X波段测波雷达海流信息反演的影响因素分析

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

X波段测波雷达海流信息的提取决定着有效浪高结果的准确度。因此,对可能影响X波段测波雷达海流信息提取的各种环境因素以及雷达工作模式等进行了海浪回波成像仿真,然后采用目前测波雷达通用的算法对仿真回波图像进行了海流信息反演。主要研究了海表面风速、雷达天线架设距离海平面高度、天线转速、海流流速、海流流向与海浪方向夹角、所选取的图像帧数以及每帧图像大小对海流信息反演的影响。对比分析设定值与反演结果,可知海表面风速在6~14 m/s之间,天线高度大于20 m并且转速为50~70r/min,流速小于200cm/s并且主波浪向与流向夹角不接近90°,图像帧数为128帧并且每帧图像数据点数为128×128时,X波段测波雷达能获得最佳海流信息反演结果。

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.