白冠覆盖海面L和C双波段海表盐度、温度和风速耦合反演模式研究

It is a difficult problem to retrieve the sea surface salinity (SSS), sea surface temperature (SST) and wind speed (WS) of foam-covered sea surface with the microwave remote sensing technique because of complicated microwave properties of sea foam. In this project, we shall construct a coupled-model of retrieving SSS, SST and WS with the satellite data of L-band and C-band on the basis of ocean remote sensing theory for the foam-covered sea under a high WS. In the model, the effective medium theory of sea foam composites, the microwave radiation transfer theory and the microwave scattering theory of rough sea surface will be applied to investigate the effects of sea foam on the retrieval of SSS, SST and WS considering the physical properties of sea foam. Moreover, sea foam parameters (foam thickness and volume fraction of air in foam), whitecap coverage, the sea surface roughness, WS and temperature difference of sea and air are considered in the coupled-model. The passive models of L and C bands will include the brightness temperature increments due to the sea foam and sea surface roughness. Meanwhile, to improve the effect of sea roughness, the active model of L band focuses on the scattering of sea foam. This research is valuable to construct a coupled-model of retrieving SSS, SST and WS for the satellite of SSS remote sensing of our country in the future.

海洋白冠层微波辐射和散射特性是影响海表盐度、温度和风速等参数反演精度的重要因素，也是海洋遥感研究的难题。项目依据主被动L波段盐度遥感和C波段海表温度遥感机理，利用L、C双波段辐射计和L波段散射计的白冠覆盖海面实验观测资料以及卫星资料，建立白冠覆盖海面L和C双波段海表盐度、温度和风速耦合反演模式。该耦合模式主要依据白冠层物理特性，采用有效介质、微波辐射传输和随机粗糙海面电磁散射等理论，重点研究风场、海面粗糙度（波谱）、白冠覆盖率、白冠层参数（白冠层厚度和空气体积比）、大气不稳定性参量等对L和C双波段海面微辐射亮温以及L波段后向散射系数的影响。其中，L和C双波段亮温模式考虑白冠和风速引起的粗糙海面亮温增益；L波段散射模式充分考虑海浪破碎产生白冠层和海面粗糙度的散射影响。该项目为我国研制新型盐度卫星进行海表盐度、温度和风速遥感联合反演技术提供理论基础。

项目针对海洋白冠层微波辐射和散射特性难点问题开展研究，建立海洋白冠的微波辐射和散射模式，消除白冠和海浪破碎对微波辐射和散射的影响，获得了高风速下的海洋遥感模式。项目建立了有效介质近似理论的白冠微波辐射率模式和粗糙界面微波辐射率模型，阐明了海面起伏方差对海面微波辐射的影响机理，得到了白冠空气含量反演理论模式。同时探讨了海-气多种参数对白冠微波散射特性的影响，获得了当风速大于20米／秒时白冠才能对海面散射起到消减影响；建立了白冠覆盖海面L波段盐度反演模型，获得全球高风速下盐度反演均方根误差0.33PSU和中纬度盐度误差0.22PSU，提高盐度反演精度。同时研究了C波段和其他波段微波辐射模型的最优极化风速反演模型；另外，开展了主被动L和C双波段辐射亮温模型的风速、海面温度和盐度耦合反演仿真研究，获得风速、海面盐度和温度的最优耦合反演结果。