四川盆地冬季气溶胶污染与气象条件的关系

Relationship between Aerosol Pollution and Meteorological Conditions in Winter in Sichuan Basin

利用2014~2019年冬季ERA5再分析资料、成都市PM_(2.5)和PM_(10)逐日浓度数据以及污染物(二氧化硫、氮氧化物、烟粉尘)年排放量数据,通过分析四川盆地近6 a气溶胶污染物的时间变化特征以及PM_(2.5)浓度与气象条件的相关性,探讨了气象条件对四川盆地气溶胶污染的影响。结果表明:近6 a四川盆地冬季气溶胶污染物浓度和严重、重度污染天数均呈波动下降趋势,污染物浓度年际变化与污染物年排放量存在一定差异。首要污染物以PM_(2.5)为主,PM_(2.5)浓度与青藏高原及其下游地区气象条件的关系密切,与对流层低层、中高层气象要素的相关性存在差异,其中与青藏高原及其以北和以东地区850~500 hPa气温呈显著正相关,尤其是与易出现逆温层的四川盆地850~750 hPa温度的相关性最强。当850 hPa东北风较弱且相对湿度偏高、700 hPa西风较强且湿度偏低、500 hPa高压偏强且西风偏弱时,PM_(2.5)浓度偏高;反之亦然。

Based on the ERA5 reanalysis data,the daily concentration data of PM_(2.5) and PM_(10) in Chengdu,and the inter-annual emissions data of pollutants(sulfur dioxide,nitrogen oxides,smoke and dust)in the winter from 2014 to 2019,by analyzing the main pollutants of aerosol pollution in the Sichuan Basin in recent 6 years and the correlation between PM_(2.5) concentration and meteorological conditions,the impact of meteorological conditions on aerosol pollution in Sichuan Basin was discussed.The results showed that the concentration of aerosol pollutants and the days of severe and heavy pollution in winter in Sichuan Basin in the past six years fluctuated and declined,and the inter-annual variation of pollutant concentration was different from the annual pollutant emissions.The main pollutant was PM_(2.5).The PM_(2.5) concentration was more closely related to the meteorological conditions of the Qinghai-Tibet Plateau and its lower reaches,and there were differences in the correlation between PM_(2.5) concentration and the meteorological elements in the lower and middle-high troposphere.The concentration of PM_(2.5) was significantly positively correlated with the temperature at 850~500 hPa in the Qinghai-Tibet Plateau and its north and east.Among them,it had the strongest correlation with the temperature at 850~750 hPa where an inversion layer was likely to appear over the Sichuan Basin.When the northeast wind at 850 hPa was weak and the relative humidity was high,the westerly wind was strong and the humidity was low at 700 hPa,the high pressure at 500 hPa was strong and the westerly wind was weak,the PM_(2.5) concentration was likely to be relatively high,and vice versa.