On the features of Doppler velocities estimation with coherent radar of high spatial resolution

Abstract

The article discusses the results of theoretical and experimental studies of Doppler velocity on the sea surface. Doppler velocity is measured by radar sensing at moderate and low grazing angles. The experiments were performed using coherent X-band and Ka-band panoramic digital radars operating with the horizontal polarization for transmission and reception. These radars have high spatial resolution. An algorithm for reconstructing Doppler velocities is proposed and estimates of the fluctuation sensitivity of the method are carried out. The method is applied to the conditions of the fetch-limited wind wave growth, which is typical for enclosed waters and the sea nearshore, where the dominant wavelength is of the order of ten meters. Based on the two-scale model, the dependences of the Doppler velocity on the parameters of the ocean-atmosphere interface are considered. The effect of shadowing by the crests of wind waves on the magnitude of the Doppler velocity at low grazing angles is discussed. The manifestation of the orbital velocity of wind waves is demonstrated.