Spatial Heterogeneity Modeling And Spatial Scale Effect Of Urban Heat Island

The study of spatial heterogeneity of urban heat island is of great significance for understanding the spatial characteristics of urban heat islands.Previous studies on the spatial distribution of surface temperature did not take into account the spatial variability characteristics,so this thesis combined with spatial variability theory to further analyze the scale variation law of spatial heterogeneity of surface temperature.The purpose of this thesis is to establish a model of urban heat island spatial heterogeneity to analyze the characteristics of urban heat island spatial heterogeneity,and explore the spatial scale effect of urban heat island spatial heterogeneity.In this thesis,a Landsat 8 OLI imagery in June 16,2013 was the primary data source.First,the data sources are pre-processed and the surface temperature is retrieved by the radiation transfer equation method.Then the multi-scale characteristics of urban heat island spatial distribution are qualitatively analyzed by the variation index of temperature field.Next the nested structure model is establish based on the semi-variogram and the single structure model.At last,the spatial heterogeneity of urban heat island is quantitatively analyzed from the isotropic and anisotropic angles,and the spatial scale effect of urban heat island spatial heterogeneity is further analyzed.The results are as follows:1.The spatial distribution of land surface temperature shows non-uniformity,and the urban heat island effect is obvious.The intensity of the urban heat island decreases with the increases of spatial scale,and it is closely related to the land cover type.2.The spatial distribution characteristics of urban heat island are complex.On the spatial scale of 30 m,from the isotropic perspective,the spatial heterogeneity of urban heat island is determined by random factors and spatial structure.The spatial variation caused by random factors shows obvious nugget effect,but the spatial heterogeneity is still determined by spatial structure on the spatial scale of 30m;From the perspective of anisotropy,urban heat island shows obvious spatial heterogeneity in different directions.The spatial heterogeneity feature,in other words,there is a certain anisotropic feature.3.The spatial heterogeneity of urban heat island has obvious spatial scale effect.From the isotropic perspective,this scale effect change is mainly related to random factors.When the scale is smaller,the study of urban heat island spatial heterogeneity is vulnerable to random factors;when the scale is larger,the spatial heterogeneity of urban heat island is weak and unstable.From the anisotropy perspective,the spatial heterogeneity of urban heat island caused by the spatial structure is relatively stable,and influence of random factors on spatial heterogeneity of urban heat island is unstable.It is impossible to study the spatial heterogeneity of urban heat island in each direction with a unified spatial scale.