Effect of Using Land Use Data with Building Characteristics on Urban Weather Simulations: A High Temperature Event in Shanghai

Land use data with building characteristics are important for modeling the impacts of urban morphology on local climate. In this study, an extreme heat event in Shanghai, China, was simulated by using a WRF/BEP + BEM (Weather Research and Forecasting/Building Effect Parameterization + Building Energy Model) model. We incorporated local climate zone (LCZ) land use data that resolved urban morphology using 10 classes of building parameters. The simulation was compared to a control case based on MODIS (Moderate-resolution Imaging Spectroradiometer) land use data. The findings are as follows: (1) the LCZ data performed better than the MODIS data for simulating 10-m wind speed. An increase in building height led to the wind speed to decrease by 0.6–1.4 m s⁻¹ in the daytime and by 0.2–0.7 m s⁻¹ at nighttime. (2) High-rise buildings warmed the air by trapping radiation in the urban canyon. This warming effect was partially offset by the cooling effect of building shadows in the day. As a result, the 2-m temperature increased by 0.8°C at night but only by 0.4°C during the day. (3) Heterogeneous urban surfaces increased the 50-m turbulent kinetic energy by 0.4 m² s⁻², decreased the 10-m wind speed by 1.8 m s⁻¹ in the daytime, increased the surface net radiation by 45.1 W m⁻², and increased the 2-m temperature by 1.5°C at nighttime. (4) The LCZ data modified the atmospheric circulation between land and ocean. The shadowing effect reduced the air temperature differences between land and ocean and weakened the sea breeze. Moreover, high-rise buildings obstructed sea breezes, restricting their impact to a smaller portion (10 km along the wind direction) of inland areas compared to that with MODIS.