山西北部一次罕见的秋季连阴雨诊断分析

对2010年秋季山西北部一次罕见连阴雨过程的环流形势、物理量场等进行了分析,结果表明,连阴雨期间,亚欧上空大型环流相对稳定,乌拉尔山附近维持一稳定的阻塞高压,西太平洋副高异常偏强,亚洲中纬度多短波槽东移,700hpa、850hpa切变线频频建立,由于西太平洋副热带高压异常偏北偏西,其外围形成的高低空急流把充足的水汽输送到山西;当乌山有阻高建立时,北方冷空气沿脊前下滑,在巴湖形成切断低压,在贝湖形成低涡;贝湖底部分裂小槽南下,冷暖空气在山西北部长时间交汇,从而形成了山西北部长时间的连阴雨天气。当阻高减弱崩溃,巴湖到新疆有高压脊建立,副热带高压东移南退,山西北部上空转为西北气流控制,连阴雨天气结束。

Analysis of a Rare Continuous Autumn Rain in Northern Shanxi Province

The circulation process and physical features of a rare continuous autumn rain occurring in northern Shanxi province was analyzed in this paper.During this period,the large-scale circulation over Eurasia was relatively stable,a stable blocking anticyclone maintained nearby the Ural Mountains,the subtropical high pressure of the west Pacific was extraordinary strong,the short-wave trough was continuously split up to move toward east in mid-latitudes of Asian,700 and 850 hpa shear lines were established frequently.Because the subtropical high pressure of the west Pacific exceptionally inclined to north west,the peripheral high and low altitude jet stream transferred sufficient water-vapor to Shanxi.When Ural blocking high established,the north cold air slided before the keel,the low vortexes were formed in the Lake Baikal,and the small splitting trouph at its bottom shifted down to south,the cold and warm airs convergeed formed the long time continuous rain weather in north Shanxi.When the blocking high weakened,the high-pressure ridge shifted from the Lake Baikal to Xinjiang,the subtropical high-pressure moved southeast.The sky was controlled by northwest gas flow,and the continuous rain weather ended.