T639模式对2008年长江流域重大灾害性降水天气过程预报性能的检验分析

利用在国家气象中心业务运行的T639模式、常规观测资料以及NCEP分析资料(1°×1°),对2008年汛期(5-9月)发生在长江流域的重要降水天气过程进行了模拟和检验,结果表明:T639模式对一般性降水的雨区范围、位置及移动趋势都做出了较正确的预报,24 h小雨预报TS评分为56;对主要影响系统如高原槽、低空西南急流及西南涡和亚欧中高纬大尺度环流背景均有较准确的刻画;在各种物理量场检验中,反映暴雨动力结构的涡度场、散度场及全风速的模式预报性能稍差,反映水汽条件的比湿及水汽通量散度场预报效果较好。此工作对该模式的应用及进一步改进提供一些有意义的参考依据。

Validation of 2008 Heavy Rain Events over the Yangtze River Basin Forecast by T639 Model

By using T639 model, conventional observation data and NCEP reanalysis data (1°×1°), the model ability in predicting heavy rain events, together with the governing weather systems, over the Yangtze River Basin in 2008, is validated in the paper. The results showed that T639 model has made a correct prediction for the precipitation area, location and moving trends, the threat score of 24 h rainfall forecast is 56. The primary affecting systems such as the plateau trough, low level southwest jet, southwest vortex and Eurasia large scale circulation background in the high latitudes have obtained a more accurate portrayal. In the test field of various physical quantities, reflecting the heavy rain power structure, the model had a good prediction for the specific humidity and water vapor flux, but a bit weaker for the vorticity, divergence field and wind speed. The work will be helpful in better utilizing the model results in conventional weather prediction, as well as in providing valuable suggestions to further improvement of the model.