Ocean Surface Wind Speed Retrieval From C-Band SAR Images Without Wind Direction Input

Two new models for wind speed retrieval from C-band synthetic aperture radar (SAR) data have been developed, based on a large body of statistics on buoy observations collocated and coinciding with RADARSAT-1 and -2 ScanSAR images. The first model´s independent variables are co-polarization (HH) normalized radar cross-section (NRCS), and antenna beam incidence angle. The second model´s predictors are HH NRCS, cross-polarization (HV) NRCS, instrument noise floor, and incidence angle. The latter model has better accuracy than the first because of using an additional HV variable. Furthermore, we found that the proposed models without wind direction input demonstrated a better accuracy than CMOD_IFR2 and CMOD5.N models in combination with the SAD HH co-polarization ratio (VV/HH), which require wind direction input. These results were confirmed on a large independent subset of collected data. The developed wind speed retrieval models, in conjunction with our previously developed ice motion tracking algorithm, can be a useful tool for studying sea ice dynamics processes in the marginal ice zone. The developed models have been integrated into a quasi-operational system at the Meteorological Service of Canada.