辽东半岛一次大暴雨的中尺度模拟及物理结构分析

Mesoscale Simulation and Physical Structure Analysis for a Heavy Rainstorm Case in Liaodong Peninsula

2005年7月25日辽东半岛南部及海峡地区发生了大暴雨天气。利用中尺度模式MM5的双向二重嵌套网格对其进行模拟,表明该模式对这次暴雨过程有较好的模拟能力。模拟的地面气压场及流场基本与客观分析场一致。模拟结果较好地再现了辽东半岛大暴雨的大尺度和中尺度天气系统的发展和演变,揭示了造成此次暴雨的中尺度系统结构为高空强辐散,低空强辐合及对应的强上升运动和气旋性涡柱是造成此次暴雨的动力机制,低空西南气流对这次暴雨的产生和发展起着重要的作用。

A heavy rainstorm process occurred in the southern Liaodong Peninsula and the Bohai straits areas on 25 July 2005 are researched using the two-way dual nested grid of the mesoscale numerical model MMS, it is found that the model has a good simulated abilities in this rainstorm process. The simulated surface pressure and streamline fields are consistent with the objective analysis field basically. The simulated results successfully reappeared the development and evolution of large scale and mesoscale circumfluence systems of the heavy rainstorm occurred in Liaodong Peninsula, it is discovered that a coupling of the intense divergence on upper levels and intense convergence on lower levels as well as intensive ascending motion and the cyclonic vorticity column are the dynamic mechanisms for this heavy rainstorm occurrence. The southwest airflow on lower levels play an important rules in the out-growth and the development of this rainstorm process.