| This paper firstly used the MODIS 3km AOD products from 2006 to 2017 to analyze the spatial distribution characteristics of aerosols,and analyzed the annual,seasonal and monthly variations of the Sichuan Basin.In addition,the spatial-temporal evolution characteristics of NO2,SO2,and O3 was analyzed by using OMI L2 G atmospheric products from 2005 to 2015 of the Sichuan Basin.Using WRF,SMOKE,and CMAQ models to simulate pollutant concentrations during periods of heavy pollution,different seasons,and high levels of ozone pollution,the spatial and temporal distribution of atmospheric pollution was analyzed in depth from three perspectives of topography,meteorological factors,and economic development.The causes of the conclusions were as follows:(1)The correlation between MODIS AOD products and CE318 AOD was 0.779,and the optimal correlation with PM2.5,PM10 reached 0.894,0.83.The spatial distribution of AOD in the Sichuan Basin was characterized by a medium-high basin and lowenvironmental circumference,with “Mianyang-Deyang-Chengdu-Meishan-Leshan” as the high value area.AOD showed “decrease-increase-decrease” changes from 2006 to 2017.The minimum value was reached in 2017.Seasonal changes were high in spring and winter,and summer and autumn were low.AOD was high in February to May,August and September,followed by January,and low in other months,with the most serious aerosol pollution in February.(2)Analysis of OMI data in the Sichuan Basin found that NO2 was the highest in Chengdu Plain,followed by northeastern Sichuan,and lowest in western Sichuan.NO2 experienced a “first rise and then fall” change from 2005 to 2015 and peaked in 2011 to 2013.NO2 first declined and then rised in January to December.The performance of SO2 was high in Ziyang City and Panzhihua City,and it was “up-down-up-down,and downminimum” from 2005 to 2015,of which pollution was severe in January,March,November,and December,followed by February and September.The O3 pollution area was distributed in the northeastern Sichuan,Chengdu Plain,and south Sichuan.From 2005 to 2015,O3 first increased,then decreased,and then rose again.O3 rised from November to April and down from May to October to the lowest value.(3)WRF had better simulation results of relative humidity and temperature,followed by wind speed.CMAQ had better simulation effects on NO2,PM10 and CO than SO2,PM2.5,and O3.The simulated values of pollutants at night were higher than the measured values.During the period of heavy pollution,particulate matter was the main pollutant in the Sichuan Basin,and Chengdu-Meishan-Leshan-Yibin-Zigong-Luzhou was the pollution zone.Seasonal distribution characteristics of different pollutants were different.NO2 was highest in spring,second in winter,lowest in summer.SO2 was highest in winter,followed by spring and autumn,and lowest in summer.PM2.5/10 was high in spring and winter,and low in summer and autumn.O3 was the highest in summer,followed by spring and lowest in autumn.CO had no obvious seasonal characteristics.During the period of heavy ozone pollution,all the pollutants in the Sichuan Basin were mainly distributed in spots,of which NO2 and PM2.5 were the most polluted areas.All pollutants were heavily polluted in Chengdu,followed by Leshan City.(4)The elevation of the Sichuan Basin was low in the middle and high in the surrounding area,which is not conducive to the diffusion of atmospheric pollutants,and was dominated by calm wind all year round.The average annual wind speed does not exceed 2.0 m/s.The seasonal wind speed was highest in summer,followed by spring,lowest in winter,the convergence areas mainly occur in the Neijiang-Zigong-Chongqing West area in each quarter.The height of the boundary layer was high in spring and summer and low in autumn and winter.In 2014,the emissions of NOx,PM10,PM2.5,CO,and VOC in Chengdu ranked first among the 21 cities and states,with 13.08,25.15,7.53,42.52,and 29.58 wt.respectively.The cities with the largest SO2 and NH3 emissions were Neijiang City(12.62wt),Liangshan Prefecture(9.53wt). |
PDF Full Text Request