一次超级单体分裂过程的雷达回波特征分析

2007年7月9日16—20时（北京时）在河北南部非常罕见地观测到了多个超级单体风暴在相近地点连续生成及分裂的过程。利用石家庄新乐SA型多普勒天气雷达资料、地面自动站及常规天气资料,对超级单体分裂过程及环境条件做了分析。表明这次的多个超级单体风暴是在强的对流有效位能和垂直风切变的环境条件下发生的。由于垂直风切变矢量方向随高度逆时针旋转,因此,分裂后左移的反气旋风暴得到加强,发展成为具有深厚中反气旋的左移超级单体风暴,而右移的气旋性风暴受到抑制,与理论研究结果一致。但也有不同之处,沿着地面高湿区内热力边界偏暖一侧移动的气旋性风暴没有受到明显抑制,有利的地面环境条件抵消了气旋性风暴受抑制的程度,使气旋性风暴能够持续更长的时间。该强烈发展的带有明显中反气旋的超级单体风暴具有低层钩状回波和入流缺口、中高层有界弱回波区及位于有界弱回波区之上的高层具有反射率因子核心和强烈风暴顶辐散,与经典的气旋式右移超级单体风暴的回波特征非常类似,除了是反气旋涡旋外,其回波特征与气旋式超级单体近似成镜像。风暴分裂是在单体形成不久的发展初期开始的。分裂先从中高层开始,然后迅速向下延伸。分裂后相对于0—6 km风切变矢量,左侧的单体为反气旋左移风暴,右侧的为气旋性右移风暴。     

2010年福建一次早春强降雹超级单体风暴对比分析

利用探空、地面资料以及建阳、龙岩、长乐三部新一代天气雷达资料,对2010年3月5日福建中北部地区5cm强降雹的两个超级单体风暴进行了对比分析。结果表明,干暖盖、强垂直风切变、中高层正涡度区及地面中尺度低压为超级单体的形成提供了良好的环境场。两个超级单体都是由多单体合并后发展起来的,在成熟阶段以右移为主,属长寿命右移风暴:第一个超级单体在发展过程中由于地形作用和新单体的并入经历了3次加强过程,低层出现明显的钩状回波、中高层三体散射特征;第二个超级单体经历了多单体风暴—超级单体风暴—多单体风暴3个阶段,成熟阶段低层呈现出明显的倒"V"形回波特征,中高层有明显向右伸展的云帖。两个超级单体风暴的中气旋都是由中层发展起来,随着中气旋强度不断加强和厚度加大,最强切变中心突降时出现冰雹、大风强对流天气。通过对第一个超级单体中气旋流场分析,发现风暴前、后侧的下沉气流与低层入流形成了明显的辐合旋转作用,下沉的干冷气流进一步推动低层的暖湿入流,形成强烈的上升气流,并在风暴顶形成强辐散,使得风暴长时间维持。第二个超级单体在风暴减弱阶段,风暴右侧出现中气旋分裂,之后减弱、消失。产生强对流天气时,中高层维持高反射率因子,出现三体散射现象、风暴顶强烈辐散以及较大的VIL密度等特征。     

Generation mechanisms of convectively induced internal gravity waves in a three-dimensional framework

The generation mechanisms of convective gravity waves in the stratosphere are investigated in a three-dimensional framework by conducting numerical simulations of four ideal storms under different environmental conditions: one un-sheared and three constant low-level sheared basic-state winds with the depth of the shear layer of 6 km and the surface wind speeds (U_s) of 8, 18, and 28 m s^?1, using the Advanced Regional Prediction System (ARPS) model. The storms simulated under the un-sheared (U_s = 0 m s^?1), weakly sheared (U_s = 8 and 18ms^?1), and strongly sheared (U_s = 28ms^?1) basicstate winds are classified into single-cell, multicell, and supercell storms, respectively. For each storm, the wave perturbations in a control simulation, including nonlinearity and microphysical processes, are compared with those in quasi-linear dry simulations forced by diabatic forcing and nonlinear forcing that are obtained from the control simulation. The gravity waves generated by the two forcing terms in the quasi-linear dry simulations are out of phase with each other for all of the storms. The gravity waves in the control simulation are represented by a linear sum of the wave perturbations generated by the nonlinear forcing and diabatic forcing. This result is consistent with the results of previous studies in a two-dimensional framework. This implies that both forcing mechanisms are important for generating the convective gravity waves in the three-dimensional framework as well. The characteristics of the three-dimensional gravity waves in the stratosphere were determined by the spectral combination of the forcing terms and the wave-filtering and resonance factor that is determined from the basic-state wind and stability as well as the vertical structure of the forcing.     

