The Correlations between the Lightning Density Distribution of Sichuan Province and the Seismic Area

We here report our observations of the intense lightning events during ~15:00, 23 September to ~12:00, 24 September 2008 along the fault of Wenchuan-Beichuan counties in Sichuan Province, China where a 8.0 magnitude earthquake strike on May 12th, 2008. This intense lightning period had the highest density in all available the lightning monitoring data of Sichuan. The altered lightning pattern is unlikely to be a coincidence. We also found that the spatial-temporal characteristic of lightning in Sichuan has changed after the earthquake. We studied the correlations and analyze the data between lightning and earthquake in order to understand the seemingly unrelated events.

Discussion about the Relationship between Thunderstorm Days and Lightning Density

[Objective]The study aimed to discuss the relationship between thunderstorm days and lightning density. [Method]Based on the data of lightning density and thunderstorm days in Dalian region from 2007 to 2011,the optimal radius for the assessment of lightning risk was determined firstly,and then the relationship between thunderstorm days and lightning density in Dalian was fitted using the least square method. [Result]The optimal radius for the assessment of lightning risk was 25 km. The relation between lightning density and thunderstorm days could be fitted well by the formula y =0. 091x2-3. 447 2x ＋34. 713. [Conclusion]The fitting result was consistent with the actual situation,so the formula can be used in relative studies of Dalian.

Revision of CG Flash Density Based on Lightning Location Data

Using the data of the Lightning Location System( LLS) over Hubei Province,through the analysis of the distribution characteristics of CG( Cloud-to-Ground) flash density in 2015,it was found that the layout of the detection station had influence on the spatial distribution of lightning.Grid CG flash density data were used to characterize the spatial distribution of the CG flash,and station distance factor was used to characterize the detection station layout. The result showed that there existed negative correlation between density and factor,significant correlation between the density component and the factor for the lightning current amplitude of 5 to 30 kA,and insignificant correlation between >30 kA of density component and factor. So it is necessary to revise the density to eliminate the influence of the station layout. On the basis of the linear regression method and its residual theory,the revision model of the grid CG flash density and the statistical model of relative detection efficiency were established. The result consistency of segment and non-segmented revision of the density was verified. Through the contrastive analysis of theoretical detection efficiency and relative detection efficiency,the feasibility for revision method of CG flash density and the statistical method of relative detection efficiency was also verified.

Plasma Characteristic of Lightning Discharge Channel

The plasma characteristics of a lightning discharge channel are reviewed.The spectrum of the natural lightning is investigated by employing the slit-less spectrograph.It is found that the spectrum characteristics are closely related to the intensity of the lightning discharge.The lines in the lightning spectrum are classified into essential lines and characteristic lines,according to the characteristics of lightning spectra with different intensities.The characteristics of the lightning channel and the radiation of the lighting plasma are analyzed in the visible and infrared regions.It is shown that,the visible spectrum of lightning is determined by the radiation generated from the early stage to the development of lightning,while the near-infrared spectrum is determined by the radiation generated after current of lightning reaches the peak.The channel temperature and the electron density are calculated using the information obtained from the lightning spectrum.Both the temperature and the density decrease with the increasing length of lightning channel.Moreover,X-rays and neutrons are produced in the process of lighting mainly due to the pinch effects.

Temporal and Spatial Characteristics of Lightning Activity in Huai'an during 2011-2014

Based on the monitoring data of lightning activity in Huai'an from 2011 to 2014,the temporal and spatial distribution of lightning activity and lightning density were analyzed. The results show that positive and negative lightning activity in Huai'an had obvious seasonal variations and diurnal variations during 2011-2014. The month changes of positive and negative lightning activity had a single peak and valley,while the diurnal variations of both positive and negative lightning activity had double peaks and valleys. The high-value areas of ground flash density in Huai'an had obvious randomness. Seen from the spatial distribution of annual average of ground flash density,lightning activity was mainly distributed in Xuyi County,Jinhu County and Huai'an District.

Application of Data from a Lightning Location System in Huai'an Region

Based on data of cloud-to-ground lightning detected by a lightning location system in Jiangsu Province from 2007 to 2012and data of thunderstorm days from seven meteorological observation stations in Huai'an during 1961-2012,the spatial and temporal distribution characteristics of cloud-to-ground lightning in Huai'an were analyzed.The results show that the total frequency of cloud-to-ground lightning in one day was closely related to the intensity and frequency of thunder and lightning.The seasonal variations in the total frequency of cloud-to-ground lightning in Huai'an.The total frequency was shown in unimodal distribution,and the extreme values always appeared in July or August.Most cloud-to-ground lightning was negative,and its frequency accounted for about95.3% of the total frequency.Cloud-to-ground lightning density was high in the south of Huai'an and low in the north,and the serious and very serious ground flash zones concentrated in the south of Hongze County,and most parts of Xuyi and Jinhu County,so lightning protection should be an important task particularly in these regions.

