Ocean wind fields and their variability derived from SAR

Mesoscale wind fields over the ocean surface are of great interest for studying processes in the boundary layer and for obtaining a better understanding of coastal processes. Spatial covering wind fields are frequently derived from space-borne scatterometers (SCAT). The SCAT and the Synthetic Aperture Radar (SAR) aboard the European remote-sensing satellites ERS-1 and ERS-2 operate both at 5.3 GHz (C-band) at moderate incidence angles between 18° and 59°. For these incidence angles, the backscatter signal of the rough ocean surface is primarily caused by the short surface gravity waves, which are in resonance with the incident radiation of the sensor. For incidence angles of ERS SARs, between 20° and 26°, the range of scattering wavelengths extends from 8.2 to 6.5 cm. These waves are strongly influenced by the local wind field and allow the backscatter to be a measure of the wind.