2014—2016年开封市空气污染特征及重污染过程气象成因分析

利用2014-2016年高空、地面气象资料和大气环境监测资料,分析了开封市空气质量特征及10次连续性重度污染过程天气形势。结果表明:2014-2016年,开封市空气质量整体呈转好趋势,优良率由53%增加到67%,污染时数由47%下降至33%,轻度污染和中度污染时数下降明显;重污染日主要出现在1月、11月和12月,其中1月出现重污染日和连续性重污染过程次数最多;3年内共出现连续性重污染过程23次,最长持续日数达6 d;开封市重污染天气主要受PM2.5和PM10浓度变化影响,PM2.5和PM10浓度具有明显的季和日变化特征,平均浓度最高值主要出现在秋冬季和09时。重污染过程期间的500 hPa形势中,平直纬向环流型出现次数最多,占总次数的63%;其次为低槽型,出现次数占21%;西北气流型出现次数最少,占16%。地面气压场形势主要分为4类:1)高压前部型,出现重污染次数最多,占总次数的55%;2)均压场型,出现次数占25%;3)低压带型占16%;4)高压后部型出现次数最少,仅占4%。当上游地区有较严重污染时,本地污染物浓度将快速升高,区域传输作用明显。

Analysis on Air Pollution Characteristics and Meteorological Causes of Heavy Pollution Events in Kaifeng from 2014 to 2016

Based on conventional meteorological data and air quality data from 2014 to 2016, the air pollution characteristics and synoptic situations of 10 continuous heavy pollution weather processes in Kaifeng were analyzed. The results showed that the air quality of Kaifeng is in an improving trend during 20142016. The rate of good air quality increases from 53% to 67%, and the hours of pollution decreases from 47% to 33%, with light and moderate pollution significantly reduced. Heavy pollution events occurred mainly in January, November and December, of which the heavy pollution days and continuous events were most frequently found in January, 23 times in 20142016 and the longest duration a time was 6 days. In terms of the pollution impact factor, PM2.5 and PM10 are the main players generally, which have obvious seasonal and diurnal variation characteristics. The maximum values of averaged PM2.5 and PM10 concentrations are mainly found in autumn and winter, and at 09:00 of the pollution days. In the 500 hPa situation during heavy pollution processes, the parallel zonal circulation pattern appears most frequently, accounting for about 63% of the total number of times, followed by the trough pattern with 21% and the northwest airflow pattern with 16%.The pressure field situation on surface can be divided into four categories mainly: 1high pressure front type, with the most heavy pollution occurring, accounting for 55% of the total times; 2uniform pressure field type, with the occurrence frequency accounting for 25%; 3low pressure belt type accounting for 16%; 4high pressure posterior type, with the least occurrence percentage, only 4%. When there is serious pollution in the upstream area, the local pollutant concentration increases rapidly, indicating that the regional transport effect is obvious.