基于主被动联合的降雨影响下的海表盐度遥感模型研究

This project intends to use the combined active and passive microwave remote sensing method to decompose and simulate the rain induced sea surface roughness change, decreasing of temperature and salinity effect. The Aquarius satellite data and a large number of satellite rainfall rate data are used. In order to simulate the coupling effect of rainfall and wind to sea surface roughness, the project will combine raindrop spectrum and wave spectrum, introduce them into the integrated equation model (IEM) for back scattering cross section simulation. The.L-band scatterometer data are used to validate and calibrate the IEM model. The calibrated rain and wave coupling spectrum will be used in the two scale model for brightness temperature (TB) simulation. The variation of the rain induced signal change of TB increment to wind direction detected by radiometer are used for further validation of model. The quiet sea surface TB will be obtained by the total brightness temperature minus the TB increment due to rain and wind induced roughness. The quiet sea surface TB only contain the rain induced temperature and salinity change, according to the different sensitivity of salinity and temperature to quiet sea surface TB, the rain induced salinity and temperature change relative to buoy and numerical model can be retrieved.

降雨使盐度遥感数据产生较大的误差，影响了其在气候预测、水循环等方面的应用。本项目拟利用多极化主被动微波遥感联合的方式，利用多颗盐度遥感卫星和大量卫星降雨率数据，对降雨引起的海面粗糙度改变、温度降低和盐度降低的影响进行分解和模拟研究，提高盐度遥感的精度。为模拟降雨和风对海面粗糙度的耦合影响，项目将降雨波谱与海浪谱结合，将波谱引入积分方程模型对后向散射截面进行模拟，利用L波段散射计实测数据对模型进行验证和校正。用散射计校正后的降雨和海浪耦合谱被用于双尺度模型对海表亮温进行模拟，由卫星实测亮温数据得到的降雨时亮温增量随风向信号的改变用于对模型的进一步验证。在观测得到的总亮温中减去粗糙海面亮温增量，得到平静海面亮温。平静海面亮温中只包含降雨对温度和盐度的改变，根据温度和盐度变化在不同极化状态和入射角下对平静海面亮温的影响不同，反演得到海表盐度。

项目实施三年来，项目负责人和研究团队，按照研究计划，围绕项目任务书中的研究目标，旨在完善基于主被动联合的降雨海面海洋盐度遥感模型。目前，已完成海面L波段微波辐射亮温模型的构建，通过改进海浪谱模型和海浪谱模型中的方向传递函数，提高了模型在低风速时的仿真精度，解决了模型在低风速时风向信号仿真不准确的问题，通过改进高风速泡沫模型，模型的适用范围可以提高到35m/s。通过改进海浪谱模型，提高了理论模型对L波段微波散射的仿真精度。完善了降雨海面波谱模型，可以较为精确地仿真降雨在小风速下对海面微波辐射和散射的增强，在大风速下对海面微波辐射和散射的削弱作用。基于主被动联合算法，开发了使用散射计直接校正辐射计粗糙海面影响的算法，提高了盐度反演精度。项目发表论文3篇，其中SCI两篇。研究成果可用于国产盐度卫星数据处理。