Ermoshkin A.V., Kapustin I.A., Molkov A.A., Bogatov N.A.

The paper proposes a methodology for determining the speed and direction of the sea surface current from measurements of Doppler radar panoramas with an X-band Doppler radar. Numerical simulation of the Doppler velocity of the Bragg waves in the field of wind waves and currents were carried out. The range of distance was selected for measuring the velocity of the surface current at which the effect of shading of the sea surface sections by wave crests can be ignored. Long field experiments were conducted, during which the proposed method was tested. The velocity and direction of the surface current were calculated as the vectorial sum of the velocity of the water column and 3% of the wind speed, while at the same time Doppler radar panoramas of the sea surface were measured. It was shown that, for upwind/upwave radar sensing, the average Doppler velocity of the scattering microwave waves of sea surface elements are significantly higher than the predictions of the two-scale scattering model. To restore the velocity of the surface current the registration was carried out empirically. For downwind/downwaves radar sensing, good agreement with the simulation results was observed. A correlation analysis of the surface current, calculated through hydrometeorological parameters and Doppler radar panoramas, showed a maximum correlation coefficient for a velocity value is about 0.88 with a root mean square error of 8 cm/s, and for a direction is about 0.98 with a root mean square error of 14 degrees. It is noted that film slicks on the sea surface lead to a significant decrease in the average Doppler velocity, which may serve as an additional criterion for the remote detection of oil spills

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