首页 | 官方网站   微博 | 高级检索  
     

一次系列下击暴流事件的多普勒天气雷达分析
引用本文:俞小鼎,张爱民,郑媛媛,方翀,朱红芳,吴林林.一次系列下击暴流事件的多普勒天气雷达分析[J].应用气象学报,2006,17(4):385-393.
作者姓名:俞小鼎  张爱民  郑媛媛  方翀  朱红芳  吴林林
作者单位:1.中国气象局培训中心, 北京 100081
基金项目:中国气象局“以大气监测自动化系统为基础的强对流天气预警和短时预报应用技术研究”课题,安徽省“十一五”科技攻关项目“以大气监测自动化系统为基础的中尺度强对流天气监测预警研究”(06013140B)共同资助
摘    要:该文首次利用我国新一代天气雷达资料对一次系列下击暴流过程进行了详细分析。2003年6月6日在安徽定远县和肥东县交界处附近发展起来的一个孤立的强烈多单体风暴, 产生了一次伴随强降雹的系列下击暴流事件。此次系列下击暴流事件实际上是由多单体风暴中3个相继发展的对流单体分别产生的3次下击暴流构成的。每轮下击暴流触地前, 都伴随着相应对流单体反射率因子核心的逐渐下降。在首轮下沉气流触地前6 min, 1.5°到4.3°仰角的径向速度图上都出现向着风暴中心的辐合, 其中以2.4°仰角 (地面以上约3~4 km) 的辐合最明显。因此, 反射率因子核心的逐渐降低并伴随云底以上的速度辐合的多普勒雷达回波特征, 可以用来提前数分钟预警下击暴流的发生。

关 键 词:下击暴流    云底以上辐合    反射率因子核心下降    大冰雹
收稿时间:2005-07-04
修稿时间:2006-03-22

Doppler Radar Analysis on a Series of Downburst Events
Yu Xiaoding.Doppler Radar Analysis on a Series of Downburst Events[J].Quarterly Journal of Applied Meteorology,2006,17(4):385-393.
Authors:Yu Xiaoding
Affiliation:1.China Meteorological Administration Training Center, Beijing 1000812.Anhui Provincial Institute of Meteorological Science, Hefei 2300613.Anhui Atmospheric Science and Remote Sensing Key Laboratory, Hefei 2300614.Anhui Provincial Meteorological Bureau, Hefei 230061
Abstract:For the first time a downburst event is analyzed in detail with Doppler weather radar in China. A severe multi-cell storm develops near the border between Dingyuan county and Feidong county in Anhui Province, and produces a series of downbursts accompanied by severe hails on 6 June 2003. As for the synoptic background, the axis of the trough tilts eastward, so that the dry and cold air mass from the rear of high-level trough superposes upon the moist and warm air mass in front of the lower level trough, building up the convective instability. The lower troposphere is moist with weak vertical wind shear, while the mid and upper troposphere is dry. This is a situation favorable for wet downburst. This series of downburst consists of three sequential bursts of strong downdrafts, produced by three convective cells developping in the multi-cell storm. From 16:14 to 16:33, the continued descending of reflectivity core of the first cell occurs, and at 16:33, a significant midlevel convergence appears. At 16:39, the first downburst hits the ground, with significant divergence on the lowest elevation (600 m height above ground). The same precursor appears before the second and third consecutive downbursts. Before each burst of the downdraft, the core of the corresponding cell descends, accompanied by the convergence above cloud base. This fact can be used to issue downburst warnings with a lead time of about 5 to 6 minutes. At the same time, a rotation appears on the midlevel in the storm. These facts are in agreement with those discovered by Roberts and Wilson with the statistics of 31 microbursts occurred in Colorado, USA. When the downburst attains its maximum strength, the largest velocity difference along the 0.5° scan over a distance of 6 km is 44 m/s, corresponding to a divergence value of 1.5 ×10-2s-1. The downburst series, consisting of three sequential downbursts, lasts 74 minutes, with each lasting 25 minutes on average. During the whole period, the storm moves very slowly, due to the cancellation of the advection and propagation, leading to the occurrence of the three downbursts at nearly the same site. Analysis shows that it is the hail and rain's descends that initiate the downdraft, which is then greatly enhanced by the entrainment of dry air into the downdraft and subsequent evaporative cooling, for the environmental air is relative dry at mid troposphere. Furthermore, the steep decrease rate of environmental temperature from surface to 0 ℃ level is quite large, around 8 ℃/km, keeping the downdraft with negative buoyancy down to the ground.
Keywords:downburst  convergence above cloud base  descending of reflectivity core  large hail
本文献已被 CNKI 万方数据 等数据库收录!
点击此处可从《应用气象学报》浏览原始摘要信息
点击此处可从《应用气象学报》下载全文
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号