2022年秋末初冬贵州一次超强寒潮天气过程分析

Analysis of One Super Cold Wave Weather Process in Guizhou in the Late Autumn and Early Winter of 2022

【目的】2022年11月29日—12月1日贵州出现一次超强寒潮天气过程,为分析此次超强寒潮及其伴随的剧烈降温、大风和雪凝天气的成因。【方法】利用常规观测资料和NECP 1°×1°逐6 h再分析资料,运用天气学原理和天气动力学诊断分析方法。【结果】(1)此次超强寒潮天气过程是在中高纬地区配合有-48℃冷中心的冷涡低槽发展东移南压,引导强冷空气大举南下以及副高加强西伸北抬、高原上多小槽东移的背景下产生的。(2)前期热低压发展加深,贵州大部地区最高气温异常回升至27℃以上,850 hPa冷平流强盛且维持时间长,是造成降温幅度大、气温低、降温持续时间长的主要原因。冷平流强度低于-32×10-5℃·s^(-1)的区域与过程最低气温降幅超过16℃的区域基本一致。【结论】(1)强气压梯度和变压梯度是此次超强寒潮强风形成的主要原因,大风区ΔP3普遍超过3 hPa,ΔP24普遍超过10 hPa。ΔP3>3 hPa、ΔP24>10 hPa可作为寒潮大风预报指标。(2)西南低空急流维持加强,持续输送水汽并使贵州大气层结呈中间暖、上下冷的“三层”结构模式,850 hPa到地面温度T<0℃,为雪凝天气的发生发展提供了水汽和温度条件。当850 hPa温度T≤-2℃、地面温度T≤0℃时,降水相态由雨转冻雨或雨夹雪或雪。

A super strong cold wave weather process occurred in Guizhou from November 29 to December 1,2022.This article analyzes the causes of this event and its accompanying strong winds,snow condensation weather,and sharp drop in temperature,by using the conventional observation data and NECP 1°×1°occur reanalysis data,as well as the synoptic principles and synoptic dynamics diagnostic analysis methods.The results show that:(1)This super cold wave weather process occurred in the middle and high latitudes,accompanied by the development of a cold vortex trough with a-48℃cold center moving eastward and southward,which guided strong cold air to move southward,strengthening the subtropical high to extend westward and move northward,and multiple small troughs to shift eastward on the plateau.(2)In the early stage,the development of the thermal low-pressure system deepened,and the high temperature in most areas of Guizhou abnormally rebounded to above 27℃.The 850 hPa cold advection was strong and maintained for a long time,which was the main reason for the large cooling amplitude,low temperature,and long cooling duration.The regions with cold advection intensity below-32×10-5℃·s^(-1) were basically consistent with the regions where the minimum temperature drop during the process exceeded 16℃.(3)The strong pressure gradient and variable pressure gradient were the main reasons for the formation of the super strong cold wave and strong wind.In the windy areaΔP 3 generally exceeded 3 hPa,ΔP 24 generally exceeded 10 hPa.So,ΔP 3>3 hPa,ΔP 24>10 hPa area for the formation of the super strong cold wave and strong wind.(4)The southwest low-level jet maintained and strengthened,continuously transporting water vapor and forming a three-layer structure pattern of warm in the middle and cold in the upper and lower parts of the atmosphere in Guizhou.From 850 hPa to ground temperature T<0℃,the southwest low-level jet provided water vapor and temperature conditions for the occurrence and development of snow condensation weather.When 850 hPa T≤-2℃and ground T≤0℃,the precipitation phase changed from rain to freezing rain,sleet or snow.