致灾型华南暖区暴雨的多尺度垂直环流建立和加速机制研究

As a type of important high-impact weather, the disaster-bearing warm-sector rainstorms frequently occur in south China in summer. Focusing on the critical role of multi-scale vertical circulations to the diagnosis and prediction of warm-sector rainstorm, and by taking new techniques of multi-scale separation, lagrangian simulation and matrix analysis methods, this research project mainly studies several aspects. (1) The founding process of multi-scale vertical circulations before the occurrence of the rainstorm is identified. The three-dimensional image of a multi-scale vertical circulation system, which directly contributes to the construction of convection, is depicted. (2) The formation and acceleration mechanism of multi-scale vertical circulation is revealed. From the synoptic perspective, the key physical factors and physical mechanisms which influence the formation of circulation members are illuminated. The dynamic driving force of circulation acceleration, and how this driver act on speed-up of circulation, are clarified. (3) The duty and relative contribution of each vertical circulation member to the construction of vertical motion, water vapor transport and instability establishment above the rainstorm location are investigated. The multi-scale vertical circulation model is constructed to diagnose and predict the initiation and evolution of warm-sector rainstorm in south China. By above researches, the products of this project would no doubt deepen our knowledge and systematic understanding about the multi-scale vertical circulation, improve the quantitative description on its critical role on rainstorm. From the viewpoint of the vertical circulation, the project would reveal initiation and strengthening of warm-sector rainstorm based on the establishment and evolution of vertical circulation. The output of this research would provide us solid theoretical basis and useful information for scientific forecasting of the disaster-bearing warm-sector rainstorm in south China in the future.

我国致灾型华南暖区暴雨频发，是一种重要的高影响天气。本项目以对暴雨发生发展起至关重要作用的多尺度垂直环流为着眼点，利用最新的拉格朗日模拟、多尺度垂直环流作用分离技术以及矩阵分析技术等，（1）剖析暴雨发生之前多尺度垂直环流的建立过程和结构特征，识别参与对流共建的多尺度垂直环流的三维立体图像；（2）揭示多尺度垂直环流的发展与加速机制，特别是从天气学上分析影响环流成员发展的关键物理过程和机制，从动力学上阐明环流加速驱动力，揭示其强迫环流加强的动力机制；（3）定量评估各垂直环流成员在暴雨区垂直运动共建、水汽输送、不稳定建立过程中的分工和相对贡献，构建致灾型华南暖区暴雨发生发展的多尺度垂直环流作用模型。通过以上研究，以期进一步深化对该类暴雨中多尺度垂直环流的系统性整体认识，完善其在暴雨中作用的定量描述，并从垂直环流建立和演变的视角揭示暴雨的启动和演变机理，为该类暴雨的预测预警提供理论依据和业务参考。

本项目选取致灾型华南暖区暴雨的多次典型天气过程，采用观测资料分析、高分辨数值模拟和敏感性试验、动力过程理论推导等，（1）识别出致灾型华南暖区暴雨发生前多尺度垂直环流的建立过程，可较好地描述暴雨触发和对流组织化过程，这无论对暖区暴雨触发机制理论研究还是对暖区暴雨的预测理论发展都有贡献；（2）揭示多尺度垂直环流的发展与加速机制，得出华南暖区暴雨对流发展的关键影响因子，这在我国华南前汛期暖区暴雨中具有一定普适性，为暖区暴雨强度演变分析提供了新思路；（3）阐明各垂直环流成员在暴雨发生发展中的作用。以上研究，从多尺度垂直环流角度揭示了致灾型华南暖区暴雨的发生发展机理，为该类暴雨的预测预警提供了理论依据和业务参考。