Modeling of urban lake breeze circulation: Implications for the mitigation of urban overheating

Abstract

The urban overheating phenomenon, induced by both global warming and the urban heat island (UHI) effect, has been exacerbated by worsened urban wind environments. Urban lakes may aid in mitigating urban overheating through the process of lake breeze circulation (LBC). In this study, we developed a multi-scale water-energy coupled CFD model to simulate the transport of heat and moisture between lake surfaces and built-up areas and to resolve dynamics of atmospheric temperature, humidity, and wind at both street canyon scale (1m) and city scale (50km) with relatively low computational costs. Based on this model, we conducted sensitivity analyses to study the impact of urban, lake, and atmospheric parameters on thermal comfort conditions in the city. Our results show that the cooling capacity of LBC is more evident in hotter and denser cities. Furthermore, in the process of urban expansion, horizontal sprawl (i.e., increasing city size) is more advantageous than vertical growth (i.e., increasing building height) and infilling growth (i.e., increasing building density), considering the cooling potential of LBC. Our results can provide significant references for urban planning and city design for the sake of the mitigation of urban overheating via lake breezes.