台风“海燕”（2013）暴雨非对称结构及中尺度特征分析

利用NCEP再分析资料、地面雨量加密自动站资料及多普勒雷达产品资料，对2013年第30号超强台风“海燕”暴雨的非对称结构及中尺度降雨的形成机制、落区特征进行分析。研究结果显示:（1）“海燕”停编前有4个MCS呈东西向带状分布在广西南部，维持时间约9~12 h；台风减弱停编后在广西东南部有1~2个呈南北向的MCS，维持时间为2~4 h，造成此次台风过程的最强降水；（2）在“海燕”影响过程中，能量锋在贵州和广西维持并明显北倾、能量低值中心南下控制桂西北，使该地暴雨骤停、而桂东南在南风急流及地形作用下暴雨维持，是台风暴雨呈现东南强西北弱的非对称结构的主要成因；（3）台风登陆广西至停编时段的中尺度降雨是在高层的位涡异常与低层的位温异常叠加所形成的大气结构下，锋面触发不稳定能量形成的，中尺度降雨集中在边界层能量锋区最大梯度中心、MPV1梯度区零值附近与MPV2正值中心叠加处；（4）台风减弱在停编后的中尺度降雨是由冷空气侵入六万大山东侧抬升暖湿气流形成初始中-γ对流回波，在南风急流及两山脉间的盆地地形作用下，逐步加强发展成中-β对流回波并以“列车效应”传播而形成的。 

THE ANALYSIS OF THE ASYMMETRIC STRUCTURE AND THE MESOLSCALE CHARACTERISTICS OF TYPHOON HAIYAN(2013)

The No.30 super typhoon Haiyan in 2013 made landfall in northern Vietnam and then went northeast forward until the middle of northeast Guangxi, in the process of which, the rain was strong in southeast, but weak in northwest. Besides, there were two mesoscale rainfalls during the process, which strengthened the asymmetric structural characteristics of the typhoon storm. Based on the data from National Centers for Environmental Prediction data and automatic weather stations, Doppler radar products, the asymmetric structure, mesoscale precipitation formation mechanism and rain distribution features of Haiyan are analyzed. It shows as follows: (1) Before the typhoon's decoding, there were four mesoscale convective rainfall centres maintaining for 9 to 12 hours, and their rainfalls were distributed from west to east, and there were two mesoscale convective rainfall centres happening after the typhoon was decoded, which caused the heaviest rain during the landing process of Haiyan; (2) During the influence process of Haiyan, the fundamental formation reason of the asymmetric precipitation, which was strong in the south area but weak in the north area, is that Guangxi and Guizhou were covered by a north-dipping energy front, because of which, low energy center was controlling the northwest of Guangxi and the rainfall there was stopped, while the heavy rain still maintained in the southeast area. The formation reason of the mesoscale rainfall which happened in the period of typhoon landing till the time when it was decoded is that the unstable energy was generated by the front which happened in the atmospheric structure of high-level abnormal potential vorticity superimposed the underlying abnormal potential temperature. The maximum gradient center of the energy front, the intersection area between the zero-value area of MPV1 and positive-value center of MPV2 in the atmospheric boundary layer were the areas where the rainfall concentrated; (3) After the typhoon stopped decoding, cold air invaded the eastern side of Liuwan Mountains to force the warm air to lift up and generate a meso-γ convective echo, followed by a meso-β convective echo, under the influence of a southerly jet stream, and the basin topography between two mountains propagated as train effect, which helped the mesoscale rainfall happen.