,Berdyugin,A.,Piirolah,V.

WereportrecentscientificoutputsobtainedwiththeHaleakalaT40andT60telescopesincludingtheJuno-Hisakicampaignperioddata,andalsopresentafutureprojectPLANETS.Continuousmonitoringisessentialtounderstandtheplanetaryatmosphericphenomena,andtherefore,ourownfacilitieswithevensmall-andmediumsizedtelescopesandinstrumentsareimportant.ThelocationofourtelescopesatthesummitofMt.Haleakala,issufficientlyhigh(3050m),andoneoftheworldbestsiteswithclearskyconditions.

UsingT40andT60telescopes,wearecarryingoutcontinuousmonitoringoffaintatmosphericfeaturesofIoneutralgasandplasmatoruswhichareresponsibleforIo’svolcanicactivities.Forthelong-termtrendofIo’ssodiumemission,theintensitydecreasedduringtheperiodfrom1999to2005,andthenincreasedafter2005.FortemporaryenhancementsofIo’ssodiumemission,weshowedgoodrelationshipbetweensodiumemissionandoxygenemissionat130nmobtainedwithHisakiontheeventinJanuary2015.WealsoobtainedpositivecorrelationbetweensodiumemissionandIRaurorameasuredbyIRTFassociatedwithsolarwindshockfromJunodatainMay2016.Inaddition,weconcentrateondevelopinginstruments.Theseactivitiesareopentoanypossiblecollaborators.Ourandguestinvestigators’observationsarealsolinkedtospacecraftmissionsforMercury,Venus,MarsandJupiter.

Wearecarryingouta1.8-moff-axistelescopeprojectPLANETSatHaleakala,whichismanagedbythePLANETSFoundation(www.planets.life)underinternationalcollaborationofJapan,USA,Germany,Brazil,andFrance.Thisoff-axisopticalsystemwillenableustomeasureverylow-scattering-lightcontaminationandhigh-contrastdata.ThemainmirrorismadeofClearceramZ-HSblank,whichisnowonthefinalpolishingprocessinMaui.Inthispresentation,wegivethemostrecentprogressofthedevelopmentofprimarymirror,andstatusofthisproject.Resultsfrom2yearsofhightime-spacesamplingofJupiter’sradiationwithJUNO/MWRSantos-Costa,D.,SouthwestResearchInstituteBolton,S.J.,Levin,S.M.,Janssen,M.A.,Gulkis,S.,Oyafuso,F.,Brown,S.T.,Steffes,P.,Bellotti,A.,Adumitroaie,V.,Connerney,J.E.P.

Forthepasttwoyears(Perijove1thru13),theJunoMicroWaveRadiometer(MWR)hascontinuouslymeasuredathighresolutionstheradiationemittedbyJupiterandthesurroundingenvironment,overafrequencyrangefrom0.6to22GHz,fromJuno’shighlyelliptical53-daypolarorbitaboutJupiter.TheradiosourcesmeasuredbyJUNO/MWRareprimarilygeneratedbytheplanet,sky(i.e.cosmicmicrowavebackground),andultra-relativisticelectronsboundtotheJoviansystembythemagneticfield.Allthreeradiosourcesdemonstrateasignificantdependenceonthefrequencyofobservation.Inthispaper,wepresentanoverviewofourcurrentunderstandingofthedifferentsourcesofsynchrotronemissionthathavebeenidentifiedfromtheanalysisofJUNO/MWRandJUNO/MAGdatasets.Ourresultscurrentlypointtowardsthreedistinctivesourcesofsynchrotronradiationofdifferentsignalstrengths:theinnerelectronbelts(<4Rj),electronsseemlytrappedbetweenIoandEuropa(~6-9Rj),andnearfield-alignedelectronsfromthemiddlemagnetosphere.AfterabriefdescriptionoftheMWRinstrumentanditsscienceobjectives,wedescribehowweidentifythedifferentsourcesofsynchrotronemissionsandspeculateonthelarge-scaledynamicalbehavioroftheelectronpopulationsatJupiterthatmayexplaintheirrespectiveorigins.

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ResponseofJupiter'smagnetospheretovaryingsolarwindconditions:InsightsfromglobalMHDsimulationsSarkango,Y.,UniversityofMichigan-AnnArborJia,X.,Toth,G.,Hansen,K.C.

Jupiter'smagnetosphereisdrivenpredominantlybyinternalprocessesduetorapidrotationandpresenceofinternalsourcesofplasma.RemoteobservationsofJupiter'saurorahavehintedatacorrelationbetweenupstreamchangesandauroralbrightness,buthowtheexternalfactorslikethesolarwindandIMFinfluencethemagnetosphereremainsanopenquestion.WeusetheglobalMHDcode,BATSRUS,tosolvethesemi-relativisticsingle-fluididealMHDequationsinalarge3DdomaintomodeltheJovianmagnetosphere.MassloadingassociatedwiththeIoplasmatorusisincludedinourmodelthroughsourcetermsintheMHDequations.TounderstandhowJupiter'smagnetosphererespondstothesolarwindforcing,wedriveourglobalmodelwithdifferentidealizedupstreaminputscontainingdynamicpressureenhancementsanddifferentIMForientations.Wecomparethedistributionofplasmadensity,temperatureandplasmabetatoin-situobservationsforvalidation.Togaininsightintotheresponseofauroratosolarwindvariations,weanalyzethechangesinfieldalignedcurrentsinourmodeledionosphereinresponsetodifferentidealizedupstreamconditions.Wealsoexaminehowtheopen-closedfieldlineboundaryinoursimulationvarieswiththeupstreamconditions,andcomparethatwiththechangesinthefieldlinecurrents.Asaproxytocharacterizetheglobalcouplingefficiencybetweenthesolarwindandthemagnetosphere,wealsocalculatethereconnectionpotentialacrossthemagnetopausefordifferentsolarwindandIMFconditionsandcomparethatwithresultsfromempiricalmodeling.Wave-ParticleInteractioninJupiter'sMagnetosphere:AuroralandMagnetosphericParticleAccelerationSaur,J.,UniversityofCologneSchreinerA.,JanserS.,ClarkG.B.,MaukB.H.,KollmannP.,EbertR.W.,Allegrini,F.,SzalayJ.

Weinvestigatespatialandtemporalscalesatwhichwave-particleinteractionoccursinJupiter'smagnetosphere.Weconsiderelectrons,protonsandheavyionsandstudytheregionsalongamagneticfluxtubewheretheplasmaisthedensest,i.e.,theequatorialplasmasheet,andwheretheplasmaisthemostdilute,i.e.,atthehighlatitudes,nearwhichauroralparticleaccelerationisexpectedtooccur.Wecross-comparethekineticplasmalengthandtemporalscalesintheseregionsassumingbothregionsareconnectedthroughAlfvenwaves.Guidedbythiscomparison,weinvestigatetheroleofelectronLandaudampingofkineticAlfvenwavesinstochasticallyconvertingelectromagneticfieldenergyintoauroralparticleacceleration.WealsopresentpropertiesofthedispersionandpolarizationrelationshipsofkineticAlfvenwavesintheaccelerationregion,wheretherelativisticcorrectionstemmingfromthedisplacementcurrentinAmpere'slawisessentialtobeincluded.Finally,wediscusstheimportanceofioncyclotrondampingoftheheavyionsinheatingthemagnetosphericplasma.

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AnInvestigationofSuppressionofMagneticReconnectionatSaturn’sMagnetopauseSawyer,R.P.,UniversityofTexasatSanAntonioFuselier,S.A.;Mukherjee,J.;Petrinec,S.M.;Masters,A.

Magneticreconnectionisthefundamentalprocessthatmediatestheinteractionbetweenthesolarwindandaplanetarymagnetosphere.However,Saturnisafastrotatingplanetwhichleadstoastronginternallydrivenmagnetosphere.Thisinternaldominancemayproduceco-rotationalflowsasfaroutasthemagnetopause.Theresultingshearflowacrossthemagnetopausemaythenacttosuppressreconnection.PredictionshavebeenmadeastowherethissuppressionoccursatthemagnetopauseofSaturn.Inthisstudy,weexaminedmagnetopausecrossingeventsfromCassiniundernorthwardIMF,whereheatedelectronswereobservedinthemagnetosheath.Theseheatedelectronsprovideevidenceofreconnectionatthemagnetopause.Theelectronspectrometer(ELS)portionoftheCassiniplasmaspectrometer(CAPS)suiteprovidedobservationsoftheelectrondensityandtemperaturesaswellaselectronpitchangledistributionsandtheirassociatedenergies.Furthermore,weusedamodifiedmaximummagneticshearmodeltodeterminethelocationofthereconnectionlineonSaturn’smagnetopause.Wethencomparedourpredictedlocationofthereconnectionlinetopredictedregionswherereconnectionmightbesuppressed.Fromthiscomparison,severalinstanceswerefoundwithinthepredictedsuppressionregionswheresignaturesofreconnectionwereobserved.VisibleWavelengthSpectroscopyoftheIoTorusDuringtheHisakiMissionSchmidt,C.A.,BostonUniversitySchneider,N.,Leblanc,F.,Gray,C.,Morgenthaler,J.,Turner,J.,Grava,C.

