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1.
We examined microsecond- and submicrosecond-scale pulses in electric field records of cloud and cloud-to-ground lightning discharges acquired in summer 2006, in Gainesville, Florida. A total of 12 cloud and 12 ground flashes were analyzed in detail, with the electric field record length being 96 or 200 ms and sampling interval being 4 or 10 ns. The majority of pulses in both cloud and ground discharges analyzed in this study were associated with the initial breakdown process and were relatively small in amplitude and duration. The typical durations were an order of magnitude smaller than tens of microseconds characteristic of “classical” preliminary breakdown pulses. We estimated that 26% of the pulses in the 12 cloud discharges and 22% of the pulses in the 12 cloud-to-ground discharges had total durations less that 1 µs. 相似文献
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Using a 3D lightning radiation source locating system (LLS), three pairs of associated lightning discharges (two or more adjacent lightning discharges following an arbitrary rule that their space-gap was less than 10 km and their time-gap was less than 800 ms) were observed, and the interaction between associated lightning discharges was analyzed. All these three pairs of associated lightning discharges were found to involve three or more charge regions (the ground was considered as a special charge region). Moreover, at least one charge region involved two lightning discharges per pair of associated lightning discharges. Identified from electric field changes, the subsequent lightning discharges were suppressed by the prior lightning discharges. However, it is possible that the prior lightning discharge provided a remaining discharge channel to facilitate the subsequent lightning discharge. The third case provided evidence of this possibility. Together, the results suggested that, if the charges in the main negative charge region can be consumed using artificial lightning above the main negative charge regions, lightning accidents on the ground could be greatly reduced, on the condition that the height of the main negative charge region and the charge intensity of the lower positive charge region are suitable. 相似文献
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利用2011年1月至2019年12月安徽省ADTD闪电定位系统监测资料,对安徽南部山区与北部平原的闪电频次、极性、雷电流强度等参数进行对比分析。结果表明:安徽南部山区总闪电频次约为北部平原的2.84倍,北部平原正闪比高于南部山区,这与两地区强对流天气类型有关。两地区闪电频次的月、日变化均呈单峰分布,春季、夏季闪电活动明显多于秋季、冬季,午后至傍晚为一天中的雷电活跃时段,但南部山区在雷电高发月份及时段的闪电频次波动程度远大于北部平原。在雷电流强度方面,北部平原整体上大于南部山区,正、负地闪强度分别高出10.77 kA、9.52 kA,其中正地闪强度峰值均出现在2月,负地闪均为10月,南部山区正、负地闪及北部平原负地闪日强度峰值与频次峰值时段相反。对安徽省总闪频次进行主成分分析表明,EOF分解的前5个特征向量累计方差贡献达到59.137%,空间上表现出安徽南部山区与北部平原雷电活动变化趋势既具有一致性,也具有明显的南北差异。 相似文献
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为了掌握重庆市雷电活动规律,采用数理统计方法及ArcGIS软件,对2008—2019年ADTD闪电定位资料进行分析,得到了重庆市地闪频次的时空分布特征,雷电流幅值、陡度的分布特征和累积概率分布函数。结果表明:重庆市平均每年发生地闪2.08×105次,其中负地闪占95.7%;地闪频次年际变化大,最多年为3.04×105次,最少年为1.27×105次,月分布呈单峰型,7—8月为雷电高发期,占全年的57.9%,日变化呈双峰型,负地闪在夜间03时及下午17时到达峰值,正地闪峰值出现时间比负地闪要晚1—2 h,且午后的峰值远小于夜间;地闪密度空间分布与地形关系密切,大值区主要集中在山脉的交汇处及台地—丘陵向山地的过渡地带;江津北部至重庆中心城区、开州南部至万州北部、忠县南部至石柱西部、永川南部—荣昌至大足西部为地闪密度大值区,密度普遍大于3次·km-2·a-1,局部大于6次·km-2·a-1;总地闪平均幅值为37.9 kA,其中10—50 kA... 相似文献
