机载合成孔径雷达海面风场探测辐射定标精度要求研究

复杂的机载合成孔径雷达系统使得探测精度要求研究难以系统有效. 依据辐射定标精度在机载合成孔径雷达海面风场探测信息流程中的作用, 提出通过辐射定标精度要求整体考察系统探测精度要求的研究方法, 仿真研究了CMOD4地球物理模型函数的参数关系,系统地确定出不同入射角和风向条件下机载合成孔径雷达海面风场探测的辐射定标精度要求.研究结果表明, 辐射定标精度要求随着入射角的增加而降低,且随着风向变化呈周期性变化, 这一规律与CMOD4地球物理模型函数中由风速变化引起的后向散射截面变化值的变化规律一致. 依据这一规律,研究发现通过采用有源定标器定标、设计载机做侧风飞行以及选择大入射角的探测图像作为反演图像区这三种手段,能够提高风速反演精度.

Radiometric calibration accuracy of airborne synthetic aperture radar in ocean surface wind field sounding

Sounding accuracy is difficult to study systematically and effectively because of complex airborne synthetic aperture radar system. In this paper, according to the role of radiometric calibration accuracy in ocean surface wind field sounding process of airborne synthetic aperture radar, a method is proposed to investigate the system sounding accuracy by radiometric calibration accuracy. The parameter relationship of CMOD4 geophysical model function is simulated. The radiometric calibration accuracy of airborne synthetic aperture radar ocean surface wind field sounding at different incidence angles and in wind directions is ascertained. The results show that the radiometric calibration accuracy decreases with incidence angle increasing and changes periodically with wind direction changing. The law is accordance with the change of backscattering cross-section, cased by wind speed in CMOD4 geophysical model function. According to this law, we find that the accuracy of ocean surface wind field retrieval can be improved by using active calibration scale, designing carrier aircraft crosswind flight and selecting the large incidence angle sounding imagery as retrieval area.