2010年2月辽宁地区冻雨天气诊断分析

应用常规天气资料，从天气、气候及大气物理量场等方面，对2010年2月下旬发生在辽宁地区历史罕见的冰冻雨雪灾害性天气发生发展的成因、主要特征以及造成严重灾害的主要原因进行诊断分析。结果表明：500 hPa低涡分裂的小槽东移是冻雨天气的环流背景；700 hPa源源不断的水汽输送和低层辐合作用是降水产生的基本条件。地面强冷空气是冻雨天气的触发机制；高层为冷的冰晶层，对流层中低层有温度t>0℃的暖的融化层，近地面1-2 km为气温t<0℃的冷层，同时地面达到 0℃以下，这种复杂的逆温层是冻雨产生的天气条件。高层暖平流是维持中空暖层结构的重要条件之一，对暖层的建立和破坏起较大作用，暖层消失冻雨天气也随之结束。中低空水汽饱和度、地面温度和中低空上升、下沉运动与冻雨的强度有密切关系。

Diagnostic analysis of freezing rain weather event in February of 2010 in Liaoning region

Based on the conventionally observational data,a freezing rain snow disaster on the last ten days of Feb- mary in 2010 in Liaoning region was diagnosed by weather and climatic conditions as well as atmospheric physical variable field, including forming reasons of generation and development,main features and key reason leading to serious disaster. The results show that a small trough spfitting from low vorticity at 500 hPa moves eastwards, which is the circulation background of fieezing rain weather. The unending water vapor transport and low level convergence at 700 hPa are the basic conditions of precipitation generation. The strong surface cold air is a trigger mechanism of freezing rain weather. Cold ice crystal layer in the upper level, warm melt layer in the middle and low levels that temperature is above 0 ~C, cold layer near the ground from the ground to 1-2 km upper level that temperature is below 0 ~C and the ground temperature is also below 0 ~C, these complex inversion temperature lay- ers are the weather conditions of freezing rain generation. Upper warm advection is one of the key conditions for retaining warm layer structure in the middle level, which is important to warm layer. If this warm layer disappears, the freezing rain process would end. The intensity of freezing rain has a close relation with water vapor saturation in the middle and low levels, surface temperature, ascending and descending movement in the middle and low levels.