海南岛秋季暴雨的形成机制及微物理过程研究

The study of South China heavy rainfall is focused on pre-flood heavy rainfall, the autumn heavy rainfall in Hainan is paying little attention. In recent years, Hainan Island is suffered autumn heavy rainfall frequently and the heavy rainfall causes enormous disaster.The research content of this project is the formation mechanism of the autumn heavy rainfall and its major microphysical processes. The major research content are: The main research content of this project are: (1) Climate characteristics of autumn heavy rainfall in Hainan Island, including the temporal and spatial evolution of heavy rainfall, the interdecadal variations characteristics of the frequency of heavy rain, the amount of heavy rain, heavy rain days and the possible trends. (2) Through the analysis of the influence factor, the circulation background and synoptic systems of heavy rain, to establish the synoptic scale conceptual model of Hainan Island autumn heavy rain. (3) Through the research of the mesoscale system of heavy rainfall, including its formation, development and four-dimensional structure, and its interaction and influence mechanism with large-scale synoptic systems. Meanwhile, considering the role of the topography, reveal the formation mechanism of the autumn heavy rainfall in Hainan Island and establish a mesoscale physical model of the system of autumn heavy rainfall in Hainan Island. (4) Through the diagnosis and simulation analysis, reveal the main microphysical processes and its accompanying three-dimensional structure of the latent heat income and expense balance in the formation, development, and suddenly enhanced stage of heavy rainfall and point out the major microphysical processes which play an important role in the suddenly enhanced stage of heavy rainfall. Research results are used for the establishment of the conceptual model of short-and medium-term forecasting and early warning in Hainan meteorological observatory. This conceptual model is based on the combining of synoptic meteorology and numerical prediction method.

。以前对华南暴雨研究多是汛期暴雨，海南秋季暴雨研究甚少。近几年海南岛秋季暴雨频发，灾害巨大，引人关注。本项目研究海南岛秋季暴雨的形成机制和微物理过程。研究内容主要是：（1）海南岛秋季暴雨的气候特征，包括暴雨的时空演变规律，暴雨发生频率，暴雨量、暴雨日的年际年代际变化特征，以及可能的变化趋势。（2）通过对暴雨的影响因子、环流背景和天气系统的分析，得到海南岛秋季暴雨的天气尺度概念模型。（3）通过对暴雨中尺度系统发生、发展、四维结构及其与大尺度天气系统的相互作用和影响机制的研究，考虑地形的作用，揭示海南岛秋季暴雨的形成机制，建立海南岛秋季暴雨系统的中尺度物理模型。（4）通过诊断和模拟试验分析，揭示暴雨发生发展以及突然增强阶段的各主要微物理过程及其伴随的潜热收支的三维结构，指出在暴雨突然增强阶段起主要作用的微物理过程是哪些。研究成果用于海南省气象台建立短临、中短期预报预警系统。

1） 海南岛秋季降水量东部和中部地区显著高于西部地区。秋季降水年际变化大，且呈上升趋势。由于秋季海南东部为迎风坡，西部为背风区，因此使海南岛降水东多西少。暴雨天数与降雨量有很好的对应关系。暴雨天数与降雨量呈上升趋势。海南岛以对流降水为主，对流中心主要位于中部。.2）陆面过程中的土壤最大容积含水量和地表粗糙度对短期暴雨过程的影响较大。地形对暴雨的发生发展有明显的影响。当降低地形高度，降水减少，暴雨中心强度减弱。.3） 3-10天高频振荡和10-20天低频振荡对海南持续性暴雨过程都有影响,但是影响机制不同。模拟试验结果发现，能较好地模拟大气季节内振荡特征的试验，对降水模拟效果也越好。但是积云参数化方案和微物理方案都可能对大气季节内振荡产生影响，正是湿物理过程和大气季节振荡的相互作用导致了海南岛秋季持续性强降水的发生发展。.4） 在暴雨过程中，正潜热的主要云微物理过程是水汽凝结成云水、雨水的凝结、云冰、雪、霰的凝华增长，负潜热的主要云微物理过程是雨水的蒸发、霰的融化和霰的增强融化。不同云微物理过程潜热释放对于降水强度有明显的影响。没有雨水凝结蒸发潜热后，整体潜热加热都会减弱，水成物含量明显减少，降水明显减少；没有凝华和升华潜热释放，高层加热减弱，降水减弱；没有冻结和融化潜热释放，低层加热有所增强，降水略有减弱。.5） 在暴雨的发展增强阶段，雨水的来源最主要是霰的融化和霰的增强融化。不同霰密度试验各水成物含量均随降水强度增强而增多。随着降水强度增强，小密度霰融化量增多，但霰收集雨水量增多更显著，霰向雨水的净转化量减小，霰融化对降水贡献减小，高强度降水减小；大密度霰收集雨水量随降水强度变化不大，霰融化量随强度增大而增大明显，因此大密度霰向雨水净转化量增大，霰融化对降水贡献增强，高强度降水增多。. 这些研究内容和成果对于提高海南岛秋季暴雨的预报水平具有理论意义，也有应用价值。