PCT-SI综合指数法反演陆面雨强

Refutation of Rainfall Density over Land by PCT-SI

利用TRMM微波成像仪(TMI)数据,采用极化订正温度及散射指数综合指数法(PCT-SI),反演赣州及周边地区2011年11月9日雨强,与同时期的PR星载雷达测雨资料进行对比分析,并用赣州地区47个地面站点的小时降雨对反演结果进行了验证。结果表明:采用K-均值法分类并判别降雨区,可以较好地确定降雨区的范围;TMI各通道亮温与对应时空匹配PR雨强的相关系数不同,利用低频组合拟合85 Hz通道亮温来求得大气散射指数,散射指数越大,雨强越大;PCT-SI综合指数法反演的降水中心的降水强度明显偏小,降水范围扩大,但其反演的雨强与PR反演的雨强基本一致,与地面实际雨量站点雨强相关系数为0.784,表明采用PCT-SI综合指数法反演陆面雨强是合理可信的。

Based on TRMM Microwave Imager（TMI） data, by polarization corrected temperature （PCT） and Scattering Index （SI） method, the rainfall density in and around Ganzhou on November 9, 2011 were retrieved. The retrieved rainfall density were analyzed by comparing with contemporaneous data of TRMM Precipitation Radar（PR） , and validated with the hour rainfall data of 47 stations in Ganzhou area. The results showed that using K-average method to classify each channel and distinguish precipitation area, can better ascertain the scope of the rainfall area. Correlation coefficient of each channel of TMI brightness temperatures and its corresponding Time-Space matching PR rainfall density were different, and low frequency combination fitting 85 Hz channel of brightness temperatures can calculate atmospheric scattering index, the bigger scattering index, the larger rainfall density. The rainfall density of rainfall center of PCT-SI method were retrieved results were smaller, but the rainfall range expanded. The rainfall density retrieved by PCT-SI was basically identical with that by PR, and its correlation coefficient with actual rainfall density of ground rainfall site was 0. 784. It proved that using PCT-SI to retrieve rainfall density was reasonable and credible.