Potential Impact of Urbanization on Sydney’s Climate During Heat Waves: Factors and Future Perspectives

This study is concerned with the impact of urban expansion on urban heat during heat Waves (HWs). The City of Sydney is planning to expand its urban areas in the coming years to meet the increasing demand for housing and other needs, which may potentially alter the temperature in urban areas as well as the surrounding areas. This study is designed to evaluate the potential impact of urban expansion on the urban climate in the Sydney area. Three scenarios have been considered: 1) replacing the urban areas with forests, 2) using the current LCZs in urban areas, which includes different LCZ types, and 3) implementing all urban areas with high-density urban LCZ1 to investigate the maximum possible impact. Simulations are carried out by coupling the weather research and forecasting (WRF) model with the single-layer urban canopy model (SLUCM) during three HW events in 2017, 2019 and 2020. The Random Forest (RF) model is used to determine the importance of individual features. The results indicate that urbanization increases the temperature, especially the surface temperature, in both urban and surrounding rural areas, and the maximum temperature can reach up to 1 °C. The impact of urbanisation on urban climate is more substantial when the HW is more intense. The study also reveals that albedo consistently exhibits the highest importance scores, particularly during HW days, when its influence on surface temperature exceeds 0.6 in most cases.