EmissionsinIo'storusofferauniqueopportunitytosnapapictureofamagnetospherethroughthelensofatelescope.WereportonspectroscopicobservationswiththeARC3.5matApachePointObservatory,measuringradialdistributionsofeightemissionlinesofS+,O+,andS++atvisiblewavelengths.TheresultscomplementandindependentlyconfirmkeyHisakifindings.Thetorus'dawn-duskdisplacementisconsistentwiththeelectricfieldstrength(3.8mV/m)andvariability(1-8mV/m)inferredfromtheEUVbrightnessasymmetry.AsintheEUV,thevisibletorusalsoshowsbrightnessenhancementsatlongitudesneartheintersectionoftheorbitalandcentrifugalplanes.Previouslyunseencharacteristicsyieldadditionalinsights.EmissionenhancementsdownstreamofIoareobservedforthefirsttimeinthevisible.ThisIophaseeffectdiffersfromthatintheEUVandlagsfurtherbehindtheimmediatewake.SuchmayreflectdensityandtemperatureperturbationsastheplasmasweepspastIo,offeringimportantcluesabouthowthemoon'satmosphericlosssuppliesthetorus.InnercoldtorusemissionsareonlyobservedfromS+transitions<2eV.RadialdistancestothecoldtorusandribbonfeaturesdependonJovianlongitudeindistinctlydifferentways,posingnewinformationabouthowJupiter'sfieldregulatestheplasmatransportinthesepopulations.

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ASearchforIonScaleHeightVariabilityinHisakiIoTorusObservationsSchneider,N.M,LASP,U.ColoradoC.A.Schmidt,M.Kagitani,Y.Kasaba,T.Kimura,G.Murakami,F.Tsuchiya,A.Yamakazi,I.Yoshikawa,K.Yoshioka

IontemperatureisacriticalvariableinIoplasmatorusenergetics,butisdifficulttoderivefromremotesensingmeasurements.Therelativeimportanceofhotionsvs.hotelectronsinpoweringthetorusemissionsremainsanopenquestion.Torusbrightenings,whethercausedbyepisodicchangesinthevolcanicsupplytothetorusorperiodicSystemIII/IVenhancements,offerthebestchancetosearchfordrivingvariationsinhotelectronsorions.Muchattentionhasbeenpaidtohotelectronpopulations,derivablefromdetailedspectralmodeling,butlessworkhasbeendoneoniontemperature.Ground-basedstudieshavesuccessfullyderivedT⊥fromveryhighresolutionspectra,andTllfromscaleheightmeasurementsinimages,bothoverlimiteddatasets.Schneideretal.1997foundstronglongitudinalvariationsinTllduringaweek-longdataset,andanti-correlatedSystemIIIbrightness,butmoreextendedfollowupdatasetshavenotpreviouslybeenavailable.

TheHisakidatasetpresentsthepossibilityofanunparalleledopportunitytostudylong-termandshort-termvariationsiniontemperatures.Theinstrumentisnotdesignedtotakeimagesofspecificemissions,butitslargeentranceslitacceptsthefullheightandwidthofthetorus.Intheidealcase,eachspectralemissionfeaturewouldappearasanimageofthetorusatitsappropriatepositioninthespectrum,creatingan“overlapogram”(asdidtheCassiniUVISinstrument).Inreality,theemissionsareblurredduetoinstrumentalresolutionandaberrations,andmultiplespectralfeatureoverlap.Furthermore,thechangingopeningangleoftherotatingtorusaddsaspuriousapparentscaleheightvariationwhichmustberemoved.Withallowancesforalltheseeffects,wewillreportonoursearchforiontemperaturevariationsduringthefirsttwoyearsofHisakiobservations,andcompareourresultstoapreviousindependentstudybyM.Shishido(M.S.thesis,U.Tohoku).

DistributionofhotionplasmainSaturn’smiddlemagnetosphere,from>13yearsofCassiniorbitsSergis,N.,AcademyofAthensAchilleos,N.A.,Guio,P.,Arridge,C.S.,Sorba,A.M.,Roussos,E.,Paranicas,C.,Krimigis,S.M.,Dougherty,M.K.,Hamilton,D.C.,N.Krupp,N.,Mitchell,D.G.

InthisstudyweexpandpreviousworkdonebySergisetal.(2018)forCassini’sProximalOrbits,usingCassiniparticleandmagneticfielddatatoquantifyboththesteadystateandthedynamicsoftheSaturnianmagnetosphere-asrevealedthroughthevariabilityoffundamentalplasmaparameterssuchashotionpressureandrelatedplasmabeta.ByemployingtheUCL/Achilleos-Guio-Arridge(UCL/AGA)magnetodiskmodel,wemapthesequantitiestothemagneticallyconjugatepositiononSaturn’srotationalequator,producingequivalentequatorialradialprofilesfortheseparameters.Asourrecentresultshaveindicated,theUCL/AGAmagnetodiskmodelprovidesagoodapproximation,forthesepurposes,oftheadditionalmagneticfieldgeneratedbythedistributedcurrentflowingintheSaturnianmagnetodisk.Themodelcanthusbeusedtoprojectdatawithreasonablygoodaccuracyfromhighlatitudestothemagneticallyconjugateregionsattheequator.Inthiswork,weexpandonourinitialProximal-Orbitstudybyincludingdatafromothernon-equatorialCassiniorbits,thusexploitingallavailablehotplasmameasurementsfromthemissiontoproducethemostcompletepicturetodateofSaturn’sringcurrentandglobalplasmaenvironment.

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Gemini-TEXESmid-infraredspectralobservationsofJupiter’sauroralregions:comparisonwithultravioletandnear-infraredobservationsSinclair,J.A.,JetPropulsionLaboratory/CaltechOrton,G.S.,Greathouse,T.K.,Lacy,J.,Giles,R.S.,Momary,T.,Grodent,D.,Bonfond,B.,Fletcher,L.N.,Irwin,P.G.J.

Jupiterexhibitsauroralemissionoveralargerangeofwavelengths.AuroralemissionatX-ray,ultravioletandnear-infraredwavelengthsdemonstratetheprecipitationofionandelectronsinJupiter’supperatmosphere,ataltitudesexceeding350kmabovethe1-barlevel.Enhancedmid-infraredemissionofstratosphericCH4,C2H2,C2H4andfurtherhydrocarbonsisalsoobservedcoincidentwithJupiter’sauroralregions.OnMarch17-19th2017,weobtainedspectralmeasurementsofH2S(1),CH4,C2H2,C2H4andC2H6emissionofJupiter’shighlatitudesusingTEXESonGemini-North.ThisrareopportunitycombinesboththesuperiorspectralresolvingpowerofTEXES(R≤85000)andthehigh-spatialdiffraction-limitedresolution(~2°latitude-longitudefootprintat70°N)providedbyGemini-North’s8-metreprimaryaperture.ThehighspatialresolutionhasforthefirsttimerevealedtransientspatialstructureintheemissionofCH4,C2H2andC2H4inJupiter’snorthernauroralregion.FromMarch17thto19th2017,duringasolarwindcompression,adusksidebrighteningofthesespecieswasobservedinthenorthernauroralregion.Wewillpresentaretrievalanalysisoftheseobservationstodemonstratethealtitudesintheatmosphereandthemagnitudeoverwhichtemperaturesandhydrocarbonabundancesweremodifiedduringthisevent.Wewillalsocomparethemorphologyofthemid-infraredemissionwithnear-simultaneous(i)HST-STISimagesoftheultravioletauroralemissionand(ii)IRTF-SpeXobservationsofthe3.42-μmH3

+emission.ConfirmingandconstrainingthepresenceofaEuropa-generatedneutral(asymmetric)torusSmith,H.T.,JohnsHopkinsUniversityAppliedPhysicsLabMauk,B.H.,Johnson,R.E.,Mitchell,D.G.

Neutraltoricanprovidekeyinsightinlargeplanetmagnetospheres.Thesefeaturesformwhenparticlesescapeandformapopulationthatco-orbitswiththemoon.Toridistributionsandcompositionsareadirectresultofthesatellitecompositionandsourcemechanisms.Thus,understandingthefeaturescanoftenprovidecriticalinsightintothesourcemoonsthatmightbedifficulttodirectlyobservable.

