earth observation using gnssindico.ictp.it/event/a09138/session/7/contribution/4/... ·...
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Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Earth Observation Using GNSS
Francesco VespeAgenzia Spaziale Italiana
Centro di Geodesia Spaziale75100 Matera
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Earth Observation Using GNSS
• EO with ground GNSS facilities
• EO with spaceborne GNSS
• ASI projects in GNSS Radio OccultationActivities
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
The Global Navigation Satellite Systems: The Principles
AccuracyAccuracy few few metersmetersThe GPS The GPS isis a a ToyToy !!!!The The enterpriseenterprise seemsseems hopelesshopeless !!ButBut……....
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
The Differential Approach
The The uncertaintiesuncertainties are are reducedreduced at fewat fewmm mm levellevel !! GNSS can !! GNSS can bebe usedused forfor
scientificscientific purposespurposes
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Survey modes
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GNSS principles
Maintainance of the Terrestrial Reference Frame
ITRFxx
Seismicity and Landslides
Mean Sea level
Ionosphere
Neutral Atmosphere (Meteorology & Climate)
Space Applications•Radio Occultation•Gradiometry
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Satellite/Lunar Laser Ranging
Very Long Baseline Interferometry
Global Positioning System
International Space International Space GeodesyGeodesyCoordinationCoordination
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
IGS Network
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Data analysisITRF- Earth
1984 1986 1988 1990 1992 1994 1996 1998-1
-0.8-0.6-0.4-0.2
00.20.40.60.8
1 x 10-9
ΔJ 2
WRMS=15.6 10-11
Year
( ). . /J2= − ± ⋅ −25 07 10 11 yr
Data coverage:•LAGEOS-I•LAGEOS-II
Gravity Field
TectonicsPolar Motion and Orientation
P Ground Ground MonitoringMonitoring of of AreasAreas LiableLiable toto SeismicSeismicand/or and/or LandslidesLandslidesHazardsHazards
Combined SLR-VLBI-GPS Solutions
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
mill
isec
onds
/day
Interannual component of ΔLOD
ENSO ENSO
Length of Day
Mean Sea Level
Seismic Area
Fixed S tations
Mobile S tations
Operation Center
ASI
Remote Sensing D
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
TRF & TectonicsTRF & Tectonics
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Global Strain Rate
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Length of day (LOD)
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
1800.0 1850.0 1900.0 1950.0 2000.0
LOD = Difference of day from 86400. seconds
LOD (ms)LOD (ms)
LOD
(ms)
Year
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GNSS principles
Maintainance of the Terrestrial Reference Frame
ITRFxx
Seismicity and Landslides
Mean Sea level
Ionosphere
Neutral Atmosphere (Meteorology & Climate)
Space Applications•Radio Occultation•Gradiometry
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
ANTENNA DISPOSITVO DI
REGISTRAZIONE PREAMPLIFIC.
SEZIONE RADIO MICROPROCESS. ALIMENTATORE FREQUENZA
CDU
Noto
Cagliari
Matera
MedicinaGenova
VeneziaPadovaBasovizzaTorin
o
TrentoBolzano
Foggia
Potenza
Vallo d. LucaniaCosenza
Perugia
ASI receiversInstitutes collaborating
otherswith ASI
Roma
Fucino
Boretto
Scanzano
Lampedusa
Tirana
Prato
L’Aquila
Elba AnconaCamerino
Reggio C.
Novara
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
97 98 99 100 101
238.34
238.36
238.38
238.42
Slope without harmonics (v1)
H (m)
Years
CagliariSlope estimated with harmonics (v2)
Plot of slope+jumps + harmonics
Contribution to the ITRF Maintainance (IGS/EUREF)
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
V1=
V2=
Period (days) amp (mm) 0.0128243
Ou t[2 54 ]= 1.28243
rms=12.5 mm
Cagliari
- 0.00354114 0.000501929
0.00909238
-3.61±0.36 mm/yr
- 0.00361253 0.000360408
-3.64±0.35 mm/yr rms=12.0 mm
t 10.5 yr
359 2.2180 3.7121 1.8
hVfittheofscattert )(3∗≥Δ
-0.03 -0.02 -0.01 0.01 0.02 0.03
20
40
60
80
meters
-0.0331073-0.0321041-0.0311008-0.0300975-0.0290943-0.028091-0.0270878-0.0260845-0.0250813-0.024078-0.0230748-0.0220715-0.0210683-0.020065-0.0190618-0.0180585-0.0170553-0.016052-0.0150488-0.0140455-0.0130423-0.012039-0.0110358-0.0100325-0.00902926-0.00802601-0.00702276-0.00601951-0.00501626-0.00401301-0.00300975-0.0020065-0.0010032500.001003250.00200650.003009750.004013010.005016260.006019510.007022760.008026010.009029260.01003250.01103580.0120390.01304230.01404550.01504880.0160520.01705530.01805850.01906180.0200650.02106830.02207150.02307480.0240780.02508130.02608450.02708780.0280910.02909430.03009750.03110080.0321041
20
40
60
80
ahlpgrcslttot VVVVVVV +++++=
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Strain Rate Strain Rate ComputationComputation
11 The planar (x,y) The planar (x,y) velocitiesvelocities in the in the verticesvertices of of eacheach selectedselectedtriangletriangle are are expandedexpanded at the first at the first orderorder byby meansmeans of the of the velocityvelocity gradientgradient tensortensor LL
bii vΔxLv +=
( )TLL21E +=
22 EstimationEstimation of the of the tensortensor L L in a in a leastleast squaressquares sensesense
33 Strain rate (E) Strain rate (E) computationcomputation
b
iv
4 Measurement unit of strain rate: 1 nano-strain/yr is equal to a deformationof 1mm/yr per 1000 Km
⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢
⎣
⎡
∂
∂
∂
∂∂∂
∂∂
=
yV
xV
yV
xV
Lyy
xx
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Landslides
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Extension of the experiment toCraco (Mt)
A site A site candidatescandidates toto bebeIncludedIncluded in WMF listin WMF list
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
DTM built with GPS RTK
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GNSS principles
Maintainance of the Terrestrial Reference Frame
ITRFxx
Seismicity and Landslides
Mean Sea level
Ionosphere
Neutral Atmosphere (Meteorology & Climate)
Space Applications•Radio Occultation•Gradiometry
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Why do we study MSL?