基于雷达资料四维变分同化和三维云模式对一次超级单体风暴发展维持热动力机制的模拟分析

利用三维云尺度数值模式和雷达资料快速更新循环四维变分同化(4DVar)技术,对京津冀地区一次强降水超级单体风暴发展演变的热动力机制进行了数值模拟和结果分析,并结合雷达、加密探空和自动站资料,揭示了快速变化的近风暴大气环境及风暴自身的热动力三维特征对超级单体形成、发展和演变的影响.雷达回波观测分析表明,这是一次由多单体合...     

一次雷暴大风的物理环境场和多普勒雷达回波特征

2009年8月27日15-18时,石家庄地区出现雷暴大风等灾害性强对流天气过程,石家庄地区北部新乐县境内的多普勒雷达探测到了此次天气过程中完整的阵风锋、飑线、中气旋等中尺度天气系统,并对此次雷暴大风的环境场和多普勒雷达产品进行分析。结果表明：低层逆温、中低层垂直风切变较强的不稳定层结为强对流天气的发生发展提供了有利的环境条件。阵风锋对对流风暴发展强度具有反馈作用,当二者逐渐远离时,对流风暴强度减弱甚至消亡;当二者逐渐靠近时,对流风暴发展加强,甚至发展为超级单体对流风暴。多单体对流风暴带状排列构成飑线系统,所经测站出现风速突增、风向急转、气压涌升、气温下降,钩状回波、人字型回波、弓形回波和深厚持久发展的中气旋是本次天气过程中的超级单体对流风暴所具有的典型特征。地面破坏性大风主要由超级单体对流风暴所引发。     

山东中西部一次超级单体分裂过程的雷达回波结构和环境条件分析

利用常规观测资料、济南多普勒雷达资料、FY-2G资料和加密自动站等资料分析了2016年6月14日一次在华北冷涡背景下发生的超级单体风暴生成及分裂过程,对超级单体分裂过程的雷达回波特征和环境条件进行了详细的分析。结果表明,超级单体风暴发生在地面中尺度辐合线附近,中层短波槽前,高空有中空急流的环境下,触发的对流云团向偏东方向移动中,在不稳定层结和较强的垂直风切变作用下,对流风暴发生分裂且右移性对流风暴发展加强。风暴分裂后环境风左侧的风暴单体并没有受到明显抑制,中尺度辐合线附近的露点锋生抵消了反气旋性风暴的受抑制程度,使反气旋性风暴能有所加强并持续更长的时间。环境风右侧的风暴单体发展加强,且持续时间长达2 h。风暴分裂是在单体发展的初期开始,分裂先从中高层开始,然后向下延伸,分裂后相对于环境风方向,左侧单体为反气旋性左移风暴,右侧为气旋性右移风暴。气旋性右移风暴强烈发展为具有低层的入流缺口、中高层的弱回波区及风暴顶的强辐散,与经典超级单体风暴回波特征类似。分裂后右移风暴伴有深厚持久的中气旋,其起源于中层4～5 km,然后向上和向下发展,最强旋转出现在高层,旋转速度达29 m/s,这与典型超级单体内中气旋都是中层旋转最强有所不同。     

Winter storms in Switzerland North of the Alps 1864/1865–1993/1994

Summary In the framework of the Swiss National Research Program 31 Climate changes and natural disasters the question was brought up whether a global warming of the atmosphere would have an influence on the frequency and/or intensity of the extratropical storms of the Swiss winter season. In order to investigate a possible trend, time series of days with a minimum wind speed estimate or measurement equivalent to Beaufort 7, 8 and 9 were established. The longest being a record of the mesonet station Zürich from the period 1864 until 1993 (130 years). Slightly shorter time series for three additional stations in Northern Switzerland were compiled to control the behavior of the longest record and to verify the observed temporal trend. From the location of the four investigated wind records the observational domain was restricted to the part of Switzerland north of the Alps whereas for further meteorological considerations the whole North-Atlantic-European area was included.A negative regional trend in the number of storm days has been observed during the last century. In particular, the period before 1940 has to be interpreted as windier than the following decades. The duration of a storm event also decreased on average. In spite of an increase in cyclonic westwind situations since about 1960 over Europe, Switzerland was hit by fewer storms during the same period. One explanation could be that the whole westwind belt has moved slightly further north where a deepening of the cyclones was observed in recent times. Switzerland is usually situated at the southernmost edge of the particular storm fields and is therefore less influenced by strong gales. Rare exceptions are the cases when a secondary depression directly hits Central Europe, e.g. as happened in February 1990 (storm Vivian).With 11 Figures     

