华南前汛期降水日变化的云分辨率数值模拟与机制研究

Diurnal variation of rainfall is a response to atmospheric dynamical and thermal processes and has closed relationship on complex regional forcing. Presummer rainfall over South China has daily and spatial variation that is the key to study regional climate and extreme weather. High-resolution observations and new developed long-term cloud resolution numerical simulations promote the research on the complex characteristics and mechanism of rainfall diurnal variation. Based on previous studies, the numerical analysis and observation statistics are performed to study northern inland and southern coastal nocturnal rainfall systems. Further analyses are conducted to obtain diurnal characteristics (precipitation property, time and space distribution, and propagating speed), related physical mechanism and simulation ability. The simulations will reveal the contributions of land-sea distribution, multi-scale terrain, boundary process, summer monsoon and weather disturbance. The main contents of this project have two parts. Firstly, the assessment of numerical model will be investigated using multisource observations. Further numerical analyses are performed to explore the dynamical and thermal mechanisms and key factors for the two precipitation systems. The research results will reveal the fine features of rainfall over South China and response mechanism to atmospheric circulation and regional forcing. Meanwhile, understanding and forecasting of regional weather and climate will also be promoted.

降水日变化体现了降水系统对大气热力动力基本过程的响应，也与大尺度环流背景下的诸多局地强迫密切相关。华南前汛期降水存在显著的日变化和区域差异，是科学认识区域气候和极端天气的关键。结合密集观测网和新发展的云分辨率数值模拟长时间序列数据集，有望阐明华南降水日变化的复杂特征和具体机制。本项目在前期研究积累基础上，进一步对华南前汛期北部内陆和南部海岸两类夜间降水系统开展观测统计与数值分析，深入探讨日变化活动特征（降水属性、时空分布、传播速度等）、相应的物理机制和模拟能力，定量揭示海陆分布、多尺度地形、边界层过程、季风气流、天气系统扰动等因素的贡献作用。主要内容包括：1）利用多源观测资料定量评估云分辨率模式对降水日变化的模拟水平；2）数值分析研究两类降水系统日变化的动力热力机制和关键因素。研究成果将揭示华南降水的精细特征及其对大气环流或局地强迫的响应机制，提升对区域天气气候的认识和预报。

降水日变化体现了降水系统对大气热力动力基本过程的响应，也与大尺度环流背景下的诸多局地强迫密切相关。华南前汛期降水存在显著的日变化和区域差异，是科学认识区域气候和极端天气的关键。本项目针对华南前汛期不同区域（东部内陆、西部内陆、海岸地区）、不同降水系统（向东传播的降水系统、清晨局地降水系统、海岸性降水系统强度）、不同等级降水（小雨、中雨、大雨）评估云分辨率中尺度气象模式的模拟能力。深入探讨日变化活动特征（降水属性、时空分布、传播速度等），相应的物理机制和模式误差的来源。项目还研究了珠三角地区前汛期区域降水事件的特征（包括日变化特征）和降水演变过程，并且探讨了不同类型区域降水事件的成因机制。另外还对比分析了登陆华南强台风造成不同级别降水的精细化特征和可能机制。研究成果将揭示华南降水的精细特征及其对大气环流或局地强迫的响应机制，提升对区域天气气候的认识和预报。