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根据2007—2019年地闪监测资料,采用数理统计方法,分析湖北省闪电活动时空分布特征,融合地闪密度和雷电流强度,提出雷电强度的概念,并完成湖北省雷电强度等级划分。结果表明:湖北省以负极性闪电为主,占94.7%,平均正地闪强度为50.2 kA、负闪36.0 kA、总闪37.0 kA。闪电活动主要集中在全年的3—9月、全天的14—20时,闪电活动较弱的月份、时段发生正地闪的比例较高。正地闪强度月变化大致呈“V”型,总闪电和负地闪强度逐月波动变化。雷电流强度日变化主要呈单峰单谷型,正地闪强度09时最大,15时最小,总闪电和负地闪13—14时雷电流强度最小,05时最大。地闪密度和雷电流强度存在地域性差异,整体呈东高西低分布特征。湖北省雷电强度可划分为高、中、低3个等级,高值区主要位于湖北东部的大别山、幕阜山与江汉平原交汇地带以及湖北西部山区向江汉平原的过渡地带;湖北西南、湖北西北以及湖北个别边缘区域雷电强度等级较低;中值区主要分布在湖北中部平原一带。 相似文献
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E. T. Pierce 《Meteorology and Atmospheric Physics》1955,9(1):78-86
Summary It is shown that lightning flash counters responding only to the electrostatic component of the change in field are likely to be least subject to error; this implies a preferential selection of very low frequencies. Data and examples indicating the extent of the inaccuracies encountered are given. From statistics, showing rates of flashing and the duration of discharges, it is concluded that counters should have an insensitive period of approximately a second. Some remarks on general design considerations are appended, and a simple circuit for counting discharges to ground is given.
With 5 Figures 相似文献
Zusammenfassung Es wird gezeigt, daß Blitzzähler, welche nur auf die elektrostatische Komponente der Feldänderungen reagieren, die geringsten Fehlerquellen aufweisen. Diese Methode erfaßt eine bevorzugte Auswahl sehr niedriger Frequenzen. Beobachtungsdaten und Beispiele für das Ausmaß der festgestellten Ungenauigkeiten werden angegeben. Aus der Statistik der Blitzzahlen und der Dauer der Entladungen wird geschlossen, daß die Zähler eine unempfindliche Periode von etwa 1 Sekunde haben sollen. Einige allgemeine Bemerkungen über die Konstruktion sowie ein einfaches Schaltschema für die Zählung von Entladungen gegen die Erde werden beigefügt.
Résumé On montre que les compteur d'éclairs qui ne réagissent qu'aux variations du champ électrostatique présentent le moins de causes d'erreur. Cette méthode comprend un choix préférentiel des très basses fréquences. On donne des exemples de l'importance des erreurs constatées. On déduit de la statistique du nombre des décharges et de leur durée que les compteurs doivent avoir une période d'insensibilité d'environ une seconde. Suivent quelques remarques générales sur la construction des appareils et sur un schéma simple de montage permettant de dénombrer les coups de foudre.
With 5 Figures 相似文献
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文章运用2013年内蒙古气象局闪电定位系统监测资料和雷灾统计资料,对内蒙古地区2013年雷电活动及雷电灾害的时空分布特征进行分析。结果表明,2013年共监测到雷电35万多次,其中正、负地闪比为1:13,高于南方省市的比例;正地闪平均强度为负地闪的2.6倍,破坏性强。全年地闪的97%集中在7—9月,最大地闪密度为18次/km2。据不完全统计,2013年共发生雷电灾害27起,直接经济损失107.91万元,死亡9人,受伤3人。雷电灾害造成人员伤亡主要发生在农牧区的户外环境,农牧民的防雷意识有待进一步提高。 相似文献
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山东地区闪电密度时空分布特征 总被引:8,自引:4,他引:8
利用山东地区2006年6月至2007年10月13站的闪电资料,分析了该地区闪电密度的时空分布特征。结果表明:13站相比5站布局,获取的闪电样本更多,代表性更好,探测精度更高,分析结果存在差异;闪电密度高值区域出现一定的南移,在半岛内陆地区和东部荣成市出现了新的高值区域,负闪所占比例增加,占99.06%,平均闪电强度增大,负闪平均强度11.47 kA明显低于正闪平均强度25.04 kA;正、负闪电频次年、日变化均呈双峰值特征,但不同时间、不同区域之间存在差异;闪电强度季节变化呈单峰谷形式,但各区域峰谷时间有差异,且冬季没有正闪电发生。 相似文献