• Climate
• Geodesy: Vertical Datum
• Shore and Sea Instabilities (Subsidence, Erosion, water loading etc.)
• Topography, Cartography etc.
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
We do need a simphony of different techniques
• Tide-gauges:
– Relative MSL against the ground
• GPS local network co-located with tide-gauges
• Bathymetry
• Global GPS network to link the local one to ITRF
• Ocean circulation and waves-motion monitoringwith SAR, Radar Altimeter, GPS buoys etc.
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
SELF 1&2
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
How altimetry works:
Altimetry principle
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GNSS principles
Maintainance of the Terrestrial Reference Frame
ITRFxx
Seismicity and Landslides
Mean Sea level
Ionosphere
Neutral Atmosphere (Meteorology & Climate)
Space Applications•Radio Occultation•Gradiometry
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Data analysisAtmosphere
Ionosphere
OccultingGPS Satellite
AtmosphereAtmosphere
IonosphereIonosphere
( ) ( )[ ]evevevev ⋅−⋅−⋅−⋅=Δ RTRRTTcff
⎪⎭
⎪⎬
⎫
⎪⎩
⎪⎨
⎧
⎟⎟⎟
⎠
⎞
⎜⎜⎜
⎝
⎛
⎟⎟⎠
⎞⎜⎜⎝
⎛−+−= ∫
∞
a
dxdxd
ax
axan γ
π
21
2
2
1ln1exp)(
...1073.36.7710)1( 256 +⋅+=⋅−=
Te
TPnN
GPS Limb Sounding
GPS PW influence w.r.t the model
GPS for Meteorology
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GNSS principles
Maintainance of the Terrestrial Reference Frame
ITRFxx
Seismicity and Landslides
Mean Sea level
Ionosphere
Neutral Atmosphere (Meteorology & Climate)
Space Applications•Radio Occultation•Gradiometry
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
From GPS TD to Num. Weather Pred.
( )Φ = + − + − + +ρ λ εc dt dT A d dion trop
( )d ZTD m el
ZTD Ndztrop ≅ ⋅
≅ − ∫10 6
( )( ) )( ZHDZTDT
ZWDTIWV
m
m
−Π
=Π≅
GPS observables
ZTD
IWV
data reduction
separation
assimilation MeteoForecasts
ZTD possono essere assimilati direttamente
(HIRLAM)
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Italian GPS Italian GPS FiducialFiducial NetworkNetwork
Elba
Reggio Calabria
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Vallo della Lucania
Pavia
L’Aquila
Prato
16 HOURLY SITES
12 OTHER INSTITUTION SITES
12 ASI SITES
Trapani Milo
Maratea
Roma
Ferrara
Elba
Reggio Calabria
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Vallo della Lucania
Reggio Calabria
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Noto
Cagliari
Matera
Medicina
Genova
VeneziaPadovaTorino
Bolzano
Cosenza
Perugia
Lampedusa
Camerino
Novara
Vallo della Lucania
PaviaPavia
L’Aquila
Prato
16 HOURLY SITES
12 OTHER INSTITUTION SITES
12 ASI SITES
Trapani Milo
Maratea
Roma
Ferrara
Matera ASI-CGS
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
ASI Analyzed GPS ASI Analyzed GPS Ground NetworkGround Network
8oW 0o 8oE 16oE
24oE
30oN
35oN
40oN
45oN
50oN
55oN
AQUI
BRUS
BZRG
CAGL
CAME DUBRELBAGENO
GOPE
GRAZ
INGR
KARL
KOSG
LAMP
MALL
MATE
MEDI
MILO
NOT1
NOVA
OBE2
ORID
PADO
PAVI
PFAN
POTS
PRAT
SFER
SOFI
TGRC
TLSE TORI UNFE
UNPG
VALE
VENE
VILL
VLUC
WTZR
ZIMM
8oW 0o 8oE 16oE
24oE
30oN
35oN
40oN
45oN
50oN
55oN 40 stations in
Post-Processing Mode
30 stations in Near-Real Time
Mode
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Meteorology
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GNSS principles
Maintainance of the Terrestrial Reference Frame
ITRFxx
Seismicity and Landslides
Mean Sea level
Ionosphere
Neutral Atmosphere (Meteorology & Climate)
Space Applications•Radio Occultation•Gradiometry
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Radio Occultation with GPS
MAGEOS principleRadio Occultation Principle
Non-Occulting GPS Satellite Occulting
GPS Satellite
Orbit AltitudeLEO Satellite = 600kmGPS Satellite = 20,231 km
Orbit AltitudeLEO Satellite = 600kmGPS Satellite = 20,231 km
AtmosphereAtmosphere
IonosphereIonosphere
SkymedCosmoSatellite
( ) ( )[ ]evevevev ⋅−⋅−⋅−⋅=ΔRTRRTTc
ff
⎪⎭
⎪⎬
⎫
⎪⎩
⎪⎨
⎧
⎟
⎟
⎟
⎠
⎞
⎜
⎜
⎜
⎝
⎛
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛−+−= ∫
∞
a
dxdx
d
a
x
a
xan
γ
π
2
1
2
2
1ln1
exp)(
...1073.36.7710)1( 256 +⋅+=⋅−=Te
TP
nN
Noto
Cagliari
Matera
MedicinaGenova
VeneziaPadovaBasovizzaTori
no
TrentoBolzano
FoggiaPotenza
Vallo d. LucaniaCosenza
Perugia
ASI receiversInstitutes collaborating otherswith ASI
Roma
Fucino
Boretto
Scanzano
Lampedusa
Tirana
Prato
L’Aquila
Elba
AnconaCameroon
Reggio C.
Novara
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Mariner V Occultation at Venus: Separate Stanford & JPL Experiments
Stanford JPLOne-way: Earth –>
Venus
50 & 423 MHz uplinks
50 MHz data were not usable; the 423 MHz receiver lost lock at about 37 km altitude
One-way: Venus –> Earth
2.3 GHz downlink
Obtained data from 90 to ~34 km altitude, then encountered critical refraction
Amplitude and phase based retrievals
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Mariner V Occultation at Venus: Temperature Profile Comparison
2.3 GHz Phase Retrieval
423 MHz Amplitude Retrieval
Critical Refraction Lost Lock
Fjeldbo et al., 1971
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Occultation Subjects: A Group Portrait
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Just right…
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
What took so long…?
