SMAP卫星后向散射系数与海表面风场关系

Relationship Between SMAP L-band NRCE and Sea Surface Wind Field in Pacific Region

海面风是海气互相作用的重要参数之一,如何通过雷达后向散射数据有效提取海表面风场信息,对于海洋动力环境遥感监测具有重要的研究意义。使用SMAP卫星L波段真实孔径雷达数据和国家环境预测中心再分析风场数据进行匹配,利用地球物理模型函数分析了SMAP卫星数据的后向散射系数与海表面风场之间的关系,讨论了不同风速和不同相对风向角时SMAP卫星数据反演海表面风场的潜力。研究显示,水平极化和垂直极化的后向散射系数与风速的关系紧密,适于海表面风场的反演;SMAP卫星数据存在正-侧风不对称现象和逆正-侧风不对称现象;在相对风向角为90°和270°时后向散射系数与风场的关系较为模糊;随着风速的增加,后向散射系数与相对风向角的规律关系也越来越明显,振幅也随风速增大而增大。GMF函数计算的风速偏差为1.19m/s(水平极化)和1.51m/s(垂直极化),均方根误差为1.58m/s(水平极化)和1.67m/s(垂直极化)。

Sea surface wind field is one of the important parameters of air-sea interaction.How to extract the information of sea surface wind field effectively through radar backscatter data is significant for marine dynamic environment monitoring.In this paper,we examined the relationship between ocean wind vectors and L-band normalized radar cross sections(NRCS)by using L-band geophysical model function.The studies show that the backscatter coefficient of horizontal polarization and vertical polarization are more suitable to the sea surface wind field inversion;there is negative upwind-crosswind asymmetry phenomenon in L-band radar data;when relative wind direction angles are near to 90°and 270°,the relationship are ambiguous between NRCS and wind field.With the increase of wind speed,NRCS’s amplitude increases with wind speed and the relationship is becoming more and more obvious.