| Aerosols are liquid and solid systems suspended in the air.Fume,dust,fog,and haze that are common in life are all forms of aerosols.It is a necessary condition for the formation of haze.PM 2.5 is a particulate matter that can enter the lung with a diameter of less than 2.5 μm.This kind of air pollution has negative effects on people’s health.The acceleration of urbanization and industrialization has made China’s air pollution problem increasingly serious.Shanxi Province is the energy and heavy chemical base has been facing severe air pollution for a long time.In order to study the aerosol pollution in Shanxi Province,this study first used the Terra MODIS Aerosol Optical Depth（AOD）from 2003 to 2017 provided by NASA.The daily product data was preprocessed by Arc GIS and ENVI,and the monthly value data of Shanxi Province’s AOD was synthesized by the maximum value synthesis method.The seasonal average and annual average data were obtained by averaging the monthly value data.According to this,the spatial and temporal distribution characteristics of Shanxi Province’s AOD were analyzed.Then,through gray correlation analysis,several meteorological,natural,and socio-economic factors with high correlation with AOD were identified,and the relationship between each impact factor and AOD was discussed.The specific impact factors are:meteorological factors include precipitation,average temperature and relative humidity,Natural factors include NDVI and altitude,human activity factors include number of household registration at the end of the year,SO 2 emissions and corn planting area.Then through correlation and regression analysis between the measured PM 2.5 data and the AOD value,a MAOD-PM 2.5 concentration prediction model was established to provide a scientific basis for the prediction and prediction of air pollution in Shanxi Province.The results showed that:In terms of interannual variation,the year average of AOD in Shanxi Province from 2003 to 2017 changed between 0.62 and 0.87,showing a trend of declining fluctuations,and the annual average change rate was-6.5%.On seasonal changes,nearly 15 The AOD value of Shanxi Province in summer was generally summer（0.96）> spring（0.81）> autumn（0.71）> winter（0.39）.In the past 15 years,the AOD showed a downward trend with a decline of 15.6%;the summer AOD also generally showed The downward trend,the largest decline in the four seasons,fell by 23.3%;autumn AOD generally shows an upward trend,the increase is second only to winter;winter has the largest rate of change in the past 15 years,and shows an increasing trend,a total increase of 73.6 %.In terms of spatial distribution,the annual average AOD content generally shows a pattern of high in the southwest and low in the north,and the central basin area is higher than the surrounding mountainous areas.The 15-year average AOD of the whole region is about 0.65;from the AOD value of each municipality,Yuncheng（1.29）> Linfen（1.23）> Taiyuan and Jinzhong（0.91）> Lu Liang（0.89）> Jincheng（0.85）> Xinzhou（0.73）> Shuozhou（0.50）> Datong（0.47）.The range of high-value areas in summer is the largest It is followed by autumn.In winter,except for the Yuncheng Basin and the surrounding sporadic areas,the AOD values of the remaining areas are lower than 0.2.The statistical analysis of meteorological factors showed that AOD had negative correlation with annual precipitation,and precipitation had a scouring effect on aerosol particles.It had a significant positive correlation with temperature and relative humidity,and was conducive to the growth of moisture absorption of aerosol particles,which was the main reason for the change of seasonal AOD.The social and economic factors and natural factors especially topographic is the main reasons for the emission and diffusion of aerosol particles.The unique topography of Shanxi causes uneven distribution of population,industrial enterprises and planting industries,concentrating on graben basin,producing more pollutants from production and discharge,and at the same time,the vegetation coverage in the central basin is lower than that in the mountainous areas on both sides.The purification capacity is weak,and affected by the topography,the pollutants in the basin are not easy to spread due to the influence of convergent airflow.The AOD after vertical correction has a significant correlation with the PM2.5 concentration after humidity correction.Take the AOD value after vertical correction as the independent variable and PM2.5 after humidity correction as the dependent variable.The results showed that the logarithmic function has the best prediction effect,and the model test accuracy is 86.2%. |
