云南强对流暴雨的闪电和雷达回波特征及相关性

利用闪电监测资料和多普勒天气雷达探测资料,对2007年汛期强对流暴雨的闪电和雷达回波特征及相关性进行分析,结果表明:云南大多数暴雨属于强对流性暴雨,而且以负闪电为主,负闪电占总闪电的90 %以上;暴雨日降水量与日闪电数相关小,强的降水不一定有强的闪电活动,但大的日闪频数一般对应的暴雨日降水量大;伴随有闪电活动的强对流暴...     

THE STATISTIC RELATION BETWEEN LIGHTNING AND CINRAD DOPPLER RADAR ECHOES IN CENTRAL GUANGDONG

Based on the CINRAD Doppler radar data in Guangzhou and the lightning data in 2004 by power suppliers of Guangdong, statistical study is done by overlaying lightning’s position on radar’s echo. The result shows the followings. The concentrated period in which more negative lightning occurred at the middle levels (2 – 14 km), where radar echo was moderate (12 – 45 dBz), rather than at the low levels with the weakest echoes or at high levels with the strongest echoes. At levels 3 – 11 km, where the radar echo was between 10 dBz and 35 dBz, the area of negative lightning was much larger in central Guangdong than in the rest of the province. At levels 0.5 – 7 km where the radar echoes were between 44 dBz and 51 dBz, the probability for a point to have negative lightning varies from 0.4 to 0.7.     

ANALYSIS OF CLOUD-TO-GROUND LIGHTNING CHARACTERISTICS IN MESOSCALE STORM IN BELIING AREA

The research indicates that there is a positive correlation between the negative CG flash rate and the area of radarecho with its reflectivity being equal to or greater than 30 dBz in the mesoscale convective system in Beijing area.A max-imum of the positive CG flash rate exists at both the initial and the dissipating stages.The CG flashes are usually locatednear but not within the high reflectivity center.The negative flashes are associated with.the positions of the updraft re-gion,and with the regions of wind convergence and wind shear.Generally,the negative CG flashes are concentrative andthe positive ones are dispersive.     

ANALYSIS OF CLOUD-TO-GROUND LIGHTNING CHARACTERISTICS IN MESOSCALE STORM IN BELIING AREA*

The research indicates that there is a positive correlation between the negative CG flash rate and the area of radar echo with its reflectivity being equal to or greater than 30 dBz in the mesoscale convective system in Beijing area.A maximum of the positive CG flash rate exists at both the initial and the dissipating stages.The CG flashes are usually located near but not within the high reflectivity center.The negative flashes are associated with.the positions of the updraft region,and with the regions of wind convergence and wind shear.Generally,the negative CG flashes are concentrative and the positive ones are dispersive.     

COMPARISON OF SINGLE-STATION LIGHTNING LOCATION WITH THREE-STATION MEASUREMENTS AND RADAR DATA

A single-station or monostatic lightning detection and ranging system (M-LDARS),that is based on Wait's wave propagation theory and arrival-time differences between sky- and ground-wave atmospherics,has been developed by the University of Science and Technology of China (USTC).Lightning location by the system was compared with a three-station lightning location (TLL) system during July and August 1991 in Beijing,under the support of Chinese Academy of Meteorological Sciences (CAMS).The experimental results show that M-LDARS system can be used to observe direction,distance,intensity and polarity of cloud-to-ground strokes with good confidence for ranges less than about 250 km.90 percent of M-LDARS location points were within radar echoes,i.e.about 90% of the points were inside of the 0 dB isoline or outside,but within 10 km of the 0 dB isopleth.Average direction deviation and relative average deviation of distance between the single- and three-station measurements are respectively 12.8° and 14.1%.     

OBSERVATION AND MODEL ANALYSES OF POSITIVE CLOUD-TO-GROUND LIGHTNING IN MESOSCALE CONVECTIVE SYSTEMS

The analyses of spatial and temporal characteristics of positive cloud-to-ground(CG)lightning for four mesoscaleconvective systems and two severe local convective systems in 1989 and 1990 show that positive CG flash rate usuallyhas two peak values.The major peak occurs during the developing stage of the storm and most of the positive CGflashes originate at the lower part of the storm.The minor occurs during the dissipative stage of the storm and most ofthe positive CG flashes originate at the upper part of the storm,especially in the region of the wind divergence in thestorm anvil.The positive CG flash rate is almost an order of magnitude larger in the developing stage than in thedissipative stage.The appearing time of the peak of negative CG flash rate is in accordance with that of the valley of pos-itive CG flash rate.The higher the intensity of the radar echo,the higher the positive CG flash rate.Most of the positive CG flashes oc-cur when the weak echo area is larger,and mostly originate in the region where the radar echo intensity is about 10dBzand in the back region of the moving storms.The spatial distribution of the positive CG flashes is much more dispersivethan that of the negative.The mesoscale analysis reveals a bipolar lightning pattern.The mean bipole--length reaches itsminimum during the mature stage of the storm and reaches the maximum during the developing stage of the storm.The vertical distribution of the charge density is calculated by a one-dimensional charging model.Then,we discussthe producing condition of the positive CG lightning and forming cause of charge structure mentioned above.     