ThepotentialhabitabilityofJupiter’smoon,Europa,isofparticularinterest.DetectionofaEuropa-generatedneutraltoruscouldprovideimportantinsightintothismoontoincludecriticalevidenceofpossibleactivity.ThefirstindicationsofsuchafeaturewerereportedbyLaggetal.(2003)whoproposedthepossiblepresenceofaneutraltorusinthevicinityofEuropa'sorbitbasedontheobservedenergeticelectronpopulation.Mauketal.(2003)thenreportedthedetectionofaEuropaneutraltorusbyimagingenergeticneutralhydrogenatomsproducedfromchargeexchangeinteractionswithaneutraltorus.However,unlikeatSaturn'smagnetosphere,whereneutralparticlesdominateoverchargedparticles,Jupiter'smagnetosphereisdominatedbychargedparticles.Insuchahighradiationenvironment,ENAscouldalsobeproducedasaresultofchargeexchangeinteractionsbetweentwoionizedparticles.Inthatcase,theENA’scannotbeusedtoinferthepresenceofneutralparticlesbecausetheycouldbeproducedbyinteractionswiththemoreextended(anddominant)Ioplasmatorus.

Forthispresentation,weexaminetheviabilitythattheMauketal.(2003)observationswereactuallygeneratedfromaneutraltorusemanatingfromEuropa.TheseresultsarethencombinedtoreconstructandplaceconstraintsontheEuropaneutraltorus.

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TowardsaUnifiedTheoryofAuroralParticleAccelerationatEarthandJupiterSong,Yan,UniversityofMinnesotaRobertL.Lysak

EarlyobservationsfromNASA'sJunomissionhaveshownmanysurpriseresults.Amongthefindings,theobservationsofthepowerfulJupiter’saurorasaresurprisinglydifferentfromaurorasatEarth.Inthispresentation,wewilldescribedynamicaltheoriesrelatedtothemechanismsoftheauroralparticleaccelerationandthegenerationofhighenergyparticleaccelerators,whichincludemainly(i)thedynamicaltheoryofthegenerationofelectrostaticfieldsandfieldalignedcurrents,(ii)bothquasi-staticandAlfvenicarcformationhaveAlfvenicnature,andcanbedescribedbyaunifiedtheory;(iii)thegenerationofhighenergyparticlegenerators,suchasAlfvenicdoublelayersandchargeholesinauroralacceleration,whichcanaccelerateparticlestohighenergy.

WewillexaminetheapplicationofthesetheoriestotheinterpretationoftheobservedJovianaurorae.Investigatinghowthelarge-scalestructureofSaturn’smagnetospherevarieswithlocaltimeusingacombineddataandmodelingapproachSorba,A.M.,UniversityCollegeLondonAchilleos,N.,Sergis,N.,Guio,P.,Arridge,C.andDougherty,M

Saturn’smagnetospherehassignificantinternalplasmasources.Cold,denseplasmaintheequatorialregionoriginatingfromtheicymoonEnceladus,coexistswithahotter(>3keV)plasmapopulationoriginatinginSaturn’soutermagnetosphere,whichisobservedtobemuchmorevariablewithradialdistanceandlocaltime.Thishotplasmacontributestotheformationofadisc-likemagneticfieldstructureviaanenhancementofthemagnetosphericringcurrent,andalsoinfluencespressurebalanceatthemagnetopauseboundary,causingthemagnetospheretoinflate.However,theoriginofthispopulation,andtheextenttowhichitcontrolsmagnetosphericstructureandsize,arestillareasofactiveresearch.

Inthisstudy,weusehotplasmamomentscalculatedfromCassiniMagnetosphericImager(MIMI)data,incombinationwithanaxisymmetricforce-balancemodelofSaturn’smagnetodisk,toinvestigatehowthevariablehotplasmapopulationinfluencesthelarge-scalemagnetosphericstructure.Inparticular,weuseequatorialprofilesofaveragehotplasmapressurecalculatedfordifferentlocaltimesectorsasinputstothemagnetodiskmodel,tocreateafamilyofmodelsthatdescribeSaturn’smagnetosphereacrossalllocaltimes.Inthisway,weinvestigatehowtheglobalmagneticfieldstructureandpressurebalancevaryacrosslocaltime,tobuildaglobalpictureofSaturn’smagnetosphere.WethencomparethesemodelresultstoobservationsmadebytheCassiniMagnetometer(MAG)instrument.ThisstudyaimstoadvanceourunderstandingofglobalpressurebalanceinSaturn’smagnetosphere.

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GenerationofULFwavesbytheDrift-MirrorPlasmaInstabilitySoto-Chavez,A.Rualdo,NewJerseyInstituteofTechnologyLanzerotti,Louis,Gerrard,A.,Cohen,R.,Cooper,M.,andManweiler,J.W.

Thehotplasmaconditionsofthemagnetospheresofthegiantplanetspresentenvironmentsthatcanbesourcesofinternally-generatedwaves.Amongtheseareultra-lowfrequency(ULF)wavesgeneratedbytheDrift-Mirror(DM)plasmainstability.TheDMinstabilityusuallyrequirestheplasmabeta(β)parametertobeβ>1.Becauseofthis,itisdifficulttostudytheDMinstabilityinconfinedlaboratoryplasmaexperimentswhereusuallyβ<1.Therefore,astrophysicalmagnetizedobjectsaretheonlyenvironmentsthatonecanusetotesttheories/models,predictions,andconsequencesoftheDMplasmainstability.WehaveconclusiveevidenceofaULF(Pc4-5range)wavegeneratedbyDMplasmainstabilityinEarth’sinnerMagnetosphere.Dataanalysis,fromtheRadiationBeltStormProbesIonCompositionExperiment(RBSPICE)onboardNASA’sVanAllenProbesSatellites,demonstratesthattheDMplasmainstabilityconditionforsingleandmultiplespeciesiswellsatisfied.Weareabletomeasurethewavegrowthrate,forthefirsttime,anddemonstratethatitagreeswellwiththepredictedlineartheorygrowthrate.Wealsopresentovertwo-yearmeasurementsofhigh-betaeventstakenbytheRBSPICEinstrument.TheimplicationsofthesenewmeasurementsandtheirroleinEarth’sinnermagnetospherearediscussedforunderstandingwave-particleinteractions,suchasparticleaccelerationanddiffusion,inthemagnetospheresoftheouterplanets.Saturnianplanetaryperiodoscillations,angularmomentumtransferandplasmasub-corotationSouthwood,D.J.,ImperialCollegeLondonUKHunt,G.J.,Dougherty,M.K.

ThehighinclinationorbitsofCassiniin2008revealedthelatitudinalstructureofboththequasi-steadyfieldalignedcurrents(FACs)andthenorthernandsouthernFACsystemswith~10.7hrperiodicity.TheF-ringandproximalorbitshaveconfirmedthegeneralstructurebutwithamplitudesweaker,probablyduetoseason.Thepeakamplitudeoftheperiodiccurrentisverysimilartothesteadycurrentandbothpeaksoccuratasimilarlatitudeintheauroralzone.Theperiodicsystemsarethesourceofthefamiliarglobalmagneticplanetaryperiodicoscillations(PPO)detectedbytheCassinispacecraftmagnetometerthroughoutthemagnetosphere.Thequasi-steadycurrenthasbeenbelievedtobetheprimarymechanismforcouplingangularmomentumfromtheionospheretothemagnetospheretoheavyionisedmaterialoriginatingfromtheinnermagnetosphereandbeingtransportedoutwardsonclosedfieldlines.Wequestionthatassumptionhereasthesteadycurrentsystemseemstobeprimarilylocatedatinvariantlatitudesabove70deg.Indeed,weproposethatthemajorangularmomentumtransferfromionospheretomagnetosphereonclosedfieldlinesisaccomplishedbythePPOsignals.AsimpleMHDargumentshowsthatthemotionofplasmainducedbythePPOisarotationinthesamesenseastheplanetintheclosedfieldregion.TheangularmomentumdensityinthePPOsignalcanbecalculated.Itisinthesamedirectionastheplanetaryrotation.Moreover,in2013wherenorthernandsouthernsignalshadthesamefrequencyandwerelockedinphase,thephaseoftheoverallsignalswasconsistentwithangularmomentumbeingdepositedbytheoscillationsneartheequator.Thesameeffecthasbeenseenincomputations.Theradicalconclusionisthatthesub-corotationofplasmaintheclosedfieldregionoftheSaturnmagnetosphereiscontrolledbythePPOamplitude.

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SpatialDistributionofCondensedOxygenonEuropaSpencer,J.R.,SouthwestResearchInstitute

Condensedoxygen,probablygeneratedaspartofaradiolyticcyclethatincludesO3andH2O2,islikelytoplayanimportantroleinthecomplexchemicalenvironmentofthesurfacesoftheicyGalileansatellites.IthasbeenidentifiedonGanymede(Spenceretal.1995),andsubsequentlyonEuropaandCallisto(SpencerandCalvin2002)bymeansofitsshallowbutdistinctive5773and6250Angstromabsorptionbands.5773Angstrombandstrengthisupto2%onGanymede,butonly~0.3%onEuropa.O2onGanymedeexhibitsastrongconcentrationonthetrailinghemisphere,suggestingamagnetosphericorigin,butthedistributiononEuropahasbeenpoorlyknownduetotheextremeweaknessoftheabsorptionband.WereportonthehighestSNRspectroscopyoftheO2bandsonEuropayetobtained,usingtheDeVenySpectrographonthe4.3-mLowellDiscoveryChannelTelescopeinJune2017.TheimprovedSNRofthenewdataprovidesthebestconstraintsyetonthelongitudinaldistributionofO2onEuropa,whichmayprovidecluestotheoriginandevolutionofthisspecies.

