沙尘暴过程中沙尘气溶胶对气象场的影响

Influence of the Dust Aerosols on Meteorological Fields during Dust Storm

沙尘暴是干旱区常见的天气现象,沙尘暴天气过程中,边界层内气象要素发生剧烈的变化。利用WRF/Chem模式结合Shao 2004的参数化方案,模拟了发生在2010年4月24—26日的一次沙尘天气过程,通过控制沙尘气溶胶是否排放到大气中,对比分析沙尘暴过程中沙尘气溶胶对边界层中气象要素的影响。结果发现,在沙尘暴过程中,夜间在沙尘层以下,沙尘气溶胶具有加热大气的作用,使得温度升高,最大值约1.8 K,这种"保温"作用还与地表反照率有关,反照率越大"保温"作用越强;而在沙尘气溶胶层内的中上部具有降温的作用,温度降低,最大值约3 K。夜间沙尘气溶胶能够抬升边界层高度,最大达1000 m;白天则降低,可降低700 m;沙尘气溶胶导致水平风速增大约1.0 m·s-1,使垂直风速在沙尘层下增大,在沙尘层以上减小。

Dust storm is a normal seen weather phenomenon occuring in the dry-land. During the dust storm process,the key factors of boundary layer will witness a dramatically change. By using the combination of WRF/Chem modelling and parametric scheme given by Y. Shao in 2004,simulated a dust weather process happened on24—26 April 2010. By controlling whether the dust aerosol is emitted into the atmosphere,compared and analyzed the effect of boundary layer atmospheric factors during the dust storm process. We found that in the night under the dust layer,the dust aerosol has the effection of heating the atmosphere,the maximum value is 1. 8 K.This ＂heating ＂effect is related to the surface albedo also ： The larger of the albedo the stronger of the ＂heating ＂effect. In the middle-up layer the dust aerosol have a ＂cooling ＂effect,the maximum of temperature decreased value is 3 K. Dust aerosol can raise the boundary layer in the night,1000 meters to the maximum,opposite effect during the day time is approximate to 700 meters. Dust aerosols results in the horizontal wind speed up,about1. 0 m ·s-1. Dust aerosol can also increase the vertical wind speed blowdust aerosols layer,but decrease above the dust layer.