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SEA ICE DETECTION Yannice FAUGERE, Joël DORANDEU , CLS , France

SEA ICE DETECTION Yannice FAUGERE, Joël DORANDEU , CLS , France. Objectives. Find a simple, straightforward, empirical method to detect sea ice Apply the ERS-2 method on Envisat Test the Peakiness parameter Combine the 2 methods to propose an ice flag algorithm for ENVISAT.

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SEA ICE DETECTION Yannice FAUGERE, Joël DORANDEU , CLS , France

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  1. SEA ICE DETECTION Yannice FAUGERE, Joël DORANDEU, CLS, France

  2. Objectives • Find a simple, straightforward, empirical method to detect sea ice • Apply the ERS-2 method on Envisat • Test the Peakiness parameter • Combine the 2 methods to propose an ice flag algorithm for ENVISAT

  3. Data processing • - Cycle 10 GDR • - No data editing • - Update of radiometer correction • -> Parametric algorithm, +1dB on Sigma0

  4. Ice Flag used for ERS-2 - Algorithm proposed by J. Stum for OPR quality assessment |Lat|>50 - A measurement is ice flagged if: or N18Hz < 17 |Radiometer Tropo – Ecmwf|>10cm

  5. Ice Flag used for ERS-2 Ice Flagged data

  6. Ocean data

  7. The ERS-2 Algorithm RMS of Ku range > 20cm over open ocean

  8. The ERS-2 Algorithm 150 pass 503 Rms of Ku Range 0 20 N18Hz pass 503 17 30 |Tropo – Ecmwf| 0 Ice flagged Non ice flagged

  9. The Peakiness parameter The Peakiness is proportional to [maximum / mean] of wave form 1.3 2.2

  10. The Peakiness parameter 1.5 1.9

  11. The Peakiness parameter Ice Flagged data Peakiness > 1.8

  12. The Peakiness parameter Ocean data Peakiness > 1.8

  13. The Peakiness parameter Ice Flagged data Peakiness > 2

  14. The Peakiness parameter Ocean data Peakiness > 2

  15. The Peakiness parameter pass 503 Rms of Ku Range Peakiness 2

  16. Proposed Envisat algorithm |Lat|>50 A measurement is ice flagged if: N18Hz < 17 or Peakiness > 2 or |Radiometer – Ecmwf|>10cm ~ 5000 measurements

  17. Proposed Envisat algorithm Clean SLA data set for oceanographic applications

  18. CONCLUSION -Ice flag is important to have a clean data set -The ERS-2 algorithm is efficient on Envisat data except on sea ice / ocean transitions -The Peakiness allows ice detection but optimal threshold not easy to find -A combination of |Radiometer – ECMWF| and peakiness seems to perform well - The method has to be tested on several seasons

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