2015—2021年采暖季华北平原污染过程气象条件分析

华北平原是中国三大平原之一，特殊的地理位置、较多的重工业企业及采暖季相对更高的污染排放，导致采暖季极易出现大范围、长时间的污染过程，PM_2.5浓度明显高于周边区域。为了更好地了解天气系统及气象要素对采暖季华北平原城市空气质量的影响，以北纬32°—40°、东经114°—120°华北平原地区50个城市为研究对象，分析2015—2021年采暖季(11月至次年3月)气象条件对华北平原采暖季大范围重污染过程的影响。研究表明，华北平原发生重污染时，高空500 hPa环流曲率减小，环流相对更加平直，垂直方向逆温出现概率增大，水平及垂直方向更加静稳，污染物扩散能力减弱，近地面山东中南部、河南异常偏南风导致区域升温、增湿，有利于颗粒物吸湿增长及二次转化，河北中西部异常偏东至东北风，导致污染物受太行山山脉影响，在太行山东侧堆积，易在山前形成大范围污染过程，且与山东中南部、河南的异常偏南风形成区域风场辐合，污染物扩散条件不利。分析2021年1月20日至28日一次污染过程发现，污染发生期间华北平原高空大气环流相对平直，地面以均压场控制为主，多静风辐合，湿度持续较大，整体污染扩散条件不利，...

Analysis of meteorological conditions of the pollution process in the North China Plain during heating seasons from 2015 to 2021

As one of the three plains in China, the North China Plain is prone to large-scale and long-term pollution processes during the heating season due to its special geographical location, large number of heavy industry enterprises and higher pollution emissions in the season. The PM_2.5 concentration in the North China Plain is significantly higher than that in the surrounding areas during the heating season. To better understand the impact of weather system and meteorological elements on urban air quality in the North China Plain during the heating season, 50 cities in the North China Plain (32° to 40° N and 114° to 120° E) were selected as the research objects to analyze the impact of meteorological conditions on large-scale high pollution processes during the heating seasons from 2015 to 2021. Results show that when high pollution occurred in the North China Plain, the curvature of 500 hPa circulation decreases and is straighter. Due to the increased probability of temperature inversion, the horizontal and vertical directions were more stable, and the diffusion ability of pollutants was weakened. Near the surface, the abnormal southerly winds in Henan and central and southern Shandong led to regional warming and humidification, which was conducive to the growth of particle moisture absorption and secondary transformation. The abnormal easterly or northeasterly winds in central and western Hebei led to the accumulation of pollutants on the east side of Taihang Mountain, causing widespread pollution processes in the piedmont. They also formed wind convergence with the abnormal southerly winds in Henan and central and southern Shandong, diffusion conditions were unfavorable. The analysis of a pollution process from January 20, 2021 to January 28, 2021 shows that the upper air circulation in the North China Plain during the pollution was relatively straighter., the ground was mainly controlled by the pressure equalization field, and the main type was calm wind, and the humidity was continuously high. Unfavorable diffusion conditions were the main cause of this pollution process.