modeling/inferring coronal and heliospheric field from photospheric magnetic field
DESCRIPTION
Modeling/Inferring Coronal And Heliospheric Field From Photospheric Magnetic Field. Yang Liu – Stanford University [email protected]. Outline. HMI/SDO observables; HMI science with vector magnetograms; Modeling the coronal and heliospheric field from the photospheric magnetic field. - PowerPoint PPT PresentationTRANSCRIPT
February 26, 2007 KIPAC Workshop on Magnetism
Modeling/Inferring Coronal And Modeling/Inferring Coronal And Heliospheric Field From Heliospheric Field From
Photospheric Magnetic FieldPhotospheric Magnetic Field
Yang Liu – Stanford Yang Liu – Stanford UniversityUniversity
[email protected]@solar.stanford.edu
February 26, 2007 KIPAC Workshop on Magnetism
OutlineOutline HMI/SDO observables;HMI/SDO observables; HMI science with vector HMI science with vector
magnetograms;magnetograms; Modeling the coronal and Modeling the coronal and
heliospheric field from the heliospheric field from the photospheric magnetic field.photospheric magnetic field.
February 26, 2007 KIPAC Workshop on Magnetism
HMI observablesHMI observables Continuum intensity;Continuum intensity;
Full disk with a CCD of 4096×4096 pixels;Full disk with a CCD of 4096×4096 pixels; resolution is 0.5’’/pixel;resolution is 0.5’’/pixel; Cadence less than 1 minute.Cadence less than 1 minute.
Doppler velocity;Doppler velocity; Full disk with a CCD of 4096×4096 pixels;Full disk with a CCD of 4096×4096 pixels; resolution is 0.5’’/pixel;resolution is 0.5’’/pixel; Cadence less than 1 minute.Cadence less than 1 minute.
Line-of-sight magnetic field;Line-of-sight magnetic field; Full disk with a CCD of 4096×4096 pixels;Full disk with a CCD of 4096×4096 pixels; resolution is 0.5’’/pixel;resolution is 0.5’’/pixel; Cadence less than 1 minute.Cadence less than 1 minute.
Vector magnetic field.Vector magnetic field. Full disk with a CCD of 4096×4096 pixels;Full disk with a CCD of 4096×4096 pixels; resolution is 0.5’’/pixel;resolution is 0.5’’/pixel; Cadence less than 2 minute.Cadence less than 2 minute.
More information
February 26, 2007 KIPAC Workshop on Magnetism
HMI Science (Magnetic HMI Science (Magnetic Field)Field)
Sources and drivers of solar activity and Sources and drivers of solar activity and disturbances;disturbances; Evolution of small-scale magnetic elements (coronal Evolution of small-scale magnetic elements (coronal
heating);heating); Emergence of magnetic flux and solar transient events;Emergence of magnetic flux and solar transient events; Magnetic configuration and mechanisms of solar flares Magnetic configuration and mechanisms of solar flares
and CMEs.and CMEs. Links between the internal processes Links between the internal processes
and dynamics of the corona and and dynamics of the corona and heliosphere;heliosphere; Complexity and energetics of solar corona;Complexity and energetics of solar corona; Coronal magnetic structure and solar wind.Coronal magnetic structure and solar wind.
Precursors of solar disturbances for Precursors of solar disturbances for space-weather forecast.space-weather forecast. Determination of magnetic cloud Bs events.Determination of magnetic cloud Bs events.
February 26, 2007 KIPAC Workshop on Magnetism
Modeling the coronal and Modeling the coronal and heliospheric field.heliospheric field.
Potential field source surface model Potential field source surface model (PFSS);(PFSS);
Hybrid model;Hybrid model; Non-linear force-free field model;Non-linear force-free field model; MHD simulation.MHD simulation.
February 26, 2007 KIPAC Workshop on MagnetismSchatten, Cosmic Electrodynamics, 2, 232, 1971.
),(YrB + rA = ),(r, lm1)+-(l
lml
lm
l
-l=m0 = l
where,
0 = 2
Potential Field Source Potential Field Source Surface ModelSurface Model
Coefficients Alm and Blm are determined from the boundary conditions.
j = 0
From Arge 2005.
February 26, 2007 KIPAC Workshop on Magnetism
Solar Boundary: Magnetic Solar Boundary: Magnetic FieldField
February 26, 2007 KIPAC Workshop on Magnetism
Potential field source Potential field source surface modelsurface model
PFSS
February 26, 2007 KIPAC Workshop on Magnetism
Validation of PFSSValidation of PFSS
Zhao and Webb (2003)
February 26, 2007 KIPAC Workshop on Magnetism
Validation of PFSSValidation of PFSS
February 26, 2007 KIPAC Workshop on Magnetism
February 26, 2007 KIPAC Workshop on Magnetism
3D MHD simulation shows that type 2 and 3 3D MHD simulation shows that type 2 and 3 CMEs are faster than type 1.CMEs are faster than type 1.
