宁夏不同强度沙尘暴环流差异特征的对比分析

Analysis on Circulation Difference of Sandstorms with Different Intensities in Ningxia

利用宁夏1970—2003年沙尘暴过程资料及NCEP/NCAR(1971—2000年)逐日全球再分析资料,依据沙尘暴强度划分标准,对同期宁夏不同强度沙尘暴过程的环流差异特征进行合成对比诊断分析。结果表明:在不同环流背景下,特强、强及一般性沙尘暴过程频次明显不同,一脊一槽、西北路径冷空气是宁夏区域性特强和强沙尘暴过程最主要的环流和冷空气类型;而在基本相同的大尺度环流背景下,由于乌拉尔山高压脊、贝加尔湖冷低压、蒙古气旋及地面冷高压等的强度和位置不同,造成的沙尘暴强度有显著差异。同时,200 hPa高层西风急流的不同分布,与宁夏沙尘暴的强度也有密切关系。

The circulation difference feature of sandstorm with different intensities at the same period of Ningxia was diagnostically analyzed using the sandstorm process data of Ningxia in 1970--2003 and reanalyzed global daily data of NCEP/NCAR （1971--2000）, according to the sandstorm intensity standard. Results show that the frequencies of very severe, severe and general sandstorms have obvious different under different circulation backgrounds, one ridge and one trough pattern, northwest route cold air path is the most main circulation and cold air pattern in very severe and severe sandstorm process of Ningxia region; since the intensity and location of Ural high pressure ridge, Baikal cold low pressure, Mongolia cyclone and surface cold high pressure are different, the caused sandstorm intensities have significantly differences. At same time, the different distributions of upper level westerly jet on 200 hPa is closely related to the intensity of Ningxia sandstorm.