NORUT IT explained how an upgraded ASAR Wave Mode algorithm had been developed following detailed comparisons of ASAR coverage across the world's oceans with in-situ data from buoys and platforms, as well as numerical ocean and atmospheric models, to arrive at a database of co-located spectra. The cross-comparison revealed a number of problems and ambiguities in terms of swell estimation which the processing algorithm was then upgraded to remove.

Validation of the results clearly shows an increase in meaningful spectra as opposed to 'non-physical spectra' previously observed and an improved flagging of ambiguous data, as well as a decreased average deviation between the data and wave forecasting system of the European Centre for Medium-Range Forecasting (ECMWF). Reprocessing of the entire ASAR Wave Mode archive is now being undertaken at the Centre ERS d'Archivage et de Traitement (CERSAT) operated by the French Research Institute for Exploitation of the Sea (IFREMER).

Envisat ASAR wave data analysis over coastal areas

ASAR measurements are also providing a unique ability to estimate the wave climate over coastal areas. The processing of SAR images in general and Envisat's ASAR in particular offers potential for imaging large areas with a high resolution capability to provide fine information about the spatial variations of the wave field.

As presented during SeaSAR, ASAR measurements revealed details of the swell transformation that can be related to the underlying bathymetry and/or coastal currents. Encouraging results have been obtained to produce SAR-derived maps of significant wave heights at a resolution of about 1 km, to be combined with simple ray-tracing models.

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Contact: Mariangela D'Acunto
mariangela.dacunto@esa.int
39-069-418-0856
European Space Agency
27-Mar-2006

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