Studies on the Distribution Characteristics of the Cloud-to-Ground Lightning and Its Disasters Prevention in Xinjiang, China in 2017

Xinjiang, China is affected by geographical terrain and other factors, and is prone to lightning disasters. In order to effectively carry out lightning protection and disaster reduction work and improve defense capabilities, based on the data of lightning location monitoring in Xinjiang in 2017 and the statistics reports of the lightning disasters from 2015 to 2017, the characteristics of the cloud-to-ground (CG) lightning activities and disasters in Xinjiang were statistically analyzed. The results show that the CG lightning in Xinjiang is mainly the negative one, accounting for 79.7% of the total lightning. In 2017, the distribution of positive, negative and total the CG lightning months mainly focuses on June to August, and the main occurrence period is from 14 to 23 hours. The intensity of total the CG lightning and negative the CG lightning mainly distributes from 20 to 40 kA, and the peak value appears in 30 kA. The CG lightning intensity is mainly distributed in 30 - 70 kA. The distribution of the CG lightning density in Xinjiang is larger in the north than in the south and larger in the west than in the east. Lightning disasters mainly occur from May to August, accounting for 93.2 percent of the total, with the largest number in June. From 2005 to 2017, 44.6% of lightning accidents occurred in farming and pastoral areas, followed by civil electronic equipment damage. In addition, electrical equipment, buildings and factory equipment are damaged by lightning strikes to varying degrees.

OBSERVATIONAL STUDY OF LIGHTNING CHARACTERISTICS IN HAIL-PRODUCING CLOUDS

1 INTRODUCTION Lightning is a phenomenon of atmospheric electricity with convective storms. Since the 1960＇s, its characteristics during weather processes of torrential rain, hails and tornadoes have been widely studied and a lot of attempts made to probe into the mechanisms responsible for the formation of lightningIll, giving rise to two theories explaining the lightning genesis, from the points of convection and ice-phase precipitation, respectively, In addition, some studies show, from various aspects, that lightning of severe convective weather. indicates the occurrence There has been lack of concrete indices to identify lightning features and determine hail-producing clouds. Apart from diagnostic . analysis based on conventional data , this work studies the evolution of lightning in 11 hails using relevant records and Doppler radar information and sums up a number of lightning features for hail weather in the sub-plateau area of Gansu province by taking as the criterion whether convective clouds cause hails in determining hail-producing clouds. In Gansu, hailproducing clouds usually originate from mountainous areas, follow fixed routes of movement and are often accompanied with heavy rainfall as they produce hails in more than a spot in the life cycle. To mitigate losses, it is essential to use scientific detectors to warn of hail weather in advance and conduct weather modification to check the growth of hails. The weather radar is an efficient tool to watch and forecast severe convective weather like hails, for it not only detects the structure but also tracks down the generation and evolution of hail-producing clouds to aid in isolating where the hail falls. It is, however, not realistic to perform real-time radar watch in Northwest China and existing radars are not capable of observing thunderstorms. Costing relatively low to purchase and maintain, the lightning locator has wide range of measurement and works nonstop without human attendance, making it easier to watch large-scale convective clouds in the region. With hails, heavy rains and tornadoes isolated and warned of based on features captured by the locator, operations of weather modification can be made more efficient with further identification from radar echoes and observed facts of electric mechanisms can be better understood for convective weather.

Temporal and Spatial Distribution Characteristics of Lightning Activity in the Pan-Pearl River Delta

Based on the lightning data acquired by a lightning imaging sensor(LIS)carried on the TRMM satellite from 1998 to 2013,the spatial distribution,seasonal,monthly,and diurnal characteristics of lightning activity in the Pan-Pearl River Delta were analyzed.The results show that in the Pan-Pearl River Delta,lightning activity was more in the south and less in the north.Near 23°N,lightning density was high from Guangdong and Guangxi to the southern edge of Yunnan.Lightning density weakened continuously as the latitude increased.Among the provinces in the Pan-Pearl River Delta,the maximum and average of lightning density in Hainan Province was greater than that of other provinces.Besides,the lightning activity showed obvious seasonal changes.In the whole year,lightning activity was the weakest in November and next February.Lightning activity in most areas of the Pan-Pearl River Delta was the strongest in August.The peak of lightning activity in most areas of the Pan-Pearl River Delta occurred from 12:00 to 20:00.Lightning activity was the weakest between 07:00 and 10:00 in most areas.