强雷暴天气的闪电和雷达回波特征个例分析

利用粤港澳闪电定位系统、广州多普勒天气雷达和自动气象站等资料,分析了2017年6月2日发生在广州市中北部的一次强雷暴天气过程的地闪变化特征及闪电与雷达回波特征的关系.(1)本次强雷暴天气是华南一起典型的以西南急流和切变线为环流背景的强对流天气过程.在整个雷暴生命史中以负地闪为主,占69.3％;正闪在雷暴发展的初始和结束...     

鄂西北夏季对流降水回波特征的研究

该文通过对鄂西北1995～1999年6～9月273个对流回波个例进行统计分析，得出生成对流云的主要天气背景为西风低槽过境和副高外围的影响。对流云回波出现频率6、9月较少，7～8月较多。当地地形对对流云活动具有促进生成、约束移动、抬升加强等作用。对流云可分为单体、多单体、超级单体和混合云中对流等种类。6、9月对流云平均的生命时间较短，回波强度、顶高和强回波区顶高较低。相反，7～8月对流云回波特征值较高     

OBSERVATION AND MODEL ANALYSES OF POSITIVE CLOUD-TO-GROUND LIGHTNING IN MESOSCALE CONVECTIVE SYSTEMS*

The analyses of spatial and temporal characteristics of positive cloud-to-ground(CG) lightning for four mesoscale convective systems and two severe local convective systems in 1989 and 1990 show that positive CG flash rate usually has two peak values.The major peak occurs during the developing stage of the storm and most of the positive CG flashes originate at the lower part of the storm.The minor occurs during the dissipative stage of the storm and most of the positive CG flashes originate at the upper part of the storm,especially in the region of the wind divergence in the storm anvil.The positive CG flash rate is almost an order of magnitude larger in the developing stage than in the dissipative stage.The appearing time of the peak of negative CG flash rate is in accordance with that of the valley of positive CG flash rate.The higher the intensity of the radar echo,the higher the positive CG flash rate.Most of the positive CG flashes occur when the weak echo area is larger,and mostly originate in the region where the radar echo intensity is about 10dBz and in the back region of the moving storms.The spatial distribution of the positive CG flashes is much more dispersive than that of the negative.The mesoscale analysis reveals a bipolar lightning pattern.The mean bipole-length reaches its minimum during the mature stage of the storm and reaches the maximum during the developing stage of the storm.The vertical distribution of the charge density is calculated by a one-dimensional charging model.Then,we discuss the producing condition of the positive CG lightning and forming cause of charge structure mentioned above.     

"2003.6.2"十堰强对流天气雷达回波和数值模拟分析

利用714C天气雷达回波和数值模拟资料,结合其它天气资料,分析了2003年6月2日发生在十堰境内的强对流天气过程。结果表明,此次强对流天气过程是在有利的大尺度天气形势背景下,由复杂地形触发出初始单体并发展为多单体强风暴产生冰雹和大风天气,雷达回波特征明显。风暴回波强度强,回波结构紧密,顶部有旁瓣假回波,低层存在弱回波区（WER）,环境风的垂直切变较强。中β低涡的产生为强对流天气的产生和维持发挥了重要作用。     

雷达资料时间循环同化应用于闪电落区等研究初探

为研究夏季雷暴天气条件下的对流、降水、闪电的发展过程,有效使用高时空分辨率的遥感手段,如多普勒雷达、闪电定位仪等,利用中尺度数值模式ARPS及敏感的数据同化系统ADAS将VCP21模式下每6 min一次的雷达基数据资料进行时间循环同化,模拟得到相对可靠的三维空间、每10 min输出一次的对流云初步性态描述信息;进而结合目前公认的感应及非感应起电机制,通过云中电场强度与同化得到的云内相态模拟资料之间粗略微分关系,设定放电阈值,初步得到放电主要落点等信息;把本次模拟结果与江苏省闪电定位系统(LLS)实测资料做了对比,发现二者具有一定的可比性:(1)实测30 min内共有78次闪电,感应起电机制下共模拟出40次,非感应起电下有76次且首发时间较早。这也说明了非感应起电机制更易于雷暴云内电荷的衍生;(2)30 min内两种机制下模拟得到雷电发生的主要位置差别不大,和实测基本一致。     

应用于强对流天气预报的模式探空产品

仿照实测探空,根据数值模式站点预报的气象要素设计了包含十种常用稳定度指数的斜T-InP模式探空图。在综合评估的基础上,设计了一种模式探空的订正和产品的形成方法,并制作产品显示系统,它可以方便地提供地面站点模式探空和交互式模式探空的图形产品。模式探空产品的统计评估和具体强对流天气的个例分析中表明,模式探空产品对强对流天气预报有帮助。     

辽宁省7～8月降水回波特征

为配合辽宁省夏季人工催化积云试验,沈阳、鞍山雷达和雨量站网在2002~2003年7~8月进行了系统的观测。本文利用雷达资料,分析了辽宁夏季降雨回波类型,并重点研究了积层混合云降水的主要特征。结果得出,辽宁夏季冷涡天气系统降水和江淮梅雨一样,以积层混合云降水为主,大到暴雨常属于强积层混合云降水。     

