ERS-1 scatterometer off-line products: calibration/validation results and case studies

Calibration and validation tests performed at IFREMER has shown the need to reprocess the ERS-1 scatterometer archive. The new data-set is carefully examined. The data accuracy is determined by comparison with the NOAA buoy data, showing that good accuracy is achieved (1.2 m/s and 15° standard deviations). Nevertheless the scatterometer wind data are biased low at very high wind speed (>20 m/s) and also exhibit a bias depending on the atmospheric boundary layer stability. The resolution and the very low level of noise in the scatterometer data allows the measurement of small scale features in the wind field that are not seen by the meteorological numerical models. Two cases of tropical cyclones are presented