Spatial Variability Of Causative Factors Of Heat Island On Perspective Of Artificial Functional Blocks In Beijing-Tianjin-Hebei Agglomeration

With the advancement of urbanization,the heat island effect is increasingly affecting human beings.The past research of heat island effect factors lack of factor combination and spatial heterogeneity analysis of the status quo,based on the beijing-tianjin-hebei urban agglomeration in 13 cities as the research area,based on the POI data divided urban land function blocks,geographical probe method is used to research on urban agglomeration and the single city levels to explore the factors affecting heat island effect of space points to the opposite is mainly the following conclusions:(1)Different functional blocks of cities identified by POI data.Commercial service blocks of each city are mainly distributed in the central area of the city,and the distribution is relatively concentrated;Public management blocks and residential blocks are mainly distributed in and around commercial service blocks.The traffic block is mainly distributed in the periphery of the city.Industrial blocks are also scattered along the outskirts of cities.There are spatial differences in the land surface temperature of each block within the city,and the average land surface temperature of most commercial service blocks in the city is obviously higher.(2)The results of single factor effect show that vegetation is the largest factor affecting LST at the urban agglomeration level,but the effect degree of vegetation within each block is obviously different,and the effect degree of other functional blocks is the largest 45%.The proportion of impervious surface is a secondary factor affecting land surface temperature,and the influence of residential area is up to 21%.In a single city level on the spatial heterogeneity of the dominant factor for specific to different cities,NDVI to all urban function block surface temperature response is bigger,MNDWI inner city to the coastal cities or water distribution more Shang Fu,transportation and other function block surface temperature influence is bigger,the ISA Shang Fu in big cities,and pipe and other blocks significantly influence is relatively common.(3)The results of factor interaction show that the interaction between any two factors has a much greater impact on LST than a single factor,and the interaction degree and mode of factors are different in different land use function blocks,with nonlinear enhancement phenomenon.At the level of urban agglomeration,commercial block and residential block are similar,and the most important interaction factors are NDVI and ISA.Transportation block and public management block are similar,and the interaction between NDVI and population is the most prominent.In industrial block,there is little difference in the role of leading interaction factors.At the level of a single city,the interaction between NDVI and ISA,NDVI and night light index,NDVI and population,NDVI and MNDWI in the vast majority of cities are strong,and there are differences among different cities.The interaction between MNDWI and NDVI in each functional block of cities with more water bodies and coastal cities(Beijing,Tianjin,Tangshan,Qinhuangdao)was more significant.The interaction between NDVI and night light index,NDVI and population,and NDVI and ISA have a higher influence on LST in big cities such as Beijing,Tianjin,Shijiazhuang and Tangshan.