International cooperative wind retrievals.
CFOSAT is a joint mission of the Chinese (CNSA) and French (CNES) space agencies. The goal of the mission is to monitor the ocean surface wind and waves and to provide data for ocean and atmospheric science in order to improve forecasts for marine meteorology and the knowledge of climate variability. There are two main instruments on board: SCAT (a wind scatterometer with ku-band supplied by CNSA) and SWIM (a wave scatterometer supplied by CNES). CFOSAT is planed to be orbited in 2018 (Fig. 1).
SCAT will be the first RFSCAT (Rotating Fan-beam SCATterometer) in ku-band with HH and VV polarization for a global ocean vector wind observations. Fig. 2 shows the illustration of the RFSCAT. It produces large overlaps within the swath by successive sweeps and large number of sigma0 with diverse azimuth angle within the WVC (Fig. 3 the footprint of scanned antenna).
KNMI is involved in the development of wind processing software, CFOSAT wind product and wind retrieval quality improvement. KNMI has a long experience in the software development and operational provision of scatterometer wind products, both in near real time and as climate data records. This work is done under the frame of the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), Ocean and Sea Ice Satellite Application Facility (OSI SAF) and Numerical Weather Prediction Satellite Application Facility (NWP SAF). Currently, the pseudo-L1B data simulator and end-to-end RFSCAT simulation are available for the wind product testing. In order to improve the wind direction retrieval in a more generic way, beam weighting method has been testing on RFSCAT. The wind retrieval performances such as wind direction rms error, wind speed bias and FoM (Figure of Merit) are estimated.