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Mayer-Gürr et al.ESA Living Planet, Bergen 1 27.06.2008 Torsten Mayer-Gürr, Annette Eicker, Judith Schall Institute of Geodesy and Geoinformation University of Bonn Regional high resolution geoid and mean sea surface topography determination by a combination of GOCE, GRACE and altimetry data
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Mayer-Gürr et al.ESA Living Planet, Bergen 2 27.06.2008 Overview ITG-Goce: Global GOCE SGG only solution ITG-Goce: Global GOCE SGG only solution Regional gravity field refinement GRACE + GOCE + Altimetry Regional gravity field refinement GRACE + GOCE + Altimetry Regional gravity field refinement GRACE + GOCE Regional gravity field refinement GRACE + GOCE
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Mayer-Gürr et al.ESA Living Planet, Bergen 3 27.06.2008 GOCE data ITG-Goce (preliminary results) 1 month of data: - gradiometer data - star camera data - orbit data Computed with the short arc method: For each short arc (15 min) - full variance covariance - bias parameter for each SGG component - SST contribution is missing yet ITG-Goce (preliminary results) 1 month of data: - gradiometer data - star camera data - orbit data Computed with the short arc method: For each short arc (15 min) - full variance covariance - bias parameter for each SGG component - SST contribution is missing yet
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Mayer-Gürr et al.ESA Living Planet, Bergen 4 27.06.2008 Median degree variances formal errors signal
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Mayer-Gürr et al.ESA Living Planet, Bergen 5 27.06.2008 Median degree variances formal errors signal Difference ITG-Goce – EIGEN-05c Difference ITG-Goce – EIGEN-05c
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Mayer-Gürr et al.ESA Living Planet, Bergen 6 27.06.2008 Median degree variances formal errors signal Difference ITG-Goce – EIGEN-05c Difference ITG-Goce – EIGEN-05c Difference ITG-Goce – ITG-Grace2010s Difference ITG-Goce – ITG-Grace2010s
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Mayer-Gürr et al.ESA Living Planet, Bergen 7 27.06.2008 Regional gravity field recovery Global reference solution Regional refinement Spherical harmonics Spherical splines GOCE GRACE
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Mayer-Gürr et al.ESA Living Planet, Bergen 8 27.06.2008 ITG-Grace2010s gravity anomalies
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Mayer-Gürr et al.ESA Living Planet, Bergen 9 27.06.2008 ITG-Grace2010s gravity anomalies
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Mayer-Gürr et al.ESA Living Planet, Bergen 10 27.06.2008 Representation of geoid heights The residual gravity field represented by a linear combination of localizing basis functions Harmonic Splines shape coefficients (expected spectral content)
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Mayer-Gürr et al.ESA Living Planet, Bergen 11 27.06.2008 Observation equations This approach has similarities to: - regularization - combination with spectral weighting - least squares collocation This approach has similarities to: - regularization - combination with spectral weighting - least squares collocation normal equations GOCE GRACE field For the descripition of the theory see Eicker (2006)
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Mayer-Gürr et al.ESA Living Planet, Bergen 12 27.06.2008 ITG-Grace2010s Results – gravity anomalies +
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Mayer-Gürr et al.ESA Living Planet, Bergen 13 27.06.2008 Regional gravity field recovery Global reference solution Regional refinement Spherical harmonics Spherical splines GOCE GRACE
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Mayer-Gürr et al.ESA Living Planet, Bergen 14 27.06.2008 Regional gravity field recovery Global reference solution Regional refinement Spherical harmonics Spherical splines GOCE GRACE Altimetry T/P, ERS 1/2,... Altimetry T/P, ERS 1/2,...
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Mayer-Gürr et al.ESA Living Planet, Bergen 15 27.06.2008 Altimetry data (T/P, ERS 1/2, …) Altimetry Altimetry can improve the resolution of the GRACE/GOCE geoid. But: Altimeter satellites measures the sea surface height (SSH) and not the geoid height => Combined estimation of geoid and MDT Altimetry can improve the resolution of the GRACE/GOCE geoid. But: Altimeter satellites measures the sea surface height (SSH) and not the geoid height => Combined estimation of geoid and MDT MDT Geoid height SSH Sea surface Geoid Ellipsoid
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Mayer-Gürr et al.ESA Living Planet, Bergen 16 27.06.2008 Altimetry data (T/P, ERS 1/2, …) Altimetry Observation equation MDT Geoid height SSH Sea surface Geoid Ellipsoid mean sea surface height geoid height mean dynamic topography =+ Localizing basis functions adapted to the spectral contenent of the residual gravity field Localizing basis functions adapted to the spectral contenent of the MDT
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Mayer-Gürr et al.ESA Living Planet, Bergen 17 27.06.2008 Observation equations Complete observation equations Relative weighting of each set of observations by the variance component estimation method (VCE) (Koch & Kusche 2001) Altimetry GRACE field apriori (stochastical) information from MDT GOCE gravityMDT
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Mayer-Gürr et al.ESA Living Planet, Bergen 18 27.06.2008 Results – gravity anomalies + + +
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Mayer-Gürr et al.ESA Living Planet, Bergen 19 27.06.2008 Results – mean dynamic topography
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Mayer-Gürr et al.ESA Living Planet, Bergen 20 27.06.2008 Results – gravity anomalies + + +
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Mayer-Gürr et al.ESA Living Planet, Bergen 21 27.06.2008 Results – gravity anomalies + +
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Mayer-Gürr et al.ESA Living Planet, Bergen 22 27.06.2008 EGM2008 Results – gravity anomalies + +
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Mayer-Gürr et al.ESA Living Planet, Bergen 23 27.06.2008 EGM2008 Results – gravity anomalies + + Differences (RMS 8 mGal)
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Mayer-Gürr et al.ESA Living Planet, Bergen 24 27.06.2008 Summary Refinenemt of GRACE + GOCE gravity field with Altimetry (T/P, ERS 1/2,...) leads to: - Regional high resolution Geoid - Estimation of the mean dynamic topography (MDT) Refinenemt of GRACE + GOCE gravity field with Altimetry (T/P, ERS 1/2,...) leads to: - Regional high resolution Geoid - Estimation of the mean dynamic topography (MDT) GeoidTopography -GOCE improves the gravity field compared to GRACE in the high degrees - Our first GOCE solution (ITG-Goce) fits better to ITG-Grace2010s than to EIGEN-05C in the medium degrees (n=90…150) -GOCE improves the gravity field compared to GRACE in the high degrees - Our first GOCE solution (ITG-Goce) fits better to ITG-Grace2010s than to EIGEN-05C in the medium degrees (n=90…150)
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