The Mesoscale Characteristics and Causes of a Severe Hail Event in Tianjin
-
摘要: 利用地面加密自动站、天津塘沽多普勒雷达、FY-2C静止卫星以及NCEP/NCAR再分析资料,对2008年6月25日下午天津地区一次罕见大冰雹过程风暴系统发展演变、结构特征和形成原因进行了观测分析和诊断研究。结果表明:此次大冰雹过程是在华北冷涡背景下,前倾结构的高空槽使高层干冷空气叠加在低层暖湿空气上,导致不稳定层结发展。中尺度对流系统由3个β-中尺度对流云团先后2次合并而成的α-中尺度对流系统,呈近似圆形结构。风雹发生前,天津地区大气层结呈现出强的对流性不稳定;700 hPa与近地面之间的风速差达到20 m/s,0~3 km垂直风切变明显增大;当上述有利的热力和动力条件形成后,在地面辐合线和干冷空气侵入的触发机制下,就造成了本次大冰雹过程。同时,由多单体合并而成的超级单体风暴,在其发展成熟阶段,多普勒雷达图上呈现出弓型回波、低层弱回波区和中高层悬垂回波区及三体散射结构;塘沽地区降雹前,垂直液态水含量出现一次明显的跃增。Abstract: A severe hail process occurs in Tianjin on 25 June 2008, based on the data of intensive AWS observation, Doppler weather radar, FY-2C geostationary satellite and NCEP/NCAR reanalysis data, analysis and diagnosis studies are carried out to seek the characteristic of this rare storm system and its evolution. The results show that with the cold vortex over North China, the upper-layer cold and lower-layer warm potential instability stratification is formed. In the left front of the core of upper-level jet, non-geostrophic effect enhances the development of the storm system. Three meso-β convective clusters merge into a quasi-circular structure meso-α scale convective system and maintain for about 4 hours in Tianjin. The CAPE increases rapidly before thunderstorm while the CIN decreases gradually, thus the lower atmosphere becomes slightly unstable from stable. As the storm approaches, the trend of θsewind profile is arcuate, and the convective instability atmosphere in the middle-low levels remain
.Water vapour transported through southwesterly flow from the southern part of Hebei forms a high humidity area, and Tianjin region is located in the area of wet tongue. Wind speed difference between 700 hPa level and near-surface reaches 20 m/s at 14:00, SHR (0—3 km) increases significantly, reaching moderate intensity (6.5 m · s-1· km-1). Super cell storms merged by a number of multi-cells have direct effects on the hail during the development of its mature stage. With the aid of Doppler radar, bow echo, weak echo region are found in the lower level, strong hanging echo in the middle-upper level and three-body scattering spike (TBSS) are observed. VIL jumps significantly from the lowest value to 65 kg· m-2before the hail occurs in Tanggu, and the top height of the storm remains 14 km, when VIL density increases to 4.6 g· m-3, exceeding the threshold of heavy hail. Analysis indicate that the dry intrusion of upper troposphere and cold air from the middle troposphere near the ground may also be the triggering factor in this process, besides the northwest-southeast convergence line located in Tanggu and the northeast of Hebei Province. -
图 2 2008年6月25日14:00 500 hPa高度场 (实线,单位:gpm)、温度场 (虚线,单位:K)、700 hPa风场 (矢量,单位:m/s)(粗实线表示500 hPa槽线;粗虚线表示700 hPa切变线)(a) 和200 hPa风速 (实线,不低于35 m/s)、散度场 (阴影,不大于-25×10-6s-1)(b)
Fig. 2 The geopotential height (solid line, unit:gpm), temperature (dashed line, unit:K) of 500 hPa, wind field of 700 hPa (solid thick line denotes the rough of 500 hPa; dashed thick line denotes the shear of 700 hPa)(vector, unit:m/s)(a), wind speed (solid line, no less than 35 m/s), divergence (shaded area, less than-25×10-6s-1) of 200 hPa (b) at 14:00 25 June 2008
图 4 2008年6月25日天津塘沽多普勒天气雷达风暴单体反射率因子 (双箭头指示同一位置)
(a)15:42, 2.4°仰角,(b)15:42, 4.3°仰角,(c)15:42, 9.9°仰角,(d)15:42, 14.6°仰角,(e)15:24, 1.5°仰角,(f)15:42, 沿图 4a中AB的反射率因子垂直剖面
Fig. 4 Reflectivity images of Tianjin Tanggu Doppler weather radar on 25 June 2008(the double-arrow in the figure indicates the same location)
