Influencing Factors of Ocean Current Inversion with X-Band Wave Monitoring Radar

Sea surface dynamic parameters such as significant wave height and current velocities are obviously important for climate studies as well as the safe and efficient operation and routing of marine traffic. The key point determining the accuracy of the significant wave height extracted by the X-band wave monitoring radar is the accurate estimation of SNR which depends on whether the dispersion shell is correctly obtained. To obtain the dispersion shell, the accurate current velocity should be estimated first. This is done by fitting the theoretical dispersion relation to the signal coordinates in the complex wave number frequency spectrum. Without accurate measurement result of current, there will be serious bias in SWH inversion due to the erroneous calculation of SNR. This paper carried out simulation of ocean surface with different working state of radar and various environment factors which may influence the performance of X-band wave monitoring radar in extracting ocean current, and then inversed the ocean current from the simulated echo images with a general algorithm for wave monitoring radar. The study mainly focused on the factors which may influence ocean current inversion like wind speed, the height and the rotation speed of antenna, the velocity and the angles between current and main wave direction, images quantity and its size. Comparing preset values and inversion results, it shows that when the wind speed ranges from 6 to 14 meters per second, the antennars 20 meters higher than sea level and its rotation speed is limited from 50 to 70 r/min, the velocity of ocean current is less than 200 centimeters per second and the angles between current and main wave directions are not close to 90 degrees. When the quantity of images is 128 and an image size of 128×128, X-band wave monitoring radar could achieve the best ocean current inversion results.