Estimation of Lightning-Generated NO_(x) in the Mainland of China Based on Cloud-to-Ground Lightning Location Data

Lightning-generated nitrogen oxides(LNO_(x))have a major influence on the atmosphere and global climate change.Therefore,it is of great importance to obtain a more accurate estimation of LNO_(x).The aim of this study is to provide a reference for the accurate estimation of the total LNO_(x) in the mainland of China based on cloud-to-ground lightning(CG)location data from 2014 to 2018.The energy of each CG flash was based on the number of return strokes per CG flash,the peak current of each return stroke,and the assumed CG breakdown voltage.The energy of intracloud lightning(IC)was based on the estimated frequencies of IC and the assumed energy of each IC flash.Combining the energy of lightning and the number of nitric oxide(NO)molecules produced by unit energy(ρno),the total LNO_(x) production in the mainland of China was determined.The LNO_(x) in the mainland of China estimated in this study is in the range(0.157-0.321)×10^(9) kg per year[Tg(N)yr-1],which is on the high end of other scholars’works.Negative cloud-to-ground lightning(NCG)flashes produce the most moles of NO_(x),while positive cloud-to-ground lightning(PCG)flashes produce the least total moles of NO_(x).The breakdown voltage of PCG is greater than that of IC or NCG,while the latter has a greater output of LNO_(x).

The Characteristics of Cloud-to-Ground Lightning Activity with Severe Thunderstorm Wind in South and North China

The characteristics of cloud-to-ground(CG) lightning activity with severe thunderstorm wind(STW) in South and North China are analyzed using CG lightning data, radar data, and serious weather reports. The percentage of positive CG(PCG) flashes with STW in North China is larger than that in South China. STW takes place during the period when the total CG and PCG density is increasing fastest. STW also occurs close to the high-value center of CG and PCG density. In North China, the CG and PCG density in the grid of STW maximizes approximately 20 minutes after the STW occurs; while in South China, the PCG density and percentage of PCG in the grid of STW maximizes about 10 minutes before the occurrence of STW. The high-value centers of CG density and PCG density in North China move slightly faster than those in South China, which is opposite to the rate of increasing CG activity.

Temporal and Spatial Distribution of Lightning Activity in Ulanqab City

From January 2020 to December 2021,Ulanqab Meteorological Bureau of Inner Mongolia used VLF/LF lightning locator to carry out three-dimensional lightning monitoring in Ulanqab City,and compared with ADTD lightning location data in the same period.The results show that both VLF/LF lightning locator and ADTD lightning locator had excellent monitoring ability for lightning during flood season in Ulanqab.VLF/LF lightning locator was slightly superior to ADTD lightning locator in observation accuracy,the observation ability of low-current cloud-to-ground lightning,intracloud lightning observation and so on.There were obvious temporal and spatial characteristics of cloud-to-ground lightning during flood season in Ulanqab,and there was a certain correlation between the areas where lightning appeared frequently and surface water.Intracloud lightning was mainly concentrated at a height of 1-7 km.Negative cloud-to-ground lightning accounted for about 75%of total cloud-to-ground lightning,and negative intracloud lightning accounted for 39%of total intracloud lightning.

Characteristics of a Negative Cloud-to-Ground Lightning Discharge Based on Locations of VHF Radiation Sources

The lightning very high frequency （VHF） radiation location system based on the short-baseline time-difference of arrival （TDOA） technique provides an effective approach to describe the temporal and spatial development of lightning discharge in two dimensions with high resolution. A negative single-stroke cloud-to- ground （CG） lightning flash was analyzed in detail using the radiation location results and synchronic fast/slow elec- tric field changes. The long-duration preliminary break- down process appeared to propagate with hi-directional leader channels. The two negative simultaneous discharge channels sloped down with a considerable horizontal com- ponent in the lower positive charge region at speeds of about 105 m s-1. The stepped leader was clearly converted from one channel of the preliminary breakdown process and spread downwards with branches. The speeds of the stepped leaders were about 105 m s -1. The K processes after the return stroke could either directly initiate from the start region with negative polarity lightning discharge, or initiate from a new region in the cloud as negative recoil streamers. All K processes propagated along the preceding electrified channel, while not all K processes initiated from the tips of positive breakdowns. The speeds of the K processes were about 106-107 m s-1.

