天山地形对新疆大风和降温天气作用的数值模拟研究

Numerical simulating research upon Tianshan's orographic function on gale and cold wave in Xinjiang

2009年5月24日夜间～26日夜间,新疆地区自西向东出现了明显的降水、大风、降温天气过程。为研究此次天气过程中天山地形的作用,文中用WRFV3.1模式对其进行了数值模拟,并通过改变天山山脉的地形高度设计了一组敏感性试验,分析了天山地形对此次强天气过程中大风和降温的影响。结果表明,天山山脉地形对准格尔盆地西北部直至天山山脉北侧的气流有明显的阻挡与减缓作用,对三十里风区、百里风区、汗腾格里峰北坡强风带的形成有直接而重要的作用;地形高度越高,产生垂直运动的地形抬升机制越强,地形强迫抬升作用产生的垂直上升运动越剧烈;天山山脉明显地减轻了寒潮天气过程中南疆塔里木盆地的降温幅度,对准格尔盆地北部的寒潮降温幅度也有一定的减缓作用,对塔里木盆地的"保温"作用较准格尔盆地明显。

A rainstorm accompanied by gale and cold wave occurred from the night of 24th till the night of 26th, May 2009 in Xinjiang. To learn the orographic function of Tianshan mountain upon this weather process, the au- thors numerically simulated it by WRFV3. 1 and then designed a set of terrain sensitive experiments through changing the orographic height of Tianshan Mountain. It was found that Tianshan Mountain plays a great part not only in obstructing and retarding the air stream range form the northwest part of Zhunger Basin to the north slope of Tianshan Mountain, but also in forming the gale band in 30 - Miles - wind region and 1 - hundred - miles - wind Region as well as the north slope of Hantengeli peak. The higher the orographic height of the mountain is, the stronger the forcing uplifting function it possess, and the more fierce vertical rising movement it would cause. Furthermore, Tianshan Mountain significantly alleviates the extent of cooling down in Tanlimu Basin and Zhunger Basin. while that in the former is much more obvious than that in the latter.