The Relationship Between High-resolution 2D/3D Urban Form And The Land Surface Temperature

The unprecedented urbanization has altered the climate characteristics at local,regional,and global scales.The accompanied problems,such as the urban heat island(UHI)effect,are threatening our health and development.Information on the driving forces of the UHI effect is crucial for ameliorating the urban thermal environment.The urban form could affect the partitioning of urban energy balance and therefore modify the microclimate within urban areas.Although prior studies have investigated the relationships between urban form and land surface temperature(LST),most of them have relied on two-dimensional(2D)geophysical information,although the three-dimensional(3D)expansion is a crucial characteristic of urbanization.In addition,in the current literature,there have,as yet,been few attempts to investigate the variation of the relationships between urban forms and LST in different urban functional zones(UFZs),in spite of their significance on environmental implications and planning practices.Therefore,in this research,we investigated the relationship between 2D and 3D urban form and LST in Wuhan,a representative megacity in Central China,by adopting high-resolution remote sensing data and geographical spatial data.The urban form in this study consists of 2D landscape parameters,3D building morphological parameters,and UFZs.Our results indicate that: 1)The intensity of the UHI is more extreme in summer.There are several plate-shaped and axial heat centers.The Yangtze River,Han River,and urban lakes effectively suppress the close expansion of the UHI.In summer,The LST varies significantly with UFZs.The residential zone is the largest heat source,whereas the highest LST appears in commercial and industrial zones.Most of the heat sinks are water areas.2)The correlations between urban form and LST are generally consistent in spring,summer and autumn.The scattered distribution of high-rise buildings can facilitate the decrease of LST.Trees are the most influential factor in reducing LST.The fragmented and irregular distribution of grass/shrubs can also help reduce LST.Although sky view factor(SVF)is an important measure of 3D urban geometry,its influence on LST is complicated and context-dependent.In winter,the importance of 3D building morphology increases significantly,especially for SVF,which is positively correlated with LST.3)The relative contribution of 2D and 3D urban form parameters to LST varies among different UFZs.Generally,2D landscape outperforms 3D building patterns in LST modulation.In winter,the explanatory power of urban form decreases greatly.These findings can help us to understand the relationship between 3D urban morphology and the SUHI effect,and can provide insights for urban planners and designers on how to ameliorate the urban thermal environment via rational landscape design and urban management.