Cone Metrics for C and Ku-Band Scatterometers

Scatterometer radar systems in space prove very stable in calibration, but how do we know this? The most accurate method to determine stability to date is called “cone metrics”. Cone metrics uses the consistency of NRCS measurements in measurement space and methods have been developed that determine the location of NRCS sets associated to a particular wind vector to within 0.05 dB. This number corresponds to an uncertainty of roughly 0.05 m/s of retrieved wind speeds. Therefore, if instrument stability is established to within 0.1 m/s for a scatterometer, then it would globally establish the required decadal stability of 0.1 ‘m/s, which is unique. Furthermore, cone metrics is being used for Geophysical Model Function (GMF) development. Whereas focus has been mainly on European scatterometers, the cone metrics methodology may also be applicable for other scatterometer concepts. Cone metrics will be presented to initiate a discussion on its use as a standard tool with the international community gathered at IGARSS ‘21.