Spatialandtemporaldistributionand Influencing Factors Of Aerosol Optical Depth Based On MODIS Data In Southwest China

With the rapid development of China's economy and urbanization,the carrying capacity of ecological environment is gradually declining and the haze phenomenon is frequent.It has a serious impact on human travel,physical health,environmental quality and so on,which makes the atmospheric environmental quality situation of concern.In recent years,most of the large and medium cities in China have air pollution phenomenon and aerosol has become the main factor of air pollution.The aerosol optical depth is a common parameter to measure aerosol content and distribution.Therefore,it is very important to explore the distribution of aerosol by satellite remote sensing technology.Based on the MODIS L1 B remote sensing image in 2004,2008,2012 and 2016,the Dark Dense Vegetation method was used to retrieve the aerosol optical depth of Southwest region.And validated the inversion results by the data provided from the AERONET global monitoring network,and the inversion results are analyzed from time and space scale respectively.Finally,combining with the traditional mathematical statistical analysis method and the gray correlational analysis method,the influencing factors are analyzed from the aspects of nature and human activities.The purpose of this paper is to make further research on changes,distribution and influencing factors of aerosols in the study area and to promote the harmonious development of the atmospheric environment.The main conclusions are as follows:(1)The results of MODIS remote sensing inversion are verified by AERONET observation data,and the results showed that the Dark Dense Vegetation method is basically consistent with the trend of ground-based remote sensing observation data.(2)From the point of view of temporal variation,between 2004 and 2016,the Southwest region in the AOD increased-decreased-decreased generally,and the AOD value was between 0.26-0.6.The seasonal variation is more obvious,the spring is higher than summer and autumn,and the trend in spring shows increased-decreasedincreased status.(3)From the point of view of spatial distribution,the spatial distribution of the AOD values in the Southwest region is significantly different,and the high values are concentrated in the northeast and the southwest is relatively low.The AOD values in Chongqing province are higher than the other three provinces among the four provinces.(4)From the point of view of the impact of factors,the vegetation factors and the AOD is significant correlation at the significant level of 0.01;Meteorological factors are not a single factor,but many factors have an impact.Analysis showed that the average wind speed,mean temperature,relative humidity and horizontal visibility have an effect on the distribution of aerosols.The average wind speed> relative humidity> horizontal pressure> horizontal visibility> average temperature,but the correlation degree is lower than 0.7;The main factors of human activity aresocial and economic development factors,fuel combustion,motor vehicle flow,industry and other factors;The social and economic development factors mainly use the gray relational analysis method to explore the degree of association between the social factors and the AOD.The selected factors are closely related to the AOD,and the correlation coefficients are above 0.5.