2014年“5.8”广东大暴雨中尺度特征分析

利用NCEP/NCAR的1°×1°再分析资料、地面常规观测、FY-2E卫星TBB资料,对2014年5月8-9日发生在华南南部的一次暖区暴雨过程进行了研究.得出以下结论：1）第1阶段暴雨发生变性高压脊后部,未受冷空气影响,属于华南典型的回流暖区暴雨过程,第2阶段在东路弱冷空气的触发下再次产生暴雨,属于非典型回流暖区暴雨.2）1个中α尺度MCC和1个中β尺度MCS是该次广东大暴雨直接制造者,其中MCS-D在广西境内生成并逐渐东移,多个对流系统的并入延长了MCS-D的生命史,最后形成中α尺度MCC.3）东南气流是该次暴雨的主要水汽来源,中层小股干冷空气侵入,高层强烈辐散、深厚的上升运动的配置条件有利于中尺度对流系统发展和维持.4）区域自动站风场资料分析表明,夜间陆风（偏北风）与加强的东南风在112.5°E附近的汇合,可能触发了中尺度对流系统MβCS-H的生成.

Analysis of the Mesoscale Characteristics of an Unusually Heavy Rain on May 8, 2014 in Guangdong

Based on the 1°×1° reanalysis data from NCEP/NCAR, conventional surface observations, and TBB data from the FY-2E weather satellite, a warm-sector torrential rain that happened on May 8 -9, 2014 in the southern part of South China was studied. The result is presented as follows. （ 1 ） The first stage of the rain happened at the rear part of a transformed high ridge and was affected by cold air, belonging to the type of torrential rain caused by a return airflow in the warm sector, which is typical of South China. The second stage of the rain, however, was triggered by weak cold air from an eastward route, belonging to the type of torrential rain that is not caused by a return airflow. （2） This process of torrential rain was directly caused by a meso-ot scale MCC and a meso-13 scale MCS, in which an MCS-D was formed over Guangxi and moved eastward gradually and multiple convective systems merged to prolong the lifecycle of the MCS-D to result in the generation of the meso-α scale MCC. （3） A southeasterly flow was the main supplier of water vapor for this torrential rain. The intrusion of small-scale dry and cold air at mid-level, intense divergence at high levels and deep ascending motion were so allocated that mesoscale convective systems developed and maintained. （4） As shown in an analysis of a wind field data from regional automatic weather stations, nighttime land wind （a northerly） converges with a strengthened southeasterly wind near 112. 5°E, possibly intriguing the generation of an MβCS-H, a mesoscale convective system.