江苏沿江地区一次强冰雹天气的中尺度特征分析

利用常规气象资料、卫星、多普勒天气雷达、风廓线雷达等资料,对发生在江苏沿江地区一次强冰雹天气形势背景、环境热动力条件、强冰雹发生前地区环境场变化、超级单体雷达回波中尺度特征等进行了详细分析。结果表明:(1)在东北冷涡槽后干冷气流影响下,中高层干冷、低层暖湿的不稳定层结,高低空急流以及地面辐合系统的配置为此次强对流天气的产生提供了有利热动力条件;高CAPE值、逆温层、低层适当水汽条件及较强的深层垂直风切变有利于强冰雹天气的发生。(2)利用多普勒天气雷达、风廓线仪数据反演垂直分布的物理量场(平均散度、平均垂直速度、相对风暴螺旋度、垂直风切变)能够反映本站上空环境场的快速变化情况:强对流系统移入本站前雷达站上空逐渐调整为低层辐合、中高层辐散的风场配置结构,螺旋度和垂直风切变数值逐渐增加,表明环境场有利于强对流系统的维持发展。(3)强降雹超级单体除具有三体散射现象、入流缺口等雷达回波中尺度特征外,持久深厚的中气旋存在造成了显著的有界弱回波区和高悬垂强回波区。应用双多普勒雷达风场反演技术揭示了超级单体内部环流结构:低层气旋性旋转,中层旋转加强,高层风场辐散。超级单体内部涡旋特征的出现和维持有利于支撑空中大冰雹的增长。     

雅安一次极端强降水的超级单体风暴特征及成因分析

2020年8月10—11日雅安市出现了一次区域大暴雨天气过程,其中芦山县出现了特大暴雨,此次大暴雨天气过程持续时间长,最大累积降水量和最大小时雨强较大,均突破了历史极值,具有较强的极端性。通过分析雷达回波可知,此次极端强降水是由强降水超级单体风暴的稳定少动造成,具有有界弱回波区、V字型缺口以及被包裹于强降水区的中气旋等特征。该文根据雅安市365个区域自动站雨量数据、MICAPS实况资料、雷达以及NCEP 1°×1°再分析资料等资料,分析了造成此次强降水超级单体风暴产生的原因为：(1)行星尺度和天气尺度系统稳定少动,低层夜间低层急流发展,输送暖湿平流,有利于对流不稳定层结的建立,为强降水超级单体风暴的发生提供了有利的环境条件。(2)地面到低层的假相当位温异常偏高,有利于对流不稳定的进一步发展,在强对流风暴附近还存在中尺度的假相当位温的密集区,锋区的动力强迫生成的次级环流有利于低层不稳定能量和水汽向高层输送,同时也触发不稳定能量的释放,产生较强的上升运动。(3)强的垂直风切变以及大的对流有效位能有利于强降水超级单体风暴的发生和维持其有组织的程度。(4)水汽条件异常也是此次强降水超级单体风暴...     

2004年初春武汉机场临近的两次强雷暴天气过程分析

使用常规地面和高空原始报文资料,采用最优插值法,对2004年4月29日出现在武汉天河机场临近的两次强雷暴天气过程进行了客观诊断分析。结果表明:两次强雷暴天气,前一次为典型的飑线天气过程,后一次为超级雷暴单体天气过程;高空槽、冷锋、中尺度低值系统是当天两次强雷暴天气的触发机制;低空深厚湿层(水汽丰富)、高低空存在急流强风带对当日飑线天气的形成和发展较为有利,强的不稳定层结、强的环境风垂直切变以及上层干、下层湿的湿度层结对当天超级雷暴单体的形成和发展十分有利。     

