大气对星载盐度计辐射传输特性及盐度反演的影响研究

Effects of Atmosphere on Radiative Transfer Characteristics and Salinity Retrieval on Spaceborne Salinity Meter

利用MPM93模型,根据微波辐射传输方程,仿真不同天气情况下的L波段大气辐射参数及盐度计观测亮温,并用最大似然估计法反演海表盐度,研究不同天气情况对海表盐度反演值的影响。仿真结果表明:考虑了悬浮液滴影响的云、雾及霾情形的大气辐射参数与晴空时差别不大,可以忽略天气的影响。然而,降雨对大气辐射参数的影响不可忽略,并且随着降雨率的增加,盐度反演误差明显增大。在降雨率不变的情况下,盐度反演误差随着海表温度增加而减小,在盐度低值时误差较小。盐度反演误差随海表气温的升高呈现先变大后变小的趋势,受海面风速、海面气压以及海面水汽密度的影响极小。

Using the MPM93 model,the L-band of atmospheric radiation parameters and salinity meter observation brightness temperature under different weather conditions are numerically simulated based on the microwave radiation transfer equation,and using the maximum likelihood estimation algorithm to the inversion of sea surface salinity,which research the influence of different weather conditions on the sea surface salinity retrieval value.The simulation results show that the atmospheric radiation parameters of cloud,fog and haze which considered the effects of suspended droplets are almost the same as those in clear sky,and the influence of them can be neglected.However,the influence of rainfall on atmospheric radiation parameters can’t be neglected,and the error of salinity retrieval increases obviously with the increase of rainfall rate.When the rainfall rate is fixed,the salinity inversion error decreases with the increase of sea surface temperature,and the salinity retrieval error is smaller under low salinity value.Besides,the salinity retrieval error changes decrease after increasing with the increase of sea level atmosphere temperature.Furthermore,the influence of sea surface windspeed,sea level pressure and sea level vapor density on salinity retrieval error are very small.