High-resolution regional modeling of urban moisture island: mechanisms and implications on thermal comfort

The urban moisture island (UMI) can aggravate the thermal stress due to heat (UHI) in subtropical and tropical cities. In this study, we investigated spatiotemporal variation patterns of UMI Hong Kong, a coastal city, using fine-resolution mesoscale Weather Research Forecasting (WRF) model by integrating local climate zone (LCZ) maps based on World Urban Database Access Portal Tools (WUDAPT). Our results show that at regional scale, phenomenon tends occur areas, possibly owing rich sources from sea breeze inhibited penetration barrier effects mountains. Specifically, an all-day effect was found low-density low-rise areas (LCZ5&8&10), while nocturnal daytime dry (UDI) were high-density high-rise (LCZ1&2). UDI be attributed strong vertical convection associated with intensive surface sensible fluxes strongly mixed boundary layer (UBL). night blocked ventilation aisle, dewfall UHI, weakened upward motion stable UBL. On other hand, increase risks additional 37.5% neighbourhoods Extreme caution level 6.1% Danger level. addition, impact human dominant (LCZ5&8&10) nighttime • Coastal witnessed phenomenon. compact UDI. Weakened UHI-induced are possible reasons UMI. synergistic UHI stress.