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Philip Moore Jiasong Wang School of Civil Engineering and Geosciences

ENVISAT Orbit & RA2 CCVT in Newcastle University. Philip Moore Jiasong Wang School of Civil Engineering and Geosciences University of Newcastle upon Tyne Newcastle upon Tyne NE1 7RU philip.moore@ncl.ac.uk jiasong.wang@ncl.ac.uk. ENVISAT Precise Orbit Determination.

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Philip Moore Jiasong Wang School of Civil Engineering and Geosciences

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  1. ENVISAT Orbit & RA2 CCVT in Newcastle University Philip Moore Jiasong Wang School of Civil Engineering and Geosciences University of Newcastle upon Tyne Newcastle upon Tyne NE1 7RU philip.moore@ncl.ac.uk jiasong.wang@ncl.ac.uk

  2. ENVISAT Precise Orbit Determination

  3. Altimeter Range model adopted

  4. RMS of SLR (cm) and DORIS RMS (0.1mm/s) residuals in NCL POD

  5. RMS radial orbit difference (cm) for ENVISAT cycles 10 and 11

  6. RMS cross-track orbit difference (cm) for ENVISAT cycles 10 and 11

  7. Radial orbit difference between reduced dynamic and dynamic POD: RMS values over 4º long. by 2º lat. bins

  8. Radial orbit difference between DEOS and NCL (cyc10) RMS values 4º long. by 2º lat. bins

  9. Radial orbit difference between DEOS and NCL (cyc11): RMS values over 4º long. by 2º lat. bins

  10. Altimeter statistics

  11. RMS of crossover residuals cycles 10-11: CNES v NCL reduced SLR+DORIS orbit

  12. Sea State bias and altimeter time tag estimation from single crossovers orbit1 = CNES; orbit 2 = NCL (Reduced dynamic); • Max time diff=5day, rejection criterion 20cm Note: SSB given as % of SWH Conclusion: Results independent of orbit

  13. Sea State bias and altimeter time tag estimation from single crossover Max time diff = 5day, NCL orbit applied, for Cyc 10 +11 Conclusion: Rejection level unimportant

  14. ENVISAT - ERS2 SSH: Ascending passes Corrections applied: sea state bias and USO drift (ERS2) only

  15. ENVISAT - ERS2 SSH: Descending passes Corrections applied: sea state bias and USO drift (ERS2) only

  16. ENVISAT - ERS2 SSH: All passes All Corrections applied:

  17. Note: All corrections applied: descending pass mean = 118.1cm ; ascending pass mean = 115.0cm

  18. Differences between ENVISAT (cyc 10) and ERS2 (cyc 78) solid Earth tide corrections: Note mean = -1.1cm

  19. Differences between ENVISAT (cyc 11) and ERS2 (cyc 79) solid Earth tide corrections: Note mean = -0.8cm

  20. Differences between ENVISAT (cyc 10) and ERS2 (cyc 78) total tidal corrections. Note mean = 1.4cm. Noise from total geocentric ocean tides, see next slide

  21. Differences between ENVISAT (cyc 10) and ERS2 (cyc 78) inverse barometer corrections: Note mean = -3.0cm

  22. Differences between ENVISAT (cyc 11) and ERS2 (cyc 79) inverse barometer corrections: Note mean = -2.8cm

  23. Differences between ENVISAT (cyc 10) and ERS2 (cyc 78) iono+wet+dry+inverse bar. corrections: Note mean = -3.1cm

  24. Differences between ENVISAT (cyc 10) and ERS2 (cyc 78) wet trop. Correction: Note mean = -0.4cm

  25. Differences between ENVISAT (cyc 10) and ERS2 (cyc 78) iono (GIM) corrections: Note mean = 0.14cm

  26. ENVISAT (cyc 10): mean = 1.237m

  27. ENVISAT (cyc 11): mean = 1.237m again!!

  28. Conclusions • Orbits • agree to near 2cm RMS radially between analysis centres • Reduced dynamic is better than dynamic OD • Sea-state bias • Zero values (for very low wave heights??) • Assuming wave heights correct first look SSB  4.6% SWH • Non-parametric approximation not yet applied

  29. Conclusions • Altimetry correction (Cyc10, 11) • inverse barometer correction has a bias of -3.0cm with ERS2 • tide effect is different from ERS2 with mean=-1.4cm • Crossover residuals • RMS about 7cm; shows benefit of DORIS tracking and to a lesser extent dual frequency altimeter. Great results c.f. 6.0cm for TOPEX/Poseidon

  30. Conclusions • Sea surface height (SSH) difference with ERS2 (Cyc10, 11) • With only SSB correction applied, bias=112cm • With all corrections for both satellite , bias=117cm • For Ascending pass and descending pass , 3cm difference for this relative bias calculation. Within error bars? • SSH compared with mean sea surface (CLS01) (Cyc10) • Bias=123.7cm (ENVISAT Cyc 10) • Bias=5.4cm (ERS2 Cyc 078) • relative bias = 118.3cmbetween two satellites

  31. Sorry for missing the meeting

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