Study Of The Spatial-temporal Coupling Relationship Between Urban Heat Island And PM2.5 In Beijing

With the acceleration of urbanization,the urban environmental problems represented by air pollution and heat island effect have become increasingly prominent.Air pollutants not only negatively affect the health of residents,but also affect urban environment.Urban heat island not only affects the meteorological climate of the city,but also causes many diseases.Air pollution and urban heat island have become obstacles to residents'daily lives and constraints to urban development.Many studies have shown that urban heat island interacts with air pollution.Selecting PM_2.5 as the air quality index,studying the spatial-temporal coupling relationship between urban heat island and PM_2.5,and exploring the current situation of urban environmental problems are of great significance for improving the quality of life of residents and promoting the sustainable development of cities.This paper takes Beijing as the research area,using historical time data of air quality monitoring stations in 2015-2018,historical daily value data of national weather stations in 2015-2018 and temperature synthesis data of MODIS in 2015 as data sources.In this paper,the methods of statistical analysis,spatial analysis and correlation analysis were used to complete the spatial and temporal differentiation analysis of Beijing PM_2.5,the analysis of Beijing heat island effect and the spatial and temporal coupling analysis between urban heat island and PM_2.5.Finally,the following conclusions are drawn.:?1?The air pollution in Beijing is serious,but it is getting better year by year.There are two peaks in the daily variation of PM_2.5.5 concentration,which are located in the morning and evening peaks in Beijing.The concentration of PM2.5 is the highest in winter and the lowest in summer.The spatial variation of pollutant concentrations in different locations is relatively large,and high pollution is more likely to occur in areas with high human activities in the six districts of Beijing City and the southeast.?2?The heat island phenomenon in Beijing is relatively serious.The heat island effect in Beijing is the strongest in winter and the weakest in summer.There are many high-temperature centers in Beijing.The distribution of heat islands in the daytime is more consistent with the scope of the built-up area.The temperature in the central city is not necessarily higher than that in the surrounding area;while the night heat island is concentrated in the central city of Beijing,and the temperature in the central city is significantly higher than that in the surrounding area.?3?The urban heat island effect and PM_2.5 are coupled in both time and space.In terms of time coupling,there is a positive coupling between heat island effect and PM_2.5in the long-term cumulative perspective and a negative coupling between them in the short-term change perspective.In terms of spatial coupling,the temperature difference caused by heat island effect has a positive effect on PM2.5 concentration.The spatial coupling coordination degree in Beijing is quite different,and it is closely related to human activities.High temperature and high pollution are more likely to occur in areas where human activities are intensive.When discussing the spatial-temporal coupling between urban heat island and PM2.5,this paper analyses the temporal coupling from the perspectives of long-term accumulation and short-term change,and spatial coupling from the perspectives of spatial correlation and internal coupling coordination,which provides new ideas for further research and provides theoretical support for improving the living environment of residents in the later period.