Envisat ASAR wave data sharpening Meteo France ocean forecasts

Also presented at SeaSAR 2006 was the latest in an ambitious project to assimilate another Envisat ASAR product Wave Mode data, which yields wind speed and wave spectra over the open ocean into the sea state prediction models of French national weather forecaster Meteo France. The forecaster already assimilates altimetry data from Envisat sensor, the Radar Altimeter-2 (RA-2), and has been working on ASAR assimilation since 2003.

"The work is still part of our research and development activities but hopefully we will step forward into operational mode soon," said Lofti Aouf of Meteo France. "The impact of the assimilation of ASAR wave spectra processed with an upgraded algorithm on wave parameters wave height, period and direction stays efficient for more than three days into the forecast period, following the end of the assimilation.

"We developed an assimilation system which conjointly uses RA-2 significant wave height and ASAR directional wave height. The results indicated a significant impact on mean wave parameters, results being validated with independent wave data, such as wave height from the French-US Jason-1 satellite altimeter.

"During a one-month test run the results showed a correction of root mean square (RMS) error of 20%, with the impact duration induced by the combined assimilation being further enhanced. This task has important consequences on related research topics such as air-sea interaction processes, including heat fluxes transfers and current circulation."

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