Page 1 ASAR Validation Workshop - ESRIN – December 2002 Preliminary Performance of the ASAR Wave Level WVS and WVW Product Frank Melger ARGOSS

Page 2 ASAR Validation Workshop - ESRIN – December 2002 WVS (Level 1b) product  ASA_WVS_1PNPDK _091558_ _00179_03740_0161.N1  ASA_WVS_1PNPDK _094531_ _00179_03740_0160.N1  ASA_WVS_1PNPDK _102031_ _00179_03740_0159.N1  ASA_WVS_1PNPDK _120010_ _00180_03741_0164.N1.  ASA_WVS_1PNPDK _130545_ _00181_03742_0168.N1

Page 3 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVS_1PNPDK _091558/_094531/_102031/_120010/_ Retrieved wave energy against ECMWF WAM wave energy  SPRA scheme, preliminary results

Page 4 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVS_1PNPDK _091558/094531/102031/120010/ Retrieved wave energy against ECMWF WAM wave energy  SPRA scheme, preliminary results

Page 5 ASAR Validation Workshop - ESRIN – December 2002 Summary WVS (Level 1) product  No problems found in the WVS product examples.  Representative but limited dataset, (large variation sea states, different oceans)

Page 6 ASAR Validation Workshop - ESRIN – December 2002 WVW (Level 2) product ASA_WVW_1PXPDE _203722_ _00143_01700_0045.N1

Page 7 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVW_1PXPDE _203722_ _00143_01700_0045.N1 Retrieved wave energy against ECMWF WAM wave energy

Page 8 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVW_1PXPDE _203722_ _00143_01700_0045.N1 Retrieved wave energy against ECMWF WAM wave energy

Page 9 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVW_1PXPDE _203722_ _00143_01700_0045.N1 Retrieved wind velocity against ECMWF WAM wind velocity  slightly underestimated  unresolved wind speed below ~ 4m/s

Page 10 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVW_1PXPDE _203722_ _00143_01700_0045.N1 Retrieved and ECMWF WAM wind velocity

Page 11 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVW_1PXPDE _203722_ _00143_01700_0045.N1 Retrieved ocean wave spectra

Page 12 ASAR Validation Workshop - ESRIN – December 2002 WVW inversion scheme  Estimate azimuth cut-off wave number (Kc)  Use Kc to estimate  inverse wave age  quasi-linear mapping relations  Estimate ocean wave spectrum within quasi linear mapping area  Ocean wave energy outside linear mapping area is not included in the WVW product.

Page 13 ASAR Validation Workshop - ESRIN – December 2002 Azimuth wave number  Expected problems at high sea states

Page 14 ASAR Validation Workshop - ESRIN – December 2002 WVW Relation azimuth cut_off wave number and shift variance  Wind direction is set to dummy value of 45 degrees relative to range direction  Without true wind (wave) direction information 45 degrees gives smallest average errors  Propagation direction short waves unknown

Page 15 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVW_1PXPDE _203722_ _00143_01700_0045.N1 Correlation normalised wave age -1 and retrieved wind velocity correlation coefficient:

Page 16 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVW_1PXPDE _203722_ _00143_01700_0045.N1 Relative low phase velocity

Page 17 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVW_1PXPDE _203722_ _00143_01700_0045.N1 Retrieved wave height relative to wave height wind waves  Dominating swell energy  Relative low wind speeds  Relative young seas( duration fetch length)

Page 18 ASAR Validation Workshop - ESRIN – December 2002 WVW or Level 2 product ASA_WVW_2PXPDE _195148_ _00300_01857_0003.N1

Page 19 ASAR Validation Workshop - ESRIN – December 2002 ASA_WVW_1PXPDE _195148_ _00300_01857_0003.N1 Retrieved ocean wave spectra

Page 20 ASAR Validation Workshop - ESRIN – December 2002 Remarks WVW (level 2) product  Current dataset not representative: long waves energy dominates. With ERS data the best results were always found in the Pacific.  Applicability of retrieved wind speed and wave age is questionable. Development of a procedure to add (missing) wind sea energy from retrieved wind vector is not trivial.  Performance is expected to deteriorate at high sea states.  Additional validation is needed to evaluate the performance for various sea states at various locations.  Dataset is too limited for definite conclusions.

Page 21 ASAR Validation Workshop - ESRIN – December 2002 Summary WVW product  Initial problems with WVW and WVS product have already been solved.  ESA scheme has performed well on this limited dataset but much more validation is needed.

Page 22 ASAR Validation Workshop - ESRIN – December 2002 What next ?  Organisation and infrastructure for validation is operational. WVS, WVW, ECMWF, BUOY data easily accessible.  Because the data stream has just started we have not really be able to benefit from these facilities.  The next year will be crucial for the validation of wave mode products.

Page 23 ASAR Validation Workshop - ESRIN – December 2002 Thank you for listening to my presentation Frank Melger ARGOSS P.O. Box ZH VOLLENHOVE the Netherlands Telnr.: Faxnr.: