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In this article, we analyzed the difference in the estimated currents from the Foshan Total Lightning Location System (FTLLS) under two triggered lightning situations, i.e., triggered lightning to ground and triggered lightning to the distribution line. FTLLS underestimated the peak currents of triggered lightning to the distribution line, which is reflected in the peak far electric field. The peak far electric field of triggered lightning to the distribution line is about 12% lower than that of triggered lightning to ground. However, this difference in estimated current is not reflected in the far electric field waveform parameters, at least for the three field parameters: zero to peak risetime, 10%–90% risetime, and half-peak width time. The presence of distribution line will increase the risetime of the lightning return stroke current, the arithmetic mean of the current risetime of triggered lightning to distribution line is 0.46 μs, and that of triggered lightning to ground is 0.27 μs. Clarification of this underestimation phenomenon is beneficial for the application of the lightning location system in power systems.

A satellite remote imaging data is used to describe the actual ground surface around east of Shandong, based on Barrick’s formulations and Wait’s formulations, and considering the time errors due to elongation of the propagation path caused by mountains, this paper comprehensively analyzes the lightning vertical electric field over the actual ground surface. Furthermore, its effects on time-of-arrival (ToA)-based lighting location systems (LLS) are discussed in details and results show that wave-shape and time-delay of the electromagnetic fields can be significantly affected when they propagate over actual ground surface. The time-delay of the field waveform becomes longer with the increasing roughness, but subtle effect on field peak. After analyzing the actual ground surface around district of Qingdao, this paper reveals the relation between azimuth, observation distance and time-delay. The location error caused by actual ground surface is about several kilometers around the district of Qingdao, and the revised stroke points which are evaluated by the improved actual ground surface propagation model are closer to the actual lightning strike points.

In recent years, a large number of radio base stations and antenna towers have been built in Shenzhen. The height of antenna tower is usually tens of meters, which may increase the probability of lightning strike. The lightning environment of radio base stations has been analyzed by the data accumulated by the lightning location system of Guangdong-Hongkong-Macao. The results show that the lightning occurrence probability in the surrounding domain cannot be increased by signal tower. The lightning parameter is basically the same in inner domain (177 m radius) and outer domain (177–250 m radius). The lightning parameter in the domain around radio base stations which were analyzed is also basically the same as those in Shenzhen.

In this paper, we present current pulses from upward lightning, which have been measured since 2011 at the new top structure of the Peissenberg Tower, Germany. The study comprises 38 negative and two positive flashes, which contained 199 current pulses. About 49 of them were return stroke current pulses, 133 of them were current pulses, which superimposed the initial continuous current (ICC-pulses), and 17 of them were M-component current pulses, which superimposed the continuing current of a preceding return stroke. The current pulses are used to evaluate the performance of the European lightning location system EUCLID. Fifty one (25.6%) out of the 199 current pulses were detected by EUCLID, 40 (81.6%) return stroke current pulses, and 11 (8.5%) ICC-pulses or M-component current pulses. The peak currents ranged from 0.1 to 40.8 kA. Two groups of current pulses could be identified. The first group is related to branches of nearby downward lightning which got in contact with the tower. Therefore, EUCLID reported much higher peak currents (more than 100%) compared to the peak currents measured at the Peissenberg Tower. The first group comprises the total of nine current pulses (six ICC-pulses, three return stroke current pulses). The second group of current pulses is related to upward lightning initiated from the top of the tower. The peak current inferred from EUCLID deviates much less from peak current measured at the Peissenberg Tower. The peak current was overestimated by about 20% by EUCLID. The second group comprises the total of 42 current pulses (4 ICC-pulses, 1 M-component current pulses, and 37 return stroke current pulses). The peak currents ranged from 3.1 to 40.8 kA, the geometric mean (GM) was 9.4 kA. About 30% of these events were misclassified as intra-cloud pulses by EUCLID. The GM of the location error was 161 m for all events, and 132 m considering only the return stroke current pulses.

The statistics of lightning activity parameters is the basis to guide the lightning protection design, transformation and study of lightning characteristics of transmission lines. The lightning activity parameters are closely related to the land type. Based on the ground lightning data of lightning location system in Hainan Island, combined with the land type data from resource and environmental science and data center, this paper uses ArcGIS geographic software to supplement the land type data of ground flash point, and studies the law of lightning activity parameters and land types, such as mean value of lightning current amplitude, ground lightning density, cumulative probability distribution of lightning current amplitude, positive lightning ratio and so on. The study shows that the average amplitude of total lightning current in paddy field is the largest; due to the heat island effect, the total land flash density, negative ground flash density and positive ground flash density of urban land are much higher than those of other land types, and more attention should be paid to the transformation of forest land lightning protection measures; the median current of cultivated land is the largest, and the probability of larger amplitude lightning current is the largest. The proportion of positive flashover in lakes is the largest, so the influence of positive lightning on lightning shielding of transmission lines should be properly considered.

In view of the lack of accurate lightning trip out rate calculation method for overhead lines with ungrounded neutral points, this paper comprehensively considers the lightning protection configuration of transmission lines and the actual lightning activity parameters in the line corridor to carry out theoretical analysis, simulation calculation and scheme research. Firstly, based on the line account information and lightning location system monitoring data, based on the electrical geometry model to determine the impact of lightning on the line, an accurate calculation method of lightning trip out rate is proposed, and the method is used to calculate and verify the lightning trip out rate of a neutral point ungrounded line in a certain area. The results show that the lightning trip out rate calculation method can accurately calculate the lightning trip out rate of the line and the line corridor after considering the lightning characteristics of the line and the line corridor.

Compared to negative cloud-to-ground (CG) lightning, positive CG are less frequent but can produce strokes with higher peak currents making them to be potentially more dangerous. This paper presents an investigation on positive cloud-to-ground (CG) lightning activity in Shah Alam, Malaysia recorded by SAFIR 3000 lightning location system (LLS). For this study, a total of 572,282 LLS data from 2013 to 2015 were analyzed. We found that only 1.6% of the total CG flashes were contributed by positive CG while the remaining 98.4% were dominated by negative CG. We also observed that the occurrence of positive CG follows the weather pattern of Malaysia, with a strong connection between positive CG and rain events. Most positive CG occurred in November, while the least occurred in February. Our results showed that the highest peak current for positive CG was 86.7 kA with average geometric mean and median values of 14.2 kA and 12.8 kA, respectively. The negative CG recorded a higher peak current of 139.6 kA with average geometric mean and median values of 13.6 kA. Previous studies conducted on positive CG in Malaysia may be an overestimate if weak positive flashes were included in the analyses. Due to a limited number of existing studies on positive CG conducted in Malaysia, more researches should be conducted.

At present the lightning flash density is a key input parameter for assessing the risk of occurrence of a lightning strike in a particular region of interest. Since it is known that flashes tend to have more than one ground termination point on average, the use of ground strike point densities as opposed to flash densities is more appropriate. Lightning location systems (LLSs) do not directly provide ground strike point densities. However, ingesting their observations into an algorithm that groups strokes into respective ground strike points results in the sought-after density value. The aim of this study is to assess the ability of three distinct ground strike point algorithms to correctly determine the observed ground-truth strike points. The output of the algorithms is tested against a large set of ground-truth observations taken from different regions around the world, including Austria, Brazil, France, Spain, South Africa and the United States of America. These observations are linked to the observations made by a local LLS in order to retrieve the necessary parameters of each lightning discharge, which serve as input for the algorithms. Median values of the separation distance between the first stroke in the flash and subsequent ground strike points are found to vary between 1.3 and 2.75 km. It follows that all three of the algorithms perform well, with success rates of up to about 90 % to retrieve the correct type of the strokes in the flash, i.e., whether the stroke creates a new termination point or follows a pre-existing channel. The most important factor that influences the algorithms' performance is the accuracy by which the strokes are located by the LLS. Additionally, it is shown that the strokes' peak current plays an important role, whereby strokes with a larger absolute peak current have a higher probability of being correctly classified compared to the weaker strokes.

Along with climate change, cloud-to-ground lightning (CG)-caused forest fires are becoming increasingly pronounced. This study employed the Chinese lightning location system data (2009–2015) and worldwide lightning location network data (2005–2015) to jointly analyze CG characteristics and study the correlation between CG and climate change. The Muli county in southwest China was taken as research area. The CG number showed a clear increasing trend on yearly timescale. At the monthly timescale, CG occurred from March to October, with a peak in June. At the daily timescale, 15:00–23:00 (local time) and 00:00–05:00 both had a high CG frequency, and the peak was at 18:00–19:00. We divided CG electric current intensity into six grades and found that negative CG accounted for more than 90% of total CG and, among these, the 3rd and 4th intensity grades accounted for about 70%. To examine the spatial distribution, we focused on lightning-caused forest fires high occurrence seasons. In spring, CG distribution changed from the initial southeast to the northwest, gradually spreading to the whole area of Muli, whereas the CG area gradually moved back to the southeast in autumn. Our research suggested that minimum temperature was the most sensitive temperature to CG change. In March, the relationship between CG and minimum temperature showed a strong positive correlation. Considered jointly, we suggest the CG and related lightning-caused forest fires could increase in the future under an increased minimum temperature and decreased precipitation, especially in March.

Modern lightning location systems (LLSs) have become a useful tool in confirming or negating lightning as a cause of damage in forensic investigations. There are uncertainties in the reported locations of detected lightning that arise from electromagnetic propagation errors and need to be considered when used in forensic investigations. Methods to evaluate regions of confidence for individual stoke reports or to calculate probabilities of individual strokes having attached in a region are available but no consistent method for evaluating the probability that an area or asset of interest was struck/damaged by lightning. This paper discusses a methodology for calculating a probability that considers all detected lightning events relevant to such an investigation, and not just individual strokes. The method is based on previous work done by Huddleston et al. and adds to it using conditional probability theory. A case study, a photovoltaic plant where a solar panel was found damaged subsequent to a storm, is used to demonstrate the concepts of the methodology. It is possible to show that there is a 71% chance that the panel group from which the damaged panel came, was struck by lightning using LDN data alone. This can be compared with the rest of the solar panel plant (where it was noted that other solar panels had been replaced after the same storm) which had a 97% chance of having been struck by lightning. It is also shown how grouping strokes into flashes and using the methodology to calculate which area was struck by each flash, indicates the true strike area of interest better than only using individual strokes.

This paper presents an analysis on the influence of anthropogenic phenomena over the lightning activity in large cities located in mountainous region of tropical zone, specifically in Bogota City. Some preliminary results show an increase of lightning activity between 33% and 340% for the period under study (2007–2012), when a comparison between urban and rural adjacent zone is carried out. An additional analysis of the influence of pollution on lightning activity was also carried out; this analysis shows that there is a tendency of correlation between number of strokes and particulate matter (PM10) for the zones under study with the highest levels of contamination of the city. In order to achieve the goals of this study, data from one of the Colombian Lightning Location Systems (SID) and the monitoring network of air quality of Bogota were used. The results are consistent with other studies carried out in different cities of the world.

This study develops methods for estimating lightning climatologies on the day−1 km−2 scale for regions with complex terrain and applies them to summertime observations (2010–2015) of the lightning location system ALDIS in the Austrian state of Carinthia in the Eastern Alps. Generalized additive models (GAMs) are used to model both the probability of occurrence and the intensity of lightning. Additive effects are set up for altitude, day of the year (season) and geographical location (longitude/latitude). The performance of the models is verified by 6-fold cross-validation. The altitude effect of the occurrence model suggests higher probabilities of lightning for locations on higher elevations. The seasonal effect peaks in mid-July. The spatial effect models several local features, but there is a pronounced minimum in the north-west and a clear maximum in the eastern part of Carinthia. The estimated effects of the intensity model reveal similar features, though they are not equal. The main difference is that the spatial effect varies more strongly than the analogous effect of the occurrence model. A major asset of the introduced method is that the resulting climatological information varies smoothly over space, time and altitude. Thus, the climatology is capable of serving as a useful tool in quantitative applications, i.e. risk assessment and weather prediction.

Lightning discharges have been widely studied in many physical and engineering fields, being responsible for hazardous events such as human injuries, damages to transmission lines and wind turbines, wildfires ignitions and adverse impacts on the aviation sector. An improved understanding of the phenomenon is important for warning and safety applications, in order to perform reliable risk assessment to respond to impacts. The introduction of Lightning Location Systems (LLS) helped mitigating threats since 1920. This contribution is focused on LLSs for intra-cloud and cloud-to-ground discharges, aiming at presenting an overview on the working principles of the most used techniques to locate lightning. The companion paper will describe in detail the performances of the main LLS and present examples of some existing LLS networks, with particular attention to the ones that operate in the Mediterranean areas.

The lightning location system in Anhui province are introduced. Under the environment of SQL Server 2005, lightning location system database is established, unifying the lightning location data storage form and promoting the application of lightning location data and its secondary development. In combination with Doppler radar products, lightning nowcasting warning system has been developed. Strengthened The live monitoring, nowcasting forecast of lightning and early warning products published through web benefit the public a lot and supply the reference for forecasters in the process of early warning signal production.

The present analysis shows data of measurements of natural cloud-to-ground lightning performed during warm season thunderstorms in the Alpine region of Austria. These measurements were performed during six years from 2009 to 2018 to generate a ground truth dataset of atmospheric discharges. The used measurement system consists of a high speed video and an electric field recording system (VFRS), to observe the optical properties of lightning discharges and to record the transient electric field. Measurements have been conducted at 33 different measurement locations and 735 negative cloud-to-ground flashes have been recorded during 61 days spread over the whole measurement period. Data of the Austrian Lightning Location System (LLS), ALDIS (Austrian Lightning Detection and Information System), is correlated with the VFRS ground truth data to complete the dataset. These datasets are used to analyze possible reasons for the detected variation of single stroke flashes in the Alpine region of Austria. The calculated values for single stroke flashes of the present analysis are also compared to previously published values (12-24 %) from different countries. Additionally radar data and wind measurements have been analyzed to classify thunderstorm types in order to investigate the effect of thunderstorm organization on their lightning characteristics. Compared to values from the literature the percentage of negative single stroke flashes in this study is higher (27 %). Results of this report shall contribute to a better understanding of atmospheric discharges in general and their behavior in the Alpine region in particular.

In this paper we analyze the currents and electric fields of 5 negative return strokes and compare them with data from the European lightning location system (LLS) EUCLID. The return strokes were measured between May and August 2017 at the Peissenberg Tower, Germany. 1 out of the 5 return strokes was a first return stroke and the remaining 4 were subsequent return strokes. Their peak current Ip varied between 7.5 kA and 24.9 kA, the arithmetic mean value was 14.4 kA. We present high speed video images of the first return stroke showing the extremely long upward connecting leader. The connecting leader produced a continuous current of approximately 30 A. The LLS detected 4 out of the 5 presented return strokes. We present the time errors of the individual sensors, which contributed to the localization. After an optimization process, the time errors were reduced and the location error was minimized. The location error varied between 101 m and 239 m. The peak current inferred by EUCLID was overestimated by 32.3% on average.

The parameters of lightning are important in the protection of distribution lines, however, the lightning parameters' measurement of lightning location system (LLS) is not accurate for its measuring principle and method, so online overvoltage monitoring devices are applied to measure the parameters. For the effective monitoring of distribution lines by on-line overvoltage monitoring devices and more accurate lightning parameters, a method for evaluating the installation of monitoring devices in engineering is proposed based on the measurement data of LLS in the area where the lines are located. Different influencing factors will be considered to determine the location of overvoltage monitoring devices effectively through quantitative calculation so as to acquire more accurate monitoring data of lightning parameters, which provides data basis for further evaluation of lightning assessment and improvement of distribution lines' lightning protection.

The paper Introduced the validating results of the Guangdong-Hong Kong-Macao lightning location system based on 3 High-speed camera recorded flashes striking the Shenzhen Meteorological Gradient Tower. The GD-HK-MC-LLS is one of the based source of the lightning warning system in Shenzhen. Based on the analysis of both data in these 3 flashes, it is shown that the the lightning return stroke detection efficiency of this LLS is about 92.9% and the lightning return stroke loaction error is better than 300 meters. The cloud ground flash identification accuracy is 84.6%, however, we found that the first RS on HSC data was always not recorded as the first RS in the LLS database, indicated a pointed improvement of the LLS is needed.

Thunderstorm electrical structures favouring cloud-to-ground lightning were investigated through a Lightning Mapping Array (LMA), an accurate three-dimensional lightning location system that allows inferring the heights of the regions of charge. The present study focused on classical, convective-scale thunderstorms, aiming to shed new light on how the charge structure affects lightning production, especially the cloud-to-ground fraction, including flash rate and polarity. Results showed that lightning flashes mainly initiate at two levels, around -41 °C (9,150 m MSL) and around -7 °C height (4,730 m MSL). These initiation levels, located between the dominant positive and negative charge regions, allowed to define three main charge structures: an upper dipole (positive above negative), a classical tripole and a lower dipole (negative above positive). Several differences were found between the three categories in terms of the cloud-to-ground lightning production: (i) the classical tripole structure is the one presenting a higher cloud-to-ground flash rate (5.2 flashes·min-1); (ii) in terms of intensity, the presence of an upper positive charge region is more relevant than a lower positive below the main mid negative; (iii) conversely, the lower positive favours higher cloud-to-ground peak currents; (iv) A higher upper positive charge region favours a higher cloud-to-ground rate.

In order to improve the accuracy of lightning strike fault location and identification based on the distributed traveling wave monitoring system and lightning location system, the location algorithm and recognition algorithm are improved and integrated. The distributed traveling wave monitoring device is regarded as the lightning detection sub-station, and the calculation results of the lightning location system are corrected to get the accurate lightning flashover tower position. The lightning flashover voltage of the positioning tower is calculated based on the lightning current amplitude and the procedure method. After the lightning fault type is predetermined, the recognition calculation based on waveform feature extraction can be carried out. The actual lightning tripping fault and waveform were used to verify, the results show that the proposed method can effectively improve the accuracy of lightning strike fault location and identification.

Lightning is one of the most dangerous natural phenomena, able to produce high impacts and damage on human beings and infrastructures (civil, electric, telecommunications, etc..) even though perception of it as a hazard is low. The aim of this study is to provide a detailed analysis of lightning occurrence throughout the Italian territory to support the work of different operators and researchers (physicists, meteorologists and electric/ITC engineers) improving knowledge about the main properties of lightning. Thus, an in-depth study of the statistics of lightning activity across the Italian territory for the period 2010–2019 is performed in detail using the data collected by the Italian Lightning Detection Network SIRF (Sistema Italiano Rilevamento Fulmini), part of the European network EUCLID (European Cooperation for Lightning Detection). This analysis presents general properties such as Ground Stroke Density (GSD) and the positive to negative strokes ratio by highlighting how seasonal, geographical and orographic factors influence their values. Then, attention is focused on lightning peak current, on flash multiplicity and on the distance between the points of impact of different strokes within a flash. Comparison made with other articles available in the literature reveals good agreement with studies conducted with other LLS data in Mediterranean regions. On the other hand, some differences appear with direct current measurements that can be partly ascribed to Lightning Location System (LLS) detection contamination (confirming other comparative studies of LLS and instrumented tower findings), to differences between tower and ground measures, and to the presence of regional differences.

This study provides the first comprehensive quantitative detection efficiency (DE) estimation of the Met Office long-range very low-frequency (VLF) lightning location system, the Arrival Time Difference Network ATDnet, with a focus on cloud flash detection. ATDnet uses sensors in and around Europe to detect lightning in Europe, northern Africa, and northern parts of the Atlantic.In the present paper, ATDnet is validated against the Hydrological Cycle in the Mediterranean Experiment (HyMeX) Lightning Mapping Array (HyLMA) deployed in the south of France in autumn 2012 as a part of the HyMeX project Special Observation Period 1 (SOP1). Three storms (on 5, 11, and 25 September 2012) were selected for this study, as their activity was sufficient to provide good statistics but also low enough to avoid ambiguous situations due to temporally overlapping flashes.The overall ATDnet flash DE was approximately 89% for the 281 ground flashes [cloud to ground (CG)] and 24% for the 1324 cloud flashes [inter/intracloud (IC)] during the storms. It was also demonstrated that variations in cloud flash characteristics (e.g., flash vertical extent) have a significant impact on DE between and during the studied storms.

