2015年上海地区空气质量状况及其与气象条件的关系

摘要

Using the air quality data from 2001 to 2015 and the meteorological data from 2014 to 2015,the air quality status,variation characteristics,and the corresponding meteorological factors in Shanghai in the context of strong El Nin~o atmospheric circulation in 2015 were analyzed.The results show that average annual concentrations of PM10and SO2in 2015 in Shanghai reach the lowest values during the recent 15 years,and that of NO2reaches its second lowest value.The air pollution situation in Shanghai has shifted from the traditional coal burning pollu-tants,such as sulfur,nitrogen,and PM10,to a compound pollution represented by PM2.5and photochemical pollu-tion represented by O3.Among the three first-tier cities,the excellent and good rate of air quality and average con-centrations of PM2.5and PM10in 2015 in Shanghai are all between those in Beijing and Guangzhou.The average annual concentrations of NO2and O3in Shanghai are the lowest,and that of SO2in Shanghai is the highest.The concentration of PM2.5in Shanghai in 2015 is higher than that in 2014.Compared with 2014,the concentration of PM2.5in Shanghai decreases significantly in spring and summer in 2015,and those in the easily-polluted seasons in-cluding January,February,October,November and December increase significantly.This is mainly due to the lower wind speed,fewer times of continuous small winds,stronger in the inversion intensity,more times of inverse tem-perature,and increasing intensity in the west wind transport in the easily-polluted seasons in 2015.Influenced by the strong El Nin~o event,a weaker cold air activity is formed due to the polar vortex contraction in the northern hemisphere,strengthening in the Eurasian Zonal Circulation,and weakening and eastward in the East Asia Trough in the pollution season.It provides an atmospheric circulation background for the bad air quality condition in 2015 in Shanghai.%利用2001-2015年上海地区空气质量监测资料和2014-2015年气象观测资料,详细分析了2015年(强厄尔尼诺年)大气环流背景下上海地区的空气质量状况及其变化特征,并分析了引起这种变化的气象因子的特征.结果表明:2015年上海地区PM10和SO2年平均浓度均达2001-2015年的最低值,NO2为次低值.上海地区空气污染已从S、N和PM10等传统煤烟型污染转为以PM2.5为代表的复合型污染和以O3为代表的光化学污染.在上海、广州和北京3个一线城市中,2015年上海市空气质量优良率、PM2.5和PM10年平均浓度均介于北京和广州市之间,上海市年平均NO2和O3浓度最低,SO2年平均浓度最高.2015年上海市PM2.5浓度较2014年出现上升趋势,其中春季和夏季PM2.5浓度明显下降,而易污染季节(1月、2月、10月、11月和12月)PM2.5浓度显著上升,主要是由于易污染季节平均风速减小,连续小风次数出现增多,逆温强度增强和逆温次数增多及西向输送增加.受强厄尔尼诺事件影响,易污染季节北半球极涡收缩,欧亚纬向环流增强和东亚大槽偏东偏弱,导致冷空气活动减弱,为2015年上海市空气质量变差提供了大气环流背景.