星载被动微波遥感资料为云天条件下地表洪涝特征分析提供了可能。微波极化比 (PR)可以有效刻画地表洪涝特征 ,宏观反映地表湿度信息。正演模拟分析结果表明地表粗糙度、地表植被覆盖状况和地表湿度对上行微波亮温有影响 ;TRMM/TMI低频微波通道微波极化比能减弱大气因素的影响 ,清晰反映地表的洪涝特征。合理确定分类阈值 ,对 1 998年长江流域洪涝区进行地表洪涝特征分析 ,可以在TMI像元尺度 ,将洪涝区分类为不同等级。洪涝区分类结果与经过天 -地校验过的机载和星载SAR资料地表洪涝分类实况对比 ,TRMM/TMI低频微波通道微波极化比 1 0GHz的PR1 0和 1 9GHz的PR1 9的分类正确率不低于 75 %。

By using a radiative transfer model for simulation of microwave brightness temperatures over land surface, the effects of canopy and roughness on passive microwave soil moisture retrieval results have been analyzed. In order to reduce the influence of atmosphere, surface temperature, roughness and canopy, microwave polarization ratio of TRMM/TMI was employed and we got a good result when put the polarization ratio of TRMM/TMI into the use of surface flood area detection and classification. When practied our method over Dongting and Boyang lake area of China in the summer of 1998, the classification results of Radarsat SAR and L SAR surface flood area were used, and we got a Vol./Cal. over 75 0%. Low frequency channels of TRMM/TMI at 10GHz and 19GHz, were effectual in surface flood area detection and classification.