Two hailstorms that occurred in Beijing and Tianjin, respectively, are investigated, based mainly on the total lightning data observed by the System d’Alerte Fondre par Interferometric Radioelecctrique (SAFIR3000), the cloud-to-ground (CG) lightning data of a CG lightning location system, and the echo data of a Doppler radar. Both hailstorms exhibited two lightning frequency peaks: the first was before the hailfall and the second was after the hailfall, with the second peak greater than the first. The dominant polarity of the CG lightning was positive in the stage around the first frequency peak, but changed to negative in the stage around the second frequency peak. The evolution of radar echoes and the height distribution of lightning radiation sources are explored, revealing that both hailstorms had stronger convection and the main positive charge occurred at mid levels during the stage around the first frequency peak. However, whilst the Beijing hailstorm experienced the enhancement of convection, with the main positive charge at upper levels around the second frequency peak, the Tianjin hailstorm generated its second frequency peak during the period when the convection kept weakening and the main positive charge dropped to mid–lower levels. Through evaluation of the radar parameters, we investigate the mechanisms responsible for the second stage of active lightning discharge. Furthermore, the lightning activity exhibited a close relationship with radar echo parameters and hailfall. Lightning jump signals were found before the hailfall and were associated with the change ratio of the 40-dBZ echo volume above the −15°C level, which demonstrates the application value of lightning data in severe weather warning.

This study examined lightning activity and its relationship to precipitation and convective available potential energy (CAPE) in South China during 2001–12, based on data from the Guangdong Lightning Location System, the Tropical Rainfall Measuring Mission satellite, and the ERA-Interim dataset. Two areas of high lightning density are identified: one over the Pearl River Delta, and the other to the north of Leizhou Peninsula. Large peak-current cloud-to-ground (LPCCG) lightning (>75 kA) shows weaker land–offshore contrasts than total CG lightning, in which negative cloud-to-ground (NCG) lightning occurs more prominently than positive cloud-to-ground (PCG) lightning on land. While the frequency of total CG lightning shows a main peak in June and a second peak in August, the LPCCG lightning over land shows only a single peak in June. The ratio of positive LPCCG to total lightning is significantly greater during February–April than during other times of the year. Diurnally, CG lightning over land shows only one peak in the afternoon, whereas CG lightning offshore shows morning and afternoon peaks. The rain yield per flash is on the order of 107–108 kg per flash across the analysis region, and its spatial distribution is opposite to that of lightning density. Our data show that lightning activity over land is more sensitive than that over offshore waters to CAPE. The relationships between lightning activity and both precipitation and CAPE are associated with convection activity in the analysis region.

While in-depth studies of lightning deaths can be found in the literature, rarely do such investigations they utilize a multidisciplinary approach, analysing both the medical and electrical aspects of a case. Even more rare, is to find such studies on cases from the developing world such as Africa and South-East Asia - particularly in tropical countries with very high lightning exposure. This paper details the forensic investigation of two lightning deaths that took place during a weekend in February 2020, in South Africa. One event was eye witnessed and the other was not (Case A and B). The investigation involves multidisciplinary forensic examination including case histories, site analysis (including soil resistivity measurements), medical autopsies, lightning location system data analysis and voltage gradient estimations. In both cases, lightning is determined to be the cause of death. In Case A, we confirm that the responsible flash must have attached within close proximity to the deceased, if not a direct strike and in Case B we confirm direct strike as the most probable mechanism of death. The importance of clothing examination in the forensic studies of lightning victims is noted along with a discussion of the lightning safety issues at play, and recommendations for avoiding such incidents in developing world countries.

Using an S-band Doppler radar and a very high frequency (VHF) radiation source location system, 254 lightning flashes occurring in stratiform regions (stratiform lightning flashes) of 14 mesoscale convective systems (MCSs) in Chongqing, China, were observed and used to analyze the structure of vertical reflectivity in the area around the lightning channel. In most stratiform lightning flashes, the vertical reflectivity structures can be grouped into three general categories: single-layer, double-layer, and triple-layer. The single-layer structure flashes are the most numerous (65.0%), followed by the double-layer (26.8%) and triple-layer (1.2%) flashes. The regions with the single-layer structure and the double-layer structure are inferred to have mesoscale updrafts of different intensity in the middle of stratiform region. Around 62.3% of the single-layer structure flashes initiate within 0–4 km above the vertical reflectivity core, and the main initiation range of these flashes widens with increasing value of the vertical reflectivity core. Around 49.2% and 12.7% of the double-layer structure flashes initiate within 3–6 km and 1–2 km above the vertical reflectivity core, respectively. The probability of lightning initiation at a greater distance to the vertical reflectivity core is higher than that at a shorter distance. This may imply that some electrifications occurring during the melting process are not as strong as expected and a non-riming non-inductive charging process occurring in a weak but broad mesoscale updraft in the middle of stratifom region may be more important for initiation of stratiform lightning flashes.

