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. 复制到剪切板

Yu Xiaoding, Zhang Aimin, Zheng Yuanyuan, Fang Chong, Zhu Hongfang, Wu Linlin. Doppler Radar Analysis on a Series of Downburst Events[J]. Journal of Applied Meteorological Science, 2006, 17(4): 385-393 复制到剪切板

一次系列下击暴流事件的多普勒天气雷达分析

俞小鼎¹, 张爱民^2,3, 郑媛媛⁴, 方翀⁴, 朱红芳⁴, 吴林林⁴

1. 中国气象局培训中心, 北京 100081;
2. 安徽省气象科学研究所, 合肥 230061;
3. 安徽省大气科学与遥感重点实验室, 合肥 230061;
4. 徽省气象台, 合肥 230061

2005-07-04 收到, 2006-03-22 收到修改稿.

资助项目: 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”课题和安徽省“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

Doppler Radar Analysis on a Series of Downburst Events

Yu Xiaoding¹, Zhang Aimin^2,3, Zheng Yuanyuan⁴, Fang Chong⁴, Zhu Hongfang⁴, Wu Linlin⁴

1. China Meteorological Administration Training Center, Beijing 100081;
2. Anhui Provincial Institute of Meteorological Science, Hefei 230061;
3. Anhui Atmospheric Science and Remote Sensing Key Laboratory, Hefei 230061;
4. 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.

Key words: downburst convergence above cloud base descending of reflectivity core large hail

[1]	廖玉芳, 俞小鼎, 郭庆. 一次强对流系列风暴个例的多普勒雷达资料分析. 应用气象学报, 2003, 14, (6): 656–662.
[2]	郑媛媛, 俞小鼎, 方翀, 等. 一次典型超级单体风暴的多普勒天气雷达观测分析. 气象学报, 2004, 62, (3): 317–328.
[3]	郑媛媛, 俞小鼎, 方翀, 等. 2003年7月8日安徽系列龙卷的新一代天气雷达分析. 气象, 2004, 30, (1): 38–40.
[4]	陈秋萍, 冯晋勤, 陈冰, 等. 新一代天气雷达观测的福建夏季对流云特征. 应用气象学报, 2003, 14, (增刊): 180–186.
[5]	漆梁波, 陈永林. 一次长江三角洲飑线的综合分析. 应用气象学报, 2004, 15, (2): 162–173.
[6]	朱君鉴, 刁秀广, 黄秀韶. 一次冰雹风暴的CINRAD/SA产品分析. 应用气象学报, 2004, 15, (5): 579–589.
[7]	Fujita T T, Byers H R. Spearhead echo and downbursts in the crash of an airliner. Mon Wea Rev, 1977, 105: 129–146. DOI:10.1175/1520-0493(1977)105<0129:SEADIT>2.0.CO;2
[8]	Fujita T T. The Downburst. SMRP Research Paper 210. Chicago:University of Chicago, 1985:1-122.[NTIS PB-148880]
[9]	Fujita T T. Manual of Downburst Identification for Project. SMRP Research Paper156, Chicago:University of Chicago, 1978:1-104.[NTIS PB-2860481]
[10]	McCarthy J, Wilson J W, Fujita T T. The joint airport weather studies project. Bull Amer Meteor Soc, 1982, 63: 15–22. DOI:10.1175/1520-0477(1982)063<0015:TJAWSP>2.0.CO;2
[11]	Wolfson M M, Distefana J T, Fujita T T.Low Altitude Wind Shear in the Memphis, TN Area Based on Mesonet and LLWAS Data.Preprints, 14 Conf on Severe Local Storms, Indianapolis, Amer Meteor Soc, 1985:322-327.
[12]	Atkins N T, Wakimoto R M. Wet microburst activity over the southeastern United States. Wea Forecasting, 1991, 6: 470–482. DOI:10.1175/1520-0434(1991)006<0470:WMAOTS>2.0.CO;2
[13]	Roberts R D, Wilson J W. A proposed microburst nowcasting procedure using single Doppler radar. J Appl Met, 1989, 28: 285–303. DOI:10.1175/1520-0450(1989)028<0285:APMNPU>2.0.CO;2
[14]	Eilts M D. Damaging Downburst Prediction and Detection Algorithm for the WSR-88D.Preprints, 18th Conf on Severe Local Storms, San Francisco, CA, Amer Meteor Soc, 1996:541-544.
[15]	俞小鼎, 王迎春, 陈明轩, 等. 新一代天气雷达与强对流天气预警. 高原气象, 2005, 24, (3): 456–464.
[16]	Srivastava R C. A simole model of evaporatively driven downdraft:application to microburst downdraft. J Atmos Sci, 1985, 42: 1004–1023. DOI:10.1175/1520-0469(1985)042<1004:ASMOED>2.0.CO;2
[17]	Proctor F H. Numerical simulation of an isolated microburst. Part Ⅰ:dynamics and structure. J Amtos Sci, 1988, 45: 3137–3160.
[18]	Proctor F H. Numerical simulations of an isolated microburst. Part Ⅱ:sensitivity experiments. J Atmos Sci, 1989, 46: 2143–2165. DOI:10.1175/1520-0469(1989)046<2143:NSOAIM>2.0.CO;2
[19]	Lemon L R. The radar " Three-Body Scatter Spike":an operational large-hail signature. Wea Forecasting, 1998, 13: 327–340. DOI:10.1175/1520-0434(1998)013<0327:TRTBSS>2.0.CO;2
[20]	Rinehart R E, Borho A, Curtiss C. Microburst rotation:simulation and observations. J Appl Met, 1995, 34: 1267–1284. DOI:10.1175/1520-0450(1995)034<1267:MRSAO>2.0.CO;2
[21]	Parsons D B, Weisman M L. A numerical study of a rotating downburst. J Atmos Sci, 1993, 50: 2369–2385. DOI:10.1175/1520-0469(1993)050<2369:ANSOAR>2.0.CO;2


图 2. 2003年6月6日16:02合肥多普勒天气雷达0.5°仰角反射率因子图 (方框内为新生的雷暴。距离每圈50 Km)


图 3. 穿过产生下击暴流的多单体风暴反射率因子核心随时间演变的垂直剖面图


图 4. 2003年6月6日16:33和17:09多单体风暴在3.4°仰角反射率因子图


图 5. 2003年6月6日下午下击暴流发生前后0.5°和2.4°仰角 (图中左上角标注) 雷达径向速度随时间演变 (距离每圈50 km)


应用气象学报 2006, 17 (4): 385-393	PDF


图 1. 2003年6月6日16:00安徽省地面图