QuantifyingthestressofSaturn'smagnetosphereduringtheentireCassinimissionStaniland,N.R.,ImperialCollegeLondonDougherty,M.K.,Masters,A.

IntheinnerregionofSaturn’srotation-dominatedmagnetosphere,thegoverningmagneticfieldcontributorsaretheinternalfieldandthecurrentsheet.AzimuthalcurrentsflowingintheequatorialplasmadiskradiallystretchSaturn’smagneticfieldlinesintoa‘magnetodisc’geometry.Theextentofthiseffectvariesduetobothexternalandinternaldynamicalprocessesthatcanstretchandcompressthesystem.

Inthisstudy,weusethecompletedatasetcollectedbytheCassinispacecrafttocharacterisethestressofSaturn'smagnetosphere.Wefitamodelofthenear-equatorialregionoftheinnermagnetospheretodeterminewhetherthesystemiscompressed,stretchedornearsomeprescribedgroundstate.ResultsshowthattrackingvariationsinthecurrentintensityofSaturn’smagnetodiscaccountsforchangesinthestressofthesystem.Approximatelytwothirdsofourdatasetiswelldescribedbythemodel,signifyingasteady-statecurrentsheetduringthesepasses.Thisworkfurtherindicatesthatthereisageneraltrendintheaveragecurrentparameterperlocaltimesector,whichagreeswithourpreviousassumptionsthatSaturn’smagneticfieldisasymmetricabouttheaxisofrotation.Additionally,wenotevariationsduetoseasonalchangeandthesolarcycle,andalsodiscussthestressduringnon-steady-statepasses.WeconcludethatSaturn'smagnetosphereremainednearitsgroundstateforasignificantperiodoftheCassinimission.

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AnewempiricalmagneticfieldmodelforSaturn'smagnetosphereStephens,G.K.,TheJohnsHopkinsUniversityAppliedPhysicsLaboratoryMitchell,D.G.;Paranicas,C.;Sitnov,M.I.;Vandegriff,J.D.

WepresenttheinitialfindingsonanempiricalmodelofSaturn’smagneticfield,usingCassinimagnetometerdata,whichgoesbeyondtheinternalfieldanddescribesthefieldduetoexternalcurrentsystems,suchastheringcurrentandmagnetopausecurrent.ItfollowstheapproachesusedinTsyganenkoTerrestrialmagneticfieldmodelsandinparticulartheTS07Dmodel,whichfundamentallychangedhowtheEarth’smagnetosphericmagneticfieldwasmodeled.First,theclassicalapproachofhand-tailoringthecurrentdescriptionswasreplacedwitharegularexpansionoforthogonalbasisfunctions.Secondly,dataminingisusedtocapturethemodel’stimeevolutionandreplacesthefunctionaldependenceonsolarwindparametersandgeomagneticindicesusedinearliermodels.Together,thesechangessoughttomoreeffectivelyutilizeinformationcontainedinthedatabyincreasingthemodel’sflexibilityfromtheeliminationofrigiddescriptionsofthecurrentsystemsandtheirdynamics.CoupledinteriorstructureandexteriorplasmamodelsofEuropaStyczinski,M.J.,UniversityofWashington

Inthesearchforlifeelsewhere,Europamaybethetopcandidate.Remotesensingdatasuggestthatbeneathitsicyshellliesaliquidwaterocean,incontactwitharockysilicatemantle.MagneticfieldmeasurementsfromtheGalileomissionprovideastrongconfirmationthatEuropahasasubsurfaceocean;aninducedmagneticfieldisobservedthatimpliesaconductinglayerconsistentwithsaltywater.However,Europaisimmersedinacomplexplasmaenvironmentthatreactsto—andgenerates—itsownmagneticfields,complicatinganyandallattemptstomodelEuropa’smagneticinduction.PaststudiesofEuropa’soceanstructurehaveappliedsimplifiedmodelsforEuropa’sinterior,orincompletemodelsofthesurroundingplasmaenvironment.

Inthiswork,wesimulateEuropa’smagneticinteractionswithcoupledmodelsforboththeinteriorandexterior,tobetterunderstandhowoceanstructureaffectsEuropa’smagneticinductionsignature.Weapplya1DthermodynamicmodelfortheinteriorofEuropa,generatedbyPlanetProfile,toobtainrealisticgeophysicalparameterssuchaselectricalconductivity.

Theseparametersforminputsto3DglobalmultifluidsimulationsofEuropa’sinductionandplasmaenvironment.Theresultingcoupledmodelhasstrongexplanatorypower,throughself-consistentmodelingofplasmabehaviorovermanyscaleranges,flexiblerepresentationofinteriorconductinglayers,andmoreaccurateaccountingofplanetaryandupstreamplasmaconditions.

Adetaileddescriptionofourcoupledmodel,initialresults,andplansforitsusewillbepresented.

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AuroralhissemissionsduringCassini’sGrandFinale:DiverseelectrodynamiccouplingbetweenSaturn,itsrings,andEnceladusSulaiman,A.H.,UniversityofIowaKurth,W.S.,Hospodarsky,G.B.,Averkamp,T.F.,Persoon,A.M.,Ye,S.-Y.,Menietti,J.D.,Pisa,D.,Farrell,W.M.,Gurnett,D.A.

TheCassiniGrandFinaleorbitsofferedanewviewofSaturnanditsenvironmentowingtomultipleorbitsofhighinclinationandunprecedentedproximitytotheplanet.TheRadioandPlasmaWaveScience(RPWS)instrumentdetectedstrikingsignaturesofintenseauroralhissemissionsduringthisphase.Ourresultsshow:1)Anemissiondetectedneartheionosphereandlikelyoriginatingfromanextendedsourceregionintherings.2)FirstobservationsofVLFsaucersdirectlylinkedtoSaturn’sionosphere.Botharebelievedtobeassociatedwithprevailingionosphere-ringcurrents.Andfinally,3)AnemissiondetectedneartheionosphereanddirectlylinkedtoEnceladus.ThesedetectionshavebeenaffordedexclusivelybytheGrandFinaleorbitsbyvirtueofhigh-latitudeandlow-altitudepasses.Altogether,theyrevealboththegreaterimportanceandspatialextentofwave-particleprocessesoperatingbetweenSaturn,itsrings,andEnceladus.ThefinalphaseofthemissionhasunderlinedSaturnasoneofthemostdynamicanddiverseenvironmentsinthesolarsystem.JunoObservationsConnectedtotheIoFootprintTailAuroraSzalay,J.R.,PrincetonUniversityB.Bonfond,F.Allegrini,F.Bagenal,S.Bolton,G.Clark,J.E.P.Connerney,R.W.Ebert,R.E.Ergun,G.R.Gladstone,D.Grodent,G.B.Hospodarsky,V.Hue,W.S.Kurth,S.Kotsiaros,S.M.Levin,P.Louarn,B.Mauk,D.J.McComas,J.Saur,P.W.Valek,R.J.Wilson

TheJunospacecraftcrossedfluxtubesconnectedtotheIofootprinttailatlowJovianaltitudesonmultipleoccasions.Thetransitscoveredlongitudinalseparationsofapproximately10˚to120˚alongthefootprinttail.Juno’ssuiteofmagnetosphericinstrumentsallowfordetailedmeasurementsofavarietyofphysicalparametersfortheIofootprinttail.Junoobservedplanetwardelectronenergyfluxesof~70mW/m2neartheIofootprint,and~10mW/m2fartherdownthetail,alongwithcorrelated,intenseelectricandmagneticwavesignatureswhichalsodecreaseddownthetail.Allobservedelectrondistributionswerebroadinenergy,possiblysuggestinganAlfvénicaccelerationprocess,anddidnotshowanyinverted-Vstructurethatwouldbeindicativeofaccelerationbyaquasi-static,discrete,parallelpotential.Here,wediscusstheJADE,UVS,Waves,andMagneticfieldmeasurementstakenduringJuno’stransitsthroughtheIofootprinttailfluxtubesduringperijoves5-7andcomparethesemeasurementswithexistingtheoreticalmodelsdescribingthetailformation.

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VolcanicControlofJupiter'sAuroraandMiddleMagnetosphereDynamicsObservedbyHisaki/EXCEEDandAnalysisImprovementsbyJunoTao,C.,NationalInstituteofInformationandCommunicationsTechnology(NICT)Kimura,T.,Tsuchiya,F.,Murakami,G.,Clarke,G.,Ebert,R.W.,Yamazaki,A.,Yoshioka,K.,Kita,H.,Misawa,H.,Badman,S.V.,Kasaba,Y.,Yoshikawa,I.,andFujimoto,M.

