Urban Heat Island Effect In The Megacities Of The Philippines

The three megacities namely Cebu City, Davao City and Manila City are considered as highly urbanized cities in the Philippines. The migration of the rural dwellers to these cities are the cause of fast urbanization. To meet the demand for housing, better roads and economic growth, the use of land was shifted from natural ecosystems (such as vegetation, parks, forest) into artificial environments (such as high-rise commercial and residential buildings). These changes in both population densities and land uses greatly alter the weather and climate of these areas. Studies show urbanization greatly affects local weather, particularly temperature and rainfall patterns of the urban and nearby rural areas. The development of Urban Heat Island (UHI) effect is also documented as this brings discomfort and health related issues among urban dwellers. Using the Diurnal Temperature Range (DTR) values of the selected cities, the researchers investigated the development of UHI. The meteorological parameters of the three cities were generated by the Weather Research and Forecasting Model (WRF). Results showed that there are more hot days during the hot and wet period than hot and dry periods as revealed by the values of Tmax. Manila was warmer than areas under study during the hot and dry period. Early morning (Tmin , 5-AM) temperature of Manila is hotter with mean value of 27.3°C. In general, among the three cities Davao had the coolest morning temperature by approximately 1°C – 3°C. The differences of DTR are ranging from 0.15°C to 1°C. The predominance of UHI is observed during the dry and wet period and weak during the cool and dry period. Overall, UHI development occurred for the entire period of study.