(a)15:42, 2.4°, (b)15:42, 4.3°, (c)15:42, 9.9°, (d)15:42, 14.6°, (e)15:24, 1.5°, (f)15:42, vertical cross-section of reflectivity along segment AB in Fig. 4a
图 5 2008年6月25日天津塘沽多普勒天气雷达径向速度图 (圆圈为中气旋所在区域)
(a)14:00,3.4°仰角,(b)14:42, 3.4°仰角,(c)1542,3.4°仰角,(d)15:42,6.0°仰角,(e)15:42,9.9°仰角,(f)15:42,14.6°仰角
Fig. 5 Racial velocity images of Tianjin Tanggu Doppler weather radar on 25 June 2008(the circle indicates the position of mesocyclone)
(a)14:00, 3.4°, (b)14:42, 3.4°, (c)15:42, 3.4°, (d)15:42, 6.0°, (e)15:42, 9.9°, (f)15:42, 14.6°
-
[1] 许焕斌, 段英.冰雹形成机制的研究并论人工雹胚与自然雹胚的"利益竞争"防雹假说.大气科学, 2001, 25(2):277-288. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXK200102016.htm [2] 许焕斌, 段英.强对流 (冰雹) 云中水凝物的积累和云水的消耗.应用气象学报, 2002, 60(5): 575-584. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=qxxb200205007&dbname=CJFD&dbcode=CJFQ [3] 许焕斌, 田利庆.强对流云中"穴道"的物理含义和应用.应用气象学报, 2008, 19(3):372-379. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20080361&flag=1 [4] 康凤琴, 张强, 马胜萍, 等.青藏高原东北边缘冰雹形成机理.高原气象, 2004, 23(6):749-757. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX200406003.htm [5] 孙继松, 王华.重力波对一次雹暴天气过程演变的影响.高原气象, 2009, 28(1):165-172. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX200901021.htm [6] 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. doi: 10.11676/qxxb2004.032 [7] 俞小鼎, 郑媛媛, 张爱明, 等.安徽一次强烈龙卷的多普勒天气雷达分析.高原气象, 2006, 25(5):915-923. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX200605019.htm [8] 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. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20040571&flag=1 [9] 王令, 郑国光, 康玉霞, 等.多普勒天气雷达径向速度图上的雹云特征.应用气象学报, 2006, 17(3):281-287. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20060349&flag=1 [10] 张晰莹, 方丽娟, 景学义, 等.黑龙江省产生冰雹的卫星云图特征.南京气象学院学报, 2004, 27(1):106-112. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZGQX200312007009.htm [11] 李英, 段旭.湿位涡在云南冰雹天气分析时的应用.应用气象学报, 2000, 11(2):242-248. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=yyqx200002014&dbname=CJFD&dbcode=CJFQ [12] 雷雨顺, 吴宝俊, 吴正华.冰雹概论.北京:科学出版社, 1978:100. [13] 何立富, 周庆亮, 陈涛."05.6"华南暴雨低纬度系统活动及相互作用.应用气象学报, 2010, 21(4):385-394. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20100401&flag=1 [14] NESDIS/NOAA.The GOES Users Guide.1983:7-389. [15] 江吉喜, 范梅珠.夏季青藏高原上的对流云和中尺度对流系统.大气科学, 2002, 26(2):263-270. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXK200202011.htm [16] 石定朴, 朱文琴, 王洪庆, 等.中尺度对流系统红外云图云顶黑体温度的分析.气象学报, 1996, 54(5):600-610. doi: 10.11676/qxxb1996.062 [17] 俞小鼎, 姚秀萍, 熊延南, 等.多普勒天气雷达原理与业务应用.北京:气象出版社, 2006:109;150. [18] 李云川, 王福侠, 裴宇杰, 等.用CINRAD-SA雷达产品识别冰雹、大风和强降水.气象, 2006, 32(10):64-71. doi: 10.7519/j.issn.1000-0526.2006.10.010 [19] Witt Arthur, Eilts Michael D, Stumpf Gregory J, et al. An enhanced hail detection algorithm for the WSR-88D. Wea Forecasting, 1998, 13:286-303. doi: 10.1175/1520-0434(1998)013<0286:AEHDAF>2.0.CO;2 [20] Tipton G A, Howieson E D, Margrae J A, et al. Optimizing the WSR-88D mesocyclone/tornadic vortex signature algorithm using WATADS—A case study. Wea Forecasting, 1998, 13: 367-376. doi: 10.1175/1520-0434(1998)013<0367:OTWMTV>2.0.CO;2 [21] 刘建文, 郭虎, 李耀东, 等.天气分析预报物理量计算基础.北京:气象出版社, 2005:91-92;141. [22] 寿绍文, 励申申, 寿亦萱.中尺度气象学, 北京:气象出版社, 2009:228. [23] 廖晓农, 王华, 石增云.北京地区雷暴大风日θe平均廓线特征.气象, 2004, 30(11):35-37. doi: 10.3969/j.issn.1000-0526.2004.11.008 [24] 伍荣生.现代天气学原理.北京:高等教育出版社, 1999:262. [25] Amburn S A, Wolf P L. VIL Density as a hail Indicator.Wea Forecasting, 1997, 12:473-478. doi: 10.1175/1520-0434(1997)012<0473:VDAAHI>2.0.CO;2 [26] 陈明轩, 俞小鼎, 谭晓光, 等.对流天气临近预报技术的发展与研究进展.应用气象学报, 2004, 15(6):754-766. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20040693&flag=1