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ENVISAT Calibration Review RA-2/MWR Cross-Calibration and Products Validation

ENVISAT Calibration Review RA-2/MWR Cross-Calibration and Products Validation Products Validation: Preliminary Results. J. Benveniste, M.Milagro, B. Greco. Presentation Overview. Preliminary results Range noise SWH histogram and comparison ERS-2, ECMWF

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ENVISAT Calibration Review RA-2/MWR Cross-Calibration and Products Validation

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  1. ENVISAT Calibration Review RA-2/MWR Cross-Calibration and Products Validation Products Validation: Preliminary Results J. Benveniste, M.Milagro, B. Greco

  2. Presentation Overview • Preliminary results • Range noise • SWH histogram and comparison ERS-2, ECMWF • Sigma0 histogram and cross calibration W/ERS-2 • Wind Speed histogram and comparison ECMWF • Ionospheric Correction • Altitude data • Conclusion • Recommendation

  3. Range noise profile Range residual at 18Hz 620 km

  4. Range noise histogram Histogram of Range residuals at 18Hz

  5. Range Noise Estimation • Preliminary estimation on a limited data sets give a range noise estimate of: • 8 cm rms at 18 Hz • < 2 cm rms at 1 Hz for SWH < 2 m

  6. Range Standard Deviation Ku peak at 8 cm S peak at 27 cm Ku S

  7. Significant Wave Height

  8. Significant Wave Height ERS-2

  9. Significant Wave Height ERS-2

  10. Significant Wave Height ECMWF

  11. Significant Wave Height ECMWF

  12. Significant Wave Height

  13. Significant Wave Height Ku

  14. Significant Wave Height S

  15. Significant Wave Height Ku

  16. Significant Wave Height Ku

  17. Significant Wave Height Ku

  18. Significant Wave Height S

  19. Significant Wave Height S

  20. Significant Wave Height • Comparison Summary for Ku band (August 2002)

  21. Significant Wave Height • Comparison Summary for S band (July 2002)

  22. Significant Wave Height: ERS-2 vs. ENVISAT

  23. Ku Sigma0 Ocean Ku sigma-0 histogram (12-31 March). ERS-like “1 dB spaced peaks” are not present in the ENVISAT histogram.

  24. Ku Sigma0 Ocean Ku sigma-0 histogram (12-31 March). ERS-like “1 dB spaced peaks” are not present in the ENVISAT histogram. ERS-2

  25. S Sigma0 Ocean S sigma-0 histogram (12-31 March).

  26. RA-2/ERS-2 RA Ku-band 0 Bias and Relative Linearity • Bias Value = - 12.72 dB • Standard Dev  0.2 dB • Error = +/- .05 dB • NB: This was estimated on earlier data. After algorithm correction the actual bias is around 3 dB

  27. Wind Speed

  28. Wind Speed

  29. Wind Speed

  30. Wind Speed

  31. Wind Speed

  32. Wind Speed • Comparison Summary (August 2002)

  33. Ionospheric Correction Ra-2 dual frequency ionospheric correction of the Ku band path delay against the Bent model. Both profiles are consistent, The scaling factor b/w both solutions has disappeared with the range bias algorithm correction. Bent RA-2

  34. Ionospheric correction

  35. Altitude in FDGDR/FDMAR 30 meter Orbit error 4 cpr Jumps Use DORIS Navigator instead (30 cm)

  36. Product Handbook Verification • The Product Handbook is being verified by two dedicated reviewers, as well as through its use within the RA–2/MWR CCVTeam

  37. Conclusion (1/2) • The RA-2/MWR Cross-Calibration and Validation plan has been finalised pre-launch - a brief overview was given here. • During the first months after RA-2 switch on, the main altimeter geophysical quantities have been checked: the reference ground processor has been upgraded to remove residual errors. • The preliminary performance estimation of the ENVISAT Radar Altimeter yields very good results; • Range noise: 1.8 cm • SWH compares well with ERS-2 and ECMWF - RA-2 measures low waveheights much better than ERS -- Algorithm will be further improved • Wind speed compares well with ERS-2 and ECMWF - Cross-cal w/ERS-2 on more data • ===> Range, SWH and wind speed remain to be calibrated.

  38. Conclusion (2/2) • The next steps are the fine tuning of processing parameters, a consolidated performance evaluation, an exhaustive validation and the cross-calibration with ERS-2 and other flying altimeters. • The RA-2/MWR Cross-Calibration and Validation Team has worked with a month of FDMAR and will receive IGDRs, GDRs, SGDRs data products by early-October to start the cross-calibration activity.

  39. The support to scientific users • Easier and fastertostart new A.O. projects under the new Data Policy. • Category 1 Advisory Group (International panel of scientists) to peer review new proposals. • Support to A.O. P.I.’s through dedicated Correspondents and Results Reporting Web Site. • Single web site for the submission, exploitation and promotion ofyour A.O. project: http://projects.esa-ao.org

  40. http://envisat.esa.int

  41. RA-2/MWR Product Tree

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