Impact of using several altimeters for improving numerical wave analyses and forecasts

Meteo-France Marine and Oceanography Division is using data from the European Space Agency (ESA) satellite ERS2 to improve analyses and forecasts of the sea-state. As it travels along its orbit above the earth\´s surface, the measuring platform\´s onboard altimeter measures significant wave heights and wind speeds. These parameters are assimilated into Meteo-France\´s sea-state forecasting model. Envisat (ESA satellite) and Jason (satellite of CNES, the French space agency and NASA, the US space agency), successors of ERS2 and Topex respectively will provide similar and validated data in 2003, in "real time". In addition, data from the US Navy satellite GFO are also available on a NOAA ftp server, the United State Oceanographic and Atmospheric Administration. Preliminary results related to the benefit of using these new data in addition to ERS2 ones for numerical wave analyses are presented. The usefulness of using several altimeters for wave forecasting systems is shown by experiments for assessing their input which are conducted within Meteo-France\´s Marine and Oceanography Division, with the support of the CNES.