ids analsum032009 flv01 · doris awg meeting paris, france - 23 march 2009 3 gravity & tide...
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DORIS AWG MeetingParis, France - 23 March 2009 1
Analysis Analysis IssuesIssuesFrank Lemoine (NASA/GSFC)
Doug Chinn (NASA/GSFC - SGT Inc.)
DORIS AWG MeetingParis, France - 23 March 2009 2
OutlineOutline
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1. Newest orbit differences (GAU vs GSFC)2. Modelling summary for AC’s.3. Paper Proposal for ASR.4. Perspectives, Challenges, and Future work.
DORIS AWG MeetingParis, France - 23 March 2009 3
Gravity Gravity & & Tide SummaryTide Summary
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¶ wd20 dsc file and Nov. AWG Presentation do not match.# From June 2008 AWG Presentation; Does not reflect latest.
GOT00IERS2003?No?GGM02CGGM02CNCL
GOT00IERS2003Yes.Yes/NCEP50x50.
GGM02CGGM02CGAU
GOT4.7IERS2003Yes.Yes. ECMWF50x50.
+ annual20x20fromGRACE
Eigen-Gl04s(120x120)
GSC(wd09)
FES2004IERS2003?Yes. NCEP,20x20.
+seasonalto 50x50
Eigen-GL05C orEIGEN-GL04s?(?x?)
ESA
CSR3IERS2003?Yes. ECMWF?x?.
+ratesEigen-GL04S(100x100)
GOP
CSR3IERS2003No?NoGGM01CGGM01CINA#
FES2004IERS2003YesYes,ECMWF?x?
+rates? +periodic
Eigen-Gl04
LCA¶
??Wahr ?NoNoGGM03sGGM03S(120x120)
IGN
OceanTides
EarthTides
Airtides
Atmosph.Gravity
Time-VaryingGravity
StaticGravity
Center
DORIS AWG MeetingParis, France - 23 March 2009 4
Nonconservative Nonconservative ForcesForces
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?NoYes.@6hrsMSIS83NCL
Yes/YesYes.Yes@6hrsSp245ENV
MSIS86GAU
Yes/YesYes. TOP.UCL(ENV,JA1)SP2
Yes. Source?@6hrsSp245ENV
MSIS86GSC(wd09)
Yes, Model?Angara(ENV only)
MSIS90ESA
NoN/AGOP
Yes/Yes.Top.Others?
Yes. Source??DTM94INA#
Models orECMWF?
?Yes. Not CNES? @4hrsSp245ENV
DTM94LCAwd20
Yes/No?NoYes. Source? @1hrSp245ENV
DTM94IGNwd08
Albedo/IRSat.SpecificModels
MacromodelsCd Freq.Atmos.Model
Center
DORIS AWG MeetingParis, France - 23 March 2009 5
Troposphere ModellingTroposphere Modelling
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Wet??GPT?NCL
Wet+DryNoNeill (wasHopfield)
Doris Met12ºGAU
Wet+DryNoNeill (wasHopfield)
GPT (wasDoris met)
10ºGSC(wd09)
WetNoGMFGPT10ºESA
Wet?GMFGPT 15º?GOP
WetNo??15ºINA#
WetDownwt ftnapplied <20 deg
Guo andLangley
< 2002DORIS met> 2002ECMWF
12º fromdsc file.No toFGL
LCAwd20
WetNo?Lanyi?GPT?FromCNES
IGNwd08
AdjustLow Elevdownwt.
MappingFunction
ModelApriori
ElevCutoff
Center
DORIS AWG MeetingParis, France - 23 March 2009 6
Model Comparison CommentsModel Comparison Comments1. Description files for SINEX don’t match presention information
(from November IDS workshop, for example).2. Information is Incomplete.3. Information or Description files do not exist.
DORIS AWG MeetingParis, France - 23 March 2009 7
Joint Paper Proposal for ASRJoint Paper Proposal for ASR1. Orbit Comparison, 2003?, 1 year all centers, all satellites (+
another year, 1995 for Spot 3). Orbits should correspond to finalSINEX submission or an archived SINEX submission.
2. Intercompare Residual empirical opr amplitude (along & cross-track), one year, all satellites.
3. Troposphere comparison: 1 week, 4? stations; Total Zenith delay(see next slide as example)
4. Paper would include modelling summary to show status ofmodelling at the centers ….
DORIS AWG MeetingParis, France - 23 March 2009 8
Troposphere comparisonsTroposphere comparisons
Hartebeesthoek Kokee Park
Preliminary (example) comparisonsfrom VLBI & GPS (Johannes Boehm)and DORIS (Pascal Willis).
• DORIS, like VLBI & GPS must estimate troposphere corrections.• Corrections are estimated pass-by-pass (typically 10-15 min, ~2Xper satellite & DORIS station, and per day).
DORIS AWG MeetingParis, France - 23 March 2009 9
Perspectives and Challenges.Perspectives and Challenges.
1. What do we need to do to complete the IERS submission?2. What is the impact of data distribution, elevation cutoffs, troposphere
modelling, mapping functions on scale? Is it possible to have an absoluteDORIS scale?
3. What is impact of offsets? How do improper cgmass/offset knowledge affectCOM corrections?
4. Second Order Ionosphere. How important is this effect?5. What are the impact of software changes on the Level 1B DORIS data? (Eg
ENVISAT Late 2004).6. Atmospheric Loading? What is impact on DORIS processing? Are we ready
for this?7. Operational time series: Will we soon have three centers making weekly
deliveries?8. Improvements in Nonconservative Force modelling; UCL-type models for
SPOT satellites; Availability of quaternions for TP & Jason-1,2; Improvementsto atmosphere modelling from GRACE+CHAMP Accelerometer data?
9. Open issue. Define orbit format for deliveries by AC’s. sp3 or sp1? (Mixture offormats at CDDIS).
DORIS AWG MeetingParis, France - 23 March 2009 10
Thank you for your attention!