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一次夏季雷暴天气过程中闪电活动特征分析 总被引:5,自引:4,他引:1
利用探空资料、多普勒天气雷达和闪电定位仪数据,分析了2009年7月30日发生在南京地区一次雷暴天气过程的雷达及闪电数据时空演变特征。结果表明:对流有效位能Ecap比起K指数(IK)等对于对流潜势预报具有更明显的指示作用,0 ℃层和-10 ℃层高度的降低有利于雷暴云的雷电活动;整个过程以负闪为主导,闪电强度越大,闪电频数也越高,每次闪电峰值后,都对应一次谷值;闪电数据与多普勒天气雷达回波叠加后分析发现,回波的生消演变对应着闪电频数和强度的生消演变,负闪主要落在强回波中心区域,正闪零星分布于回波强度梯度较大的区域;雷达径向速度图像特征变化更能揭示闪电发生发展的机制,逆风区对应雷暴中心区域,不仅是强降水的中心区也是闪电的中心区,对逆风区的识别监测能够更好的指导雷暴预警报工作;利用雷达数据计算的云底动能施力参量,能够很好的描述支持闪电起电的热动力特征,云底动能施力对雷电增长的贡献有一段持续传输过程,该参量峰值比频闪峰值和强度峰值都约有0.5 h的提前量。 相似文献
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利用江苏省闪电监测定位系统探测2007—2013年地闪观测资料和2013年云闪观测资料,研究了苏南地区高速公路沿线地闪和云闪的时空分布特征。研究表明:1)苏南地区高速公路的年、月地闪频次具有西部多于东部的分布特征,其中扬溧高速最多;6—8月是地闪出现的高峰期,且西部地区出现峰值时间(7月)早于东部地区(8月);但日地闪频次的峰值出现时间东部(13~16 h)要略早于西部地区(14~18 h)。2)地闪强度(峰值电流)主要集中在20~50 kA,总体趋势是东部大于西部;高速公路地闪强度高值区主要集中在宁镇丘陵以及太湖、长江沿线附近,其中南京绕城高速、扬溧高速镇江段、宁杭高速南京段、沿江高速无锡段、沪宁高速等都是地闪密度较高路段。3)云闪集中发生在5—9月,西部地区云闪频次波动明显,总体呈双峰型月变化分布特征;东部地区云闪频次相对集中,呈单峰型月变化分布特征;西部地区出现云闪日高频次的时间(13~18 h)要早于东部地区(17~18 h)。 相似文献
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利用2006—2015年6—8月章丘探空站逐日探空资料,计算了K指数、抬升指数、对流稳定度指数等6个环境参数,探讨了单个环境参数和多个环境参数组合与闪电活动的关系。结果表明:1)单个环境参数在一定数值范围内可作为闪电活动预报的指标,且较强的闪电活动更容易由大气的不稳定状态来预报;2)多个环境参数的组合可在一定程度上反映闪电活动的特征,闪电出现的概率随着达到大气不稳定临界值物理量参数个数的增多而增大,预报效果比单个参数更好;3)应用事件概率回归方法建立了闪电概率潜势预报方程,方程通过了α=0.01的显著性水平检验,通过检验和评估,闪电概率预报的TS评分达到78%,该方法的建立为闪电潜势预报提供了参考依据。 相似文献
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利用10 a TRMM卫星的总闪电资料和3 a的地闪定位资料,研究青岛地区闪电的时空分布特征及其规律.结果表明:青岛地区逐月闪电次数差异较大,闪电的季节变化明显,8月闪电最多.闪电活动日分布呈现双峰形式,最高峰值出现在17:00-19:00之间.从空间分布来看,闪电多发生在靠近青岛市的四个边缘地带,而青岛市中部闪电发生较少.青岛地区的平均总闪电密度为5.95次·km-2a-1,地闪平均密度为1.077次·km-2a-1.青岛地区的云闪与地闪比值平均为4.52,正地闪占总地闪的5.9%.正地闪的平均强度为51.63 kA,最大值为561 kA;负地闪的平均强度为34.53 kA,最大值为481 kA. 相似文献
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Yijun Zhang Weitao Lu Jun Li Wansheng Dong Dong Zheng Shaodong Chen 《Atmospheric Research》2009,91(2-4):326-332
Using high-speed cameras, we have recorded the leaders contained in four natural negative cloud-to-ground (CG) lightning flashes in the summers of 2006 and 2007 at Conghua, Guangdong, China. It was found that the downward negative leaders preceding the first return stroke could propagate at quite different speeds. In one flash, the average speed of the downward negative stepped leader with no branches is about 2.2 × 106 m s− 1, while that of the other 3 flashes are all of the order of 105 m s− 1 with multilevel branches. The luminosity of the leaders shows an increasing tendency in propagating downward to the ground. For the leaders preceding the subsequent strokes, although all of them exhibit high speeds as reported previously. One subsequent leader exhibits an increasing speed from 5.2 × 105 m s− 1 to 1.7 × 106 m s− 1 during its propagation from about 1.26 to 0.36 km above the ground, and its luminosity also increased. The speed and luminosity of a leader between subsequent strokes of a natural lightning appear to decrease as it developed downward. Its speed ranges from 1.1 × 106 to 1.1 × 105 m s− 1, with a height between 1.15 and 0.81 km above the ground. 相似文献
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利用常规观测资料、FY-2G/2E卫星黑体亮温(
