Daytime Surface Urban Heat Island with Respect to Urban Morphology: A Case Study in Hangzhou, China

Surface urban heat island (SUHI) as indicated by the land surface temperature (LST) is primarily determined by the physical characteristics of ground surfaces. In high-density cities, the urban morphology, including building height and density, and especially the fractions of sunlit walls, roofs and ground surface during daytime also plays an important role in affecting the daytime spatial variation of LST. This paper investigates such influences from the city scale using the city of Hangzhou as an example. Remotely sensed data of Landsat TM images acquired on summer days in 2010 were used to retrieve LST. A LST gradient traversing the city center was selected with various urban building morphological characteristics across the gradient. Morphometric analyses were conducted based on high resolution 3D geodatabase, and critical parameters in the urban energy balance equation were calculated by developed spatial analysis modules. Regression models were built between LST and morphological parameters, which were further interpolated to the whole city. The study can shed light on the role building morphology plays in the formation of SUHI, as compared to the commonly studied land cover features.