Statistical Analysis on Lightning Characteristics in Hebei Province

By using monitoring data of lightning locating system in Hebei during 1999- 2010 and lightning disaster data in Hebei during 2002- 2010,temporal-spatial distribution characteristics of ground flash and lightning disaster in Hebei Province were analyzed. Annual,monthly and daily changes of ground flash,lightning current intensity and ground flash density in Hebei were analyzed,and we compared ground flash with lightning disaster distribution.

Discussion on Common Problems in Risk Assessment of Lightning Disaster

The problems in calculating parameters of equivalent collection area,earth resistivity and lightning protection category as well as their effects on lightning disaster risk assessment were analyzed,and practical examples proved the effects of those differences on lightning protection identification,intercept efficiency calculation in evaluating lightning disaster risk. In the meantime,several new concepts,such as the height of buildings for lightning protection were defined,and a fixed radius value was set to the ground flash density for calculation,establishing the ground flash density formula to solve the problems in parameter calculation,which would be beneficial to promote the standardization of lightning disaster risk assessment.

太原夏季短时强降水与闪电的关系及应用

利用太原地区夏季三维闪电定位系统的2017—2021年闪电数据、小时降水量及国家站10 min降水量,分析短时强降水日的闪电特征,并将短时强降水站点与前1 h的闪电密度进行空间叠加。结果表明,短时强降水日闪电以负闪为主。负闪密度远大于正闪密度,且有明显的空间差异,负闪密度中心主要位于尖草坪北部和阳曲县南部。闪电频数峰值比10 min降水量峰值提前10~60 min,且闪电频数峰值(大于等于50次/10 min)及其后的20 min内闪电频数陡降其峰值的一半或以上,这对短时强降水有更好的指示作用。短时强降水站点与前1 h的闪电高密度区有很好的对应关系,且大多分布在闪电密度梯度相对较大的地区。当太原地区闪电频数大于100次/h时,闪电密度大于等于0.1次/km2·h对短时强降水落区预警命准率较高。

Climatological distribution of lightning density observed by satellites in China and its circumjacent regions

The 0.5°× 0.5° grid resolution distribution of lightning density in China and its circumjacent regions have been analyzed by using the satellite-borne OTD (Apr 1995-Mar 2000) and LIS (Dec 1997-Mar 2003) databases. It is shown that: (i) Firstly, the variability of the lightning density (LD) is particularly pronounced over the different subareas, 9 times greater over the south than the north side of Himalayas Mountains, 2.5 times greater over the eastern than the western area of China. While the maximum and minimum LD are respectively 31.4fl/km2/a (in Guangzhou region) and less than 0.2fl/km2/a (in the desert of western China). Secondly, the LD of China's continent regularly varies with latitude and distance off coast, which is consistent with annual mean precipitation in varying trend. In conclusion, the Qinghai-Tibet Plateau, the China's three-step staircase topography and the latitude are three important factors affecting macro-scale characteristics of the LD distribution, (ii) The regional differences in LD distribution are closely related to the mesoscale orographic forcing. In the eastern humid regions of China, the high LD belts often appear along the mesoscale mountains (with south-north or northeast-southwest direction, 500-1500 m ASL) and hills, while the low LD belts often appear on the plain and basin (valley) between the mountains. But in the western cold and arid regions of China, the relatively high LD belts mostly appear on the Qinghai Lake area of the southern side of Qilian Mountain, Yili River valley, the basin between Tanggula Mountains and Nyainqentanglha. On the coastal land, the high LD centers appear in regions where mountain and hill and large cities are located. This seems to be related to the interaction between the sea-land breeze and mountain-valley wind or city heat island effect, (iii) The China Sea is one of the relatively high LD zones on global oceans. It is very interesting that a high LD belt is located along the Kuroshio area. It is a new fact that the high temperature and high salinity characteristics of Kuroshio have obvious effect on the local deep convective activity. In addition, the intracloud/cloud-to-ground lightning ratio is close to 3.0 in Anhui Province.

EVALUATION OF GROUND STROKE DENSITY DISTRIBUTION AND LIGHTNING DETECTION EFFICIENCY IN BEIJING-TIANJIN-HEBEI AREA

It is possible to understand the lightning activities in a specific region and compare test results of different apparatus only when a reliable evaluation of detection efficiency distribution pertaining to a particular lightning location system(LLS)is available. Based on the data in 1992.an approximate evaluation of detection efficiency spatial distribu- tion for single-station lightning location system(M-LDARS)and LLP three-station lightning loca- tion system in Beijing-Tianjin-Hebei area is presented in the paper,showing that the average detec- tion efficiencies are smaller than 48% and 46% respectively.In addition,the article offers an eval- uation of spatial distribution of ground stroke density(D_g)and positive stroke percentage,indicat- ing that six high stroke density zones exist along the southeastern sides of the Taihang and Yan- shan Mountains.The stroke density of mountainous region is higher than that of the plain region, in contrast to the case of positive stroke percentage.Also,it is shown that within a radius of 250 km,the average of D_g is 1.2(km^(-2) a^(-1))while the average positive stroke percentage is 10.9%. Finally,the paper proposes a possible test method of accurately evaluating the spatial distribution of detection efficiency(A).

