Urbanisation and urban climate of a tropical conurbation, Klang Valley, Malaysia

- Model performance is improved by AH landuse parameterisation.
- Maximum UHII of ~ 4.2 °C occurred in the commercial district.
- UHII decreases radially away from urban center.
- Urbanisation reduces diurnal temperature range.
- The meteorology of the tropical conurbation has periodic dependence on wind system.

Tropical urban climatology is not well understood. This study aims to provide insight on the interactions of urbanisation and the urban climate. The Weather Research and Forecasting (WRF) model is used to study the urban climate of a tropical conurbation - Klang Valley, Malaysia. Anthropogenic heat and landuse landcover datasets of the valley were parameterised to improve model's performance and to better represent the heterogeneity in surface characteristics. Simulated results indicate that urbanisation induces spatiotemporal changes in urban climate parameters, such as canopy layer temperature (T2m), planetary boundary layer height (PBLH), sensible heat flux (SH), and latent heat flux (LH). Other effects of urbanisation over the area include modification of surface energy components, which significantly affect the diurnal temperature range (DTR) above rural and urban surfaces. Urban development gradient causes T2m and urban heat island intensity (UHII) to decrease radially away from the urban centre. The commercial district with higher urbanisation density exhibited maximum heating, UHII, during the period studied. Moreover, urbanisation effect on UHI diurnal cycle was significant during morning and nighttime, meanwhile, during daytime, the spatiotemporal changes and distribution of UHI were dominated by solar radiation. The influence of wind system was also observed on the spatiotemporal variation in meteorology of the area; especially along the coastline bordering Strait of Malacca (by sea-land breezes) and the Titiwangsa mountain range (by mountain-valley breezes).