梅雨锋上中尺度涡旋相关的突发性暴雨发展机理和可预报性研究

Meiyu rainstorm over the middle and lower reaches of the Yangtze River in summer is the most serious weather disaster of East China. Particularly, the sudden storms associated with the mesoscale vortex in the middle and bottom troposphere usually develop rapidly and cause great damage to people's lives and property. So they have always been the key points and main difficulties for operational forecast. With diagnostic analysis using non-conventional data and simulation methods using high-resolution numerical models, three aspects about the sudden rainstorm associated to mesoscale vortex over Meiyu Front will be researched. The first is the morphology and evolution characteristics of the sudden rainstorm over Meiyu front. The second is the initiating, organizing, and maintaining mechanisms of such sudden rainstorms spawned by mesoscale vortex and other environmental elements. The third is the practical predictability for sudden rainstorm associated with mesoscale vortex based on NWP model initial condition uncertainty and model error analysis. This project is aimed to reveal the initiation, organizational model and main propagation characteristics of the sudden rainstorm over Meiyu front, to deepen the understanding of the formation and development mechanism about sudden rainstorm associated with mesocale vortex, to construct related physical lifetime conceptual model about such sudden rainstorm system. Finally, factors influencing key components of forecasts such as occurance time, maximum rainfall location, frequency of precipitation climax and propagation direction of new cells will be concluded, in order to improve operational forecast ability of such rainstorms as well as to build some science foundation for mesoscale numerical forecasts.

长江中下游地区梅雨锋暴雨是夏季中国东部地区最主要的气象灾害，尤其是对流层低层数百公里尺度的中尺度涡旋引起的突发性暴雨发生发展迅速，常造成人民生命财产重大损，是实际预报业务中难点和重点。本项目采用非常规观测资料诊断分析和高分辨率数值模拟等方法，拟开展长江中下游地区梅雨锋上突发性暴雨组织形态和演变特征，中尺度涡旋对突发性暴雨的启动、组织和维持机制，数值模式对梅雨锋上突发性暴雨的实际可预报性三个方面的研究，以期揭示梅雨锋上突发性暴雨的触发机制、组织化过程和主要传播特征，以加深中尺度涡旋对突发性暴雨的发生发展影响机制的科学认识，建立梅雨锋上突发性暴雨发生发展过程的概念模型。在此基础上，针对暴雨突发的时间、最大短时强降水中心落区、雨峰重复发生的次数和新单体传播方向等预报关键问题提出相应的影响因子，为改进梅雨锋上突发性暴雨预报，特别是中尺度数值预报提供一些必要的科学基础。

长江中下游地区梅雨锋期中尺度涡旋引起的突发性暴雨发生发展迅速，常造成人民生命财产重大损，是实际预报业务中难点和重点。本项目采用非常规观测资料诊断分析和高分辨率数值模拟等方法，开展了长江中下游地区梅雨锋上突发性暴雨组织形态和演变特征，中尺度涡旋对突发性暴雨的启动、组织和维持机制，数值模式对梅雨锋上突发性暴雨的实际可预报性三个方面的研究。.通过研究，建立了基于风廓线雷达的水平散度和涡度诊断技术、基于北斗卫星的大气水汽含量反演方法、模式降尺度的精细地表和近地面温度反演技术、中尺度涡旋自动识别技术等若干中尺度天气信息提取（反演）技术。系统地总结了梅雨锋上于中尺度低涡相关的7种突发暴雨系统组织形态和传播特征，指出不同低涡之间相互作用、中尺度涡旋与中尺度对流系统在发展过程中的正反馈机制、中尺度涡旋与中低空急流相互作用是梅雨锋突发性暴雨发生发展的三个重要机制，以此为基础，建立了中尺度涡旋相关的梅雨锋上突发性暴雨发生发展概念模型。研究还显示了中尺度数值预报模式资料同化对降水落区和总误差增长的影响较小，物理过程参数化方案可直接影响降水的落区和强度，高分位数集合成员的雨量预报在实际预报中有比较好的参考价值。.上述研究成果是对现有中尺度对流系统（MCSs）组织形态和传统特征研究结果的有益补充，也丰富了对中尺度涡旋暴雨结构和发生发展机理的科学认识，为梅雨期突发性暴雨预报提供了重要的科学依据，部分研究成果可直接应用于预报员对暴雨的实时分析与预报。