一次爆发性气旋引发的罕见暴风雪过程分析

冬季温带气旋强烈的发展会带来大范围严重的暴风雪天气。针对2007年3月3?5日一次气旋爆发性发展所造成的暴雪、大风和低能见度给辽宁省的交通，特别是航空带来的巨大影响，从大尺度环流背景、气旋移动路径和强度、水汽条件、冷暖空气活动及多种物理量场，对这次气旋的强烈发展及其相关联的垂直环流进行了动力学和热力学的诊断分析。结果表明，大气的强斜压性和其所伴随的冷、暖平流是气旋爆发性发展的主要原因；高位势涡度的下传促进了气旋的强烈发展；气旋中心附近最强的上升运动区基本上是上下垂直的；高、低空急流及相关的高、低空散度场和垂直运动构成了气旋所伴随的强大次级环流；沈阳地区强暴风雪的产生与气旋的强烈发展、偏南风低空急流的水汽输送及气旋内部垂直运动的强弱等密切相关。

Analysis on an Unusual Snowstorm Event Caused by Explosive Cyclone

A snowstorm event caused by explosive cyclone happened in Liaoning Province in March 3-5, 2007. The cyclone caused heavy snow, strong winds and low visibility, which had large influences onthetraffic, particularly on aviation. The authors analyze the process fromthe large-scale circulation, mobile path and intensity of the cyclone, moisture conditions, cold and warm air, etc. The results show that strong baroclinic wave is the main reason for the development of the explosive cyclone, and that high potential vorticity in the stratosphere promote the development, too. High-and low-level jets, divergence field, vertical movement constitute a strong secondary circulation. The snowstorm in Shenyang is closely related to the movement of cyclones path, water vapor transport and the degree of vertical movement.