2018年12月贵阳机场一次冰冻雨雪天气成因分析

Cause Analysis of a Freezing Rain and Snow Weather in Guiyang Airport in December 2018

摘要: 本文利用贵阳机场地面观测资料、ECMWF ERA5再分析数据等，分析了2018年12月28~30日贵阳机场冻雨和降雪期间的环流特征和物理量场，结果表明：此次过程的发生与500 hPa中高纬阻塞高压、低纬地区南支槽和副热带锋区急流、低层西南低空急流等系统的相互配合有关；温度在800 hPa~700 hPa存在逆温层，逆温层温度是否大于0℃是决定降水相态的关键条件之一；冻雨期间水汽的辐合中心集中在中低层，而降雪期间高湿区向上发展的高度远高于冻雨；冻雨与降雪发生时近地面均表现为冷空气的下沉运动，降雪发生时的上升运动更强。

Abstract: Based on ground observation data of Guiyang Airport and ECMWF ERA5 reanalysis data, this paper analyses the circulation characteristics and physical quantity fields during freezing rain and snow-fall in Guiyang Airport from December 28 to 30, 2018. The results show that: the occurrence of this process is related to the cooperation of 500 hPa blocking high in middle and high latitude, south branch trough in low latitude region, subtropical front jet, southwest low-level jet and other sys-tems. There is an inversion layer between 800 hPa and 700 hPa, whether the temperature of the inversion layer is greater than 0˚C is one of the key conditions to determine the phase state of precipitation. During the freezing rain, the convergence center of water vapor is concentrated in the middle and lower layer, while during the snowfall the upward development height of the high humidity area is much higher than that of the freezing rain. When freezing rain and snowfall occur, the near ground shows the descending movement of cold air, and the ascending movement is stronger when snowfall occurs.