双线偏振雷达探测的云和地物回波的特性及其识别方法

双线偏振雷达在定量测量降雨量的过程中，经常受到地物回波的干扰和影响。研究云和地物回波的反射率因子ＺＨ、差反射率因子ＺＤＲ的取值大小及两者的关系、空间变化梯度的结果表明：云的ＺＤＲ大于零，且有明显的随ＺＤＲ大于零、且有明显的随ＺＨ增加而增大的趋势，这反映了在强降雨回波中大粒子占的比例较大；而地物回波的ＺＨ和ＺＤＲ无明显变化规律，ＺＤＲ可正可负；云回波的空间变化率也明显小于地物回波。     

华南一次典型雷暴过程双偏振雷达参量与闪电活动关系研究

基于2017年5月8日华南地区一次典型飑线过程,分析了此次过程中闪电活动和-35～0 ℃温度层内双偏振雷达参量的分布特征以及双偏振雷达参量与闪电活动之间的关系.结果 表明:此次飑线过程中,双偏振雷达参量与闪电频次的趋势在时间变化上有较好的一致性,且随着闪电活动的发生及雷暴过程的增强,双偏振雷达参量中的冰水含量、雷达反射...     

地闪与对流性天气系统中降水关系的分析

利用１９９７年夏季在中国科学院兰州高原大气物理所平凉雷电与暴雹实验站设置的３站闪电定位系统所取得的地闪资料与雷达、降水及探空等资料进行了对比分析,发现地闪与对流性天气中的降水有较好的相关性,这种相关性用来对一般性对流天气中降水进行估测是可行的。通过非线性回归近似拟合得到平均雨强与对应时段内的地闪数回归方程为Ｒ＝１．６９２ｌｎＦ－０．２７３,相关系数ｒ为０．８６４１。同时地闪频数与层结最大不稳定能量一样能够指示对流性天气的发生和发展。     

绵阳地区夏季雷电特征分析及雷电流辐值概率分布算法修正

利用四川省绵阳地区2017—2019年6—8月闪点定位系统资料,对绵阳地区闪电频次、雷电流幅值和闪电密度分布进行研究。利用GIS软件获取地闪点的高程,分析了闪电频次空间分布特征,结果表明:闪电频次随纬度增加呈先增后减趋势,随经度分布呈现双峰特征,多发生于下垫面海拔高度400~600 m区域;绵阳地区地闪密度有三个高值中心分别位于安县西桑枣和雎水、江油东北二郎庙、绵阳市游仙区杨家湾地区,结合高程分析发现地闪多发区位于山地与平原交汇处偏向低海拔一侧。分析比较了目前常用的防雷计算方法规程法和IEEE推荐公式,在此基础上对绵阳雷电流幅值数据拟合分析,提出适用于本地的雷电流累计概率分布函数和概率密度计算公式。      

基于雷达和微波辐射计的湖北省冷季“高架雷暴”特征分析

利用常规观测、加密自动气象站、三维闪电定位仪、天气雷达和地基微波辐射计资料等,对湖北冷季(2014年11月)发生的3次高架雷暴过程进行了分析。(1)3次过程发生在地面冷锋后部地面冷气团中,主要以短时强降水和频繁的雷电活动为主,是典型的冷季"高架雷暴",对流区位于地面冷锋后部500 km左右。(2)地面到925 hPa的冷垫,迫使暖湿气流爬升,在925 hPa逆温层附近触发对流,冷垫之上西南暖湿气流越强,对流越旺盛,雷达径向速度剖面可以明显看到1 km之下的冷垫。(3)冷季高架雷暴雷电活动剧烈,CG(地闪)占总闪比例60%以上,而+CG则占CG的40%左右,闪电频次和降水有很好的时空对应关系,CG出现在较强降水中心附近及周围,IC和CG突增对降水均有一定的时间提前量。CG更靠近强回波中心,且和≥30 dBZ的回波位置对应较好,IC则分布在雷暴单体外侧回波强度≥15 dBZ的区域。0Ⅱ等温线以上的(最大)回波强度达到43 dBZ以上或者18 dBZ回波顶高超过7.5 km是湖北冷季高架雷暴是否发生雷电的重要预警因子。(4)地基微波辐射计温度、湿度廓线和探空曲线基本吻合,可以看到明显的冷垫、...     

对流云增雨作业效果回波对比分析

人工催化对流云的效果检验是一个非常复杂的科学难题，它受当前科研水平、仪器装备水平、研究对象复杂性等多方面的制约。该文通过运用加密雷达资料对一次对流云催化作业个例的效果进行分析，采用目标云和对比云比较分析的方法，探讨了根据雷达回波各种参数的变化来判断催化作业效果的途径。结果表明，目标云在降水、生命期特征、回波垂直特征参数变化等方面都表现出与对比云明显的差异，从而推断本次作业达到了增加降雨的效果。     

风切变对强对流云降水影响的模拟研究

本文用二维冰雹云模式，以实际探资料作为初始场，对风切变在强对流降水中的影响，进行了数据模拟。