Research On The Influence Of Urban Block Morphology On The Surface Urban Heat Island

With the promotion of urbanization,the urban heat island(UHI)increase rapidly.The block morphology is a key issue of living environment,as cities are the main spatial capacity of working and living.However,there are research gaps about the relationship between building environment and UHI.Firstly,the relevant research lacks of the selection process before relevance research,so the difference of the degree of impact of the morphology indexes on UHI remains uncertain.Secondly,recent research revealed that the relationship between land surfacee temperature and environment factors is unstable in different locations,so it can be seen that most relevant research overlooked the spatial non-stationarity regarding to the relationship beteen UHI and morphology indexes.Thirdly,it is difficult to take advantage of the conclusion of the relevant research in the planning management,as the universal rules concluded may not meet the specific demand of the planning management.The data of this study includes Landsat 8 remote data,land use data and buiding data,and the study area consists of 589 zoning units in Wuhan city.Generaly,the research contents included discerning the UHI layout of Wuhan city,selecting the main morphology factors influencing UHI,the influence mechanism of morphology on UHI and planning techlology of reducing UHI by controlling morphology.This study found that UHI distribute in Wuhan widely,and the spatial layout of UHI is characterized as ‘U' style.Spacificly,the area with strongest UHI locates inside the first ring and alone the second ring and also gather around the third ring.There are 10 morphology indexes influence UHI intensily,including the percentage of industrial area,the percentage of commercial area,population density,the percentage of bare soil,NDVI,the percentage of grass,building density,the percentage of buit-up area and GSVF,among which building density and GSVF infulnece UHI the most,and all these indexes pass reliability test.Furthermore,some of the morphology indexes showe positive correlation with UHI,while other morphplogy indexes showe negative correlation.We suppose the morphology increase UHI in three ways,including urban function processing,radiation heat transfer by artificial buiding surface and heat gathered by dense buidings.While the morphology reduce UHI in two ways,including transpiration by plants and reducing shadow area by heigh buidings.We suppose that according to the threshold value of each morphology indexes,the posibility of the zoning unit becoming area with high UHI could be reduced.Furthermore,by the use of threshold value,we take Hualou district as an example and suppose several morphology optimizing strategies.Then,according to the differences of the influence of morphology indexes and environment factors on UHI,we divide all the zoning units into five different types.In each type of the zoning unit,the mechanizm of the UHI is different,so we suppose different planning strateges in different types of the zoning units according to the correlation between morphology indexes and UHI.In order to avoid the hot area influence each other,we suppose several specific planning strategies with regard to the area near arerial road and large water bodies,and large industrial area.