弱天气系统强迫下北京地区对流下山演变的热动力机制

利用三维数值云模式和雷达资料四维变分(4DVar)同化技术,通过对京津冀地区4部新一代多普勒天气雷达观测资料进行快速更新同化和云尺度模拟,初步分析了弱天气系统强迫下两次发生在北京地区对流风暴的低层动力和热力影响机制。这两次风暴过程处于弱天气系统强迫和弱层结背景下,局地冷池和环境风场的相互配合是造成山上对流风暴是否能够顺利传播下山的关键机制。起初,两个个例平原局地热、动力不均衡形成平原冷池,而冷池的“障碍物”作用进而阻碍环境风场的传播配置。在此机制下,导致在冷池东南边缘形成较强的辐合上升、垂直风切变和螺旋度。在6月26日个例中,由于冷池强度较强且位置偏南,因此阻断了东南暖湿气流向山区的输送,形成由平原至山区的辐散区使得山区的对流风暴不断减弱。但是,随着已经消散的对流风暴下沉气流,覆盖至冷池边缘东南气流上空形成了较强的风切变和垂直螺旋度,进而促使在冷池边缘形成新的对流风暴。而且,在新对流风暴生成后,由于平原地区整体切变强度较弱,因此形成了冷池扩张强度大于对流风暴传播速度的态势。这种配置会切断暖湿入流,从而导致对流风暴快速消亡。对于8月1日个例,冷池位置偏北,因而不受冷池阻挡作用的偏南风在山脚形成较强的辐合上升,同时与下山的偏西风形成明显辐合上升区,有利于山区对流风暴的不断增强;进而,受此影响,山上风暴降水产生若干冷池,新生冷池和原有冷池的相互挤压,在迫使中、北部风暴增强的同时,最终也导致这些风暴互相靠近,最终合并组织成带状对流系统。同时,北部冷池边缘形成的辐合带也为对流风暴向山下传播提供有利条件,而回波产生的冷池进一步增强,并明显扩展。低层风场指示冷池出流(阵风锋)更加强烈且存在明显的“前冲”特征,显现出部分飑线系统的热动力特征。但是由于此时平原地区处于弱切变环境中,风切变强度不能与冷池出流强度相平衡,同样冷池扩展将领先于对流风暴移动,切断东南暖湿入流,导致原有风暴快速减弱。在文章的最后,基于观测和模拟结果,对比分析这两个个例,初步得出了与对流风暴传播下山发展演变密切相关的低层热、动力配置概念模型。     

山东半岛两次海风锋引起的强对流天气对比

利用常规地面和高空观测资料、烟台和青岛多普勒天气雷达资料、加密自动气象站等资料分析2014年7月14日(“7·14”)和2009年6月29日(“6·29”)山东半岛两次海风锋引起的强对流天气。结果表明:“7·14”强对流天气发生于冷涡后部前倾槽的环流形势下, 明显的静力不稳定层结、中等大小的对流有效位能及垂直风切变相对偏弱, 是此次对流风暴持续时间短且降雹范围较小的原因; “6·29”过程是东北冷涡影响下的强对流天气。海风锋、阵风锋、地面辐合线是两次过程的触发机制, 两次过程都出现了高悬的强回波、弱回波区、回波悬垂、钩状回波、中气旋等超级单体回波特征; 大冰雹形成期表现为中气旋垂直伸展较大和旋转较强, 两次过程的超级单体风暴均由海风锋触发的靠近山脉的风暴发展加强而成, 即地形与海风锋结合导致的更强抬升在加强对流风暴并演化为超级单体风暴中起了关键作用。但“6·29”强对流天气过程出现了强中气旋, “7·14”强对流天气过程出现了弱中气旋, 因此, 前者对流范围更大、强度更强。     

The supercell thunderstorm on 8 June 1990: Mesoscale analysis and radar observations

Summary A case study of supercell thunderstorm development over Po Valley in northern Italy is discussed. The data were collected during MATREP, a field project operated in the month of June 1990. During the late morning hours of 8 June, before the passage of a cold front, a supercell and a single cell developed at the same time in eastern part of Po Valley, about 60 km apart from each other.Surface mesoscale analysis helps to explain these different storm evolutions due to interaction among local circulations, Adriatic Sea and orography. While dry wind (foehn) dumps the thermodynamic instability in single-cell environment, a moisture circulation affects the origin area of supercell. Computation of corresponding instability indices again supports the peculiar evolution of the two storms which is also analyzed by means of radar data.With 20 Figures     

产生致灾大风的超级单体回波特征

基于中国东部平原地区31部S波段多普勒天气雷达数据和实况记录,筛选出2002-2020年56次由超级单体风暴导致的25m·s-1以上的直线型大风事件,分析超级单体风暴多普勒天气雷达回波特征与其导致的直线型大风间关系,获得产生直线型致灾大风的超级单体的量化结构特征,为超级单体产生的大风的主客观监测预警提供参考.统计结果表...     

