Mesoscale winds from the new ASCAT scatterometer

Introduction satellite based scatterometers provide high resolution all-weather wind vector fields over the seas. Wind speed and wind direction are provided at high accuracy under all weather conditions. The allweather EsA ERs scatterometer observations have proven its significant impact for the forecasting of fast developing and severe weather. Moreover, scatterometer wind fields are provided on the scale of ocean eddies. These wind fields are important for driving the ocean’s motion. As a consequence, oceanographic applications and climate research have been initiated using winds from the seaWinds scatterometer on the Quikscat satellite. The EUMETsAT Advanced scatterometer AsCAT on MetOp-A was launched on 19 October 2006 as the third wind scatterometer in space joining up with the EsA ERs-2 and the NAsA/NOAA seaWinds scatterometers. Together, the AsCAT, ERs-2 and seaWinds scatterometers provide good coverage over the oceans in the morning and evening (Local solar Time). They are used routinely in marine and weather forecasting. The KNMI contribution to the EUMETsAT satellite Application Facilities (sAFs), the AsCAT calibration, the production of high spatial resolution wind products at KNMI and their application are elaborated below. The KNMI global ocean wind product from the AsCAT scatterometer is the first routine MetOp-A geophysical product. During the coming years KNMI will continue to develop high resolution operational products for coastal areas.