探空观测资料在西南暴雨中的同化试验

Assimilation Experiment of Sounding Data on the Rainfall in Southwest China

利用探空观测资料、T213资料、NCEP再分析资料以及GRAPES三维变分同化系统,研究不同探空观测资料预处理过程对同化结果和西南暴雨预报的影响。得到以下主要结论:(1)资料接收方式和取资料的截断时间不同会影响可用探空观测资料的站点个数。不同探空观测资料预处理过程,使同化系统得到的可用资料数量不同。(2)同化系统同化的探空资料数量越多,对背景场调整幅度越大。(3)利用GRAPES 3D-VAR系统同化探空观测资料能够改善背景场质量,随着同化的资料条数增多,对背景场的改善作用越明显。(4)降水预报结果表明,同化系统使用的资料条数越多,降水中心强度越接近实况。(5)2005年7月降水预报在西南地区的TS评分结果表明,国家气象中心使用的探空观测资料预处理程序优于成都区域中心的预处理程序。

Using sounding data,T213 forecast field and the NCEP reanalyzed data,the impact on different sounding data preprocessing system to assimilation results and southwestern numerical weather forecast are researched in GRAPES （ Global and Regional Assimilation and Prediction Enhanced System） 3 D - VAR assimilation system. The main conclusions are the fol- lowing ： i） Different receiving - data method and truncation time affect the number of conventional upper - air stations. The different sounding data preprocessing system leads to the different number of usable data item, and the upper - air stations and vertical levels provided by National Meteorological Center are more than that provided by Chengdu Region Center. ii） The more sounding data are used, the more adjustment extents are obvious, ii ） Assimilating sounding data can improve the quality of background field and the improvement effect is in direct proportion to the number of data used. iv） The results of rain prediction show that the more sounding data are assimilated, the more storm rainfall center value is close to the rainfall observation. v） The upper - air data preprocessing system from National Meteorological Center is superior to that of from Chengdu Region Center according to the TS score during July,2005 in southwest China.