2003年6月30日梅雨锋大暴雨 β和γ 中尺度结构的双多普勒雷达反演

STRUCTURE OF MESO β AND γ SCALE ON MEIYU IN HUAIHE RIVER BASIN ON 30 JUNE,2003 BY DUALDOPPLER RADAR

  • 摘要: 2003年6月下旬至7月上旬,淮河流域出现了持续强暴雨,文中使用双多普勒雷达三维风场反演技术(MUSCAT)对6月29~30日合肥和马鞍山多普勒雷达探测到的暴雨资料进行了三维风场反演,对暴雨系统的中尺度三维动力结构进行了研究。此次梅雨锋暴雨是由β中尺度辐合带和嵌在辐合带上的γ中尺度涡旋共同作用引起的,辐合带上的波动活动对降水具有重要的触发和维持作用。在强降水时段的前期,无为附近中低层的γ中尺度涡旋在东—西走向的中尺度辐合带上自西向东移动,γ涡旋的移动与主雨区的移动基本同步,γ中尺度波动是该时段暴雨的重要动力因素;与此同时,在雨带的北区,γ中尺度涡旋活动比较频繁,但基本上是局地生消;在后期,西南暖湿气流和西风辐合,形成雨带上空的β中尺度辐合带,辐合带随着降水的减弱而减弱;最后,给出了此次暴雨的三维动力结构。

     

    Abstract: The heavy rainfall existed for a long time in the Yangtze-Huaihe river basin on 2003 Meiyu. A heavy rain occurred in the dual-Doppler coverage, up to 159 mm rainfall in Wuhu and 146 mm in Wuwei from 08:00 on June 29 to 08:00 on June 30.The three-dimensional wind of the heavy rain were retrieved by MUSCAT (multiple Doppler synthesis and continuity adjustment technique) using the dualDoppler radar volume scan data which located in Hefei and Maanshan city. The three-dimensional kinematic structure of this rain were analyzed based on the 3-D wind. It showed that this heavy rainfall in the Meiyu front were caused by meso-β-scale convergence line and mesoγ scale vortices which mixed in the convergence line at the low level. These convergence line and vortices were the important mechanism for the broken and maintenance of the rain. The 3-D structure of the heavy rain has some difference in the early and later period.In the early part of the heavy rainfall period, meso γ scale vortices located in the meso β scale convergence line moved from Wuwei city to Wuhu city which caused the major rainfall. Mesoγscale vortices and rain band moved in the meantime. These vortices lasted for more than two hours and played an important role on the heavy rain. At the same time, It showed that the mesoγscale vortices occurred frequently in the north part of the rain band which dissipated quickly in the local area. After two and half hours, these vortices were vanished. The southwest moisture flow and west dry-cold flow combined which caused a meso βscale convergence line at the low level. The convergence line became dissipation according as rainfall weaked. The threedimensional kinematic structure model were also given.

     

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