西北地区1次罕见的冬季寒潮天气分析

Analysis on A Rare Winter Cold Wave in Northwest Area

对2008年12月2～5日,西北地区的甘肃、青海、宁夏、陕西4省区出现的1次冬季寒潮爆发的成因和物理量特征进行了综合分析。结果表明,这次寒潮过程属于"横糟转竖型";乌山脊崩溃、横槽的转竖、地面冷高压的加强南下是引发寒潮爆发的原因;乌山脊的建立和崩溃、横槽的转竖是预报寒潮天气爆发的关键;散度、垂直速度、温度平流等物理量是寒潮天气预报中非常好的参考依据。

The causes and physical characteristics of the cold wave occurred in Northwest of Gansu,Qinghai,Ningxia,Shaanxi Provinces were analyzed comprehensively.The results showed that the type of the weather belonged to＂transversal trough changed to the vertical＂;the collapse of the ridge in the Ural Mountains,transversal trough changed to the vertical and the enhance of the cold high pressure of floor caused the outbreak of the cold wave;the keys to forecast the cold wave were the forming and collapse of the ridge in the Ural Mountains and the transversal trough changed to the vertical;physical quantity such as divergence,vertical velocity and thermal advection were the good reference to forecast the cold wave.