Need a lot of transmitters and a lot of LEO receivers
GPS did not fit the paradigm:– One-way only– Need flight USOs?– Dithered GPS signal– Need classified receiver?– Suppressed GPS carrier– Crude pseudorange only?– Multipath a major concern– Need high-gain antennas?
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Earth Occultation – Early ConceptsFishbach, 1965: Stellar occultation from LEO
Lusignan et al., 1969: Radio sounding with tandem LEO’s at a fixed separation
Gurvich and Krasil’nikova, 1987: Navigation satellites for sensing Earth atmosphere
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GPS Geoscience InstrumentEOS-A, EOS-B and Space Station
(1988-1992)
Three Antennas18 ChannelsFull Sky View
PODPODGeodesyGeodesyIonosphere MappingIonosphere MappingAtmospheric OccultationAtmospheric Occultation
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
10.1 1 2.2
Predicted Temperature Accuracy (K)
Water VaporLimited
Random ErrorLimited
0
10
20
30
40
50
60
5.5
EOS Requirement
EOSGoal
GPS Geoscience InstrumentEOS-A, EOS-B and Space Station
(1988-1992)
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
The GPS-MET Experiment on MicroLab-I
1995 - ?
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
1
10
100
1000200 220 240 260 280 300
Temperature profiles near England
Occultation at 52.6N. 355 E.
Radiosonde at 54.5 N. 353.9 E.
Radiosonde at 53.5 N. 357 E.Pre
ssur
e, m
bar
Temperature, K
At about 95-4-25:00:00 UTC
The GPS-MET Experiment on MicroLab-I 1995 - ?
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Winter Jet Stream
S. S. Leroy
300 millibar surface
Northern Summer, 1995
Zonal winds from meridionalgeopotential gradient
The GPS-MET Experiment on MicroLab-I 1995 - ?
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
CHAMP
SAC-C
GRACE
Ørsted
Sunsat
IOX
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
COSMIC/Rocsat3 (6)OCEANSAT_2
METOPTerraSAR-X ?
Main Current Attractions…
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Presentation Outline
The Origin…
Description of the Radio Occultation TechniqueDescription of the Radio Occultation TechniqueChallenging Tasks
NRT x LEO-POD
Conclusions
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
The GNSS Radio Occultation Technique
In occultation GNSS SatelliteIn occultation GNSS Satellite
In view GNSS SatelliteIn view GNSS SatelliteIn view GNSS SatelliteIn view GNSS Satellite
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
(Pre-processing)
Users:•Meteorology ?•Climatology•Space Weather• IonosphereTomography (?)•Space Geodesy•Geophysics
Phase Measurement Cleaning(Double Differencing, Clock Estimation, Iono free combination)
Precise Orbital Determination
Refractivity n(r)
Shift Doppler Excess fΔ
Bending angle ( )aα
P(r), T(r), Pw
ray-tracingequationsequations
Abel Inversion
TermodinamicRelationships
Refractivity n(r)
Shift Doppler Excess fΔShift Doppler Excess fΔ
Bending angle ( )aαBending angle ( )aα
P(r), T(r), Pw
ray-tracingequationsequations
Abel Inversion
TermodinamicRelationships
Processing Chain
a)
b)
c)
d)
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
To Know Excess ShiftDoppler f
ToTo single single atmosphericatmospheric refractivityrefractivity
wewe needneed::•Have GPS and LEO precise orbits
•Cancel out clock drifts
We do need Double Differences!!
Unless….we have good clocks
Doppler Measurement depends on:
•Relative motion of GPS-LEO
•Clock Drift
•Atmospheric refraction
EarthEarth
LEO
GPS1
GPS2
GroundReceiver
Link (A)
Link (B)
Link (C)Link (D)
Trieste 07,04,2010
DOP Analysis
CSK
IGS Network
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Refractivity n(r)
Shift Doppler Excess fΔ
Bending angle ( )aα
P(r), T(r), Pw
ray-tracingequationsequations
Abel Inversion
TermodinamicRelationships
Innovation:
CT/FSI -HolographyBPVα
BPVn
Integration with Ground GNSS Observations
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
a) The Geometry of RO and the computation of the Bending Angles from f
Terra
αeR
eT
eβ1
β2
T
Ra a
δ1δ2
The effect of the atmospheric refractivityon a travelling radiowave signal can bemeasured in terms of an excess shiftDoppler
( )evevcfD RT ⋅−⋅=0
( )RRTT evevcfD ⋅−⋅=1
( ) ( )[ ]evevevevcfDDf RRRTTT ⋅−⋅−⋅−⋅=−=Δ 011)
: GPS and LEO velocityRT vv ,
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
The Geometry of RO and the computation of the Bending Angles
Terra
αeR
eT
eβ1
β2
T
Ra a
δ1δ2
( ) ( ) arr RT =+=+ 2211 sinsin δβδβ2) a is the Impact Parameter
21 ββα +=3) α is the bending angle
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The Geometry of RO and the computation of the Bending Angles: Iono Free Combination
Terra
αeR
eT
eβ1
β2
T
Ra a
δ1δ2
( ) ( ) ( ) ( ) ( )022
22
1
22
0122
21
21
0 aff
faff
faneut ααα−
−−
=
Vorob’ev e Krasil’nikova, 1994
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RAY-TRACING: α n(r)
Terra
ψη
θ
T
R
x
y
αa a
• n(r) is a continuous function• n(r)·r changes slowly and isincreasing monotonic• The horizontal gradient of n(r) is
negligible in every layer.
drdr θη =tan
( ) ( ) ( ) arrrnrrn == 000 sinsin ηη
2πθηψ −+=
( )( )
⎟⎠⎞
⎜⎝⎛
−−= dr
drrnd
arrnad log
222ψ
( )( )
( )∫ −=
0
min
log2222
r
r
drdr
rndarrn
aaα
b)
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( ) ( ) ( ) ( ) bxaxfdttutxx
a
<<=−Γ ∫ − ,1 1α
α
( ) ( ) ( ) ( )∫ <<−−Γ
= −x
a
bxadttftxdxdxu ,
11 α
α
The Abel Inversion: α→n(r)
Volterra Equation Solution
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The Abel Inversion: α→n(r)
( )[ ]∫
∞=
= −=
x
ax ax
dxndxdnaa
21
222α
( ) ( ) ( )( )
( )
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎪⎭
⎪⎬
⎫
⎪⎩
⎪⎨
⎧
⎥⎥⎦
⎤
⎢⎢⎣
⎡−⎟⎟
⎠
⎞⎜⎜⎝
⎛+= ∫
=∞=
=
0 21
2
111
1
1ln1expαα
αα
αααπ a
da
aa
arn
( )⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎪⎭
⎪⎬
⎫
⎪⎩
⎪⎨
⎧
⎥⎥⎦
⎤
⎢⎢⎣
⎡−⎟⎟
⎠
⎞⎜⎜⎝
⎛+= ∫
∞=
=
a
aa
dadad
aa
aarn
1
21
2
111 1ln1exp α
π
n(r) profile obtained withAbel inversion. Is the tangent point.
