Abstract:

The orographic gravity wave drag (GWDO) parameterization scheme was introduced into WRF model firstly, and the different drag force sensitivity tests were designed to simulate the rainfall weather process occuring in China the period of Meiyu in the Yangtzi River and Huaihe River valleys turning to rainy season in North China from 00:00 UTC 3 July to 00:00 UTC 10 July 2007 by using the Weather Research and Forecast (WRF V3.2 version) model in this paper. Five groups of numerical experiments were designed, including one control test (Ctrl) without GWDO scheme and four groups of sensitive tests with the GWDO scheme into consideration but the drag force was different. The results show when the orographic gravity wave drag was applied into the WRF model, the circulation field, vapor transport belt and the vertical velocity field were improved efficiently, and the phenomenon of forecasted wind speed being a bit strong had been mitigated, the zonal wind deviation was redressed also in some degree, and the distribution and intensity of rainfall were improved well at the same time.With the simulation time going on, the stronger drag force introduced into WRF model was, the more signficant improvement on precipitation simulation was.

Key words: georgraphy, GWDO parameterization schemes, numerical experiment

摘要：

在WRF模式中引入地形重力波拖曳参数化方案（GWDO）,利用WRFV3.2中尺度模式对2007年7月3日00时至10日00时（世界时）发生在我国江淮梅雨季向华北雨季转换时段江淮与华北地区过渡区域的降水天气过程进行了不同重力波拖曳力作用下的敏感性试验，设计了5组数值试验：不考虑重力波拖曳的控制试验（Ctrl）及考虑重力波拖曳（GWDO）但在不同拖曳力作用下的4组敏感性试验。结果表明：GWDO方案的引入，有效地改善了模式对环流场、水汽输送带、垂直速度场的模拟，缓解了对风速预报偏强的现象，一定程度上纠正了模式模拟的西风偏差，对降水落区和强度也有较好的改善。随着模拟时次的推移，引入的拖曳力越强，对降水模拟的改善越显著。

关键词: 地形, GWDO参数化方案, 数值模拟