微波被动遥感陆面降水统计反演算式的比较

用TRMM 卫星上微波降水雷达PR、微波辐射计TM I 资料和河南省站点小时雨量资料, 对几种陆面降水的统计反演算式进行比较验证。通过资料匹配分析显示, 仅用地面站点小时雨量资料和微波亮温的关系难以建立较好的陆面反演降水算式。结合时空匹配较好的卫星资料, 建立了新的算式, 并且和其它算式比较验证。比较分析结果表明, 无论是估测能力还是误差方面, 新算式都比已有算式有改善; 对于较弱(< 5 mm/h ) 或较强(> 10 mm/h ) 的降雨, 新算式比已有的算式有明显的改进(10%～20% ) , 误差减少至少25%; 对中等雨量(5～10 mm/h ) 的估算效果也有一定改善, 但和原有算式一样估算能力较低。算式的建立和验证过程还表明: 将微波低频和高频通道组合起来, 可增加反演陆面降水的信息, 能明显提高对陆面降水的估测能力。

The Comparison of Microwave Statistical Algorithms for Precipitation Retrieval over Land

In this paper, the collocated data from the precipitation radar (PR), TMI on the Tropical Rainfall Measuring Mission satellite (TRMM) and the hourly rainfall measurements from surface stations in Henan province of China were used to analyze several statistical algorithms for precipitation retrieval over land. It is shown that it is hard to establish retrieval algorithm if we only use the regression relation between the hourly rainfall from stations and the microwave brightness temperatures. By using the temporal and spatial matching satellite data, several statistical algorithms have been obtained and then validated. The results show that the new algorithms can obviously improve the retrievals about 10-20% and reduce the error at least 25% for light (<5 mm/h ) and heavy (>10 mm/h) rainfall and yield same low retrieval precision for moderate rainfall (5~10 mm/h) in comparison with the statistical algorithms in the literature. In addition, the regression analysis results also show that precipitation retrieval over land can be improved to some extent by combining the low and high frequency radiometric channels.