宁夏盐池地区沙尘暴发生特征的统计分析

Statistical Analysis on Characteristics of Sandstorm Occurred in Yanchi of Ningxia

利用盐池气象站沙尘暴历史观测资料,从沙尘暴发生频次、灾害类型分型等几个方面进行了统计和研究。在对沙尘暴灾害强度聚类分析的基础上,对影响宁夏盐池地区的沙尘暴灾害进行了危害强度客观分类,并分析了该区沙尘暴历史变化和年、月、日的不同时间尺度变化。结果表明,宁夏沙尘暴年发生次数有减少的趋势,但发生1～2次特强沙尘暴的概率明显增多;沙尘暴强度与造成沙尘暴天气的天气系统、起沙源地和位置密切相关。沙尘暴分为西北气流型、锋线型、局地中小尺度天气型。特强沙尘暴的沙源地可能在腾格里沙漠、乌兰布和沙漠和巴丹吉林沙漠等更远的沙源地,强沙尘暴源于毛乌素沙地、乌兰布和沙漠、腾格里沙漠或巴丹吉林沙漠。弱至强沙尘暴可能与盐池南部荒漠化草场植被破坏和沙漠化有关,属就地起沙类型,不能造成特强沙尘暴灾害。

Using history observation data at Yanchi Weather Station from 1951 to 2000 this article statistically analyzed the occurring frequency and disaster type of sandstorm in Yanchi of Ningxia. With clustering analysis method the destroying intensity of sandstorms in the study region was graded. Moreover, the temporal changes of sandstorm on different time scales have been analyzed. The occurring days of sandstorm in a year fluctuated down gradually since middle 1970s, but the frequency of very strong sandstorm happened for 1～2 times in a year remarkably increased. The intensity of sandstorm is nearly correlated with the weather system, the position and source region of sandstorm. Sandstorms happened in the study region are classified into three types, they are the Northwest Current originating type, the air mass frontier meeting type and the local small-medium weather inducing type. Strong and extremely strong sandstorms possibly originate in the Mu Us Sandy Land, the Ulan Buh Desert and the Badain Jaran Desert; relatively weaker sandstorms maybe have relation with vegetation breakage and land desertification of the desert grassland in the south of Yanchi, and belong to the local type, so commonly cannot bring sand calamity.