Jupiter'saurorareflectstheplanetarymagnetosphericandatmosphericenvironments.Sinceitslaunchin2013,theHisaki,Earth-orbitingplanetaryspacetelescope,hascollectedauniquelong-termdatasetofultravioletemissionsfromJupiter'sIoplasmatorusandaurora,undervarioussolarwindconditionsandIovolcanicactivity.WeanalyzedJupiterauroraspectratakenbytheEXCEED(ExtremeUltravioletSpectroscopeforExosphericDynamics)spectrometeronboardHisaki.TemporalvariationofJupiter'snorthernauroraduringenhancedIovolcanicactivitywasdetected.ItwasfoundthatinassociationwithreportedIovolcaniceventsinearly2015,auroralpowerandestimatedfield-alignedcurrentswereenhancedduringdaysofyear40–120.Furthermore,thefarultravioletcolorratiodecreasedduringtheevent,indicatingadecreaseofauroralelectronmeanenergyandtotalaccelerationby<30%.DuringtheepisodeofenhancedIovolcanicactivity,Jupiter'smagnetospherecontainsmoresourcecurrentviaincreasedsuprathermalplasmadensitybyupto42%;therefore,itwouldhaverequiredcorrespondinglylesselectronaccelerationtomaintaintheenhancedfield-alignedcurrentandcorotationenforcementcurrent.Sporadiclargeenhancementsinauroralemissiondetectedmorefrequentlyduringtheactiveperiodcouldhavebeencontributedbynon-adiabaticmagnetosphericenergization.

Inthispresentation,wealsodiscusstheimprovementsoftheremoteauroralanalysisreferringtodirectin-situobservationsachievedbyJuno.MagnetosphericStructureandDynamicsatSaturn(andmaybeJupiter)Thomsen,M.F.,PlanetaryScienceInstitute

SaturnandJupiterare,liketheEarth,stronglymagnetizedplanetspossessingpersistentmagnetospheres.UnliketheEarth,theprincipalsourcesofmagnetosphericplasmaforSaturnandJupiterareinternaltothemagnetospheres,namelygasesemanatingfromthemoonsEnceladusatSaturnandIoatJupiter.AlsounliketheEarth,thelargesizeandrapidrotationofSaturnandJupiterallowcentrifugalstressestodominatethemagnetosphericdynamics.Thecombinationofinternalplasmasourcesandstrongcentrifugaleffectsproducethetwoprincipaldynamictransportmechanismsattheseplanets:Thecentrifugally-driveninterchangeinstabilityandlossofplasmadowntailthroughmagneticreconnection.Wewillreviewthegeneraldynamiccycleinvolvingthesetwoprocessesandthenwilllookingreaterdetailattheirrelationshipandphysicalimplications.

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AuroralExcitationAlongOpenJovianMagnetosphericFieldLinesTrafton,L.M.,UniversityofTexasatAustin

ThemagneticfieldlinesatJupiter’shigherlatitudesareopentothespaceenvironment.HubbleUVandnear-IRimagesshowalooselystructured,mildlyvariableglowoveritspolarcapsinadditiontothebrightauroralovalscausedbytheprecipitationofelectronstrappedintheJovianmagnetosphere.TheglowattheselatitudesislikelytobeexcitedbychargedparticlesinthelocalspaceenvironmentthatarefocusedbytheJovianfieldlines.ThesolarEUVexcitationnearthepolescannotbeanygreaterthanitisatlowlatitudes,wheretheUVglowandemissionspectraareobservedtobemuchweaker.Potentialsourcesofpolarexcitationarethesolarwind,solarenergeticparticleevents,andfield-linereconnectioneventsintheJovianmagnetotail.

Wepresentpreliminarynear-IRspectrasamplingJupiter’spolarcapregionsintheL-band(~3.2microns)thatshowcomplexspatialvariability.BesidesH3

+andmethaneemission,thereappearstobeemissionfromotherhydrocarbons,oranunidentifiedspecies.Differentexcitationprocessesappeartobeatplay.

Multi-specieshybridmodelingofplasmainteractionsatGalileanmoonsTravnicek,P.,UCBerkeley,SSLSebek,O.,StverakS.,Walker,R.J.,Hellinger,P.

WestudyplasmainteractionsofGalileansatellitesbymeansofmulti-speciesglobalhybridsimulations.Weconsidermulti-speciesbackgroundplasmacomposedofoxygenandsulfurionsandmulti-componentneutralatmospheres.Furtherweconsiderionizationprocessesoftheneutralatmospherewhichisthenasourceofdensepopulationofpick-upions.Weapplyvariablebackgroundplasmaconditions(density,temperature,magneticfieldmagnitudeandorientation)inordertocoverthevariabilityinconditionsexperiencedbythesatelliteswhenlocatedindifferentregionsoftheJovianplasmatorus.Weexamineglobal3-dimensionalstructureoftheinteractions,formationofAlfvénwings,developmentoftemperatureanisotropiesandcorrespondinginstabilities,andthefinephenomenacausedbythemulti-specienatureoftheplasmacausedbytheenergyexchangebetweenparticlesandE/Mwaves).TheresultsareingoodagreementwithinsitumeasurementsofmagneticfieldandplasmadensitymadebytheGalileospacecraftwhichwealsodemonstrate.Theglobal3-Dnatureofournumericalexperimentsallowsusprovidedetailedanaylysisofinsituobservations.

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TheJovianIonosphericionpopulationobservedbyJuno'sJADEinstrumentValek,P.W.,SwRIAllegini,F.andBagenal,F.andBolton,S.andConnerney,J.andEbert,R.W.andGladstone,R.andKim,T.K.andKurth,W.andLevin,S.andLouarn,P.andMauk,B.andMcComas,D.andWaite,J.H.andWilson,R.J.

Juno’sJovianAuroralDistributionsExperiment(JADE)measuresplasmadistributionsusingtwonearlyidenticalelectronsensorsandoneionsensor.Theelectronsensors(JADE-E)measuretheelectrondistributionintherangeof100eVto100keVandtheionsensor(JADE-I)measuresthecompositionseparatediondistributionsintherangeof10eV/qto50keV/qforionswithmasses<64amu/q.TheJunospacecraft’shighvelocity(~50km/s)nearperijoveat~1.05RJ(1RJ~71,400km)facilitatesobservationsofverylowenergyions,tobelow1eV/qforprotons,inJupiter’sreferenceframe(whenviewinginthespacecraftramdirection).Duringperijovepasses,whenthespacecraftisatsub-aurorallatitudes,observationsrevealtwopopulationsofions:thoseofIogenicoriginandthosedirectlysampledfromtheionosphere.Theionosphericpopulationconsistsoflowenergy,lightions,mostlyprotons.Theyhaveenergiesbelow100eVinthespacecraftframe,andextenddowntothebottomoftheJADEmeasurementrange.Athighlatitudestheionosphericionsconsistonlyofprotons,butneartheequatoralowenergyheavyionpopulationisalsoobservedduringsome,butnotequatortransits.Inthisstudywewillpresentobservationsofthelowenergyionosphericionsinthesub-auroralregionsandbelowanaltitudeof1RJ.

Outflowofplasmawithoutremovalofmagneticflux:Whatistherealmagnetictopology?Vasyliūnas,V.M.,Max-Planck-InstitutfürSonnensystemforschung

Inthemagnetospheresofthegiantplanets,plasmaissuppliedpredominantlybysourcesthatliedeepwithinthedipolarmagneticfieldlineregionandislostultimatelybyflowoutintothesurroundingexteriorregion.Theoutwardtransportoftheplasmamustoccurwithoutremovalofmagneticflux;whenaplasmaelementcrossestheinterfacetothemagnetotailand/ormagnetosheath,themagneticfieldlinesthreadingtheelementmustbecomedisconnectedfromtheplanet'sdipole.Thisisaspecifictypeofmagneticreconnection,discussedalsoinsolarandterrestrialcontexts.Forouterplanetmagnetospheres,thesimplestmodelisasequenceoftopologicalchangeswidelyknownastheVasyliūnascycle.Thatthemagnetictopologyofthismodelisconceptuallypossiblehasnotbeenproved(incontrasttothetopologyofDungey'sopenmagnetospheremodel,whichcanbedemonstratedbyasimpleanalyticalmodel).IshowthatinfactthemagnetictopologyofboththepublishedVasyliūnascycleanditscounterpartsinothercontextspresupposesahiddensymmetryandissingular(non-generic):itrepresentsthecaseofnoasymmetry,whichisqualitativelydifferentfromthatofvanishinglysmallasymmetry.Withoutthesesymmetryassumptions,thevolumeoccupiedbyformerlyclosedfieldlinesthathavebecomedisconnectedisnotthecommonlyenvisagedplasmoidintwodimensionsbutathree-dimensionalquasi-toroidalstructureoftheDungeytype.Thecorrespondingsequenceofmagneticfieldchanges,whichallowsplasmatoflowoutwhilereturningmagneticfluxtotheplanet,preservesthemainqualitativefeaturesoftheoriginalVasyliūnascycle(inparticularthespatialdecouplingofreconnectionandplasmaoutflow)butnotitsspecifictopology.Possibleimplicationsforgiantplanetmagnetotailswillbediscussed.

