Effect of Street Canyon Materials on the Urban Heat Island Phenomenon in Colombo

Abstract

An Urban heat island (UHI) is best visualized as a dome of stagnant warm air, over the heavily built-up areas of the city. These have been observed practically all over the world and Colombo, Sri Lanka is no exception. It is known that the replacement of natural surfaces and radiation trapped in ‘street form’ urban canyons is one of the primary drivers of this phenomenon. This study quantifies and compares the local warming effects caused by materials used in street canyons in the warm, humid climate of Colombo. A process of ascertaining street canyon materials by survey and simulation using a simple force restore model, the Surface Heat Island Model (SHIM) generate data for specific urban canyons and the respective local warming effects they cause. Aluminium cladding in buildings, showed the highest and the lowest intensity. The highest UHI intensity of 2.87oC was recorded In LCZ2-commercial. While, the lowest UHI intensity of 1.78 oC can be seen at LCZ3-sea front zone. Analyses highlight the predominant material occurrence and discuss implications for nocturnal UHI amelioration, in warm, humid, Colombo, Sri Lanka.