Research On The Relationship Between Urban 3D Space And Thermal Environment

“Urbanization and global environmental change” are the key and difficult issues of concern in the 21 st century.However,with the accelerating industrialization and urbanization process,the ecological environment problems brought about by the spatial evolution of China's cities are very prominent.Especially in recent years,the emergence of urban heat island has seriously affected people's dream of pursuing a better and livable life.The current research mostly studies the relationship between urban expansion and thermal environment from the two-dimensional plane perspective,ignoring the quantitative influence of urban vertical extension and land intensity on the thermal environment,which affects the scientific understanding of urban development to some extent.In view of this,this paper comprehensively uses big data,RS,GIS and other technical methods,taking Zhengzhou City,Henan Province as an example,based on the definition of the main scope of the urban built-up area,constructing a 3D model of the city to analyze its temporal and spatial evolution,and then invert the surface temperature.The paper explores the interaction between urban 3D space and thermal environment,and proposes urban space optimization suggestions to alleviate thermal effects.The research results show that:(1)The result of urban built-up area identification showed: It is effective to identify built-up areas by building Density-Graph,NTL-Graph and POI&NTL-Graph models in LJ1-01 NTL,POI and POI&NTL fusion data.In terms of the expansion of built-up areas,the area of built-up areas in Zhengzhou increased by 6.17% annually from 2006 to 2018,and expanded eastward significantly.The growth rate can be divided into three stages: fast-slow-fast.(2)The analysis of urban 3D spatial and temporal evolution showed: The construction land occupied a large amount of cultivated land in 2006-2018,and the urban construction land increased to the east.The low-rise building land area decreased most significantly,and the middle and upper floors increased significantly.The overall volume has increased,the volume of low-rise buildings has decreased significantly,and the volume of high-rise buildings has increased significantly.The overall rate of floor area and building height has increased.On the skyline,the high-rise buildings in the east and south are more significant..(3)The analysis of spatial and temporal changes of urban thermal environment showed: The surface temperature obtained by inversion of Landsat 5 and Landsat 8 using atmospheric correction method has a high degree of fitting with the monitoring station data,which can approximately replace the monitoring station data.The internal temperature of the built-up area is lower than that of the non-built area.The average height is 1.75 °C,and the urban high temperature and above migrate to the east.In terms of time,the area above the high temperature in the city of Zhengzhou(high temperature,higher temperature,extremely high temperature)showed a trend of first strengthening and then weakening,but the extremely low temperature area was significantly reduced.The extremely high temperature area became significantly larger,and the urban thermal environment became more serious.(4)The relationship between urban 3D space and thermal environment showed: The urban 3D building center of gravity and urban temperature center of gravity both transfer eastward and the spatial matching degree reaches 0.894.The relationship between land type and surface temperature is significant.The degree of dispersion of the cluster will also affect the urban thermal environment.The relationship between urban 3D structural factors and thermal environment is significant.Among them,vegetation coverage is the cooling factor,but building density,imperviousness,and volumetric rate are heating factors.The 3D spatial factors of cities in different temperature ranges are closely related to the thermal environment: on the whole,the volume ratio can be increased appropriately in low building density areas,and should be reduced in high building density areas.In sub-functional zones,when the building density is less than 0.36,increasing the volume ratio will not cause temperature rise.When the building density is higher than 0.36,increasing the volume ratio will play a warming role.When the temperature of industrial land is lower than 0.28,the temperature rises sharply.On the whole,the relationship between building density and temperature is the strongest in commercial land.On the zoning,the building density increases significantly in the middle and low temperature zones,and the volume ratio increases significantly in the high temperature zones.