Study of Urban Thermal Environment and Local Circulations of Guangdong-Hong Kong-Macao Greater Bay Area Using WRF and Local Climate Zones

The Guangdong-Hong Kong-Macao Greater Bay Area (GBA), a cluster of world-class cities, is undergoing rapid urbanization. However, the heterogeneity of the urban thermal environment resulting from the diversity of urban forms is not yet fully understood. This paper assesses the heterogeneity of the urban heat island (UHI) effect in the GBA using the coupled Weather Research and Forecasting (WRF) model/multi-layer urban canopy and building energy model (BEP/BEM), with high-resolution local climate zone (LCZ) map as urban land use/land cover data. The average UHI intensity is found to peak at 1.8 +/- 0.4degree celsius in the evening, when the average UHI intensity of LCZ 2 can reach a maximum of 2.4 +/- 0.58degree celsius. Properly setting air-conditioning temperatures can effectively prevent the enhancement of the UHI phenomenon at night by the anthropogenic heat (AH) released from air-conditioning. The UHI-induced local circulations and enhanced surface roughness inhibit the penetration of sea breezes inland, and surface wind speed decreases in all LCZs, with a maximum change of more than 0.8 m s(-1). However, the increased thermal difference between land and sea leads to enhanced sea breezes offshore, especially in the Pearl River estuary. In addition, a series of sensitivity experiments have been conducted in this paper on initial and boundary conditions, building drag coefficients and urban fractions, which paves the way for further analyzing urban climate in GBA using WRF model and LCZs.