The Relationship Between Spatial Form Of The Built Up Areas And Surface Heat Island

The surface urban heat island(SUHI)is the phenomenon that the surface temperature of urban is higher than the surface temperature of the suburban area,SUHI has a strong affect on the spatial distribution and behavior of climate,vegetation,hydrology,soil and biology in urban areas,even changes the structure,process and function of complex ecosystem of urban.For a long time,government have to take a series of measures to cope with the heat island effect from the urban space form,energy consumption control and so on.Therefore,it is of great significance to explore the relationship between the spatial form of the main built up area and the SUHI.Urbanization is the most direct power that driving the urban heat island,which is developing at an unprecedented rate.The primary cause of the surface heat island is the difference of the surface properties between urban and suburban area,which is caused by urbanization.From the perspective of the spatial form of the built up area,is mainly focused on the scale of the city,the external geometric shape of the built area and the spatial heterogeneity of the internal landscape structure.What's more,the boundaries and internal structural features are different for different scale of built up area.Thus,affect the surface city heat island.This paper takes the urban science,landscape ecology,spatial information science,climatology and other interdisciplinary as the theoretical basis.Using the MODIS Aqua MYD11A2 and Landsat 8 OLI data,through the remote sensing and GIS spatial analysis function.The built-up area is divided into three typical shapes: polygon,zonal,and radial.Based on descriptive statistics,comparative analysis and Analysis of Variance(ANOVA),our study explores the relationship between the spatial form of 2136 major built-up areas and the SUHI.The results are calculated by ArcGIS,ENVI and Fragstats software.The study is conducted from the perspective of geometric shape of the built up area,boundary characteristic and the internal structure.Results show that there are significantly difference for SUHI among different shapes,and decreased in the order of: polygon>zonal>radial.There is a significant relationship between the spatial morphological characteristics and the SUHI in different built up area scale of China.The average heat source,the maximum heat island temperature and the average heat island temperature increased in the order of the urban,small cities,medium cities and metropolitan areas.The corresponding indicators of the large and medium cities are higher than the mega-city in the zonal and radial built up area,and lower than the megacity in the radial built up area.Therefore,the study about SUHI should not only focus on mega-city,but also on the large and medium-sized city.The spatial characteristics of the urban area are result of the natural conditions,population,economy,service function,traffic conditions and government regulation of the urban area.The spatial characteristics of Chinese cities are the root causes of the differences in surface heat island.The relationship between the SUHI and the form complexity are very different for different form.When the urban spatial form is compact,regulating the spatial form has a great influence on the SUHI.When the urban spatial form is loose,the spatial shape control has only little effect on the SUHI.The SUHI of the zonal built up area is influenced by the length-width ratio and width,the best combination of the length-width ratio and width can have a lowest SUHI.Meanwhile,the proper control of the radial length and width can have a lowest SUHI for the radial.The SUHI of the built up area for the different forms are all influenced by its internal structure.The spatial heterogeneity of the impervious surface and the green space and the water body of the built up area are the main reasons caused the difference in SUHI.In the future,we should focus on optimizing the adjustment of the internal landscape structure,especially for large and medium-sized cities.By restricting the contiguous development of non-permeable surface,increase the proportion of vegetation and water body,improving the urban green space system.In this study,we proposal the study approach for the quantative division of the built up area spatial form and its influence on SUHI,reveal the relationship between the spatial form of the built-up area and the SUHI.It can provide a reference for the study of SUHI for different built up area scale,the plan of urban spatial morphology and its ecological optimization in China.