Intensity of atmospheric motions in the MABL retrieved from ocean surface radar imagery

Results of microwave sounding of ocean surface are discussed. The study is based upon the data from airborne two-polarisation side-looking Ku-band radar, satellite based ERS SAR and the 'ALMAZ' SAR. The paper is dedicated to the theory and practice of analysis of radar images of sea surface, obtained under unstable atmosphere, when ocean is warmer than near-surface air. In this case, the sea surface reveals wind field variations in the MABL caused by atmospheric convective processes, accompanied by air motions with mainly vertical direction. Changes in radar manifestations of convection signatures are connected with the degree of thermodynamic instability of the atmosphere. It is shown that radar images of ocean under unstable atmosphere provide the imprints of convective processes in forms prescribed by theory, but in natural conditions air circulation in cylinder- or cell-formed structures differs from the model ones. It is suggested that the detection and investigation of active ocean-atmosphere energy exchange should be based on the polarization differences of radar cross section, especially under low grazing angles. The 2D-correlation functions of VV and HH-polarized radar images are considered with the aim to establish a quantitative criterion for the identification and discrimination between stable, unstable and neutral ocean-atmosphere stratifications.