宁夏多、少沙尘暴年4月平均环流特征的对比分析

对宁夏春季多、少沙尘暴年4月平均大气环流特征进行了对比分析。结果表明，宁夏春季多沙尘暴年，500hPa东半球极涡偏强，大气环流的经向度加大，我国北方高空纬向西风偏强；少沙尘暴年，则极涡弱，大气环流经向度减小，我国北方高空纬向西风偏弱。不仅如此，西太平洋副高北侧的位势高度距平在偏多年和偏少年也发生了截然相反的分布，说明宁夏乃至我国北方的沙尘暴天气的发生可能还与低纬大气环流有一定的联系。

Contrast Analysis of April General Circulation between More and Less Sandstorm Years in Ningxia

The characteristics of April mean general circulation between more and less sandstorm years in Ningxia are compared with each other. The results show that the intensity of the pole eddy at 500 hPa and the latitudinal west wind in North China are stronger in more sandstorm years and weaker in less sandstorm years. Also the longitudinal general circulation is stronger in more sandstorm years and weaker in less sandstorm years in April. Furthermore, the anomaly of geopotential height on the north side of West Pacific subtropical high in more sandstorm years is contrary to that of the less sandstorm years. It shows that the sandstorms in North China including Ningxia maybe have important relations to low\|latitude circulation.