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Towards the time-variable gravity field from CHAMP

M. Weigelt, A. Jäggi , L. Prange, W. Keller, N. Sneeuw. Towards the time-variable gravity field from CHAMP. TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: A A A A. Questions. Did we get everything out of the CHAMP data?

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Towards the time-variable gravity field from CHAMP

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  1. M. Weigelt, A. Jäggi, L. Prange, W. Keller, N. Sneeuw Towards the time-variable gravity field from CHAMP TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAAA

  2. Questions Did we get everything out of the CHAMP data? Is the time variable gravity field really out of reach? What do we learn for future satellite missions?

  3. Previous studies & limitations Degree RMS w.r.t. ITG-GRACE2010s based on the energy balance approach two years of GPS-data with 30 s sampling no dealiasing products no covariance information

  4. Processing refinements

  5. Refinements Acceleration approach: • three times the number of observations • three dimensional observations Improved GPS positioning: • 10 s sampling • estimated absolute antenna phase center model • new IGS standards • … Prange 2010

  6. Outliers vs. poor observations • Typically threshold based outlier detection based on residuals: ? ? ? ? • Localizing outlier detection necessary • Consider (synthetical) covariance information

  7. Results using outlier detection

  8. CHAMP vs. GRACE monthlysolutions

  9. Monthlysolutions

  10. Pushing the limits – combination strategies Standard case: single month solution + Grace A andGrace B Combining n-month with unit weight + Grace A andGrace B Combining n-month with Bartlett weight + Grace A andGrace B

  11. Comparisonofcombinationstrategies

  12. CHAMP-onlysolutionwith Bartlett option

  13. Adding GRACE …

  14. Results for CHAMP + GRACE

  15. Time series of coefficients C44 Correlation C40 GRACE – GFZ Rl. 4 CHAMP + GRACE Single coefficients comparisoncapability

  16. Spatial pattern October 2003: February 2004:

  17. Conclusion • Did we get everything out of the data of CHAMP? CHAMP still offers a wealth of information • Is the time variable gravity field really out of reach? No, but processing needs further improvements • What do we learn for future satellite missions? “Real” covariance information needed Increase the number of observations

  18. THANK YOU M. Weigelt, A. Jäggi, L. Prange, W. Keller, N. Sneeuw Towards the time-variable gravity field from CHAMP TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAAA

  19. Appendix

  20. Time variable signal? GRACE – GFZ Rl. 4 CHAMP + GRACE

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