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JunoObservationsofMagnetotailReconnectionatJupiterVogt,M.F.,BostonUniversityConnerney,J.E.P.,DiBraccio,G.A.,Gershman,D.J.,Clark,G.B.,Paranicas,C.,Kurth,W.S.,Ebert,R.W.andValek,P.

Magneticreconnectionisanimportantphysicalprocessthatallowsforthereleaseofmassandenergyfromaplanetarymagnetotail.AtJupiter,tailreconnectionisthoughttobedrivenbyaninternalmassloadingandreleaseprocesscalledtheVasyliunascyclewhichisexpectedtooccurwithatypical2-4dayrecurrenceperiod.AnalysisofmagneticfieldandenergeticparticledatafromtheGalileospacecrafthasshownevidenceofhundredsofreconnectioneventsoccurringinJupiter’smagnetotailandhasattemptedtocharacterizetheirproperties,includingthesize,recurrencetime,andlocationoftailreconnectionsignatures.Forexample,theGalileoobservationsestimatethatthemasslostbyplasmoidsisonlyasmallfractionofthemassinputfromIo,thoughthemasslossratecalculationsarepoorlyconstrained.HerewepresenttheresultsofaninitialsurveyofmagnetotailreconnectionsignaturesobservedwiththeJunospacecraft.ThenewJunoobservationscomplementtheGalileodatabyprovidingimprovedmeasurementsoftheplasmadensityandvelocity,whichiscriticalforconstrainingthemasslostbyplasmoids,andbyprovidingadditionalspatialcoverageinthemagnetotail.Takentogether,theGalileoandJunoobservationsshouldprovidenewinsightintothedriversofmagnetotailreconnectionanditsroleintheoveralltransportofmassandmagneticfluxinJupiter’smagnetosphere.

ElectrodynamicsinSaturn'sThermosphereVriesema,J.W.,LunarandPlanetaryLaboratoryKoskinen,T.T.andYelle,R.V.

Saturn'smagnetosphereisknowntobeelectrodynamicallycoupledtoitsthermosphere,especiallyinauroralregions,butlessisknownabouttheelectrodynamicsofthethermosphereatlowlatitudes.TowardthegoalofdevelopingamorecompleteunderstandingofelectrodynamicsinSaturn'supperatmosphere,weinvestigatetheeffectofequatorialwindsonSaturn'sionosphericwinddynamoatlowerandmiddlelatitudesusinganaxisymmetric,steady-statemodel.Asinputsforourmodel,wecalculateaone-dimensionalconductivityprofileandconstructatwo-dimensionalmodelwindprofilebasedonresultsfromageneralcirculationmodelbutwiththeadditionofanequatorialjet,whichweassumepersistsuptothelowerthermospherefromthetroposphere.Thismodelpredictscurrentdensitiesoftheorder10-9to10-7Am-2.Ourmodelalsopredictssubstantialresistive(Joule)heatingandiondrag,whichhavethepotentialtosignificantlyaltertheenergeticsandcirculationbalanceoftheupperatmosphere.

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OntheCharacteristicsofChargedDustinSaturn’sEquatorialIonosphere–ImplicationsfromCassiniRPWS/LPdataWahlund,J.-E.,SwedishInstituteofSpacePhysics(IRF)Vigren,E.,Morooka,M.W.,Hadid,L.Z.,Farrell,W.M.,Persoon,A.M.,Kurth,W.S.,Gurnett,D.A.,Mitchell,M.E.,Perry,D.G.WaiteJr.,J.H.,Moore,L.,Cravens,T.E.,Galand,M.,andNagy,A.F.

TheCassinispacecraftobservationsclosetoSaturnhaverevealedthat1-100nm-sizeddustgrainsprecipitatefromtheD-ringintotheatmosphere.RPWSLangmuirprobeionnumberdensitymeasurementssuggestthatthechargeddusthasaprofoundeffectontheionosphericstructure,enhancingtheionnumberdensitywellabovephotochemicalequilibriumlevels,whiletheelectronstendtobecomeattachedtothedustpopulation.WepresentmodelcalculationsofSaturn’sequatorialionosphereandincludetheeffectofchargeddustgrainsthatbreakdownintosmallergrains/clustersdeeperintheatmosphereatanaltitudeneartheionosphericpeak.ThemodelisconstrainedasfaraspossiblebyinputfromCassiniINMS,RPWSandINCA/CHEMSmeasurements,andthencomparedwithobservedelectronandionnumberdensitiesbyRPWS.Fromthesedust-ionospheremodelcalculationsitisclearthatalayerofsmallsinglychargedsub-nm-sizeddustgrainscanexplaintheRPWSLangmuirprobemeasurements.

Self-consistentmodelingofplanetaryelectrondynamicsWang,L.,PrincetonUniversityDong,C.F.,Bhattacharjee,A.,Raeder,J.,GermaschewskiK.,Hakim,A.H.

Electrons,particularlytheenergetic,suprathermalcomponentscouldplayimportantrolesinmagnetosphericdynamicsinmanyplanetarysystems.However,theinclusionoftheseeffectsintoglobal-scalemodelingofmagnetospheresystemshasnotbeeneasy.Weproposetousethemulti-fluidhigh-momentmodeltoaddressthisissue.Themodelevolvesanarbitrarynumberofelectronandionspecieswithdifferentcharge/massnumbers,and/orenergylevels,toaccountforthecomplexplasmacompositioninthemagnetospheres.Themodelcapturesnon-idealphysicsliketheHalleffectandanisotropic,non-gyrotropicpressureeffectsthatareimportantincontrollingthestrengthofreactiontoexternaldrivingsandthebalanceinaquasi-steadystate.WehavesuccessfullyappliedthemodeltothemagnetospheresofGanymedeandMercury,andtheresults,includingdata-modelcomparison,willbediscussedinthispresentation.Wewouldalsodiscussthecapabilitiesofthismodelinimprovingtheplanetarymagnetospheremodelingthatwewillutilizeinthefuturework.

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AngularSizeofIoMagneticFootprint’sMainAlfvènWingSpot:InCorrespondingtoSatellite’sLocationsWannawichian,S.,DepartmentofPhysicsandMaterialsScience,FacultyofScience,ChiangMaiUniversity,ChiangMai,ThailandJohnT.C.,JonathanD.N.

Satellitesinplanetarymagnetosphereareoftenaffectedbytheinteractionbetweenmagnetosphericplasmaandsatellites’atmospheres.Duetotheinteraction,pickedupcurrentstravelalongthemagneticfieldlinefrominteractionregiontowardtheplanet’sionosphere.ThesecurrentsclearlyconnectthevicinityofIotoJupiter’ionosphereviamagneticfieldlines.Inionosphere,spotemissionscanbedetectedattheendmagneticfieldline,whichisknownas“AuroralMagneticFootprint”.Io’smagneticfootprintisaprominentauroralfeature,whichlocatesfewdegreeslatitudelowerfromJupiter’smainauroralemission.CorrespondingtointeractionregionatIoapproximately1.5Ioradii,thesizeofIo’smagneticfootprintisexpectedtobeapproximately~100km.Inthisstudy,thesizeofthefootprints,especiallytheMainAlfvènwingspot(MAW),willbeanalyzedbasedonFUVimagingbyAdvancedCameraforSurveys(ACS)instrumentonHubbleSpaceTelescope(HST).TheimagesofJupiter’sauroralregionweretakenin1998,2000,2001,and2007duringHST’scampaigns.Fordifferentepochsofobservations,theangularsizesofIo’smagneticfootprintvariedwithgeneraltrend,inwhichseveralemissionpeaksweredetected.Thisresultcouldbeinterpretedtohavesomecorrelationwiththefootprintbrightness.AccordingtoinsituobservationsofplasmaenvironmentnearIo,temporalandspecialvariationsofJupitermagnetosphericplasmacouldbeoneofthefactorsthataffectthebrightnessandangularsizeofIo’smagneticfootprint.

PulsationcharacteristicsofJovianinfraredpolarauroraobservedbySubaruIRCSwithadaptiveopticsduringJuno’ssolarwindcampaignWatanabe,H.,TohokuUniversityKita,H.,Sakanoi,T.,Tao,C.,Kagitani,M.,Kasaba,Y.

