Effects of urban heat island on vertical atmospheric structure in urban areas of Thailand

Abstract

This study focuses on urban heat island (UHI) effect and the effects of UHI on the vertical atmospheric structure in urban areas namely Chiang Mai, Bangkok, Ubon Ratchathani, Songkhla and Phuket. The data used were hourly meteorological data from 2004 to 2008 and the upper meteorological data of 2008 from Thai Meteorological Department and the upper meteorological data from the project of Characteristics of atmospheric profile and its effects on variation of air pollutions in Thailand (CAPE) during February 2008. The study results from all study areas showed that the maximum UHI intensity was 0.1℃ - 4℃ and there were the diurnal variation and seasonal variation. The study results were found that the UHI intensity did not correlate either with the rate of change of temperature or wind speed with height and the difference of temperature or wind speed between the surface and the higher levels. However, in the case study areas which followed CAPE project, there was the positive correlation between the UHI intensity and the mixing height which the coefficient of determination (R²) for Chiang Mai and Bangkok was 0.49 and 0.64 respectively. These values were significant for meteorological study. From estimation of the morning mixing height by Holzworth method, the suitable constant of UHI intensity for Thailand should be 3℃ - 4℃.