摘要
利用国家重点基础研究发展规划项目“我国重大气象灾害形成机理和预测理论研究”2 0 0 2年外场试验首次获取到的双多普勒雷达资料 ,研究了 7月 2 2～ 2 3日在长江中游的宜昌、荆州区域暴雨回波和风场的中尺度结构及演变过程。结果表明 :本次暴雨是混合云降水所致 ,在层状云降雨区内有许多对流单体 ,这些对流单体常以带状结构组成回波群 ,对流云的回波强度和风场有明显的中尺度结构 ,与周围的层状云有很大差别。西南气流和东风形成的中尺度切变和辐合是造成强对流降水的主要原因 ,风场的中尺度结构主要发生在 4km以下的中下层。在对流回波周围 ,经常有中尺度切变、涡旋、辐合和辐散存在 ,这些风场的中尺度结构与对流云的演变有密切的关系 ,对强降水的发生和维持有重要影响。
The Dual Doppler radar data observed by the National Key Program for Developing Basic Sciences “Research on the Formation Mechanism and Prediction Theory of Hazardous Weather over China” in 2002 are used to analyze the mesoscale structures of reflectivity and wind in the heavy rainfall system from July 22 to July 23 in middle reach of the Yangtze River over Yichang and Jingzhou region. The results show that the heavy rainfall is cause by merging cloud process. The convective clouds, which often organized in band shape, are developed within stratus cloud. The wind and reflectivity in convective cloud have obvious mesoscale structures which are different with that in stratus. The wind shear and convergence below the height of 4 km cause the heavy rainfall. The convective rainfall is often related with mesoscale wind shear, vortex, convergence and divergence.
出处
《大气科学》
CSCD
北大核心
2004年第2期278-284,i005-i006,共9页
Chinese Journal of Atmospheric Sciences
基金
国家重点基础研究发展规划项目G1 9980 40 90 9资助
