A Study On The Relationship Between Urbanization And PM_2.5 Concentration In Shanxi Province Based On Remote Sensing Data In Spatial And Temporal Evolution

With the continuous economic development and industrialization,urbanization in China has been developing rapidly.However,the rapid development in the short term is accompanied by the emergence of phenomena such as unbalanced development and ecological environment deterioration in the region,among which fine particulate matter(PM_2.5)pollution less than 2.5μm in diameter is the most typical.Shanxi Province is located in the eastern flank of the Loess Plateau in western North China.In the process of urbanization,the rapid growth of population and economy as well as the rapid expansion of urban scale has brought huge air pollution problems to the region,which has seriously affected people’s health and lifestyle.Therefore,an in-depth study of the relationship between urbanization and PM_2.5in Shanxi Province can provide a reference for regional air pollution prevention and green sustainable development.Most of the current studies use statistical information to construct urbanization indicators and then analyze the relationship between regional urbanization and PM_2.5,however,this method is susceptible to the lack of statistical data and human errors.Night-light remote sensing data has the unique property of detecting faint urban lights,which can well detect urban and rural lights,and has been gradually introduced into the research of urbanization-related fields.In this paper,from the spatial and temporal levels,firstly,we use the pre-processed nighttime light data to calculate the average nighttime light index and verify its validity in characterizing the urbanization level,and then analyze the spatial and temporal evolution of urbanization;secondly,we analyze the spatial and temporal changes of PM_2.5concentration in Shanxi Province based on the PM_2.5data from remote sensing inversion.On this basis,the relationship between urbanization and PM_2.5concentration in Shanxi Province is studied in depth by combining GIS spatial analysis,Pearson correlation analysis,and geographically weighted regression analysis,and the PM_2.5population exposure risk model is used to identify areas with high values of PM_2.5population exposure risk;finally,the geographic detector method is introduced to explore the influence of urbanization factors on PM_2.5concentration and the extent of the impact.The main findings of the study are as follows:（1）The average nighttime light index calculated by using the corrected nighttime light images can better reflect the urbanization level.In addition,the extraction results of urban built-up areas are more consistent with the distribution of actual built-up areas,which can visually reflect the spatial change of the city.（2）The urbanization in Shanxi Province varies greatly from region to region,with the core city and the rest of the cities being polarized,with Taiyuan always being a highly urbanized area and Xinzhou being relatively less urbanized.In addition,the urban built-up areas in Shanxi Province are expanding rapidly,and the overall spatial pattern of"scattering first,then gathering,and continuous development"is shown,in which Taiyuan gradually extends to Yuci District in the southeast direction,with the development trend of"co-location",while Datong and Yuncheng expand at a rate of The expansion rate of Datong and Yuncheng is"increasing first and then decreasing";the migration of urban center of gravity is somewhat repetitive,and the overall fluctuation changes along the north-south direction.（3）During 2000-2018,the average PM_2.5concentration in Shanxi Province showed a trend of increasing and then decreasing over time,with the overall PM_2.5pollution tilting northeast-southwest and a diffusion trend in the east-west direction,with the center of gravity mainly located in Jinzhong,showing a"southwest retreating and northeast advancing"trend;the PM_2.5concentration in the region Spatial differences are obvious,with the overall spatial pattern of"high in the south and low in the north",where the high value areas are mainly located in the southern cities of Yuncheng and Linfen.In addition,PM_2.5concentrations show significant spatial clustering characteristics,with high values clustering mainly in the central and southern regions and low values clustering mainly in the northwest region.（4）Urbanization and PM_2.5concentration in Shanxi Province are positively correlated,but the influence of urbanization on PM_2.5concentration differs among regions with different geographical locations,with Xinzhou in the northern region and Linfen in the southern region having a greater influence on PM_2.5concentration,Taiyuan having a moderate influence on urbanization on PM_2.5,and Datong being relatively weaker;The further detection of urbanization factors shows that there are differences in the influence of each factor on PM_2.5concentration,with the nighttime lighting index and greening coverage of built-up areas having a greater influence on PM_2.5concentration in the early stage,and the influence of per capita gross regional product on PM_2.5concentration gradually increasing in the later stage.