基于卫星遥感和地面观测资料的汾渭平原一次空气污染过程分析

利用MODIS和CALIPSO卫星资料、地面空气质量监测资料和地面气象要素资料,分析了汾渭平原2018年11月26日—12月3日持续性的重空气污染过程的形成、特征及污染物的可能来源。结果表明:此次污染过程中汾渭平原以中度以上污染为主,首要污染物为PM2.5和PM10;11个代表城市在11月20日—12月7日期间AQI连续超过100的天数除吕梁外均达到或超过10 d,西安、咸阳和渭南污染持续天数和严重污染天数均最多;污染发生时,地面至3 km以内的AOD与总AOD柱的比值为81%,沙漠沙尘和污染沙尘气溶胶出现频率最高,分别为60.18%和25.72%;26日12时BT左右沙尘自西向东传输,受秦岭的阻挡作用,同时低层以偏东风或者静风为主,大气静稳,无明显冷空气活动和降水产生,静稳和高湿的天气持续以及偏东风的阻挡和传输使得该次过程以沙尘和霾混合为主。

Analysis on an air pollution event in Fenwei Plain based on satellite remote sensing and ground observation data

The formation, characteristics and possible sources of this persistent severe air pollution event from November 26 to December 3, 2018 in Fenwei Plain were analyzed based on the MODIS and CALIPSO satellite data, ground air quality monitoring data and surface meteorological element data. The results show that in the air pollution process the pollution grade of Fenwei Plain is above moderate level. PM2.5 and PM10 are the main pollutants. During the period from November 20 to December 7, the days which AQIs of 11 representative cities continuously exceed 100 are equal to or greater than 10 except Lvliang. The pollution duration and days of serious pollution in Xi"an, Xianyang and Weinan are the most. When the pollution occurs, the ratio of AOD from the ground to 3 km to total column AOD is 81 %. The frequency of desert dust (60.18 %) is the highest and is followed by polluted dust aerosols (25.72 %). At about 12 on the 26th, sand dust are transmitted from west to east, are blocked by the Qinling Mountains. At the same time, the lower level is dominated by easterly wind or calm wind and the atmosphere is calm and stable. There is no obvious cold air activity and precipitation. The persistence of calm and high humid weather and the obstruction and transmission of easterly wind make the event mix with dust and haze.