2008年初广西罕见低温雨雪冰冻天气的成因初探

利用广西1971~2000年地面气象资料记录和Micaps提供的常规地面、高空观测资料,对2008年1月12日~2月5日广西低温雨雪冰冻天气成因进行分析,结果表明,欧亚地区出现罕见、持续而稳定的大气环流异常形势,是造成这次低温雨雪冰冻天气的直接原因。这种大气环流异常形势主要表现在:(1)长时间持续的中高纬度欧亚地区的大气环流呈现西高东低分布,有利于强冷空气自西北方向沿河西走廊连续不断入侵中国;(2)青藏高原南缘的南支低压槽活跃,促使西南方向暖湿空气沿云贵高原向中国输送;(3)由于冷暖空气交汇区,暖湿空气在上,在对流层中低层形成稳定的逆温层,是广西北部地区大范围冻雨出现的主要原因。

Causality Analysis on a Severe Chilling Icy Rain and Snow Freezing Disaster Weather Event in early 2008 in Guangxi

Based on the surface observational data and sounding data,the causes of the rare chilling icy rain and snow freezing disasters event happened during January 12 to February 5 is analyzed.Results show that the rare lasting and stable abnormal circulation over Eurasian continent is the direct reason for the extreme event.The abnormality are mainly in the factors as follow.(1) The favorable circulation background is high-pressure in the west and low-pressure in the east which is benefit for the strong cold air moving to China.(2) the active tough is the motivation of the warm and moist air flowing from Tibetan Plateau to China.(3) the invert layer existence in the mid-low level is the main reason for large range icy rain occurrence.