Far-field measurements of lightning-produced electromagnetic fields are of high importance for lightning location systems. Data from recorded lightning strokes can be, for example, used to assess the risk of lightning-induced damage in some geographical areas. Artificially triggered lightning, usually generated using rocket-wire technology, plays an important role in the study of lightning physics. Multiple-station observations of far (typically larger than 20 km) electric field waveforms produced by rocket- triggered lightning are quite rare. In 2014, electric field waveforms were measured for return strokes through the rocket-and-wire technique at Conghua. They were measured by electric field sensors at nine sites belonging to the lightning locating system in Foshan, Guangzhou, China. A total of 38 events were recorded and overall statistics of those waveforms are presented. The results were compared to previous experimental data related to natural and artificially triggered lightning to validate their similarity.

Scientific community is focusing on the effect of lightning activity on people safety and infrastructures security because of the dangerous consequences of this kind of phenomenon. Each study of safety and security associated to lightning flashes needs as input reliable data in terms of lightning activity related to the analyzed territory. In this framework, the analysis presented in this work focuses on the lightning activity measured in the Italian territory for the period 2013-2014 thanks to the use of the Lightning Location System provided by the Meteorological Service of the Italian Air Force. The results show the differences between seasons, stroke polarity and stroke locations in terms of some parameters such as the Ground Flash Density and seasonal daytime distribution, as well as the channel-base current peak.

The current status of the Japanese coastal region shows that winter lightning has seriously damaged wind turbines owing to its larger electrical charge than summer lightning. In Japan, 64% of serious wind turbine damage occurred in winter. Typically, lightning flash density is used to evaluate lightning risk in an area. Herein, we discuss the extent of lightning damage on wind turbines in Japan and cloud-to-ground (CG) lightning flash density based on the Japanese Lightning Detection Network, the largest lightning location system in Japan. Consequently, we found no correlation between the number of lightning flashes hitting wind turbines and summer lightning ground flash densities in the surrounding areas of a wind turbine. Approximately 95% of the lightning flashes that hit the turbine occurred in winter. The probabilities of lightning flashes hitting wind turbines were 0.12% in summer and 5.6% in winter. We developed a map showing the probability of lightning flashes hitting wind turbines in Japan. The probabilities obtained using this map were quite similar to the CG lightning flash density in winter. Therefore, we propose that lightning risk for wind turbines should not be evaluated based on the annual CG lightning flash density in Japan.

The paper presents the analytics of lightning data collected by monitoring system in real - time for the measurement of the direct lightning current (LAMS) and the lightning location system (LINET). The both systems and their operation mode are shortly described. A great number of collected data are analyzed, explained and compared. The data analyses showed the Lovcen mountain has the overall highest number of registered lightning strokes in the whole analyzed area.

Cloud-to-ground (CG) lightning data from the European Cooperation for Lightning Detection (EUCLID) network over the period 2006–2014 are explored. Mean CG flash densities vary over the European continent, with the highest density of about 6 km−2 yr−1 found at the intersection of the borders between Austria, Italy and Slovenia. The majority of lightning activity takes place between May and September, accounting for 85 % of the total observed CG activity. Furthermore, the thunderstorm season reaches its highest activity in July, while the diurnal cycle peaks around 15:00 UTC. A difference between CG flashes over land and sea becomes apparent when looking at the peak current estimates. It is found that flashes with higher peak currents occur in greater proportion over sea than over land.

