Comparison of empirical and electromagnetic geophysical model function for near-surface wind speed retrieval

Despite based on different approaches and objectives, it is reasonable to compare near-surface wind speed estimated by the empirical (EP) and electromagnetic (EP) geophysical model function (GMF), since both of them describe the relation between radar scattering and wind vector (directly for EP GMF and via surface roughness spectrum for EM GMF). In general, the EP and EM models give quite similar normalized radar cross section (NRCS) for radar incidence angle below 40°. Consequently, wind speed estimated by the EP and EM GMF is very close. However, for incidence angles above 40°, the EM models show poor performance of wind speed estimation.