Marine parameters from radar satellite data

In 2001 the European Space Agency ESA will launch the earth observation satellite ENVISAT. It will carry several instruments that provide new opportunities to measure oceanographic variabIes. These are the Advanced Synthetic Aperture Radar (ASAR), the Radar Altimeter (RA), the Medium Resolution Imaging Spectrometer (MERIS) and the Advanced Along-Track Scanning Radiometer (AATSR). Together, they rep-resent the main measurement techniques of satellite oceanography, and complement each other perfectly. These instruments are to be used in synergy to: ź improve the analysis of measured wind and ocean wave fields, and thereby improve weather forecasting at weather centers; ź determine the extent and variables of sea ice and develop a five-day sea ice prediction model, to support maritime shipping and offshore activities; ź monitor map sediment and suspended matter transport in coastal regions, especially in areas with large river estuaries, which greatly affects shipping lanes, harbours, and dredging activities; ź monitor hydrobiological and bio-geochemical variables related to water quality in coastal regions and large inland waters, which affects ecology, coastal development, aquaculture, drinking water supplies, and tourism. To prepare the oceanographic community to make best use of the ENVISAT sensors in the pre-Iaunch phase, existing algorithms to derive marine parameters are used and validated using data from the ERS SAR, the ERS RA, Sea WiFS, and IRS MOS sensors now in operation. Derived products, which include wind field, sea state, sea level, sea surface temperature and concentrations of water constituents, are used to address problems that can be tackled best using the synergy of radar and optical data, such as the effect of surface slicks on radar wind measurements, sea state on ocean color, wind and waves on the resuspension of suspended matter, and wind and waves on sea ice variabIes.