Characteristics of Cloud-to-ground Lightning during a Squall Line Process outside of the Subtropical High

Based on the monitoring data of cloud-to-ground( CG) lightning positioning network and Doppler weather radar as well as MICAPS1°× 1° objective analysis field,a squall line process outside of the subtropical high in low-latitude plateau on May 7,2010 was analyzed. The results showed that wind direction shear between low and high levels and low-level convergence zones provided favorable circulation background for the strong thunderstorm process,while high energy and high humidity,strong thermal instability and ascending motion at low and middle levels offered beneficial environmental conditions for the formation of the thunderstorm. 9 620 return strokes of cloud-to-ground lightning were monitored by the lightning positioning network,and cloud-to-ground lightning was distributed like bands between 584 and 586 hP a. The occurrence of cloud-to-ground lightning was mainly related to echo top and echo intensity at-10 ℃ stratification height,and it mainly appeared in zones where echo top height was larger than 13 km and echo intensity at-10 ℃ stratification height was 35-40 dB Z. Wind convergence and maintaining of high radial velocity were favorable for the development of convective echoes and occurrence of cloud-to-ground lightning.

Study on the Scope of Small Amplitude of Cloud-to-ground Lightning in Lightning Weather Monitoring

Based on lightning location data in Chongqing region during 1999-2008,the frequency of lightning in various amplitude ranges and its annual variations were analyzed firstly.Afterwards,with the aid of matlab mathematical software,the distribution of the lightning location data was fitted using logarithmic normal distribution function.The results showed that after data of cloud-to-ground lightning with current amplitude from-5 to5 kA were deleted from lightning location data,the statistical characteristics of cloud-to-ground lightning could be reflected well.Meanwhile,lightning with current amplitude from-5 to 5 kA accounted for 1.05%（less than 2%）,which accorded with the detection principle of lightning position indicator（there existed error detection）.Therefore,cloud-to-ground lightning with current amplitude of-5-5 kA in lightning location data of Chongqing region was defined as small amplitude of cloud-to-ground lightning,which could provide scientific references for the processing of lightning location data in Chongqing region as well as analysis and quality control of lightning location data in other 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.

Characteristics of Cloud-to-ground Lightning during a Local Rainstorm in Meizhou City

Based on cloud-to-ground lightning data of lightning location system,Doppler radar data,and precipitation data of regional automatic weather stations,the characteristics of cloud-to-ground lightning during a local rainstorm on June 4,2016 in Meizhou City were analyzed. The results showed that the spatial distribution of cloud-to-ground lightning from 14： 00 to 20： 00 on June 4,2016 in Meizhou City had obvious local characteristics,and the proportion of negative lightning was larger than that of positive lightning（ only 16. 8%）. The concentration period of positive lightning coincided with that of cloud-to-ground lightning. The peak of proportion of positive lightning lagged behind the peak of cloud-to-ground lightning,and appeared in the late period of thunderstorm disappearance. The dense area of cloud-to-ground lightning and the area with heavy rainfall coincided with the area with strong radar echoes. Doppler weather radar data had the feature of the headwind zone,strong combined reflectivity,vertical height of strong echoes,high echo top,and fast radial movement. The peak of cloud-to-ground lightning appeared one hour earlier than that of precipitation. There was no significant correlation between the frequency of cloud-to-ground lightning and precipitation. The peak of negative lightning corresponded to that of positive lightning,and cloud-to-ground lightning ended earlier than rainfall. After the peak of precipitation,convective system rapidly weakened and disappeared. Precipitation and the frequency of cloud-to-ground lightning fluctuated frequently during the whole process. The jumps and peaks of negative lightning were indicative of rainfall changes.

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 krn 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.

Protective effect of compressing arc extinguishing lightning protection device on superimposed lightning strikes

Traditional lightning protection measures can not solve the problem of superimposed lightning strikes.This paper presents a compressing arc extinguishing lightning protection device,which can solve the problem of superimposed lightning strikes.This device can extinguish the power frequency continuous current arc quickly in 1-2 ms.It is far less than the response time of relay protection,which can avoid lightning trips and improve the reliability of power supply.The computer simulation and engineering practice show that the compressing arc extinguishing device has good protection effect on superimposed lightning strikes.