1r
Abel Integral Equation forRefraction
x = n·r
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The Abel Inversion: α→n(r)
The The VolterraVolterra equations have illequations have ill--conditioned solutionsconditioned solutions…….small errors .small errors can induce can induce ““unstableunstable”” behaviourbehaviour of the integral solution.of the integral solution.Thus it is very important the selection of reliable initial conThus it is very important the selection of reliable initial conditions..ditions..
Particularly challanging in the upper Atmosphere because:•Small αneut•Big relative errors due to:
•GPS clocks•Orbit uncertainties•Thermic error of the receiver•Ionospheric corrections o( ) not negligible anymore
2fk
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The Abel Inversion: α→n(r)
Thus it is introduced the statistical optimization:
Sokolovskiy, S., and D. Hunt, Statistical optimization approach for GPS/MET data inversions, URSI GPS/MET Workshop, Tucson, Arizona, 1996.
mnoise αασ −=the bending angle given by the model (MSISE90)=mα
the bending angle really measured with GPS RO=α
noisemnew Cσαα += Where:
signal
noiseC
σσ
+=
1
1 msignal ασ %20=
Where C is the weighting coefficient
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The Abel Inversion: α→n(r)
signal
noiseC
σσ
+=
1
1
If C 1 the observations weight more than the Model (lower atmosphere)
If C 0 the model weights more than the Observations (higher atmosphere)
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The Abel Inversion: α→n(r)
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To solve for Pd, T and Pw it is used :
•THE HYDROSTATIC EQUILIBRIUM LAW ⇒
•THE IDEAL GAS LAW ⇒
ρg−=dhdP
TRmPRTPV =⇒= ρ
( )TR
PmmTR
Pm wdwdwd
−+=+= ρρρ
Solving (1) forTP
⇒( )
TP
Rmmg
TP
RagmaN
Ragm
dhdP wwdwdd −
++−= 21
2
1
(4)
So, we have the two equations: (1) and (4) in three unknowns: Pd, T and Pw
We consider two different cases:
(1)221 TPa
TPaN w+=
(2)
(3)
and combining (2) and (3)
from N(α)→P,T,W C)
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DRY AIR
• Pw can be ignored in the upper atmosphere (for heights where T<250 °K (h250°K)
• Given N, both T and P = Pd can be solved from (1) and (4)
WET AIRWhen in the middle and low troposphere Pw is not negligible. Thus we have a Rank Deficiency it is necessary to have an independent knowledge of one of the three parameters (T, P, Pw) in order to solve for the other two: the method proposed for the integration are:
•Take the values of P and T from ECMWF or NCEP at certain bounday layers and use them for an iterative solution of the equations (Kursinski & al. 1997);
•Apply the Optimal Estimation Approach (Merging of RO and ECMWF models)
•Add new observations as those of GPS ground permanent stations (challanging…)
•BPV method (challanging)
from N(α)→P,T,W C)
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WET AIR
1. Assume Pw(h) = 0 for a first guess;
2. Integrate (4) to obtain P(h);
3. Use P(h) and T(h) in (1) to update Pw(h);
4. Repeat step 2. And 3. until convergence.
(1)221 TPa
TPaN w+=
( )TP
Rmmg
TP
RagmaN
Ragm
dhdP wwdwdd −
++−= 21
2
1
(4)
from N(α)→P,T,W GorbunovGorbunov, M.E., , M.E., SokolovskiySokolovskiy, S.V, S.V., 1993, Remote Sensing of Refractivity from Space for Global Observations of Atmospheric Parameters, Report 119, Max Planck Institute for Meteorology.KursinskiKursinski, E. R., Hajj,, E. R., Hajj, G. A., 2001, A comparison of water vapor derived from GPS occultations and global weather analyses, J. Geophys. Res.,106, 1113-1138.
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Assuming all Errors as Gaussian, the penalty function is built as follows:
( ) ( )( ) ( ) ( )aaT
aobsyT
obs xxSxxxyySxyyx −−+−−= −− 11 ))((ξWhere:
yobs=vector of measurements
y(x)=simulated vector of measurements based on the solution state vector x (rapresents a profile of temperature and water vapor+ a surface pressure,
xa= the apriori state vector from an analysis
Sa and Sy are, in turn, the analysis error covariance and measurement error covariance plus the covariance forward model which relates the state vector to the observation
( )[ ] )(11 nxxnn xxHxx ξξ ∇−= −+The Solution is:
Hx and ∇x are the Hessian and the gradient applied to the penalty function
from N(α)→P,T,W Optimal Estimation
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PROFILES
Cold and Dry Areas Wet and Hot Areas
D)
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Presentation Outline
The Origin…Description of the Radio Occultation Technique
Challenging TasksChallenging TasksNRT x LEO-POD
Mission Analysis ROSA on OCEANSAT_2
GPS & GALILEO
Conclusions
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Extinction
120 140 160 180 200 220Refr .@N unitsD
2
4
6
8
10
thgieH@mkD
Recife
Dry Refr
RAOB Refr
Our Refr .
CHAMP Refr .
Old Refr
Our Old
120 140 160 180 200 220Refr .
2
4
6
8
10
thgieH@mkD
Recife
Dry Refr
RAOB Refr
Our Refr .
CHAMP Refr .