一次致雹强风暴的多普勒雷达特征分析

利用NCEP再分析资料和北京、天津的多普勒天气雷达产品对2007年7月9日华北中部地区一次伴有短时暴雨、局地冰雹和短时大风等强对流天气过程进行分析研究。分析表明,此次天气过程发生前高空转为前倾槽,并具有较强的不稳定层结;近地层的风切变线是雷暴生成的条件。物理量诊断分析表明：降水前水汽辐合区已从近地层扩展到850 hPa,但比较浅薄;低层辐合、高层辐散的配置加强了垂直上升运动;强对流天气发生区域处于垂直上升运动最强的区域内。多普勒天气雷达产品分析表明：致雹风暴具有中气旋特征和类似强降水超级单体的性质;路径预报的准确率与雷暴的总数目和移动异向性有关,雷暴的实际移向角度与雷达的路径预报相比存在明显偏差,总体偏差在29～67°之间,但路径预报产品仍对天气预报具有一定指示性;风廓线产品中3-7 km高度内垂直风切变矢量随高度呈顺时针旋转,在这种有利的条件下风暴有可能发展成强降水超级单体。     

Fine-resolution regional climate model simulations of the impact of climate change on tropical cyclones near Australia

Fine-resolution regional climate simulations of tropical cyclones (TCs) are performed over the eastern Australian region. The horizontal resolution (30 km) is fine enough that a good climatological simulation of observed tropical cyclone formation is obtained using the observed tropical cyclone lower wind speed threshold (17 m s^–1). This simulation is performed without the insertion of artificial vortices (bogussing). The simulated occurrence of cyclones, measured in numbers of days of cyclone activity, is slightly greater than observed. While the model-simulated distribution of central pressures resembles that observed, simulated wind speeds are generally rather lower, due to weaker than observed pressure gradients close to the centres of the simulated storms. Simulations of the effect of climate change are performed. Under enhanced greenhouse conditions, simulated numbers of TCs do not change very much compared with those simulated for the current climate, nor do regions of occurrence. There is a 56% increase in the number of simulated storms with maximum winds greater than 30 m s^–1 (alternatively, a 26% increase in the number of storms with central pressures less than 970 hPa). In addition, there is an increase in the number of intense storms simulated south of 30°S. This increase in simulated maximum storm intensity is consistent with previous studies of the impact of climate change on tropical cyclone wind speeds.     

雷暴大风环境特征及其对风暴结构影响的对比研究

2009年6月3日,受冷涡后部次天气尺度横槽的影响,在相邻的两个区域先后出现雷暴大风天气,造成两地强风的风暴类型、地面大风分布及灾害程度差异显著。风暴结构分析表明:产生晋陕大风的雷暴类型为一般单体风暴和脉冲风暴,而产生商丘致灾大风的则为典型的弓形回波。结合观测和数值模拟资料分析产生上述两类雷暴大风的环境要素,并构建其环境温、湿度廓线,结果表明:(1)晋陕大风区环境探空温、湿度廓线呈倒V形,为典型的干下击暴流探空廓线,类似探空在中国西部高原地区夏季常见;(2)商丘雷暴大风区环境温、湿度廓线类似典型湿下击暴流探空。数值模拟给出了典型的一般单体特征结构,老雷暴单体出流在其前方触发新单体。在中低层相对干的环境下多个对流单体的冷下沉形成冷池,强风由对流单体下沉辐散气流叠加在冷池密度流上造成。两类雷暴大风环境风垂直切变特点为:深层环境风垂直切变较弱、强水平风垂直切变集中在中低层。数值模拟表明:在这种风垂直切变配置下,低层湿度成为风暴结构的决定因素:中-高湿度环境下形成高度组织化的飑线,且其单体具有较强中层旋转;低湿度环境下产生组织程度差的一般单体和脉冲风暴,并基于高分辨率数值模式模拟结果给出了环境影响风暴结构的物理图像。     

A two-moment cloud microphysics parameterization for mixed-phase clouds. Part 2: Maritime vs. continental deep convective storms

Summary A systematic modeling study investigates the effects of cloud condensation nuclei (CCNs) on the evolution of mixed-phase deep convective storms. Following previous studies the environmental conditions like buoyancy and vertical wind shear are varied to simulate different storm types like ordinary single cells, multicells and supercells. In addition, the CCN characteristics are changed from maritime to continental conditions. The results reveal very different effects of continentality on the cloud microphysics and dynamics of the different storms. While a negative feedback on total precipitation and maximum updraft velocity is found for ordinary single cells and supercell storms, a positive feedback exists for multicell cloud systems. The most important link between CCN properties, microphysics and dynamics is the release of latent heat of freezing.     