February 26, 2007 KIPAC Workshop on Magnetism
Data Data We looked for the halo CMEs from the CMEs list We looked for the halo CMEs from the CMEs list
of Gopalswamy’s group. 91 halo CMEs in the of Gopalswamy’s group. 91 halo CMEs in the period from 2000 to 2004 were chosen. The solar period from 2000 to 2004 were chosen. The solar sources were identified by that group, and were sources were identified by that group, and were confirmed by other groups/works.confirmed by other groups/works.
Type 1Type 1 Type 2Type 2 Type 3Type 3
numbernumber 3939 4646 1414
PercentagePercentage 39%39% 47%47% 14%14%
Median speed (km/s)Median speed (km/s) 728728 12081208 14431443
Mean speed (km/s)Mean speed (km/s) 883±403883±403 1345±5961345±596 1530±7361530±736
February 26, 2007 KIPAC Workshop on Magnetism
Speed distribution for type 1 and types 2&3 CMEs. The types 2 & 3 CMEs are significantly faster than type 1 CMEs.
February 26, 2007 KIPAC Workshop on Magnetism
Distributions of flare class for type 1 and 2 & 3 CMEs. They have very similar distributions. This suggests that the difference of the CMEs speed is not biased by flare importance.
Wang & Sheeley (1990) simulate the solar wind speed at Earth for ~20 year period (1967-1988).
i) Test hypothesis that Vsw and fs = (R/Rss)2[BP(R)/BP(Rss)] are inversely correlated.
ii) Correlation between observed and simulated wind speed found.
Simulated speedObserved Speed
Wang & Sheeley, ApJ, 355, 726, 1990.
Long-Term Comparison of Observations and Solar Long-Term Comparison of Observations and Solar Wind Speed Predictions Using the PFSSWind Speed Predictions Using the PFSS
From Arge (2005)
NSO750
650
550
450
350
250
750
MWOCR1988 CR1987 CR1986
650
550
450
350
250
de Toma and Arge (2004)
February 26, 2007 KIPAC Workshop on Magnetism
Validation of PFSSValidation of PFSS
Measurements
Model Calculation
Wang et al. 2000
Global Coronal Field: Extrapolations and ObservationsGlobal Coronal Field: Extrapolations and Observations
Comparison of photospheric field extrapolations (left) to white light (pB) image (right) indicate a degree of qualitative correlation between closed field lines and streamers
White light (pB) data HAO/MLSO/Mk3Photospheric field extrapolation (MWO)
Gibson and Arge
February 26, 2007 KIPAC Workshop on Magnetism
Hybrid modelsHybrid models Potential field-current sheet model (PFCS Potential field-current sheet model (PFCS
model, Schatten 1971);model, Schatten 1971); Horizontal current-source surface model ( Horizontal current-source surface model (
HCSS model, Zhao & Hoeksema, 1992);HCSS model, Zhao & Hoeksema, 1992); Horizontal current-current sheet model Horizontal current-current sheet model
(HCCS model, Zhao & Hoeksema, 1994);(HCCS model, Zhao & Hoeksema, 1994); Current sheet-source surface model Current sheet-source surface model
(CSSS model, Zhao & Hoeksema, 1995).(CSSS model, Zhao & Hoeksema, 1995).
February 26, 2007 KIPAC Workshop on Magnetism
Current-sheet source Current-sheet source surface modelsurface model
From Zhao & Hoeksema 1995.
February 26, 2007 KIPAC Workshop on Magnetism
Validation of CSSS modelValidation of CSSS model
From Zhao, 1999.
February 26, 2007 KIPAC Workshop on Magnetism
Non-linear force-free Non-linear force-free field modelfield modelWiegelmann, Solar
Physics, in press, 2007.Case 1: use boundary data on both photosphere and source surface in 30<theta<150;Case 2: use boundary data on both photosphere and source surface in delta_theta<theta<180-delta_thetaCase 3: use boundary data on both photosphere and source surface.Case 4: only use boundary data on photosphere. Magnetic field on the source surface is replaced by the initial potential field.
February 26, 2007 KIPAC Workshop on Magnetism
MHD simulationMHD simulation
Magnetic Field Lines(MHD Model)
Polarization Brightness(MHD Model)
Eclipse (Williams College)*& SOHO LASCO C2 Images
Solar eclipse on March 29, 2006. Simulation was done by Linker et al at Science Application International Corporation (SAIC) at San Diego.
February 26, 2007 KIPAC Workshop on Magnetism
HMI simulationHMI simulation Extra boundary data help improve simulation Extra boundary data help improve simulation
results.results.
Hayashi et al 2006
February 26, 2007 KIPAC Workshop on Magnetism
Comparison of MHD and Comparison of MHD and PFSSPFSS
From Riley et al, 2006, ApJ.
PFSS
MHD