Old Refr
Our Old
Seldom RO is unable to retrieveprofiles down to the ground
Solutions:• High gain antenna 12 dbm•Open Loop Approach……
ROSA
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MULTIPATH:
multipath: The signal suffers reflections before arriving to the antennaGeometrical Optics principles are not applicable anymore
Multipath is due to irregularities and inversion of refractivity through the atmosphere:It can be solved with applying canonical transform (CT) or Radio holography technique and using good quality GPS receivers
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• n(r) is not continuous. Sudden and unexpected variation of refractivity occur•It induces refractivity negative bias most of all in the equatorialbulge
• Increase of ∇ (n(r).r) close to the ground.• super-rifractivity: due to a sudden drop of humidity at upper PBL
ur
lr
sa
16 15710 −−≈−< kmRn
drdN
E
( )( ) 0<⋅
drrrnd
Drawback of Abel Inversion
The relationship: is not fullfilled anymore in a monotone fashion.( ) arrn =⋅ minmin
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The CT and FIO as solution of the multipath
( ) 0122 =+−− uDD yx
Helmholtz Equation (valid for back-propagation approach) ( ) ( )( )yikyA xx Ψexp
Geometric opticalsolution (GO)
Asymptotic short wavelength solution
( ) ( )uDDyHuD yyx21, −−≡=−
( )η,y
Initial spatialcoordinates of ray path Canonical
Transform( )ξ,z
New coordinates: a spatial one and the impulse 2 undistinguished signals
(multipath) can now beseparated in phase space (have different impulse!)
Integral Fourier Operator indeeddistinguishes one and one onlyray path
( ) ( ) ( ) ( ) ηηηπ
ηηηηdvekpv x
axpk
xx~1
2ˆ arcsin1arcsin14/12
2⎥⎦⎤
⎢⎣⎡ −+−−Δ−
∫ −=ΔΦ
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The CT and FIO as solution of the multipath
•Gorbunov ME (2002) Canonical transform method for processing radio occultation data in the lower troposphere, Radio Sci, 37, 5, 1076-1085•Hocke K, Pavelyev AG, Yakovliev OI, Barthes L., Jakowski (1999) Radio occultation data analysis by theradioholography method. I. Atmos. Terr. Phys., 61, 1169-1177•Sokolovskiy SV (2001) Modeling and inverting radio occultation signals in the moist troposphere. Radio Science, Vol.36, nr. 3,441-458. May/June
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Rank Deficiency
•We have 3 unknown (P,T, Pw) with 2 Eqs.(1)221 T
PaTPaN w+=
( )TP
Rmmg
TP
RagmaN
Ragm
dhdP wwdwdd −
++−= 21
2
1
(2)
•You need external information: ECMWF modelsor NCEP re-analisis temperatures
The RO is not a stand alone technique!!
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Integration of RO + GroundGPS Data
(1)221 TPa
TPaN w+=
( )TP
Rmmg
TP
RagmaN
Ragm
dhdP wwdwdd −
++−= 21
2
1
(4)
∫∞
−
−⎟⎟⎠
⎞⎜⎜⎝
⎛+=
GPSground
w dhhThPa
hThPaZTD 221
6
)()(
)()(10
Solutions ?
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Solutions ? (cont.)• Use surface temperature information when
available– D.B. O’ Sullivan, B.M. Herman, D. E. Feng, D. E. Flittner, D.M. Ward,
“Retrieval of Water Vapor Profiles from GPS/MET Rdio Occultations”, Bull. of the Amer. Meteor. Soc., Vol. 81, 1031-1040, No 5, May 2000.
• Use an exponential model of refractivity under the assumption of constant value of the humidity…:
• M. de la Torre Juàrez, M. Nilsson, “On the Detection of Water VaporProfiles and Thin Moisture Layers from Atmospheric Radio Occultations”, J.Geophys. Res., in press, February 2003
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Solutions ? (cont.)• The BPV model (proposed at ASI/CGS
Matera):– Vespe F., Benedetto C., Pacione R., “GNSS Radio Occultation: from the bending angles to the
atmospheric profiles”, ESA book, Proc. URSI symposium Atmospheric Remote Sensing by using GNSS systems, Matera 13-15 Oct., 2003.
– Vespe F., Wickert J., Benedetto C., Pacione R.; “Derivation of the Water Vapor Content from the Radio Occultation Observations“; In Earth Observation with CHAMP: Results from Three Years in Orbit, Reigber et al. Eds, pp. 537-543, 2004
– Vespe F., Persia T.: “Derivation of the Water Vapor Content from the GNSS Radio OccultationsObservations,” Journal of Atmospheric and Oceanic Technology, Vol. 23, No. 7, pages 936–943, 2006
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1>NS
The Current Status
Upper Layers (>50 Km) : Too noise
Ihe Iono, Clock and Orbit uncertainties overwhelm the tinyeffects of refractivity through the outer stratosphere
S/N ratio is good. The atmosphere has no wet content. The inversion is fully reliable (no horizontal gradient). The system of 2 equations: hydrostatic equilibrium and refractivity can beheasily solved.
Stratopause
h=h250K
Ground Level
The atmosphere has a no negligible wet content. The inversion is not fully reliable (horizontal gradient…). The system of 2 equations: hydrostatic equilibrium and refractivity suffers of rank deficiency (3 unknows) .
