Calibration of RapidScat scatterometer

RapidScat is a Ku-band scatterometer that flew onboard the International Space Station (ISS) between September 2014 and November 2016. RapidScat's primary objective had been global wind vector retrieval over sea surface from the measured normalized radar cross section (σ°). The retrieved wind accuracy is therefore determined by the accuracy of the underlying σ
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measurements. To assure measurement accuracy, careful scatterometer calibration and validation is required. Cross-calibration among overlapping instruments is a common calibration method. ISS Sun-asynchronous orbit enables, for the first time, overlap with other satellite scatterometers that have been flying in Sun-synchronous orbits. This paper explores the implementation of a cross calibration method between the RapidScat and QuikScat scatterometers. QuikScat is Rapidscat's parent instrument whose spare parts were used to build the RapidScat. Biases between σ
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measurements from RapidScat and QuikScat have been computed as a function of wind speed and incidence angle for both polarizations. The work summarized in this paper addresses cross-calibration algorithm applied to Rapidscat and Quikscat using data collected in the period from January 2015 to March 2016.