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CHAMP Gravity Field Models using Precise Orbits by C.C.Tscherning & E.Howe

CHAMP Gravity Field Models using Precise Orbits by C.C.Tscherning & E.Howe Department of Geophysics University of Copenhagen, Denmark. 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003. Introduction. 10 s data from August 2001 TUDelft precise orbits and revised attitudes

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CHAMP Gravity Field Models using Precise Orbits by C.C.Tscherning & E.Howe

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  1. CHAMP Gravity Field Models using Precise Orbits by C.C.Tscherning & E.Howe Department of Geophysics University of Copenhagen, Denmark 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  2. Introduction • 10 s data from August 2001 • TUDelft precise orbits and revised attitudes • Same method as in earlier studies 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  3. Method Energy conservation 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  4. Friction Calculated • (1) From velocity and y-accelerometer • (2) Scalar product of velocity and acceleration vector • (3) Bias parameter determined for each half day • (1)+(3) Gives best results 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  5. Estimation of coefficients • T up/downward continued to fixed altitude or radial distance using EGM96 gravity disturbances. • Values gridded 0.5o using LSC (geogrid) • Coefficients and errors from Fast Spherical Collocation 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  6. UCPH2003_03 Geoid 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  7. Error-estimates x 10-11 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  8. Degree-variances 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  9. Error-degree variances • UCPH: solid, EGM96 ---, EIGEN-2 …. 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  10. Cumulative geoid error 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  11. Comparison with EGM96 0.5o gravity 212675 mean gravity anomalies with error below 5 mgal NMAX=60. 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  12. Comparison Greenland 2150 5’x10’ mean gravity anomalies in North-West Greenland. 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  13. Differences UCPH2003_2 - _3 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  14. EIGEN-2 - UCPH2003_03 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  15. CONCLUSION (I) • Data are still contaminated with considerable noise due to the still large solar activity in the selected period. • The uncertainty of scale-factors of the accelerometers and the noise in the attitude measurements reduced the precision of the calculation of the external forces. 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

  16. CONCLUSION (II) • Data from later periods with lower solar activity may give better results. • Attitude processing must be repeated • Gridding could be improved using general LSC and taking into account the along-track error-correlations. • Kinematic orbits may give better results 2. CHAMP Science Meeting, Potsdam, Sept. 2, 2003.

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