利用意大利国际理论物理中心区域气候-沙尘耦合模式RegCM4-Dust,模拟研究了东亚地区沙尘气溶胶直接效应对降水的影响。结果表明:(1)沙尘气溶胶导致东亚大部分地区降水减少,平均减幅为4.46%,尤其100°E以东大陆降水减少幅度更为显著;从季节来看,春、冬季降水减幅最显著,夏季最小。(2)从对总降水变化的贡献来看,春季对流性降水和非对流性降水变化相差不大,夏、秋季主要来自对流性降水减少,而冬季主要来自非对流性降水减少。(3)从分级降水来看,沙尘效应主要导致东亚大陆痕量降水日数增加,小、中、大雨的降水日数减少,而微雨和暴雨以上级别降水日数变化不大,但各季存在较大差异。(4)沙尘效应在对流层中低层产生的下沉运动和水汽减少是导致东亚大陆大部分地区降水减少的主要原因。
A regional climate model RegCM4 coupled with an on-line dust module is used to simulate the impacts of dust direct effects on the precipitation over East Asia in 20 years(from March 1990 to February 2010).Two sets of experiments are conducted,one with and one without the dust effects.The simulated results show that the precipitation is reduced over most parts of East Asian continent and the average decreased magnitude is 4.46%.The reduction is especially significant over the areas to east of 100°E.The maximum reduction appears both in spring and winter,the secondary maximum reduction in fall,and the minimum in summer.The most contribution to the total precipitation reduction is convective precipitation is summer and fall,which is contrast with the non-convective precipitation in winter.In spring,the convective precipitation change is almost same to the non-convective precipitation.Compared to the increased trace rain days by the dust effects over East Asian continent,the small,medium and large rain days are increased,while the slight and heavy rain days change little.At last,both the descending motion and the reduced water vapor in middle and lower troposphere lead to the decreased precipitation over most parts of East Asian continent.
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