华南前汛期是每年在我国最早开始的雨季，期间频发的暴雨常导致突发性洪水或持续性洪涝灾害，进而造成江河湖泊泛滥，城市内涝，山区诱发泥石流、山洪等地质灾害，给当地的经济建设、人民的生命财产及自然环境造成巨大的威胁和损失。准确的预报华南暴雨对防灾减灾尤为重要。然而，对流触发及发展过程中华南地区复杂的下垫面（地形、海陆分界、城市）、云降水微物理过程及其反馈作用以及暴雨系统本身的特征都直接影响暴雨的可预报性，目前对华南前汛期降水的预报是气象业务的难点和重点。为了系统地研究华南前汛期降水的发生发展机理和可预报性，本项目拟利用气候态的初边界条件对华南前汛期降水进行高分辨率的数值模拟，通过敏感性试验和集合预报等方法考察华南前汛期降水预报的误差来源和预报能力的极限，以讨论华南前汛期降水的实际可预报性和本性可预报性，对改进华南前汛期降水预报能力提供理论参考依据。

The presummer rainy season in South China is the first rainy season to occur in China. The frequent heavy rainfalls usually result in catastrophic consequences such as sudden floods or persistent floods, which in turn causes the flooding of rivers and lakes, urban waterlogging, landslides and flash floods, leading to considerable damage to human society and natural environment. Hence, it is of vital importance to understand and accurately predict these heavy rainfall events. However, the influence of the complex underlying surface (e.g., topography, land-sea boundary, cities) on the triggering and development of convection, the microphysical process and its feedback, the characteristics of the rainstorm system itself, directly affects the predictability of the presummer rainfall over South China, the prediction of which is important and difficult for the operational forecast center. To systematically study the mechanism and predictability of the presummer rainfall over South China, this project utilizes the climatological initial and boundary conditions to perform high-resolution numerical simulations of the presummer rainfall over South China. By designing sensitivity experiment and conducting ensemble forecast, the practical and intrinsic predictability are discussed, including the error source and forecast limits, aiming to offer a theoretical reference for improving the ability of the numerical prediction on the presummer rainfall over South China.