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The Hopfield Model
P
( ) ( )4
,
4
, , ⎥⎦
⎤⎢⎣
⎡−−
=⎥⎦
⎤⎢⎣
⎡−−
=ow
wtropow
tropw
od
dtropod
tropd rr
rrNrNrrrrNrN
( )16.27372.14840136 −+= Thd
( )4
, ⎥⎦
⎤⎢⎣
⎡ −=
d
dtropod
tropd h
hhNhN
hw= 11000 m
dod hrr +=hrr o +=
hd
hw
z(r)
zo
h=0Earth
Surface
rd
r
O
ro
TpcN trop
od 1, =232, Tec
TecN trop
ow +=
tropw
tropd
trop NNN +=
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Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Step 1
298.91283.379294.77299.1
300.688286.026294.71299.20
1017.481041.151041.151026.50
1000.191043.701027.951012.50
CT
CT
CT
CT
303.30285.95303.75300.14Temp. RAOB
[K]
299.36286.98299.01297.70GOTemp. BPVn[K]
300.93283.272299.1297.96GOTemp. BPVα[K]
1007.00100510051013Press. RAOB
[mbar]
1019.301028.571028.571024.80GOPress. BPVn[mbar]
1003.481017.451016.571012.56GO Press. BPVα[mbar]
MangaloreBrestGuamRecifeDataSiti
298.91283.379294.77299.1
300.688286.026294.71299.20
1017.481041.151041.151026.50
1000.191043.701027.951012.50
CT
CT
CT
CT
303.30285.95303.75300.14Temp. RAOB
[K]
299.36286.98299.01297.70GOTemp. BPVn[K]
300.93283.272299.1297.96GOTemp. BPVα[K]
1007.00100510051013Press. RAOB
[mbar]
1019.301028.571028.571024.80GOPress. BPVn[mbar]
1003.481017.451016.571012.56GO Press. BPVα[mbar]
MangaloreBrestGuamRecifeDataSiti
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Presentation Outline
The Origin…
Description of the Radio Occultation Technique
Challenging Tasks
NRT x LEONRT x LEO--PODPODMission Analysis ROSA on OCEANSAT_2
GPS & GALILEO
Conclusions
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(Pre-processing)
Users:•Meteorology ?•Climatology•Space Weather• IonosphereTomography (?)•Space Geodesy•Geophysics
Phase Measurement Cleaning(Double Differencing, Clock Estimation, Iono free combination)
Precise Orbital Determination
Refractivity n(r)
Shift Doppler Excess fΔ
Bending angle ( )aα
P(r), T(r), Pw
ray-tracingequationsequations
Abel Inversion
TermodinamicRelationships
Refractivity n(r)
Shift Doppler Excess fΔShift Doppler Excess fΔ
Bending angle ( )aαBending angle ( )aα
P(r), T(r), Pw
ray-tracingequationsequations
Abel Inversion
TermodinamicRelationships
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Why Near Real Time ?
Numerical Weather Prediction Numerical Weather Prediction Requirements:Requirements:
RO & LEO-POD data within 45’ (2 download/orbit at least) must be available
Within 1h.30’ the Precise Ephemeris of the LEO Satellite (σ<50 cm) must be availableWithin 1h 45’ the RO products to assimilate (level 2-3) must be available;
Within 3h must be issued the NWP
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F. Vespe1, G. Perona2, M. Molinaro2, V. De Cosmo3, A. Zin8, S. Landenna8,R. Notarpietro4, B. Nava9, S. Radicella9, C. Benedetto1 , M. Amoroso11, P. Sacco11 ,
I. Bordi5, M. Materassi, P. Spalla6, N. Tartaglione7, S. Casotto10, (1) Italian Space Agency, Centro di Geodesia Spaziale, Matera, IT;(2) Istituto Superiore M. Boella, Italy (IT);(3) Italian Space Agency, Roma, IT(4) Politecnico di Torino , Torino, IT(5) Università La Sapienza, Roma, IT(6) Istituto dei Sistemi Complessi (ISC/CNR), Firenze, Italy(7) CINFAI, Camerino, IT(8) THALES-Alenia Spazio, Milano, Italy(9) ICTP, Trieste, IT(10) CISAS, Padova, IT;(11) INNOVA, Matera, IT
THE ITALIAN ROSA PROJECT AND ITS THE ITALIAN ROSA PROJECT AND ITS BENEFITS FROM COSMIC MISSIONBENEFITS FROM COSMIC MISSION
ROSA TEAM
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ASI strategy • We have developed a GPS receiver devoted to
Radio Occultation: Radio Occultation Sounder for Atmosphere studies
• We are developing the processing chain from data to profiles
• We don’t have a space mission devoted to RO
• We try to embark ROSA on available national and/or international Earth space missions:– OCEANSAT_2 ( Currently Flying )
– SAC-D (2010)
– MEGHA-TROPIQUES ?
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ROSA main blocks
ROSA Instrument
Receiver
Navigationantenna
2 high gain RO antenna (up to 12 dB) (1x 0.6 m)
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ROSA Instrument Description
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Shift Doppler Excess Δf
Bending angle α(a)
Refractivity n(r)
P(r), T(r), Pw
TermodinamicTermodinamic RelationshipsRelationships
RayRay--tracingtracing equationsequations
AbelAbel InversionInversion
Radio Occultation – Processing Chain
(Pre-Processing)
•Phase Measurement Cleaning(Double Differencing, Clock Estimation, Iono free combination)
•Precise Orbital Determination
Users:
• Meteorology
• Climatology
• Space Geodesy
• Ionosphere
•Space Weather
• Geophysics
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ROSA DATA LEVELS
LEVEL 3 - Final Output
a. L1 and L2 Bendings vs Impact Parameters profiles
b. Iono-free Bendings vs Impact Parameters profile
c. Stratospheric initialization of Iono-free Bendings vs Impact Parameters profile
d. N, P and T Profiles
e. Water Vapour vertical profiles
f. Electron Density vertical profiles
Geom. Opt. methods
CT, FSI (Wave Optics)
Std techn. needed both L1 and L2
Tomography and use of OL data
Through Global Climatol.
Through Local Climatol.
Abel
Through Climatol. models
NWP -IDVAR or SA (BPVn),
Onion Peeling Tomography
Numerical (BPVα)
Basic Final
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Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
OCM-2: 8-narrow Band multi-spectral camera, 360 m Resolution, 1420 Kms Swath, 2 days repetevity
Scatterometer:Ku-band (13.515GHz) radar, V & H polarisation, two-beam conical scanning
ROSA
Launched : 23 Sept. 2009!!
ROSA on OCEANSAT-2
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Type - Near polar sun-synchronous
Altitude - 720 km
Inclination - 98.28°
Period - 99.31 min.
Local time of pass - 12 noon + 10 min.
Repetevity cycle - 2 days
Distance between adjacent - 1382 km
traces
Distance between successive - 2764 km
ground tracks
Average ground trace velocity - 6.781 km/s
ROSA on OCEANSAT-2
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Nadir Direction
Velocity Direction
Antenna Tilt
15°
Problems of Accomodation
∼270 Occ./day
Side looking Occ.
