| Summary: | 2019 Living Planet Symposium, 13-17 May 2019, Milan, Italy Following the success of the QuikSCAT, Oceansat-2, HY-2A, and RapidScat missions, a new Ku-band rotating pencil-beam scatterometer, ScatSat-1 from the Indian Space Research Organization (ISRO) was launched in September 2016. Scatterometer sea surface winds have been used in a wide variety of atmospheric, oceanic, and climate applications. Moreover, thanks to the near-real-time data distribution of most missions, scatterometer wind data have been successfully assimilated into numerical weather prediction models for more than two decades. In the framework of the EUMETSAT Numerical Weather Prediction Satellite Application Facility (NWP SAF) and Ocean and Sea Ice Satellite Application Facility (OSI SAF), the Royal Netherlands Meteorological Institute (KNMI) has developed the so-called Pencil-beam Wind data Processor (PenWP), which has provided and provides near-real-time Level 2 (swath-based) sea surface wind fields for all past and current rotating pencil-beam scatterometer missions. The main components of PenWP include calibration, inversion, quality control, and ambiguity removal. Research & Development activities within the NWP SAF and OSI SAF over the past 15 years have focused on the improvement of the different algorithms of the scatterometer wind data processors, including PenWP. Recent results show that both the Ku-band forward model or geophysical model function (GMF) and the quality control (QC) can be further improved. In this paper, we focus on these two relevant aspects of the scatterometer wind data processing in order to improve the ScatSat-1 wind retrieval quality. Recent developments on the wind GMF of Ku-band (~2 cm wavelength) scatterometers include a sea surface temperature (SST) dependent term. Moreover, it has been found that the SST effects on the radar backscatter are wind speed dependent, and are mainly relevant at radar wavelengths smaller than C-band (~5 cm wavelength). A new Ku-band GMF, NSCAT-5, has been developed based on ...
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