结合源解析的大气污染相关气象要素特征分析

Analysis of Characteristics of Meteorological Elements Related to Air Pollution Based on Source Analysis

文章根据恩施州环保部门2015-2019年大气污染监测资料,结合对主要污染物PM2.5的源解析结果,分析了鄂西南山区空气污染分布特征。采用相关气象资料,对影响空气质量相关气象要素、边界层重要物理量特征进行统计特征分析及影响分析,结果表明:鄂西南山区的空气污染99.9%出现在冬半年不利天气条件下,主要是在不利气象条件下由于本地污染物不断积累而形成,区域传输影响仅占10%~20%。不同季节,汽车尾气与燃煤2类源均排在贡献率前两位,机动车尾气始终为贡献占比最高的排放源;统计污染天气相关各层主要气象要素特征,高空各层无论有无污染,影响区主导气流均相同,但随着空气污染出现或加重,各要素值呈现出规律性的变化。污染天气发生时,一般呈现出逆温和低混合层存在的特点,一般而言,污染越重,混合层高度越低;地面气象要素是大气污染扩散条件形成的重要因素,当地面较长时段受暖气团控制,天气条件静稳、温高、风弱、湿度条件适宜时,对空气污染形成有利,当霾伴随轻雾或大雾,有时伴有弱降水同时发生,相对湿度持续达到90%附近时,有利于近地层水汽和大气气溶胶污染物聚集,加速了污染颗粒物的湿增长,发生重污染的可能性大。该文研究成果的业务应用,对开展环境气象预报及服务提供了业务技术支撑,对其他类似山区提升生态文明气象保障服务能力具有一定参考价值。

According to the air pollution monitoring data of Enshi environmental protection department from 2015 to 2019,combined with the source analysis of major pollutant PM2.5, the distribution characteristics of air pollution in the mountainous area of southwest Hubei were analyzed. Using relevant meteorological data, the statistical characteristic analysis and influence analysis were done on the meteorological factors affecting air quality and the important physical quantity characteristics of boundary layer. The results showed that 99.9% of air pollution in the mountainous area of southwest Hubei appears under the unfavorable weather conditions in winter and half a year, mainly due to the accumulation of local pollutants under adverse weather conditions, with the regional transmission impact only accounting for 10%~20%. In different seasons, both automobile exhaust and coal combustion sources rank in the top two of the contribution rates. Motor vehicle exhaust always contributes the highest proportion of emission sources. Statistics on the characteristics of the main meteorological elements in each layer indicated that with or without pollution, the dominant airflow in the affected area is the same, but as air pollution appears or intensifies, the values of each element shows regular changes. When pollution happens, it generally presents the characteristics of the inversion and low mixing layers. In general, the more pollution, the lower the mixing layer height. Surface meteorological elements are important factors in the formation of air pollution diffusion conditions. When the ground is controlled by a heating mass for a long time, weather conditions are stable, warm, weak wind, humidity conditions are appropriate for air pollution;when haze is accompanied by fog, sometimes with weak precipitation and the relative humidity reaching around90%, it is beneficial to the accumulation of water vapor and atmospheric aerosol pollutants in the near horizon, which would accelerate the wet growth of particulate matter, and cause the heavy pollution. The application of this research can provide operational technical support for the development of environmental weather forecasting and services, and also has certain reference value for other similar mountain areas to enhance the capability of meteorological support service.