Study On Influencing Factors And Spatio-Temporal Coupling Relationship Between PM_2.5 And Urbanization Of Zhongyuan Urban Agglomeration Based On Remote Sensing Data

In recent years,China’s urbanization has developed rapidly and the city changes with each passing day.With the continuous development of cities,there are also a series of problems such as unbalanced regional development and environmental pollution.Among them,the fog and haze weather,which has attracted much attention of the people,has become the main air pollution problem faced by most cities in China.Therefore,to study the correlation between urbanization level and PM_2.5 can provide effective suggestions for urban green sustainable development.Current research is mainly based on the traditional statistical information to construct urbanization indicators,so as to analyze the urbanization level and air quality indicators in the study area.However,due to some artificial errors in the traditional method using statistical information and the lack of data in some regions,the limit value of this direction is further studied.Remote sensing data have many advantages,such as wide range and easy access.DMSP/OLS night lighting images can effectively reflect urban characteristics by monitoring urban and rural lighting through the information of surface light sources,which has been gradually introduced into urban research.In order to eliminate the problem of image data saturation and incomparability,a method based on invariant target region correction is used to correct the night light data of DMSP/OLS.The average night light intensity index is constructed to reflect the urbanization level,and based on this,the spatial and temporal distribution characteristics of urbanization level and PM_2.5 concentration change in Zhongyuan urban agglomeration are analyzed.Combining GIS spatial analysis,geographic weighted regression analysis and coupling degree model,the spatial-temporal coupling relationship between PM_2.5 and urbanization in Zhongyuan urban agglomeration is studied in depth,and the influencing factors of PM_2.5 concentration by geographic detector are analyzed.The main conclusions of the study are as follows:（1）Based on the corrected DMSP/OLS night light data,this paper studies the urbanization of Zhongyuan urban agglomeration.The night light index has a good ability to evaluate the urbanization level,and can accurately reflect the spatial and temporal characteristics of the urbanization level change of Zhongyuan urban agglomeration.（2）There are great differences in urbanization level among cities in Zhongyuan urban agglomeration.In each year,the regions with higher urbanization level are located in the central and northern parts of Zhongyuan urban agglomeration,the northern part of Henan Province and the southern part of Hebei Province.The regions with lower urbanization level are located in the western,southern and eastern parts of Zhongyuan urban agglomeration,and mostly in the periphery of the urban agglomeration.The mean PM_2.5 concentration in Zhongyuan urban agglomeration is higher in the East and northeast,but lower in the northwest and southwest.It shows that the topography and vegetation coverage in the study area have a great influence on the spatial distribution of PM_2.5,and the high concentration areas are mainly concentrated in urban areas,and have a certain correlation with human activities.（3）Based on the extraction results of built-up areas in the study area,the PM_2.5 concentration changes in urban and non-urban areas were analyzed.From 1998 to 2013,the average concentration of PM_2.5 in urban areas was higher than that in non-urban areas.The fluctuation of PM_2.5 concentration in urban areas was consistent with that in Zhongyuan urban agglomeration in 16 years.（4）In the "peak area" of light intensity,most of them correspond to the "peak area" of PM_2.5 concentration,which indicates that human activities and urbanization have a greater impact on the spatial distribution of PM_2.5 concentration.The center of gravity of PM_2.5 concentration and the center of gravity of Zhongyuan urban agglomeration have a significant deviation.The longitude and latitude fluctuations of PM_2.5 concentration center of gravity are relatively large,and the longitude and latitude changes of urban gravity center are relatively stable.The moving direction of urban gravity center is correlated with the moving direction of PM_2.5 concentration gravity center in east-west direction and north-south direction.（5）Geographically weighted regression model can well reveal the relationship between PM_2.5 concentration and average night light index.The urbanization level represented by the average night light index in the western region has a good explanation for PM_2.5 in both city and county scales,and they are positively correlated.This shows that the development of urbanization in this region has a greater impact on the environment.The faster development of urbanization,the more serious the pollution to the environment,the higher the concentration of PM_2.5.（6）By building the coupling degree model,it is found that from 2003 to 2013,the coupling degree between PM_2.5 and urbanization level of Zhongyuan urban agglomeration shows an overall rising trend,with a slight decline,and remains at a high level.Cities with higher economic development level have higher coupling index and stronger interaction between PM_2.5 and urbanization level.（7）From 2003 to 2013,the built area and the per capita GDP of the whole city gradually became the main influencing factors of PM_2.5 concentration distribution in Zhongyuan urban agglomeration.In 2003,2008 and 2013,according to research cities each year by coupling type regions are divided into the use of geographical detector for impact factor detection,found the whole and each part of the research results have bigger difference,each year of each type is mostly light data represent the comprehensive urbanization level of explanatory power is the largest,the main factors that influence the area at each stage is different.Based on the night light data,this paper studies the urbanization level of Zhongyuan urban agglomeration,uses the geographic weighted regression model to quantitatively analyze the correlation between urbanization level and PM_2.5 concentration at the city and county scales,and constructs the coupling degree model to explore the coupling relationship between urbanization level of Zhongyuan urban agglomeration and PM_2.5 concentration,so as to provide reference basis for the sustainable development of the region.It will provide a case for introducing night light data into the field of ecological environment and other related research.