CoAuthors

Alice Dalphinet (Meteo-France, France)

The increasing number of significant wave heights from satellite altimeters and SAR directional wave spectra will improve significantly the operational wave forecast and the reliability of the wave submersion warning system. During the calibration-validation phase of Sentinel-3A it has been indicated a strong bias of significant wave height retrieved by the SAR mode altimetry. The goal of this study is to investigate this bias by using the combined assimilation of SAR wave spectra provided by Sentinel-1A and 1B and the significant wave heights retrieved by Sentinel-3A. First waves climatology based on wave products from operational data base is implemented for all ocean basins to identify the areas of swell dominant sea state. In particular we will focus on the primary swells with wavelength ranged between 300 and 400 m.
The combined assimilation is performed for the southern winter of 2017 (June to September) because of many events generating swell systems. The results shows that the combined assimilation improves significanty the mean wave parameters. The validation with independent altimeters wave heights reveals the reduction of the bias (30 to 40%) after the assimilation mostly in the high and intermediate latitudes. An index is set depending on the bias reduction and the primary swell wave length and height. The index mapping indicates a strong correlation affecting the ocean areas of swell dominant sea state defined by the waves climatology. A comparison with combined assimilation using significant wave height of S-3A retrieved by PLRM processing, is also performed.
Further conclusions and discussions will be commented in the final paper.