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.

Makalah ini cuba menghubungkait pulau haba bandar dengan keselesaan manusia di kawasan
Wilayah Kuala Lumpur/Lembah Klang. Berdasarkan TERRA/MODIS bagi kawasan Lembah
Klang untuk tahun 2008-2009 yang dibekalkan oleh Institut Sains Industri, Universiti Tokyo,
MODIS penerima permukaan Institut Teknologi Asia, Bangkok, dan suhu permukaan bumi
(LST) data telah diperolehi dan dipetakan bagi pelbagai jenis guna tanah. Kemudiannya dikira

keluasan keruangan dan lokasi Pulau Haba Bandar(UHI) bagi kawasan berkaitan. Data MODIS
bulanan dibahagikan kepada empat musim iaitu Monsun Timur laut (November ke March),
Monsun Barat daya (Mei ke September) dan dua musim antara monsun (masing-masing iaitu
April dan Oktober). Kira-kira 56 lokasi yang diketahui pikselnya di sekitar Lembah Klang
telah dipilih menerusi persampelan bersistematik bagi membina peta kontur GIS dengan
menggunakan perisian ArcGIS. Hasil awalan mendapati min LST tertinggi berlaku semasa
musim monsun Barat Daya iaitu 309° Kelvin pada waktu siang, manakala kawasan bandar yang
banyak dilitupan dengan kawasan taktelap air menunjukkan kecerunan UHI yang paling nyata.
Secara lazimnya, pulau haba bandar permukaan berlaku semasa waktu siang dan waktu malam
tetapi cenderung menjadi lebih kuat pada waktu siang, terutamanya semasa musim monsun
Timur laut. Persekitaran hangat dan panas yang berpunca daripada suhu yang tinggi dan beban
haba yang berlebihan akan menghasilkan UHI dan dengan itu mewujudkan persekitaran yang
tidak selesa. Pembentukan pulau sejuk bandar pada beberapa musim boleh dikaitkan dengan
kewujudan tompokan kawasan hijau di kawasan metropolitan. Mitigasi perlu dilaksanakan bagi
mengurangkan dan/atau menghalang daripada pembentukan pusat UHI yang baru di sekitar dan
di sekeliling kawasan kajian pada masa hadapan.