Based on the theory of rain - induced rain - induced cross - polarization discrimination ( xpd ) , the two - order small argument approximation for rain - induced xpd is developed , and a new model for predicting rain - induced xpd is proposed based on this approximation . the comparisons of this new model with other models and experiments data show that some improvement has been obtained with this model , especially for different polarizations 基于雨致交叉极化理论,提出了雨致交叉极化的二阶小变量近似方法以及新的雨致交叉极化预测模式,与其它模式和实验数据比较表明,该模式更能反映波的极化特征,较其它模式有一定的改进。