南京地区一次罕见锋前增温天气过程分析

2020年11月18日,我国南京地区出现了罕见的增温异常,利用常规气象资料和11月16日至20日ERA5逐小时1000 hPa至300 hPa的散度、位势高度、气温、水平风和垂直速度等再分析资料,根据高低空的天气系统的配置和槽脊移动的过程,结合散度、暖平流等天气学原理的相关知识分析冷锋过境前的基本环流形势,并主要结合热力学一级能量方程(温度倾向方程)对影响本次增温天气过程的因子进行了评估分析。结果表明:在这次增温中,温度平流和非绝热加热的贡献占主导作用,前者由于西南暖湿气流带来,后者与冷空气把原来占主导地位的暖气团迅速挤压到狭窄区域聚集增温有关;而垂直运动不是最显著的影响因子。

Analysis of a Rare Heating Process Before the Arrival of a Coldfront in Nanjing City

On November 18th,2020,there was a rare abnormal temperature increasing in Nanjing City.Based on this phenomenon,the conventional meteorological data and reanalysis data of ERA5 hourly data including divergence,geopotential,temperature,u-component of wind,v-component of wind and vertical velocity from November 16th to 20th were selected.According to the configuration of high and low altitude synoptic system and the movement of trough and ridge,combined with the relevant knowledge of divergence,warm advection and other synoptic principles,the basic circulation situation before the cold front transit was analyzed.The first energy equation of thermodynamics(temperature tendency equation)evaluates and analyzes the factors that affect the warming process.The results show that the contribution of warm advection and diabatic process are the dominant factors.The former is brought by southwest flow,and the latter is because the cold air rapidly compresses the previously dominant warm air mass into a narrow area.The subsidence is not the most significant factor.