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D.N. Arabelos , M. Reguzzoni and C.C.Tscherning

D.N. Arabelos , M. Reguzzoni and C.C.Tscherning. Global grids of gravity anomalies and vertical gravity gradients at 10 km altitude from GOCE gradient data 2009-2011 and polar gravity. HPF Progress Meeting # 26, München, Feb. 20-21, 2013. PURPOSE.

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D.N. Arabelos , M. Reguzzoni and C.C.Tscherning

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  1. D.N. Arabelos , M. Reguzzoni and C.C.Tscherning Global grids of gravity anomalies and vertical gravity gradients at 10 km altitude from GOCE gradient data 2009-2011 and polar gravity HPF Progress Meeting # 26, München, Feb. 20-21, 2013.

  2. PURPOSE Promote the use of GOCE products by producing (new) grids of gravity anomalies and vertical gravity gradients at 10 km altitude. Possible improvement compared to the the HPF product of grids at zero height derived from the EGM’s. Observed gradients may contain more information than expressed through an EGM. Grid values may be improved using polar gravity. Progress Meeting # 26, München, Feb. 20-21, 2013.

  3. Data used. TRF data 2009-2011 Polar gravity – but not Antarctic gravity. ITG-GRACE2010s (remove/restore)* EGM2008, GOCE DIR2 (control data). Data selected closest to mid-points of 10’ cells and 1/8 deg cells.** * permits spherical approximation in local areas, help in polar caps. ** nearly all cells filled ! Progress Meeting # 26, München, Feb. 20-21, 2013.

  4. Products: gridded gravity anomalies and vertical gradients, 10 km. Grids produced in 162 20x20 deg blocks with 10’ spacing. Error-estimates in grids with 1 deg spacing. Progress Meeting # 26, München, Feb. 20-21, 2013.

  5. Use of Least-Squares Collocation (LSC). • Covarianceestimation (from reduced data) • Selection of analyticrepresentation • Selection of data in 25 x 25 deg. block • Creation of (upper triangularpart of) normal equations • Solution of equations (Cholesky) • Prediction, comparison with EGM2008 to 512 and error-estimationin 1 deg. Grid. • Prediction of 10’ grids. Progress Meeting # 26, München, Feb. 20-21, 2013.

  6. Covarianceestimation (from reduced data),+analyticfitting Empirical (from EGM08, h=0), analytic, Analytic from GOCE vertical gradients. Progress Meeting # 26, München, Feb. 20-21, 2013.

  7. Best data selection Prediction of EGM08 derivedgravityanomalies at 10 km, mgal Tzz with 0.125 deg. spacingselected. Progress Meeting # 26, München, Feb. 20-21, 2013.

  8. Computational considerations with geocol19. OMP Processing time for 20x20 block, N=number of data,CH=chunkblocksize. Time depends on rate of disk transfer. Progress Meeting # 26, München, Feb. 20-21, 2013.

  9. Data noise standard deviation selection Prediction of EGM08 derived gravity anomalies at 10 km, block 73 Tzz with 0.02 EU noise st.dev. selected. Progress Meeting # 26, München, Feb. 20-21, 2013.

  10. Prediction, comparison with EGM08 to 512 st.dev.gravityanomalies. Progress Meeting # 26, München, Feb. 20-21, 2013.

  11. Prediction, comparison with EGM08 to 512 vert. gravity gradients (EU). Progress Meeting # 26, München, Feb. 20-21, 2013.

  12. Comparison of st.dev. differences LSC, DIR2 wrt. EGM08.LSC inferior at middle latitudes due to less data used (?). Progress Meeting # 26, München, Feb. 20-21, 2013.

  13. dg from TRF Tzz at 10 km (mgal). Progress Meeting # 26, München, Feb. 20-21, 2013.

  14. dg at 10 km from EGM2008 to 512 (mgal). Progress Meeting # 26, München, Feb. 20-21, 2013.

  15. TRF Tzz at satellite height (EU). Progress Meeting # 26, München, Feb. 20-21, 2013.

  16. Transfer of results and further work. • Grids of gravityanomalies and vertical gradients transferred to POLIMI • Production to berepeated with POLIMI data and associatederror-correlationfunctions. • Investigationusing more data at middlelatitudes • Smoothing of discontinuities at blockboundaries • Use of MPI instead of OMP on several servers Progress Meeting # 26, München, Feb. 20-21, 2013.

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