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ERS-1 SAR Wave Mode Monthly Quality Assessment

This bulletin provides a monthly assessment of the geophysical products from ERS-1 SAR Wave Mode (SAR_WVW_2P). The validation is performed globally using co-located WaveWatch3 (WW3) data from Ifremer. It is based on previous work done by Boost-Technology on Envisat ASAR monitoring.

Backscatter

http://www.ifremer.fr/cersat/images/esa/sarqc/ers1/ww3/{yyyy}/{MM}/sar_backscatter_map_glo_{yyyy}-{MM}-{dd}.png
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Global map of backscatter value (?0) [dB]
  

Backscatter comparisons

In this part, the WW3 backscatter values refer to the output of the empirical CMOD-IFR2 model fed with ECMWF winds (speed and directions). Incidence angle values of WV points are used to estimate CMOD-IFR2 outputs.

Comparisons between backscatter values ?0 of WVW data and WW3 (i.e. CMOD-IFR2+ECMWF wind) for different wind directions

Significant Wave Height (SWH) analysis

 

http://www.ifremer.fr/cersat/images/esa/sarqc/ers1/ww3/{yyyy}/{MM}/sar_model_swh_difference_map_glo_{yyyy}-{MM}-{dd}.png
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  Global distribution of the difference between WVW SWH and WW3 SWH.

 

Regional distribution of the difference between WVW SWH and WW3 SWH.

 

 

Distribution of the difference between mean period of WVW and WW3 (a). Scatter plot of mean period of WW3 vs WVW (b).

Regional analysis of the wave directional distribution

 Mean wave direction relative to SAR

http://www.ifremer.fr/cersat/images/esa/sarqc/ers1/ww3/{yyyy}/{MM}/sar_model_phi_difference_glo_{yyyy}-{MM}-{dd}_WW3.png
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Global comparison between SAR and WW3 mean wave direction relative to SAR (in deg)

 

Regional comparison between SAR and WW3 mean wave direction relative to SAR (in deg)

Global distribution of the ASAR WVW azimuth cutoff values

Global map of SAR WVW azimuth cut-off values (left), and similar coverage of co-located ECMWF wind speed values (right)

Analysis of the normalized variance

http://www.ifremer.fr/cersat/images/esa/sarqc/ers1/ww3/{yyyy}/{MM}/swh_nv_scatterplot_glo_{yyyy}-{MM}-{dd}.png
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WVW significant wave height vs. image normalized variance