2023年元宵节湖北省一次重污染过程的气象成因分析

Meteorological Causes Analysis of a Severe Pollution Event in Hubei Province During the Lantern Festival in 2023

摘要:

选取2023年2月4—7日湖北省一次重污染过程为研究对象，利用常规气象观测资料、空气质量数据、ERA-5再分析资料及全球资料同化系统（GDAS）气象数据，分别从大尺度环流形势、大气动力和热力条件、局地气象要素变化、气团轨迹等进行分析。结果表明：此次过程共有6个城市达到重度污染，襄阳最先受到影响，荆州污染最重AQI为215。根据ρ（PM2.5）和地面天气形势发展，将过程分为三个阶段，“传输—本地累积加传输—消散”，分别对应第一阶段（污染形成期）为冷锋前输送型；第二阶段（污染累积持续期）中，在前期均压场、中期暖倒槽及中层（700 hPa）暖脊、低层（925 hPa）弱冷平流的共同作用下，使得湖北省较长时间处于小风或静风（<2 m/s）、风场辐合、高湿及逆温的静稳天气形势下，加上5日元宵节烟花排放，有利于本地污染物的持续累积，这是本次污染过程形成的主要成因；后期随着贝加尔湖（以下简称“贝湖”）冷高压发展加强，有弱冷空气渗透南下，地面为冷锋前输送型，再加上前中期长时间的本地污染累积，全省在7日污染达到最重。第三阶段（污染消散期）冷空气主体南下及锋面降水双重作用下，污染清除。襄阳PM2.5主要贡献区为河南南部，荆州PM2.5贡献区为本省城市随州，说明上游省内城市的传输作用不容忽视。

Abstract:

This study focuses on a severe pollution event in Hubei Province from February 4th to 7th, 2023. Conventional meteorological observation data, air quality data, ERA-5 reanalysis data, and Global Data Assimilation System (GDAS) meteorological data were utilized for analysis of synoptic circulation patterns, atmospheric dynamic and thermal conditions, local meteorological element variations, and air mass trajectories. Results indicate that during this event, six cities experienced severe pollution, with Xiangyang being the first affected and Jingzhou recording the highest pollution level with an AQI of 215. Based on the development of ρ (PM2.5) and surface weather situations, the process was divided into three stages: "transportation-accumulation and local transportation-dissipation." These stages correspond respectively to the formation stage (transportation before cold front), the accumulation and persistence stage (affected by synoptic situation, troughs, ridges, and fireworks emissions during the Lantern Festival), and the dissipation stage (affected by the southward intrusion of the Baikal cold high and front precipitation). Xiangyang's PM2.5 mainly originates from the southern part of Henan Province, while Jingzhou's PM2.5 mainly comes from the nearby city of Suizhou in Hubei Province, indicating the significant role of upstream cities within the province in pollutant transportation.