Preliminary Performance of the ASAR Wave Level WVS

Preliminary Performance of the ASAR Wave Level WVS and WVW Product Frank Melger ARGOSS ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 1

WVS (Level 1 b) product · · · ASA_WVS_1 PNPDK 20021117_091558_000013202011_00179_03740_0161. N 1 ASA_WVS_1 PNPDK 20021117_094531_000020842011_00179_03740_0160. N 1 ASA_WVS_1 PNPDK 20021117_102031_000002552011_00179_03740_0159. N 1 ASA_WVS_1 PNPDK 20021117_120010_000002552011_00180_03741_0164. N 1. ASA_WVS_1 PNPDK 20021117_130545_000007802011_00181_03742_0168. N 1 ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 2

ASA_WVS_1 PNPDK 20021117_091558/_094531/_102031/_120010/_130545 Retrieved wave energy against ECMWF WAM wave energy · SPRA scheme, preliminary results ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 3

ASA_WVS_1 PNPDK 20021117_091558/094531/102031/120010/130545 Retrieved wave energy against ECMWF WAM wave energy · SPRA scheme, preliminary results ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 4

Summary WVS (Level 1) product · · No problems found in the WVS product examples. Representative but limited dataset, (large variation sea states, different oceans) ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 5

WVW (Level 2) product ASA_WVW_1 PXPDE 20020627_203722_000022492007_00143_01700_0045. N 1 ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 6

ASA_WVW_1 PXPDE 20020627_203722_000022492007_00143_01700_0045. N 1 Retrieved wave energy against ECMWF WAM wave energy ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 7

ASA_WVW_1 PXPDE 20020627_203722_000022492007_00143_01700_0045. N 1 Retrieved wave energy against ECMWF WAM wave energy ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 8

ASA_WVW_1 PXPDE 20020627_203722_000022492007_00143_01700_0045. N 1 · · slightly underestimated unresolved wind speed below ~ 4 m/s Retrieved wind velocity against ECMWF WAM wind velocity ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 9

ASA_WVW_1 PXPDE 20020627_203722_000022492007_00143_01700_0045. N 1 Retrieved and ECMWF WAM wind velocity ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 10

ASA_WVW_1 PXPDE 20020627_203722_000022492007_00143_01700_0045. N 1 Retrieved ocean wave spectra ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 11

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. ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 12

Azimuth wave number · Expected problems at high sea states ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 13

WVW · · · 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 Relation azimuth cut_off wave number and shift variance ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 14

ASA_WVW_1 PXPDE 20020627_203722_000022492007_00143_01700_0045. N 1 Correlation normalised wave age-1 and retrieved wind velocity correlation coefficient: 0. 9077 ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 15

ASA_WVW_1 PXPDE 20020627_203722_000022492007_00143_01700_0045. N 1 Relative low phase velocity ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 16

ASA_WVW_1 PXPDE 20020627_203722_000022492007_00143_01700_0045. N 1 · · · Dominating swell energy Relative low wind speeds Relative young seas( duration fetch length) Retrieved wave height relative to wave height wind waves ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 17

WVW or Level 2 product ASA_WVW_2 PXPDE 20020708_195148_000014542007_00300_01857_0003. N 1 ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 18

ASA_WVW_1 PXPDE 20020708_195148_000014542007_00300_01857_0003. N 1 Retrieved ocean wave spectra ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 19

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. ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 20

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. ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 21

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. ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 22

Thank you for listening to my presentation Frank Melger ARGOSS P. O. Box 61 8325 ZH VOLLENHOVE the Netherlands Telnr. : +31 -527 -242299 Faxnr. : +31 -527 -242016 E-mail: info@argoss. nl WWW. ARGOSS. NL ASAR Validation Workshop - ESRIN – 11 -12 December 2002 Page 23