GOCE Gravity Gradients in Instrument and Terrestrial Frames
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Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010 GOCE Gravity Gradients in Instrument and Terrestrial Frames J. Bouman , Th. Gruber, S. Rispens, E. Schrama, C.C. Tscherning, M.Veicherts, P. Visser
description
GOCE Gravity Gradients in Instrument and Terrestrial Frames. J. Bouman , Th. Gruber, S . Rispens , E. Schrama , C.C. Tscherning , M.Veicherts , P. Visser. This presentation. Analysis of GOCE gravity gradients Instrument and Earth related frames - PowerPoint PPT Presentation
Transcript of GOCE Gravity Gradients in Instrument and Terrestrial Frames
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
GOCE Gravity Gradients in Instrument and Terrestrial Frames
J. Bouman, Th. Gruber, S. Rispens, E.
Schrama, C.C. Tscherning,
M.Veicherts, P. Visser
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
This presentation
Analysis of GOCE gravity gradients• Instrument and Earth related frames• Data: 31 October 2009 – 11 January
2010• First GOCE gravity field solutions
use same data period (next three presentations)
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
Gravity Gradient Preprocessing
Temporal corrections
Outliers, data gaps External calibration
EGG_NOM_2
Frame trafo
EGG_TRF_2
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
EGG_NOM_2 & EGG_TRF_2
• EGG_NOM_2:– Given in instrument frame (GRF)
– Accurate: VXX, VYY, VZZ, VXZ; less accurate: VXY, VYZ
– Error increase at long wavelengths– Used in gravity field recovery
• EGG_TRF_2:– Given in Local North-Oriented Frame
– GGs VXY, VYZ: GOCE gravity model
– Long wavelength GG signal: GOCE gravity model– GG error expected to be more homogeneous
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
EGG_NOM_2 & EGG_TRF_2
• EGG_NOM_2:– Given in instrument frame (GRF)
– Accurate: VXX, VYY, VZZ, VXZ; less accurate: VXY, VYZ
– Error increase at long wavelengths
• EGG_TRF_2:– Given in Local North-Oriented Frame
– GGs VXY, VYZ: GOCE gravity model
– Long wavelength GG signal: GOCE gravity model– GG error expected to be more homogeneous
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
EGG_NOM_2:3 revolutions November 1, 2009
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
VZZ time series, 1 day
SD VZZ, 1 day
SDs VZZ temporalcorrections, 1 day
Temporal gravity field variations
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
External calibration
Three methods for GG calibration:1. Global gravity field models2. GOCE GPS data3. Terrestrial gravity data• GG scale factors 10-2 – 10-3
• See Poster 014-D3:External Calibration of the GOCE Gravity Gradients at the High-Level Processing Facility (Wednesday)
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
Estimated GG error SDsVXX, VYY, VZZ
MeasurementBand (MB)
GOCE QL gravity model:• GGs and GPS tracking• Data from November and
December 2009• SH degree 200• Error assessment using
GG residuals
• VXX and VYY same noise level in MB, VZZ 2x larger• Noise reduction in upper MB is “work in progress”
(see Fehringer et al, Floberghagen, this morning)
(Pail & Mayrhofer 2010)
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
EGG_NOM_2 & EGG_TRF_2
• EGG_NOM_2:– Given in instrument frame (GRF)
– Accurate: VXX, VYY, VZZ, VXZ; less accurate: VXY, VYZ
– Error increase at long wavelengths
• EGG_TRF_2:– Given in Local North-Oriented Frame
– GGs VXY, VYZ: GOCE QL gravity field model
– Long wavelength GG signal: GOCE gravity model– GG error expected to be more homogeneous
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
EGG_NOM_2 & EGG_TRF_2:3 revolutions November 1, 2009
EGG_NOM_2 EGG_TRF_2
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
EGG_TRF_2: VXX
GOCE - EIGEN5C (N=360) Binned averages
31 October 2009 - 11 January 2010
GOCE - EGM2008 (N=360)Binned averages
31 October 2009 - 11 January 2010
Color scale: -15 mE to +15 mE
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
EGG_TRF_2: VYY
GOCE - EIGEN5C (N=360) Binned averages
31 October 2009 - 11 January 2010
GOCE - EGM2008 (N=360)Binned averages
31 October 2009 - 11 January 2010
Color scale: -15 mE to +15 mE
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
EGG_TRF_2: VZZ
GOCE - EIGEN5C (N=360) Binned averages
31 October 2009 - 11 January 2010
GOCE - EGM2008 (N=360)Binned averages
31 October 2009 - 11 January 2010
Color scale: -15 mE to +15 mE
Bouman et al, GOCE Gravity Gradients, ESA Living Planet Symposium 2010
Summary
• GOCE gravity gradients in GRF and LNOF (EGG_NOM_2 & EGG_TRF_2)
• November 2009 – January 2010 timeframe
• Differences with EIGEN5C & EGM2008(Africa, Himalaya, …)
• Error level VZZ about 2x that of VXX, VYY in MB
• Spurious tracks VYY close to magnetic poles:
– Not well understood
– Very likely related to interaction between attitude control and magnetic field
– Seems to diminish after in-flight calibration 11/12 January 2010
• Overall, GG data look very good