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Weitao Lu Yijun Zhang Xiuji Zhou Xiushu Qie Dong Zheng Qing Meng Ming Ma Shaodong Chen Fei Wang Xiangzhen Kong 《Atmospheric Research》2009,91(2-4):353-359
Using a high-speed camera system and two electric field antenna systems, we have documented the initial processes of an altitude-triggered negative lightning (ATNL). The optical records clearly show that ATNL begins with the inception and propagation of an upward positive leader (UPL) and then a simultaneous propagation of UPL and downward negative leader (DNL), known as the bidirectional leader process, follows. Based on the optical records, it is inferred that (1) the triggering height is about 371 m; (2) the two-dimensional (2D) propagation speed of the UPL in its inception phase is about 3.8–5.5 × 104 m s− 1 during its propagation from about 393 to 452 m above the ground; (3) the grey levels of the DNL are about one order of magnitude higher than that of the UPL in their inception phase; (4) a discharge phenomenon propagating along the elevated triggering wire part of the lightning channel occurs after the mini-return stroke (MRS), with a 2D propagation speed of about 1.6–2.0 × 105 m s− 1. Combined with the simultaneous electric field change records, it is further inferred that (1) the UPL incepts about 932 μs earlier than the unstable DNL and about 4.1 ms earlier than the stable DNL; (2) the unstable DNL propagates downward intermittently three times with a time interval of about 1 ms, and each propagation contains a different number of steps with an average step length of about 7 m; (3) the stable DNL incepts at the tip of the unstable one, with a 2D propagation speed of about 1.9 × 105 m s− 1, an average step length of about 3 m, and a stepping time interval varying from 6 to 31 µs with a mean value of 15 µs. 相似文献
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Some aspects of the correlation between lightning and rain activities in thunderstorms 总被引:1,自引:0,他引:1
The lightning activity of convective systems is a sometimes fruitful indicator of their precipitation production. The present study compares rain volume with different types of lightning activity in several convective systems. The study uses data obtained in the Paris area where two lightning detection systems coexist. The Météorage network provides the location and the polarity of cloud-to-ground flashes, while the SAFIR system detects the total flash activity: cloud-to-ground, intra-cloud flashes and VHF individual sources within a given time window. The overall spatial correlation between rain and lightning appears to be very consistent for all lightning types. A pixel-to-pixel study shows that positive CG flashes are associated with higher rainwater volume than negative flashes. Introducing a weight coefficient for positive CG flashes considerably improves the correlation between rain amount and lightning production. Taking into account the specific contribution of each type of lightning flash, the amount of rain can be estimated from the total electrical activity of each system. Comparison with the amount derived from radar measurement shows reasonable agreement. Finally, the parallel time evolutions of rain and lightning rates display quite similar characteristics. 相似文献