| The improvement on the level of urbanization had brought about serious deterioration of air quality while improving people’s lives,and has attracted worldwide attention.Among them,the problem of urban air pollution with fine particulate matter(PM2.5)as the main air pollutant is the most prominent.Exploring how urban form affects the concentration of PM2.5 has become a hot topic today.This article aims to reveal the spatio-temporal differentiation characteristics of PM2.5pollution in Chinese cities and its relationship with the urban form.It combines satellite remote sensing data,geographic information technology,and spatial statistical analysis methods from the perspective of qualitative and quantitative analysis.Exploration has certain theoretical significance for understanding the relationship between urban form and air quality in China,as well as the causes of air pollution and governance measures,and is helpful for exploring environmentally friendly urbanization models and for more scientific urban spatial planning.Based on the research of PM2.5 pollution concentration in 344 cities in China from 1990 to 2015.First analyzed the characteristics of the spatial and temporal pattern of PM2.5 pollution.Quantitative analysis was conducted using Man-Kendall trend test and Sen’s Slope trend analysis,significance and fluctuation degree of the spatiotemporal variation trend of PM2.5 concentration;in addition,through the research methods of global spatial autocorrelation and local spatial autocorrelation,the agglomeration characteristics of PM2.5 spatial distribution are explored.Secondly,through statistical analysis,ordinary least squares regression and geographic weighted regression,the relationship between urban form and PM2.5 was studied.Finally,according to the GWR model,the spatial and temporal changes of the regression coefficients of each urban form index are analyzed,and the main laws of the influence of urban form on PM2.5 are obtained and corresponding decision-making suggestions are proposed.The main research conclusions are as follows:(1)On the time scale,the average annual PM2.5 pollution concentration from1990 to 2015 showed a general upward trend,and air pollution became more and more serious,butthe pollution concentration began to decline slowly after 2013.The monthly average change mainly shows a "U" shape,with light pollution in June-October and heavy pollution in March-May.(2)On the spatial scale,areas with severe PM2.5 pollution are mainly concentrated in areas such as North China,Central China,and Northwest China,and the areas of North China and Central China are greatly affected by human activities,and the degree of pollution continues to intensify;low-pollution areas are mainly concentrated In the Qinghai-Tibet Plateau region,northeast region and part of southwest region.PM2.5 pollution MK value and Sen Slope value showed a clear increasing trend from northwest to southeast,the difference between the regions was large,most pollution levels showed a significant upward trend,and the air pollution problem gradually became serious.(3)The law of spatial differentiation,PM2.5 pollution has obvious spatial autocorrelation characteristics,and continues to increase with time.Among them,North China has always been in a “high-high(H-H)” pollution hotspot area,while Northeast China and the Qinghai-Tibet Plateau have always been in a “low-low(L-L)”related cold spot area.(4)There is a significant correlation between urban form and PM2.5,and there is a significant spatial correlation.The impact of urban form on PM2.5 shows a decreasing order from north to south in spatial distribution,and it is easier in northern areas Affected.(5)In the index system of urban form,the increase in CA,AI,and per capita GDP has a positive effect on reducing PM2.5 pollution,while the higher the value of LPI,LSI,population density,and output value ratio of the secondary industry,The more serious PM2.5 pollution. |
