Spatial-Temporal Evolution And Driving Factors Of PM2.5 Concentration In Yangtze River Delta Based On Remote Sensing

With the rapid development of various regions in southeastern China in recent years,the smog incident has continued to erupt.Its main component,PM_2.5,can directly enter the lungs of the human body,causing cardiovascular and respiratory diseases,and increasing the mortality rate in various contaminated regions.Chinese mainland has started to establish PM_2.5 ground monitoring stations since 2013,but these monitoring stations are few in number and are mainly distributed in urban areas,which cannot achieve comprehensive monitoring on a large scale.Satellite remote sensing technology has the advantages of low cost,wide range,and few influencing factors.Studies have shown that satellite remote sensing aerosol optical thickness data（AOD）can be can be used to effectively monitor PM_2.5.This study uses satellite remote sensing AOD data to establish a fully covered retrieve model,taking the Yangtze River Delta region as an example to retrieve the PM_2.5 data in the region from 2013 to 2016,analyze the temporal and spatial variation characteristics of PM2.5 concentration during this period,and the related driving force mechanism.The MODIS AOD data was used in this study,but due to the serious data missing problem of its standard products,using them directly to retrieve PM_2.5 not only impairs the accuracy of the model,but also cannot obtain the fully covered PM_2.5 results.To this end,this study used a two-step fusing method,first divided into wet and dry seasons to establish a linear relationship between PM_2.5 and AOD,to fill in the missing AOD data.On this basis,using the ordinary Kriging interpolation method to interpolate AOD,and obtain the fully covered AOD data in the Yangtze River Delta region..Using the full coverage AOD data after filling,combined with the geographic and meteorological data in the Yangtze River Delta,and using the geographically weighted regression（GWR）model,retrieve the PM_2.5 concentration value with full coverage of the region.This study use the GWR Model to retrieve the full coverage of PM2.5 concentration value in the Yangtze River Delta in 2013-2016,and analyze them from time and space.It is found that the change trend of each month in different years is basically the same.The U-shaped change trend of"decrease first,then increase"with high concentration in January,February,November and December and low concentration from March to October is found.The pollution concentration basically belongs to the degree of light pollution from 2013 to 2016.In terms of interannual changes,the concentration showed an inverted U-shaped trend of"increase first and then decrease".In terms of spatial change,through box chart analysis,we found that more than half of the cities in the Yangtze River Delta were at the level of light pollution in 2013-2016,and in 2015,the pollution concentration of each city was at the level of light pollution PM2.5 and the difference of pollution is the smallest.Standard deviation ellipse analysis found that a The PM_2.5pollution is spreading to the northwest in the Yangtze River Delta.There are many factors affecting PM_2.5 pollution in the Yangtze River Delta.This study collected the GDP,GDP growth rate,added value of three industries,urbanization rate and other factors of each city from 2000 to 2016.For some missing data,useing the one-time exponential smoothing method to fill in,and obtained the data of continuous influencing factors in time.Using an Principal Component Analysis method to analyze the driving force of PM2.5 pollution in the Yangtze River Delta region.The result expressed that the GDP of the eastern coastal areas of the Yangtze River Delta is generally higher than that of the inland areas,but the GDP growth rate of the inland areas is higher than that of the coastal areas,and the urbanization rate of Anhui Province is significantly lower than that of other areas.Principal component analysis extracted three principal components,which respectively represent the contribution rate of production,natural economy driving and urbanization process.Corresponding to the analysis of driving factors,it puts forward suggestions on the prevention and control of PM2.5 pollution in the Yangtze River Delta region,adjusts the local industrial structure,uses clean energy,develops a green economy,and slows down the urbanization process.