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COMPARISON OF RESULTS WITH OUR SW vs COSMIC (COSMIC DATASET 31-12-2007)
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Ionosphere Profiles….(ICTP)
COSMIC
DELN
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ROSA on Aquarius/SAC-D
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Type - Near polar sun-synchronous exact
repeat orbit. Earth viewing &
Nadir pointing instruments
Altitude - 657 km
Inclination - 98. °
Local time of pass - 6 pm ascending node
Repetevity cycle - 7 days
ROSA on Aquarius/SAC-D
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New InfraRed Sensor Technology
SAC-D S/P
Technology Demonstration Package
DCS
NIRST
Aquarius(primary instrument)
TDPCARMEN-1(ICARE-NG & SODAD) ROSA
HSC
MWRMicrowave Radiometer
Data Collection SystemRadio Occultation Sounder for the Atmosphere
High Sensitivity Camera
Service Platform
Mass: 1675 KgPower:1443 WOper. Life: 5 yrs
Mass: 1675 KgPower:1443 WOper. Life: 5 yrs
Satélite de Aplicaciones Científicas-D
Launch date : 22 of may 2010
ROSA on Aquarius/SAC-D
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SAC-D
Problems: Aquarius is an active antenna which emits signal 400 W strong just close to L2 frequency. ROSA receiver was modified (new filtering system applied) to prevent interferences
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Ground-Based GPS Meteorology
~5km
~25km
mappingfunction
E=10°
A mapping function is applied to determine how the signal delay changes with elevation angle. The results are averaged over all the satellites to give the ZTD.
)(EMZTDΔtrop ⋅=
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Mapping FunctionMarini-Murray-like (1972)
( )
…++
++
=
sinEcsinE
bsinE
asinE
1Em
)()( EMZWDEMZHDΔ wdtrop ⋅+⋅=
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Niell (1996)
( )( )
( ) ( )
( ) ( )( ) ( )
h
cb
ac
ba
cb
ac
ba
m
h
h
h
h
h
h
⋅
⎟⎟⎟⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜⎜⎜⎜
⎝
⎛
++
+
++
+
−+
++
+
++
+
=
εε
εε
εε
εε
sinsin
sin
11
1
sin1
sinsin
sin
11
1
( ) ( ) ( ) ⎟⎠⎞
⎜⎝⎛ −
−=25.365
2cos, 0Ttaata iampiavgi πλλλ
Parameters involved: latitude “ ”Height “h”DoY “t”
For the computation of the coefficients RAOB data were used
An equivalent formulation is given for the wet MFbut its coefficients depends on the latitude only :
WE ARE USING JUST THE SAME FORMULATION OF NIELL BUT USING RADIO OCCULTATION DATA !!
( )( )
( ) ( ) wet
wet
wet
wet
wet
wet
wet
cEbE
aE
cb
a
Em
++
+
++
+
=
sinsin
sin
11
1
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Radio Occultation Data suitable now to build the MF
>1,000,000 RO events selected !!Spreaded and organized according the day of the year acquired. The selected events must provide profiles down at an height h < 1 km over the ground at least
COSMIC 6 satellites in orbit since 14 April 2006 (∼2000 occ/day).Still activeCHAMP launched on July 2000 (∼200 occ/day). Still active
SAC-C launched on November 2000 (one year only of data)
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Test Site of MT_MFProcessing Strategy(BERNESE SW used)
Strategy Network AdjustmentData handling 1 week of Data of 8 Perm. GPS StationsSatellite Orbits IGS PreciseERP IERS-IGSStation coord. aligned to IGS00Cut-off elevation 5°Ocean Loading Applied (H.G.Scherneck)Mapping Function Neill (1996), INN (2008)Ant. PCV RelativeSampling Rate 30”Estimated Parameters Coordinates, Satellite & station clocks w.r.t a
reference one, Phase ambiguities (float), ZTD time resolution: every hour
Output Coordinates, ZTD
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
ResultsZIMM - ZTD RMS (doy 138, yy 2003)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 2 4 6 8 10 12 14 16 18 20 22 24
[hours]
[mm
] INN
NIELL
MATE - ZTD RMS (doy 138, yy 2003)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 2 4 6 8 10 12 14 16 18 20 22 24
[hours]
[mm
] INN
NIELL
ONSA - ZTD RMS (doy 138, yy 2003)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 2 4 6 8 10 12 14 16 18 20 22 24
[hours]
[mm
] INN
NIELL
FFMJ - ZTD RMS (doy 138, yy 2003)
0.0
0.5
1.0
1.5
2.0
2.5
0 2 4 6 8 10 12 14 16 18 20 22 24
[hours]
[mm
] INN
NIELL
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Results_2Improvements up to ~20%
PTBB - ZTD RMS (doy 138, yy 2003)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 2 4 6 8 10 12 14 16 18 20 22 24
[hours]
[mm
] INN
NIELL
VILL - ZTD RMS (doy 138, yy 2003)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0 2 4 6 8 10 12 14 16 18 20 22 24
[hours]
[mm
] INN
NIELL
ZIMM - ZTD RMS (doy 138, yy 2003)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 2 4 6 8 10 12 14 16 18 20 22 24
[hours]
[mm
] INN
NIELL
ZIMJ - ZTD RMS (doy 138, yy 2003)
0.0
0.5
1.0
1.5
2.0
2.5
0 2 4 6 8 10 12 14 16 18 20 22 24
[hours]
[mm
] INN
NIELL
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GPS TD with Ray-Tracing
0LLLTD −=Δ=
The tropospheric delay TD is given by the difference between the optical path of the signal (L) and the geometrical distance satellite-receiver (L0):
RE
GPS
Lo
O
L
E
Φ
Earth
a
Atmosphere
Ratm
( )( )
drarrn
rrnLatm
E
R
hR∫+ −⋅
⋅=
222
2
stGPS rrL −=0
Once computed, the Once computed, the TDTD is removed is removed on both Lon both L11 and Land L22 carrier phase measurements.carrier phase measurements. The correction is applied directly to The correction is applied directly to RINEX filesRINEX files !!!!
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
RAY-TRACING TECHNIQUEThe modified RINEX The modified RINEX ““troposphere freetroposphere free”” files arefiles areprocessed by BERNESE processed by BERNESE swsw in order to estimate only the in order to estimate only the
coordinates of the stations (by applying network adjustment coordinates of the stations (by applying network adjustment approach) approach) switching offswitching off any any tropospherictropospheric delay modeldelay model !!