园区类项目区域雷击风险评估应用探讨

介绍区域雷击风险评估相关内容,包括项目前期勘测、闪电定位资料应用、评估子区域划定标准和区域雷击风险评估模型;以上海某化工园区为例,介绍项目基本情况、雷电环境特点、子区域划分,给出评价指标隶属度及区域雷击风险值的计算结果;提出在区域雷击风险评估时,应尽可能通过现场勘测、调研问卷等多种形式详细了解项目基本情况,并结合雷电分布特征详细划分子区域,开展区域雷击风险评估。

阿勒泰地区地闪时空分布特征及影响因素分析

为更好了解近年来阿勒泰地区地闪的时空分布特征及其影响因素,利用阿勒泰地区2013-2021年的地闪定位监测资料、气象参数和DEM高程等数据,采用反距离权重法、皮尔逊相关性分析等方法,对阿勒泰地闪进行分析。结果表明:年平均负地闪比例为89.03%,年平均白天地闪所占比例为64.48%。正地闪、负地闪、总地闪频次月变化均呈单峰型。总地闪、负地闪频次日变化整体呈M型。总地闪频次主要发生时段为14-18时。阿勒泰地区正地闪、负地闪频次百分比都呈单峰型,且均在20~40 kA达到顶峰。阿勒泰地区北部为地闪密度高值区。地闪频次、地闪电流强度与海拔高度通过了显著性检验。地闪频次与平均气温、平均相对湿度、降水量、2 min平均风速均通过了显著性检验。

超高层建筑防雷设计若干技术问题分析与讨论

分析了超高层建筑在防雷设计中的关键技术问题。依据现行国家标准的规定要求,从安全可靠、经济合理、切实可行的角度出发,通过总结长期以来从事的建设项目的机电顾问、建筑防雷施工图设计和防雷技术审查工作中的实践经验,提出了超高层建筑防雷设计中关于地闪密度值取值、等效面积计算、防侧击与均压环设计、接地干线与接地端子位置选择等问题处理的技术意见,对超高层建筑的防雷接地设计有一定的指导意义。

北京及其周边地区夏季地闪活动时空特征分析

利用M-LDARS闪电定位系统对北京及其周边地区1995～1997年6～9月的闪电观测数据,分析闪电活动的时空分布特征.结果表明:闪电活动在时间分布上存在两个峰值时段,13:00～21:00和23:00～次日05:00.通过对总地闪、分时段及峰值时段的地闪密度分析,发现北京及周边地区闪电活动有几个明显的集中区域,地闪高密度区主要出现在下垫面为山脉和水体的地方,闪电活动与下垫面的水汽条件关系密切,且正、负地闪的空间分布也呈现较大差异,表明雷暴云的电荷结构存在一定差异.

广州地域1999～2008年地闪密度图及雷电参数分析

为掌握高雷区雷电活动规律，以广州地区1999-2008年间雷电定位数据为基础，利用雷电参数统计技术及综合分析平台，结合GIS系统，详细研究了广州地域地闪总数、地闪密度、雷电幅值、雷电幅值概率分布及雷电日等重要雷电参数。研究表明广州地区地闪分布季节性明显，54％～83％的地闪主要集中在夏季；地闪密度空间分布具有较强的规律性，与海拔高度关系密切，相比雷电日更能科学反映实际雷电活动分布和变化特征；正负极性雷电流幅值均有明显的集中性。以广州电网500kV蓄增甲线为例，分析得到走廊沿线雷电活动与雷击故障具有较强的相关性，对于解决高雷区长期电网防雷难题更有指导意义。

杭州市雷电灾害风险区划及分析

根据浙江省2008—2010年ADTD闪电定位仪资料,首次将平均地闪强度引入雷电灾害风险评估中,结合杭州市的人口经济影响和自然地理要素,选取地闪密度、平均地闪强度、人口密度等16个雷电灾害风险评价指标,采用层次分析法计算各要素权重,从危险性、敏感性、易损性和防灾能力建立雷电灾害风险评估模型,分析雷电灾害的综合风险.从雷电灾害综合风险区划图可以看出,总体上雷电灾害综合风险在杭州市西南地区比较低,近海的东北地区则比较高;杭州市主城区、萧山区、余杭区、临安市和近富春江地区是雷电灾害综合风险较高的区域,低风险的区域主要在杭州中西部地区.对杭州市雷电灾害进行了灾度评价,以验证风险区划的正确性,证实区划结果与实际雷电灾害的发生具有较好的一致性.