Crosswind ocean radar backscatter and two-scale scattering model at low grazing angles

[1] A two-scale model of rough surface in a crosswind ocean radar illumination is considered. Model characteristics such as polarization and azimuthal dependence are illustrated through numerical calculations. Predictions of the model are compared with rare field measurements made in a crosswind environment. Measurements were obtained at a 2degrees grazing angle. These data, collected by X- and Ka-band (9.3 and 34.6 GHz) radars under crosswind during the 1995 Coastal Ocean Probing Experiment (COPE) off the Oregon Coast, indicate that the backscatter intensity of local "sea-spikes'' measured with horizontal transmit-and-receive polarization (HH) reaches or exceeds that measured with the vertical transmit-and-receive polarization (VV). We suggest that for low grazing angles and in a crosswind environment, a radar geometrical condition can occur where some HH-spikes can be dominated by vertically polarized scattered radiation due to cross tilt of a long wave, when its local slope becomes greater than 45degrees.