CRTM微波亮温模拟对地表和云参数的敏感性分析

Sensitivity of CRTM Simulated Microwave Brightness Temperature to Landsurface and Cloud Parameters

利用快速辐射传输模式CRTM研究了微波地表发射率和微波亮温对地表参数和云参数的敏感性问题。首先利用实测的云南思茅地面和探空资料,通过CRTM正演了12个微波通道的地表发射率和亮温,与AMSR-E卫星亮温资料进行对比,分析了模拟亮温的正演误差,研究了地表参数对微波地表发射率模拟的敏感性,并重点分析了微波亮温对地表和云雨参数的敏感性。结果表明,地表参数中土壤湿度、地表温度和植被覆盖度三者对CRTM模拟亮温影响较大,而模拟微波地表发射率主要受土壤湿度和植被覆盖度的影响;有云雨存在时,降水云比非降水云的影响大。6种云中,雨云对模拟的影响最大。晴空条件下,大部分通道的正演亮温误差在3 K以内,垂直极化较水平极化误差小。低频通道比高频通道受地表参数影响大,受云雨影响小,垂直极化比水平极化更稳定。其中10.65 V通道几乎不受云雨影响,但对地表参数非常敏感。

Using rapid radiative transfer model CRTM,the sensitivity of microwave surface emissivity mi-crowave brightness temperature (TB)to landsurface and cloud parameters is analyzed.First,the accurate measured ground and sounding data of Yunnan Simao are used as input of CRTM to simulate 1 2 microwave channels’surface emissivity and TB,then the simulated TB is compared with AMSR-E satellite TB data, and,moreover,the simulation error and sensitivity to each parameter are analyzed.The results show that soil moisture,surface temperature and vegetation fraction have a great influence on TB simulation,and simulated surface emissivity is affected by soil moisture and vegetation fraction.The influence of precipita-tion clouds is bigger than non-precipitation clouds.Among the 6 kinds of clouds,the rain cloud has the biggest influence.In the clear sky condition,most of the 12 channels’simulation errors are between 0 to 3 Kelven.Channel 10.65 V is hardly affected by cloud and rain,but it is very sensitive to the landsurface parameters.