The effect of urbanization on extreme precipitation in the Guangdong–Hong Kong–Macau Greater Bay Area (GBA), which has been undergoing dramatic urbanization, is explored in this study. Two comparative urban development scenarios (2000 and 2015) were designed to examine the sensitivity of extreme precipitation to urbanization in numerical experiments. The simulation reveals that extreme precipitation remarkably increased in the core and northeast areas of the urban agglomeration, a finding that is also verified by statistics of the secular trend of observed data. Through the classification of extreme precipitation, it was found that urbanization significantly impacts only convectional extreme precipitation, while it has little effect on frontal or typhoon extreme rainfall. Further comparative analysis of model outputs revealed that urbanization increases surface roughness, which enhances mechanical turbulence and results in stronger low-level convergence and convection enhancement. Urbanization also leads to a change in the surface energy balance. The increased sensible heat flux enhances the temperature and boundary layer circulation and transports more water vapor, mixing it into the upper atmosphere in urbanized areas and increasing the intensity and frequency of convectional extreme precipitation.

本研究探讨了城市化对正在经历剧烈城市化的粤港澳大湾区（GBA）极端降水的影响。设计了两个比较城市发展情景（2000 年和 2015 年），以在数值实验中检验极端降水对城市化的敏感性。模拟结果表明，城市群核心区和东北地区极端降水明显增加，这一发现也得到了观测数据长期趋势统计的验证。通过对极端降水的分类发现，城市化仅对对流极端降水产生显着影响，对锋面或台风极端降水影响不大。对模型输出的进一步比较分析表明，城市化增加了地表粗糙度，从而增强了机械湍流并导致更强的低层收敛和对流增强。城市化也导致地表能量平衡的变化。感热通量的增加增强了温度和边界层环流，并输送了更多的水汽，将其混合到城市化地区的高层大气中，并增加了极端对流降水的强度和频率。