The Temporal And Spatial Distribution Of PM_2.5 In Xi'an Based On Remote Sensing And LUR Model

In order to study the spatial and temporal distribution of haze in Xi'an,a data collection software was compiled with Python,and the aerosol optical thickness was retrieved by MODIS data.The regression equation of population,road network,catering and other data and PM_2.5concentration was constructed by using land use regression model?LUR?.The spatial and temporal distribution of PM_2.5 in Xi'an is studied from many aspects.The contents of the study are as follows:First of all,this study uses the PM2.5 hourly concentration data of the year of 2016 in Xi'an to analyze the spatial distribution difference between the urban and the suburban areas from the seasonal,monthly and daily changes.On the seasonal variation,the difference of PM_2.5concentration between the urban area and the control point showed as follows:summer,spring,autumn and winter,and the difference was the biggest in spring;On the monthly change,the concentration of PM2.5 in urban areas was basically higher than that in the suburbs.In December,the difference between them was the largest,and the difference in July was the smallest;At 0:00-10:00,the urban area was higher than the suburb,and the difference between the two was gradually smaller.At 11:00,the two were basically equal.At 20:00-23:00,the urban area was again higher than the suburb control point,and the difference became larger with time.Second,the aerosol optical depth?AOD?inversion was performed on the all of xian and urban parts of the city from May 2016 to July 2016 using the DDV and DB respectively.The inverse result of dark pixel method shows that the northeast corner of Xi'an is close to the Weinan area,the junction of Changan District and Lantian in the middle of Xi'an,the southwest of Huxian and the junction of Zhouzhi,and the southwest corner of Zhouzhi County,and the AOD is higher in the four regions.The inversion results of the deep blue algorithm show that the junction of Weiyang District and Gaoling District,the central part of Weiyang Distric,the border between Changan District and the Weiyang Distric,and the boundary between the Yanta District and Baqiao District are higher in AOD.Finally,the land use regression model?LUR?was used to analyze the spatial distribution of PM_2.5 in Xi'an during different seasons.The analysis results of the LUR show that the coefficients of the regression equations in different seasons are quite different,and they are expressed as summer>spring>autumn>winter.Using the regression equation,the spatial distribution of PM_2.5 in spring and summer was obtained.It is concluded that the concentration of PM_2.5 in the following regions is high:in spring,in the north of Chang'an district;at the junction of Chang'an district,Yanta district and Weiyang district;at the junction of Weiyang district,Baqiao district;The junction of the Yanliang district and Lintong district.In the summer,the concentration of PM_2.5.5 in urban areas was lower than that in the surrounding areas,and the PM_2.5 at the junction of Chang'an and Weiyang districts was significantly higher than that in other areas.