Seasonal urban heat islands and human comfortability in humid tropical areas

Abstract This paper attempts to relate urban heat island and human comfortability in the Greater Kuala Lumpur/Klang Valley region. Based on TERRA/MODIS data of Klang Valley area for the years 2008-2009, supplied by the Institute of Industrial Science, University of Tokyo and MODIS ground receiver of the Asian Institute of Technology, Bangkok, and land surface temperature (LST) was retrieved and mapped from various types of land uses. The spatial extent and the location of Urban Heat Islands (UHIs) were then calculated. The monthly MODIS data were divided into four seasonal periods i.e. Northeast Monsoon (November to March), Southwest Monsoon ((May to September) and two period of intermediate monsoons (April and October, respectively). About 56 locations of known pixels within the area of Klang Valley were selected through systematic sampling to develop GIS contour map using ArcGIS software. The preliminary result showed that the mean highest LST occurred during the Southwest Monsoon period i.e. 309o Kelvin in daytime, while area with high urban imperviousness coverage is the most notable UHI gradient. Surface urban heat islands are typically present during the day and night-time, but tend to be strongest during the day, especially during the Northeast monsoon period. Warm and hot environment due to high temperatures and excessive heat loads will create UHI and thus an uncomfortable environment. The establishment of urban cold island in some seasons can be associated with the occurrences of urban green patches within the metropolitan area. Mitigation must be taken in order to reduce and/or to sustain the establishment of the new UHI centres within and around the study area in future.