2016年12月江苏省两次连续污染过程气象条件对比分析

利用地面常规气象观测资料、NCEP（National Centers for Environmental Prediction）再分析资料、AQI（空气质量指数）、ρ（PM_2.5）、ρ（PM₁₀）等大气环境监测数据，对2016年12月江苏省连续出现的两次大范围大气污染过程进行了对比分析.结果表明:这两次连续污染天气过程可分为颗粒物积聚-清除-再积聚-彻底清除4个阶段，相应地，地面形势表现为均压场-低压倒槽-西路冷空气-东路冷空气.第1次污染天气形成和维持主要是长时间受均压场控制、近地层逆温和高相对湿度有利于颗粒物积聚；第2次污染天气形成和维持主要是因西路冷空气南下、上游重污染地区颗粒物随冷空气向江苏省输送.持续降水和持续2.0 m/s以上偏东风对大气中颗粒物有较明显的清除作用.淮北西部垂直、水平扩散条件差、降水清除时间短，导致该地区在全省污染等级最严重、持续时间最长.西路冷空气影响期间，各站颗粒物质量浓度转为快速上升，东部地区在偏西风持续49~58 h后空气质量改善为良，中西部地区无法得到有效改善；东路冷空气影响7~22 h后，中西部地区空气质量转为良，高压底部持续偏东风使全省颗粒物得到彻底清除，连续污染天气结束.研究显示，西路弱冷空气的输送会加剧江苏省的污染程度，持续较长时间的东路冷空气则可以改善江苏省的空气质量. 

Comparative Analysis of Meteorological Conditions in Two Continuous Air Pollution Processes in December 2016 in Jiangsu Province, China

By analyzing the conventional observation data, reanalysis data of NCEP, AQI data, the PM_2.5 and PM₁₀ concentration data, a comparative analysis of the causes and the regional differences of two continuous air pollution processes in Jiangsu province on 18^th-20^th December and 22^nd-23^rd December 2016 were discussed. The results show that the two continuous air pollution processes could be divided into four periods:pollutant accumulating, pollutant cleaning, pollutant re-accumulating and pollutant re-cleaning. The surface weather situations variations were uniform pressure field, low-pressure with an inverted trough, western cold air and eastern cold air. The sustained uniform pressure field, temperature inversion layer and surface high humidity were propitious to the accumulation of air pollutant, which causes the first pollution process. The second pollution process was caused by regional transportation pollutant from upwind under the background of the western cold air. The persistent precipitation and east wind (speed above 2.0 m/s) had obvious scavenging effects on the air pollutant. The weak diffusion condition and the short precipitation together led to the severe and long duration air pollution incident in the northwest Jiangsu province. During the western cold air affect period, the concentration of pollutant rapidly increased at first and decreased later. The air quality could be better with west wind lasting 49-58 hours at the eastern stations in Jiangsu. The air quality at central and western stations kept poor in the western cold air affect period, and improved better with east wind lasting 7-22 hours in the eastern cold air period. By that moment, the pollutant was effectively eliminated throughout Jiangsu due to sustained east wind from bottom of high pressure, and the heavy pollution processes ended. The study shows that the transportation of pollutant by weak western cold air could aggravate the heavy pollution in Jiangsu province, while the persistent eastern cold air could improve the air quality of Jiangsu.