两类不同风灾个例超级单体特征对比分析

采用分钟级加密自动气象站观测资料,盐城、淮安和岳阳、荆州雷达探测数据,以及欧洲中期天气预报中心（ECMWF）高分辨率的ERA-Interim全球再分析数据,对比分析了2016年6月23日江苏阜宁龙卷灾害和2015年6月1日湖北监利下击暴流大风灾害的环境特征与超级单体的结构特征。结果表明:（1）两次强对流大风灾害发生在相似的低空环流背景下:风灾发生在低空急流出口区左侧的暖区内、850 hPa低涡中心东侧6—7个经距的位置;环境大气的对流有效位能大于2000 J/kg。但是风灾的类型不同,江苏阜宁大风灾害主要由超级单体龙卷造成,监利“东方之星”沉船事故主要是超级单体触发的下击暴流造成。短时强降水中心与风灾中心的相对位置不同:阜宁龙卷移动方向的左侧伴随着最强短时降水;湖北监利沉船事件发生期间,风灾中心与短时强降水中心基本重合。鉴于不同性质的对流大风位置与超级单体母体的中心位置对应关系上存在差异,通过比较地面观测的瞬时大风与瞬时强降水中心的相对位置将有助于区分强对流大风的性质。（2）环境风垂直切变强度对对流风暴结构、发展、维持有重要影响:阜宁龙卷发生时,其上空0—6 km风垂直切变达4×10-3 s-1,超级单体有明显的向前倾斜结构,形成有界弱回波区;而监利强对流沉船位置0—6 km风垂直切变只有2.3×10-3 s-1左右,风暴单体中的上升气流近乎于垂直。阜宁超级单体中气旋,首先出现在0—1.5 km风垂直切变和0—3 km风暴相对螺旋度带状大值区,在向抬升凝结高度更低的环境移动过程中,其底部不断下降,形成龙卷;而在监利沉船区,中低层风切变和风暴相对螺旋度相对要弱得多,对应风暴单体中的中气旋强度、持续性较弱,中气旋底部高度维持在1.6 km左右。（3）环境湿度垂直结构特征不同可能是风暴单体形成不同类型灾害大风的重要环境因子。监利下击暴流造成的风灾发生时,在地面气温迅速下降过程中,气压变化呈现快速跳升又快速下降的“尖锥”形,气压峰值比降水峰值提前4 min出现。它与对流层中高层环境大气中较为深厚的干空气卷入对流风暴中造成水物质强烈蒸发、冷却过程有关。而阜宁风灾过程中,环境大气中层仅存在非常浅薄的干层,加之低层较为深厚的饱和大气环境,对应的地面冷池效应相对较弱。      

Analysis of Three Supercell Storms with Doppler Weather Radar Data

Three supercell storms on 24 June 2004 (0624), 28 June 2003 (0628), and 27 September 2002 (0927) induced different damages in Shandong Province. Storm 0927 was inferior in size and intensity to storms 0628 and 0624. The structure and evolvement of the three storms were analyzed in detail based on the WSR-98D radar data in combination with weather charts. The results show that mesoscale surface convergence triggered release of instable energy, which resulted in severe convection. During the development stage, storms 0927, 0628, and 0624 displayed multi-cell propagation, single-cell evolution, and multi-cell mergence, respectively. The storm tracks were similar: they were all right-moving supercell storms, i.e., moving at an angle of 30°–70° to the right of the mean wind and at a speed of about 45%-70% of the mean wind speed. In the mature stage, the maximum reflectivity appeared at the low level in storm 0927, mid level in storm 0628, and mid-upper level in storm 0624. These storms possessed almost all typical features of supercell storms: weak echo region (WER), bounded weak echo region (BWER), and mesocyclone. An organized mesocyclone formed at the middle height of an updraft, deepened gradually downward and upward, and became a typical mid-level mesocyclone with strong updrafts. The vertical structures of airflows in the three storms were similar, i.e., significant convergence at low level, nearly pure rotation at mid level, and divergent rotation at upper level. However, signatures of mid-level horizontal airflows in the three storms were different: at mid level, there was a single vortex in storm 0628, but a double-vortex flow pattern was seen in storms 0927 and 0624. The horizontal structure of the double-vortex flow was hard to be blown away by the environmental airflow, and thus the storms could persist for a longer period of time than the single vortex storm.