直接同化卫星辐射率资料在暴雨预报中的应用研究

Application Analysis of Direct Assimilation of Satellite Radiation Data on Heavy Rain Forecasting

为了考察T213-SSI同化全球ATOVS卫星辐射率微波资料在极端暴雨事件预报中的应用效果和能力,评估和分析卫星资料的应用对极端暴雨事件预报效果的影响,利用T213-SSI准业务同化系统,对2007年7月16—19日的川渝地区暴雨过程进行了模拟分析。此次暴雨过程致灾严重,同时是一次预报难度很大的、西风带系统调整下的转折性天气过程,非常值得研究。共开展了3组模拟试验:第一组试验只同化常规资料;第二组试验连续同化10天常规资料和卫星微波资料,第三组试验只同化一个时次、分别使用常规资料和不同波段微波资料(AMSUA和AMSUB)。结果表明:(1)仅同化一次卫星资料的暴雨预报不及连续同化10天卫星资料的效果好,说明卫星资料的使用需要有较长时间的累积才能产生较好效果;(2)卫星资料的长期使用可以改进大尺度环境场,使得暴雨天气过程的直接影响系统更接近实际;(3)AMSUA资料对温度场的调整有较大贡献,AMSUB资料对湿度场也有较为明显的影响。

To examine the ability of T213-SSI system on heavy rain forecasting, and to evaluate the application of satellite data on numerical prediction of heavy rain, this study used T213-SSI system to numerically simulate the heavy rainfall in Sichuan Basin during July 16 - 19, 2007. This process was transition process of precipitation under adjusting of westerlies system and caused severe damage. It is very difficult to be predicted and is very deserved to be researched. Three experiments are completed in this study using different data during different period. The first exper- iment only uses conventional observations; the second uses conventional observations and satellite microwave data during continuous 10 days. The last experiment uses conventional observation and satellite microwave data during 6 hours. The results show that the second experiment is better than the third. It means that satellite data need to be used for a long time to achieve a good ef- fect. In addition, employing of long time satellite data can improve large-scale environmental flow. Thus, the heavy rain process will be closer to the truth. In the end, AMSU-A and AMSUB data are very influential to the temperature and moisture fields respectively.