Wereportthe~10minperiodiccharacteristicsofJovianinfrared(IR)aurorafoundinH3+

narrow-bandimaging(centeredat3.4um)ofSubaru8-mwithadaptiveopticson25May2016duringJuno’ssolarwindcampaign.Inpastobservations,noIRaurorahassignificantvariationsontimescaleslessthan30min.Theyareconsideredasstableover~90min[e.g.Stallardetal.2016].However,small-scaleandrapidvariationsmayexistinIRauroraconsideringthatthetimescaleofH3

+emissionis102-104sec[Taoal.,2013],especiallyinthepolarregionwhereperiodicultraviolet(UV)emissionswithtimescalesofafewsecondsorminuteshavebeenobserved.Inthisstudy,wecarriedoutthenarrow-bandimagingofJovianH3

+aurorawithIRCS(InfraredCameraandSpectrograph)attachedontheSubarutelescopeatMaunaKea,Hawaii,withthetimeresolutionof45-110sec.BytheassistofAdaptiveOpticsinstrument(AO188),wecanachievespatialresolutionof~0.1arcsec[Minowaetal.,2010].Themainovalwasstablybrightinthedawnside(SystemIII:~190-210deg)anddimontheduskside(S-IIIlongitude:~160-180deg,calledas‘discontinuity’inUVobservation).Twoorthreepolarpatcheswerealsoseenalongthemainoval.Theyweresub-corotatingandtheirintensitieswerevaryingapartfromeachother.Inparticular,apatchappearedin62-65deginlatitudeand172-182deginS-IIIlongitudewasclearlypulsatingwithanamplitudeof~20%andtheperiodof~10minwhichwasidentifiedbytheLomb-Scarglemethod.SincethetimescaleofH3

+dynamictransportordiffusionisexpectedas104-105sec[Taoetal.,2013],thepulsatingcannotbeexplainedbythem.UsingtheauroralemissionmodelbyTaoetal.[2011],weconfirmedthattheH3

+emissionintensityiswellresponsibletothe~10minvariationofauroralelectronflux.Thisestimationisconsistentwiththeobservation.

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ACompendiumoftheSaturn-TitanInteractionasObservedwithEnergeticNeutralAtoms(ENAs)fromCassiniMIMI-INCAWestlake,J.H.,JHU/APLMitchell,D.G.;Brandt,P.C.

Forthe127TitanflybysofCassinitheINCAENAcamera[Krimigisetal.,2004]hasobservedthemoon-magnetosphereinteractionusingchargeexchangeofthemagnetosphericionswiththedenseneutralatmosphereofTitanandproduced105flybysworthofdata.FromtheseTitanflybysthereexistsmultiplevantagepointsforENAimagingofthemoon-magnetosphereinteractionrevealingintriguingENAmorphologyrelatedtothemagneticfield[Wulmsetal.2010],andtemporalfeatures[e.g.Mitchelletal,2005].DuetothenatureoftheinputplasmaanditspitchangledistributionandtheshadowingofENAsfromTitan’satmosphereitiscrucialtoutilizethemultitudeofvantagepointstofullyunderstandthisinteraction.InthispaperwepresentanupdatedcompilationoftheINCAENAobservationsatTitanshowingtheflybysandspecifictimeswheregood,cleanENAobservationsareavailableaswellaspointingoutspecificfeaturesintheENAobservationssuchasburstsofheavyionENAemissionsanduniquetemporalfeatures.ThislistofobservationtimesandfeaturesisthenusedinconjunctionwiththeupstreamconditionsandfieldconfigurationsfromtheworkofSimonetal.2010,2013,Rymeretal.2009,andGarnieretal.2010tounderstandthecomplexinterplayoftheplasma,magneticfields,andparticleenvironments.ThedataissortedbyvantagepointandflybyconditiontounderstandhowtheplasmaandparticleenvironmentvaryatTitan.

ForwardModelingMultipleHeavyIonSpeciesinJADEDataWilson,R.J.,LASP,CUBagenal,F.,Valek,P.W.,Allegrini,F.,Ebert,R.W.,Kim,T.K.,Ranquist,D.A.,Thomsen,M.F.

Jupiter'smagnetosphereishugeandtypicallyhasasizebetween~60to~120RJ(1RJ=1jovianradius),yetpastmissionshaveonlybeenabletoexplorethethermalplasmaoutto~30RJwithsparsecoverage.TheVoyagerseachhadaflybybutwere3-axisstabilizedanddidnotalwayspointinthedirectionofplasmaflow[Bagenal+,2017].TheGalileoplasmaspectrometer(GLL/PLS)wasonanorbitingspinningplatform,butwasnotverysensitiveandduetoagreatlyreduceddatarate,returnedonlyasubsetofnon-continuousenergystepsperspin[Bagenal,Wilsonetal.,2016].Juno'sJADEisasensitiveplasmainstrument,onaspinningplatformabletoviewallskyoverconsecutiveenergies.Junohas53-dayorbitswithapojovesof112RJ,allowingexplorationofthemiddle/outerjovianmagnetosphereinregionsunexploredbypreviousthermalplasmainstruments.

JunoJADEproducesdirectional'species'data,whereitdividesupthetime-of-flight(TOF)datasetinto3classes(H+,lights,heavies).NumericalmomentsarefasttocomputeandareroutinelymadebytheJADEteamtoobtainadensity,n,temperature(s),T,andvelocity,V,ofeachclassseparately,butrequireasingularmass/charge(m/q)foreachclass.TheheaviesconsistprimarilyofO+&S++(thesamem/q,whichcannotbeseparatedinthespeciesdataset)plusotherspecies,allofwhichmustbeassumedtohavethesamem/q(e.g.24/1.5).Howeverwithforwardmodelingwemayfitasmanyionspeciesaspresent(intheTOFdata)simultaneously(i.e.separatingO+&S++)tothetotalJADEspeciesdata,assumingasharedV,butallowingnandTtovarybyspecies.Theprocessiscomputationallyveryexpensive;requiringtuningbyhandtofittheparticularsofthedataset,andthispresentationshowstheinitialstagesofthiswork.WehopetowinproposalstofundafullsurveyoftheplasmasheetbyJADEtomeasuretheflowofmassandenergythroughthejovianmagnetosphere.

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TheeffectofwaveparticleinteractionsonelectronsclosetoSaturnWoodfield,E.E.,BritishAntarcticSurveyHorne,R.B.,Glauert,S.A.,Menietti,J.D.,Shprits,Y.Y.

TheGrandFinaleorbitsofCassinigiveusagreatopportunitytoinvestigatetheeffectsofwavesonparticlesveryclosetotheplanet.PreviousworkhasshownthatZ-modewavesaccelerateelectronsstronglybetweentheA-ringandtheorbitofEnceladusandthatwhistlermodechorusisalsoveryeffectiveatacceleratingelectronsattheEarthandJupiter.ThenewdatafromCassinishowsthatZ-modeandwhistlermodewaveshavebeenobservedeveninsidethemainrings.InthisstudyweinvestigatetheeffectsofthewavesobservedbyCassinionelectronsofvariousenergieslookingforaccelerationandscatteringregimesveryclosetotheplanet.WealsotakeafirstlookattheeffectsofwhistlermodewavesoutsideofthemainringsbutinsideoftheorbitofEnceladus,intheregionwhereZ-modewaveshavepreviouslybeenshowntostronglyaccelerateelectrons.

3DJovianMagnetosphere-Ionosphere-Thermosphere(MIT)Yates,J.N.,EuropeanSpaceAgencyRay,L.C.,Achilleos,N.

Jupiter’supperatmospherictemperatureisconsiderablyhigherthanthatpredictedbySolarExtremeUltraviolet(EUV)heatingalone.Simulationsincorporatingmagnetosphere-ionospherecouplingeffectsintogeneralcirculationmodelshave,todate,struggledtoreproducetheobservedatmospherictemperaturesundersimplifyingassumptionssuchasazimuthalsymmetryandaspin-aligneddipolemagneticfield.Herewepresentthedevelopmentofafullthree-dimensionalthermospheremodelcoupledinbothhemispherestoanaxisymmetricmagnetospheremodel.Thisnewcoupledmodelisbasedonthetwo-dimensionalMITmodelpresentedinYatesetal.,2014.Thiscoupledmodelisacriticalsteptowardstothedevelopmentofafullycoupled3DMITmodel.Wediscussandcomparetheresultingthermosphericflows,energybalanceandMIcouplingcurrentstothosepresentedinprevious2DMITmodelsandobservationswhereavailable.

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AnSLS5longitudesystembasedontherotationalmodulationofSaturnradioemissionsYe,S.-Y.,TheUniversityofIowaFischer,G.,Kurth,W.S.,Menietti,J.D.,Gurnett,D.A.

