URBAN HEAT ISLAND
Cooling Singapore investigates Singapore’s Urban Heat Island (UHI) and plausible ways to mitigate the effect. The UHI effect is defined as the air temperature difference between rural and urban areas. It can help us to understand how urbanisation but also human behaviour are contributing to higher temperatures in the city.
To study Singapore’s UHI, Cooling Singapore makes extensive use of computational modelling approaches. The Weather Research and Forecasting (WRF) model is used to analyse the impact of UHI as well as potential UHI countermeasures to offset the effect in Singapore. Also, the Local Climate Zones scheme (developed by Stewart and Oke, 2012) is used to classify Singapore’s land cover in terms of surface structure (e.g., building/tree height and density) and surface cover (pervious vs. impervious). The UHI magnitude is measured by comparing the simulation results of the current urbanised condition (‘current-scenario’) with results of a plausible rural condition where all urban areas are replaced with vegetation (‘all-green scenario’).
The UHI effect shows a strong diurnal cycle, being low during the morning and building up considerably in the afternoon. The UHI effect in Singapore is the highest at night since the heat is trapped and stored in urban surfaces. The maximum UHI at night-time can reach around 5-7 °C in specific areas. Different countermeasures are currently being assessed.