青海省春季沙尘暴特征及其异常气候背景分析

Analysis of Sandstorm Characteristics in Spring and Abnormal Weather Condition in Qinghai Province

主要分析了青海春季沙尘暴空间、时间演变特征及异常大气环流、海温对沙尘暴天气的影响。结果表明,青海沙尘暴高发区位于柴达木盆地、青海湖西北部、海南南部3地;20世纪60年代至本世纪初青海沙尘暴天气总体上是减少的。过程次数20世纪60年代青海北部较多、南部较少,70年代北部开始减少、南部回增,80年代开始整体减少,进入90年代后呈波动式减少趋势,且在80年代初大部分地区发生了一次由高向低的显著波动;青海沙尘暴天气与前期12～2月、同期3～5月500hPa高度场相关密切,尤其是同期3～5月,当乌拉尔山高压脊加强(减弱),蒙古低槽加深(减弱),冷空气活动频繁(减少),青海春季沙尘暴天气偏多(少),这种沙尘暴的时间变化趋势和异常天气形势与我国北方一致。青海春季沙尘暴与前期印度洋海温关系密切,当前期3～5月、6～8月印度洋中北部海温持续偏高(低),青海春季沙尘暴偏少(多)。

The spatial and temporal evolution characteristics of spring sandstorm in Qinghai province and the impact of abnormal circulation and sea temperature on sandstorm weather are analyzed. The results show that high frequency occurring sandstorm is in Chaidamu basin, northwest of Qinghai Lake and south of Qinghai province. From 1960s to the beginning of this century, the sandstorm weather has been generally decreasing, in 1960s sandstorm occurring in north of Qinghai province was much more than that in south, in 1970s it began to decrease in north and increase in south, and in 1980s it began to decrease generally, after 1990s, it presented a decreasing tendency with fluctuation, moreover, at the beginning of 1980s, a significant fluctuation from high to low frequency occurred in the most part of Qinghai province. The sandstorm weather in Qinghai province has a close relationship with 500 hPa height field in March -May and in previous period of December to February, especially in March-May, as the anticyclone ridge is getting increasing/decreasing and the Monggolia low trough is getting deepening/decreasing, cold air activity is getting more/less and sandstorm weather in spring occurs more/less. And this kind of temporal changing tendency of sandstorm and abnormal weather situation are consistent with that in northern China. The sandstorm in spring in Qinghai province is closely connected with sea temperature of India Ocean, when the sea temperature in north of India Ocean has been ascending/descending in previous period of March to August, the sandstorm weather in spring is getting less/more.