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。

南昌一次大暴雨过程中闪电与回波特征分析

为了做好大暴雨过程的监测预警工作,文章运用地面气象要素、雷达回波、闪电数据等资料,对南昌市2023-06-19-2023-06-20大暴雨过程中的闪电特征进行了分析。结果表明:大暴雨是梅雨锋雨带稳定少动,雨带出现多个短时强降水形成的;在短时强降水发生前,闪电频繁(超过闪电频次平均线),短时强降水过程中闪电频次快速减少;短时强降水是形成大暴雨的重要原因,尤其是当同一地区出现两次以上短时强降水时,出现大暴雨的概率很大;大暴雨回波带由短带回波和多个对流单体回波组成,组合反射率可达45~55 dBZ。研究结果以期为南昌地区大暴雨中闪电和短时强降水的监测预警提供分析依据。

气吹弧装置仿真与试验研究

并联间隙雷击闪络后能快速疏导电弧保护绝缘子,但无法有效切除后续工频续流。因此,基于“气吹弧”思想研究设计了一种应用于高压输电线路的气吹弧装置。该装置与绝缘子串并联安装,当雷击线路时利用绝缘配合先于绝缘子击穿闪络泄放雷电流入地,并同时利用雷电脉冲信号触发灭弧气丸产生高速气流,能够在继电保护装置最快响应动作前熄灭电弧。通过仿真在理想状态下得出该装置能够在4 ms内将20 kA的工频续流熄灭;通过试验得出该装置能够在2.6 ms内将5.1 kA的续流电弧熄灭。仿真与试验结果基本一致,共同验证了所设计气吹弧装置具有良好的灭弧效果。

基于CBAM-CNN的直流线路雷击干扰与短路识别模型

针对直流线路保护和故障测距易受非故障性雷击干扰、传统基于时域和频域特征构造的输电线路雷击干扰识别方法存在阈值难以整定和噪声鲁棒性较差的问题,提出使用深度学习方法实现雷击干扰与短路行波特征自动提取与分类,相模解耦和小波包分解后得到的电流、电压行波分量作为不同通道输入至一维卷积模块注意力模块卷积神经网络(CBAM-CNN)分类模型。通过仿真和算例分析验证了所提模型相比传统方法具有更高的识别正确率,CBAM能有效提升CNN分类模型的噪声鲁棒性,同时验证了4层小波包分解与所提CBAM-CNN模型的结合具有最佳的性能。

固相气流防雷装置熄灭工频大电流的仿真分析和试验研究

为验证固相气流灭弧装置在110 kV系统中熄灭工频大电流的能力,文中首先在Comsol Mutiphysics软件中将电场、流体及传热模块耦合,对高速气流与电弧的耦合发展过程进行仿真,以电导率确定电弧熄灭;其次到高压试验室开展固相气流下的40 kA工频大电流灭弧试验。仿真结果表明,固相气流熄灭工频大电流电弧的时间约为4 ms;试验结果证明在固相气流下6.7 ms左右熄灭40 k A的工频大电流电弧。由于仿真不能完全模拟实际灭弧条件,且电弧熄灭时间都小于继电保护装置动作时间,所以误差仍在可接受范围内。实际运行状况证明,该装置在实际运行中拥有熄灭工频大电流电弧的能力,且工况良好,性质稳定,能够有效降低线路的雷击跳闸率。

中波发射机易遭雷击烧功放问题排查及改进措施分析

扬州中波台新购更新了两部全固态PDM 1kW发射机,在安装调试正式使用中新发射机正常运行,技术指标都正常,但是遇雷暴天气极易烧功放,连续两年在雷暴天气观察都有此现象,而以前的发射机出现此故障很少。本文从梳理机房现有防雷措施入手,介绍分析该故障检修流程并逐步排查故障原因,提出具体改进措施和方案。

一次雷暴过程云闪放电通道三维结构及其始发阶段特征的观测分析

为了定量描述云闪三维通道的结构演变,通常建立闪电脉冲辐射源与雷达回波强度之间的关系,还可为雷电预警提供有益参考依据.本文基于南京地区的低频三维闪电辐射源定位系统,观测研究了2018-08-03一次强对流天气过程中典型的三次云闪,利用波形互相关算法来确定闪电脉冲到达不同测站的时间差这一定位技术,对云闪的脉冲辐射源点进行三维空间定位,并对其放电通道三维结构特征进行详细分析.结果表明:南京地区此次雷暴过程的三次云闪其始发位置均从6 km高度开始,并近似垂直向上发展,平均发展速度为2.9×10^(5)~3.6×10^(5)m/s,在到达10 km高度后,呈现水平发展趋势,而随后的水平发展阶段位于两个高度或集中于同一高度;三次云闪脉冲始发点处的回波强度均小于30 dBZ,且脉冲辐射源点几乎都是从强回波区的上部或者靠近弱回波区处始发,并在弱回波区继续垂直向上发展.利用波形互相关时间差定位技术对云闪的脉冲辐射源进行空间定位,可以较为清晰地描绘云闪的三维通道结构,进而分析得到南京地区云闪始发阶段脉冲辐射源与雷达回波强度之间的定量映射关系.