300 km
UP_RMS_DOY_104
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
AQUI BZRG COMO ELBA MATE MEDI TORI UNPGrm
s (m
m)
Standard
Ray_Tracing
UP_RMS_DOY_107
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
AQUI ELBA MATE MEDI MILO TORI
rms
(mm
)
Standard
Ray Tracing
Neutral Impact on Formal Error
Positive Impact on Formal Error
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
altitudine 23616 km
inclinazione 56 gradi
GALILEO• 30 satellites, The Orbits have a period of 14.35 hours
• 3 MEO orbits, h= 23616 km and I=56°inclinazione rispetto al piano equatoriale di 56 gradi
3 orbite Medium Earth Orbit (MEO)
• The lifetime of the satellites will be 12 ysat least, Power 1.6 kw, mass di 680 kg and dimensions: 2.7m-1.2m-1.1m
1,1 m
2,7 m
1,2 m
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Table of Radio Occultion Events without and with GALILEO
10359442891631261050556494125°
714427277152125103155347898°.6
67343322211211093849844075°
86513524113111090848442455°
76354132816516389747941825°
7936434892642258084353735°
GPS +
GALGALGPS
GPS +
GALGALGPS
GPS +
GALGALGPSInclination (°)
Nr. Occ./Day<100 km
and Δt < Torb
Nr. Occ./Day far <100 km from PFS Measurement
Tot. Nr Occultation/DayHeight: 800 km
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
CLimatology• Global
• All Weather
• Relevant (refractivity, tropopause etc.)
• Self Calibrating (could be used for “in flight”calibration of other sensors but…)
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Point where the RO occurs
Nadir point on the ground
We deem RO and Nadir pointing observation overlapped if:D<100 Km; Tro-Tnp< Orbital Period
D
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GPS+GALILEO Radio Occultation Table
10359442891631261050556494125°
714427277152125103155347898°.6
67343322211211093849844075°
86513524113111090848442455°
76354132816516389747941825°
7936434892642258084353735°
GPS +
GALGALGPS
GPS +
GALGALGPS
GPS +
GALGALGPSInclination (°)
Nr. Occ./Day<100 km
and Δt < Torb
Nr. Occ./Day far <100 km from PFS Measurement
Tot. Nr Occultation/DayHeight: 800 km
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
The number of points suitable for “in flight” calibration ofNadir pointing instruments with GNSS RO doubles
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
CLIMATE• Refractivity can be estimated with RO with a relative
accuracy of 10-3. Suitable for Climate investigations• Refractivity as a fingerprint to investigate the Climate• Fingerprint could be formed by combining
projections for about 20 different levels below 25 Km, for some 30 different locations over the globe, and for four seasons
• (Goody et al. (1998).
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Tables of the number of Radio Occultation with and without
GALILEO
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GPS for : POD and Gravity field
recoveryAccelerometro +Ricevitore GPS
t1
t2
Accelerazione Totale data dalle doppie differenzenel tempo dell’osservabile GPS;
mentre l’accelerometro fornisce accelerazioni solo delle forze superficiali che agiscono sul satellite (pressione di radiazione ed atmosfera)
t3
accgpsgrav AAA −=
Precise Orbit Determination
Noto
Cagliari
Matera
MedicinaGenovaVeneziaPadova BasovizzaTori
no
TrentoBolzano
FoggiaPotenza
Vallo d. LucaniaCosenza
Perugia
ASI receiversIstituti collaborantiAltri
Roma
Fucino
Boretto
Scanzano
Lampedusa
Tirana
Prato
L’Aquila
Elba
AnconaCameroon
Reggio C.
Novara
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Accelerometro +Ricevitore GPS
t1
t2
Accelerazione Totale data dalle doppie differenzenel tempo dell’osservabile GPS;
mentre l’accelerometro fornisce accelerazioni solo delle forze superficiali che agiscono sul satellite (pressione di radiazione ed atmosfera)
t3
accgpsgrav AAA −=
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
What are the ASI matter in Africa ?An ASI ground station exists in Malindi (Kenia)
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Italian – Kenian Working Group for the establismentof a Regional Centre for Earth Observation was created:
Kenyan delegation: F.R.O. Eshikuta, J. Kimani (Observer), E. Waithaka ;
Italian delegation: M. Castronuovo, S. Di Ciaccio, L.Garramone;
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Table of contents
Objectives of the Italian-Kenian task force;
Feasibility study: status of completion;
Main features of KCEO;
Preliminary architecture;
GPS Fiducial Network;
Cost identification;
Activities to be done.
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Objectives of the Italian-Kenian task force
Generation of a feasibility study for the implementation of an Earth Observation Regional Centre in the Sub Saharan Africa;
Identification of possible available local resources and infrastructures;
Generation of a draft Memorandum of Understanding (MOU) between Italy and Kenya;
Organization of an International Workshop in order to present results of the feasibility study;
Activities started on June 2008, when the task force meet in Malindi and the work plan for the activities was generated.
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Main features of RCEO Remote sensing antenna installed in the ASI Centre at Malindi;
Direct ingestion of the remote sensing data carried out in Malindi;
Quality Check and transcription on permanent media in Malindi;
Remote Sensing archives in Malindi and Nairobi;
Transfer of data from Malindi to Nairobi via electronic link (for Near Real Time productgeneration and distribution);
Transfer of huge quantities of data from Malindi to Nairobi through postal courier;
Application processors (higher level processors) in Nairobi;
User Interface in Nairobi.
RCEO
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GPS Fiducial Network
From the Kenian side, a request to explore the possibility of implementing a GPS fiducial network arrived.
Task force agreed on this request; as consequence, this aspect has been considered in the study.
A GPS fiducial network could represents an useful facility to establish a terrestrial reference frame in Kenya.
In addition, the establishment of a geodetic local network in the Malindi area would represent the first step for the creation of a geodetic fundamental station at the Broglio Space Center (BSC).
A strong “request” to have a geodetic fundamental station in this region of the African Continent hasbeen expressed at international level (ILRS, IVS).
International VLBI Network
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
GPSReceiver
Electronic link (Rx data to
Malindi/Nairobi)
M&C and local archive
Electronic link (Rx data from remote sites)
Archiving and cataloguing
system
Processing system
Monitor and Control
WEB
Block diagram of a Kenyan fiducial site
Block diagram of the Nairobi facility for the GPS Kenyan fiducial network
GPS Fiducial Network
Trieste 07,04,2010 II Workshop on Satellite Navigation II Workshop on Satellite Navigation Science and Technology for AfricaScience and Technology for Africa
Thank you for your kind attention!