DespitetheaxisymmetryofSaturn’sinternalfield,SaturnradioemissionslikeSaturnkilometricradiation(SKR)aremodulatedduetoplanetaryrotation.WiththecompletionofCassinimissioninSeptember2017,wenowhaveover14yearsofobservationofSaturnradioemissions,roughlyfromsouthernsolsticetonorthernsolstice.Inthisstudy,weextendtheSLS4longitudesystemtotheendoftheCassinimissionusingaphasetracingmethod.ThenewSaturnlongitudesystem(SLS5)organizestheSKRmaximaaround0°longitudeinbothnorthernandsouthernhemispheresandcanbeusedtoorganizeotherphenomenaobservedinSaturn’smagnetosphere.

PlasmaandenergytransportinJupiter’sinnermagnetosphereasdeducedfromHisakiobservationYoshioka,K.,TheUniversityofTokyoTsuchiya,F.,Kagitani,M.,Kimura,T.,Murakami,G.,Yoshikawa,I.,Yamazaki,A.,Hikida,R.,Fujimoto,M.

Sinceitslaunchin2013,theExtremeUltravioletspectrometerEXCEEDonboardtheHisakispacecraftisobservingJupiter’sauroraandtheIoplasmatoruscontinuously.ThesulfurandoxygenionswhicharethemaincomponentsoftheIoplasmatorusemitlinesthroughtheimpactexcitationbytheambientelectrons.ThespectralresolutionofEXCEEDishighenoughtodistinguishthoselines.Thentheiondensities,electrondensities,andelectrontemperaturecanbededucedusingthesocalledspectraldiagnosismethod.Todiscusstheoutwardtransporttimescaleofplasmas,energyvalanceinsidethetorus,andneutralsourceratefromthosededucedparameters,weadoptthephysicalchemistrymodelasdescribedinDelamereetal.[2003].Inthisstudy,wecomparetheplasmatransporttimescale(velocity)withvariousenvironmentalconditionssuchasJupiter’sSystemIIIrotation,Io’srotation,Io’svolcanicactivity,andsolarwindcondition.

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JupiterradioemissioninducedbyGanymedeandconsequencesfortheradiodetectionofexoplanetsZarka,P.,LESIA&USN,Obs.Paris/CNRS/PSL,Meudon,FranceSoaresMarques,M.,Louis,C.,Ryabov,V.B.,Lamy,L.,Echer,E.,Cecconi,B.

Radiodetectionofexoplanetsshallopenauniquewindowontheirmagneticfield,rotation,andplasmaenvironment.Inoursolarsystem,Jupiter’sdecametricemissionisasintenseasSolarradiobursts,butneitherisdetectablebeyond~0.1pcwithlargepresent-daylow-frequencyradiotelescopes.Thepossibleexistenceofmuchstrongerplanetaryradioemitterswasdeducedfromscalinglawsbuiltfromplanetaryradiosourcesinoursolarsystem,wheretheprimaryengineoftheradioemissionisthekineticormagneticpowerinputfromthesolarwindtothemagnetosphere(hencenamedradio-kineticandradio-magneticscalinglaws).HerewepresentthefirstquantitativestudyoftheGanymede-Jupiterradioemission,recentlydetectedunambiguouslybyanalysinga26-yeardatabaseofdecametricobservationsofJupiter.Focussingonitsenergetics,wecompareittotheIo-Jupiteremission.WeshowthatinspiteofthedifferentinteractionsofthesemoonswithJupiter’smagnetosphere(primarilyviaAlfvénwavesforIoandmagneticreconnectionforGanymede),theirinducedradiopowersareinthesameratioasthemagneticpowerinputthattheyinterceptfromthemagnetosphere.Moregenerallyauroral,Io-inducedandGanymede-inducedradioemissionsallfitaradio-magneticscalinglawthatpredictsstrong–potentiallydetectable–radioemissionsforhotjupiters.ThestatisticsofGanymede-Jupiterradioemissiondurationsalsobringssomelightontheinteractionofthesetwobodiesviamagneticreconnection.

MagnetopauseDynamicsfrom3DHallMHD-EPICSimulationsofGanymede`sMagnetosphereZhou,Hongyang,UniversityofMichiganToth,Gabor;Jia,Xianzhe

Thelargestmooninthesolarsystem,Ganymede,isalsotheonlymoonknowntopossessastrongintrinsicmagneticfieldandacorrespondingmagnetosphere.Anewmodelingtoolemployingtheimplicitparticle-in-cell(PIC)codeiPIC3DembeddedintotheBATS-R-USHallmagnetohydrodynamic(MHD)modelisappliedtosimulatethemagnetosphericstructureanddynamicsofGanymede.ImprovementsofthenewMHD-EPICmodelincludeaself-consistentlycoupledresistivebodyrepresentingtheelectricalpropertiesofthemoon’sinterior,improvedinnerboundaryconditions,andtherecentlyimplementedenergy-conservingschemeforiPIC3D.OurnewmodelissuccessfullyvalidatedforallsixGalileoflybysbasedoncomparisonsofthemagneticfield.AsmagneticreconnectionisthemaindriverofGanymede’smagnetosphericdynamics,wefocusourpresentstudyonthemagnetopausereconnection,whichisresolvedbythekineticcodeiPIC3Dinoursimulations.Wefindthatundersteadyupstreamconditions,magnetopausereconnectionoccursinanon-steadymanner.Asaresult,fluxtransferevents(FTEs)formonthemagnetopauseproducingspatialandtemporalvariationsinplasmaandfieldproperties.Wealsodeterminetheoccurrencerateandspatialdistributionofreconnectionsitesandquantifytheglobalreconnectionrateatthemagnetopauseinoursimulations.BycomparingmodelresultsfromdifferentGalileoflybys,weareabletogaininsightsintohowmagneticreconnectionandFTEformationatGanymedevarydependingontheupstreamconditions,especiallytheAlfvenicMachnumberandthemagneticshearangle.Whilethemagnetopausereconnectionappearsintermittentinallofoursimulations,noobviousperiodicityisfound,potentiallyindicatingachaoticenergy-cascadingsystem.

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Index

Agiwal 11 Gladstone 38 Louis 67 Sergis 94Alexeev 11 Griton 38 Lysak 68 Sinclair 95Allegrini 12 Grodent 39 Magalhaes 68 Smith 95

Allen 12 Guio 39 Manners 69 Song 96 Andrews 13 Hadid 40 Martin 69, 70 Sorba 96Arakawa 13 Haggerty 40 Masters 70, 71 Soto-Chavez 97

Arridge 14 Hamil 41 Mauk 71 Southwood 97Azari 14 Hardy 41 Menietti 72 Spencer 98

Bader 15 Harris 42 Misawa 72 Staniland 98Badman 15 Hendrix 42 Mitchell 73 Stephens 99Bagenal 16 Heuer 43 Morgenthaler 73 Styczinski 99

Bard 17 Higgins 43,44 Morooka 74 Sulaiman 100Becker 17 Hikida 44 Munoz 74 Szalay 100

Bergman 18 Hinton 45 Mura 75 Tao 101Berland 18 Horanyi 45 Murakami 76 Thomsen 101Bertucci 19 Hospodarsky 46 Nakamura 76, 77 Trafton 102Blöcker 19 Houston 46 Nenon 78 Travnicek 102

Bonfond 20 Hsu 47 Nerney 78 Valek 103Bradley 20 Hue 47 Neupane 79 Vasyliūnas 103

Brown 21 Hunt 48 Nichols 79 Vogt 104Bunce 21 Huscher 48 O'Donoghue 80 Vriesema 104

Burkholder 22 Huybrighs 49 Palmaerts 80 Wahlund 105Burton 22 Imai, K 49, 50 Parunakian 81 Wang 105Cao, H 23 Imai, M 50 Paty 81 Wannawichian 106Cao, X 23 Jackman 51 Perry 82 Watanabe 106Carlton 24 Jasinski 51, 52 Phipps 82 Westlake 107

Carnielli 24 Jia 52, 53 Píša 83 Wilson 107Cassidy 25 Kammer 53 Ponce 83 Woodfield 108Cecconi 25 Kane 54 Pontius 84 Yates 108

Chané 26 Kasaba 55 Poppe 84 Ye 109Clark 26 Katoh 55 Prangé 85 Yoshioka 109

Clarke 27 Khurana 56 Provan 85 Zarka 110Coffin 27 Kim 56 Pryor 86 Zhou 110Collier 28 Kimura 57 Ranquist 86

Collinson 28 Kinrade 57 Rathbun 87Connerney 29 Kita 58 Ray 87

Crary 29, 30 Kivelson 58, 59 Retherford 88Cravens 30 Koga 60 Roth 88, 89

Damiano 31 Kollmann 61 Roussos 89Davies 31 Korth 62 Rutala 90

Delamere 32 Koskinen 62 Rymer 90Dols 32 Krupp 63 Sakanoi 91

Dunn 33,34 Kurth 63 Santos-Costa 91Ebert 35 Lamy 64 Sarkango 92Elliott 36 Lee-Payne 65 Saur 92

Farrell 36 Liuzzo 65, 66 Sawyer 93Fischer 37 Lorch 66 Schmidt 93Gérard 37 Louarn 67 Schneider 94

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