2017-2020年福建省冰雹和短时强降水云三维闪电特征分析

选用VLF/LF(ADTD_2C)三维闪电监测资料和双偏振雷达资料,对2017—2020年福建省31个冰雹、32个短时强降水单体闪电特征进行统计分析。结果表明:福建省多数冰雹云单体降雹前闪电频数超过50次/6 min,而强降水单体超过50次/6 min的较少;冰雹单体正地闪和正云闪比率较高,强降水单体则较低。80%冰雹单体闪电频数峰值较降雹时间提前3~25 min,并在降雹前出现总闪频数跃增,递增率多数大于4次/min。超过1/2的强降水单体,其闪电频数峰值时间较降水峰值提前2~35 min,闪电频数在降水峰值前增大,递增率多数小于4次/min。两类单体成熟阶段的云闪频数最高,云闪主要集中分布在2~6 km高度层。冰雹单体中,融化层以下为冰雹和大雨粒子组成的低层,以上为冰雹和霰组成的高层;强降水单体中,融化层以下为大雨粒子组成的低层,以上为冰晶、过冷水滴组成的高层。闪电频数与强回波中心高度和强回波伸展高度均为正相关,对流发展高度越高,冰相过程越显著,闪电活动越强。

Observation and study on the whole process of cloud-to-ground lightning using narrowband radio interferometer

A narrowband radio interferometer has been developed and used to locate the entire sources of VHF radiations from a negative cloud-to-ground (CG) lightning discharge which contains 19 strokes. This system uses five antennas to form an array consisting of short- and long-baselines along two or- thogonal directions. The system error which comes from frequency conversion is reduced by phase detection through direct high frequency amplifying. An interactive graphic analysis procedure is used to remove the fringe ambiguities which exist inherently in interferometry and to determine the direction of lightning radiation sources in two dimensions (azimuth and elevation) as a function of time at a time resolution of microsecond orders. With the developed system, the whole progression process in time and space of a lightning flash can be reconstructed. In this paper, combining the synchronous data of electric filed change and VHF radiation, the whole processes of an example negative CG flash have been studied in detail. It is found that the preliminary breakdown event of the CG flash started from negative charge region and exhibited firstly a downward pregression and then an upward propagation. There were very intense and continuous radiations during stepped leaders which became much stronger when the first return stroke began. In contrast, there were less and only discrete radiations during dart leaders. Stepped leader and dart leader may transform to each other depending on the state of the ionization of the path. The progression speed of initial stepped leaders was about 105 ms?1, while that was about 4.1×106 and 6.0×106 ms?1 for dart leaders and dart-stepped leaders, respectively. M events produced hook-shaped field changes accompanied by active burst of radiations at their begin- nings. Followed these active radiation processes, M events appeared to contact finally into conducting main discharge channels. The mean progression speed of M events was about 7×107 ms?1, greater than that of the dart leaders and dart-step leaders. K events and attempted leaders were essentially the same as dart leaders except that they could not reach the ground and initiate return strokes.

A Comparison of the Characteristics of Total and Cloud-to-Ground Lightning Activities in Hailstorms

The region of Beijing-Tianjin-Hebei is covered by two different lightning detection networks： SAFIR （Systeme d＇Alerte Fondre par Interferometrie Radioelecctrique） for total lightning, including IntraCloud （IC） flashes and Cloud-to-Ground （CG） flashes, and the ADTD （ADvanced TOA and Direction system; TOA denotes time of arrival） network of China for CG lightning. Fourteen isolated hail-bearing thunderstorms in this region were examined in this study, using the data of SAFIR and ADTD. The peak of lightning frequency, for both total lightning and CG lightning, was often observed in advance of the occurrence of hailstones on the ground, with a trend of a rapid increase of lightning frequency before the hail was reported. The average lead times of the two types of lightning jump before hail events were obtained （total lightning： 32.2 min; CG： 25.4 min） through the 2a lightning jump algorithm. Additionally, in hailstorms with a high ratio of positive CG flashes, the diameter of hail was larger and the duration of hail was longer; when negative CG flashes dominated, the diameter of hail was relatively small. The comparison of the characteristics of total lightning and CG flashes in hailstorms in this study is expected to serve as a supplementary tool for hail forecasting.