In this paper we present a performance analysis of the European lightning location system EUCLID for cloud-to ground flashes/strokes in terms of location accuracy (LA), detection efficiency (DE) and peak current estimation. The performance analysis is based on ground truth data from direct lightning current measurements at the Gaisberg Tower (GBT) and data from E-field and video recordings. The E-field and video recordings were collected in three different regions in Europe, namely in Austria, Belgium and France. The analysis shows a significant improvement of the LA of the EUCLID network over the past 7 years. Currently, the median LA is in the range of 100 m in the center of the network and better than 500 m within the majority of the network. The observed DE in Austria and Belgium is similar, yet a slightly lower DE is determined in a particular region in France, due to malfunctioning of a relevant lightning location sensor during the time of observation. The overall accuracy of the lightning location system (LLS) peak current estimation for subsequent strokes is reasonable keeping in mind that the LLS-estimated peak currents are determined from the radiated electromagnetic fields, assuming a constant return stroke speed. The results presented in this paper can be used to estimate the performance of the EUCLID network related to cloud-to-ground flashes/strokes for regions with similar sensor baselines and sensor technology.

Investigation and analysis of a lethal event caused by a lightning discharge in Conghua, Guangzhou, in 2017, is presented in this paper. The lightning strike first hit a tree with a height of 13m, and then hit the head of a person near the tree, causing death. The data from the Low Frequency Electric Field Detection Array, Guangdong Lightning Location System, and a nearby radar station, were analyzed. The event was identified as a lightning death incident caused by “a bolt from the blue”. The accident discharge was found to be the first return stroke (RS) with a current peak of -30.9kA, which belonged to a cloud-toground lightning flash with seven RSs. The flash initiated at a height of about 13km. At a height of 2.8km, the horizontal distance from the lightning disaster point to the edge of precipitation (18dBZ) was about 3.6km, and to the edge of the convective core (30dBZ) was about 6km. At a height of 7km, the horizontal distance of the initiation point to the edge of precipitation (18dBZ) was about 0.3km, with the distance to the edge of the convective core (30dBZ) being about 3.5km. According to the equivalent circuit model of the lightning strike, we calculated the air breakdown voltage of the side flash and step voltage on the ground. The results indicated that the event process involved the flash hitting the tree, the current flowing to the “jump point”, and then the side stroke to the victim. Crucially, the victim was exposed by a step voltage of 78.3kV, while a witness, who was 10 m from the lightning strike point, was only exposed to 0.783kV.

Blitzortung.org is a worldwide non-commercial low-cost community based Time of Arrival lightning detection and lightning location network. The aim of this project is to accomplish a low budget high accurate worldwide lightning location network based on a high number of receiver sites spaced close to each other, typically separated by 50 km 250km. The stations transmit their data to a central server, where the strike locations are computed by the arrival times of the signals. The station operators are volunteers who bought and assembled the hardware by themselves. We installed this sensor in more than 24 locations throughout Japan, for example Hokkaido, Tokyo, Okinawa, Ogasawara etc. This paper describes the outline of Blitzortung and the evaluation of the position accuracy.

In order to study the occurrence and development of lightning mechanism, We establish a three-dimensional (3D) lightning location system based on difference time of arrival method in Guangdong area, this system not only can locate Cloud to Ground lightning (CG), but also Intra- Cloud lightning (IC). Location accuracy is an important index to evaluation the performance of the locating network. Based on the Monte Carlo method, we simulate the location error of Foshan Total Lightning Location System (FTLLS), and indicate that when the lightning source is located within the network, the horizontal location error is less than 300 meters, and the maximum horizontal location error within a radius of 50 km from center station is less than 500 meters. With the increase of the height of the lightning source, the vertical location error is significantly decreased, the maximum vertical location error within a radius of 50 km from center station is less than 1000 meters. The average location errors for 27times of transmission lines lightning stroke is 252 meters, with standard deviation 173 meters. The observed errors verify the simulation error results very well.

In the paper are described main features of lightning performance of 400 kV transmission line located in north-east part Poland and south-west Lithuania named LitPol Link. This line is a part of Baltic Ring - EU power grid project interconnecting transmission lines in seven countries surrounding the Baltic Sea. Some features of the line have special influence on lightning hazard mainly due to height of towers which vary from 40 to 97 m. The lightning activity in the region is based on the lightning location system LINET data. Recorded lightning CG discharges were correlated with individual outages of LitPol Link recorded by Polish operator of the line in years 2016-17. Exemplary outages were described in detail and some conclusions are presented.

Ball lightning (BL) research lacks instrumental records and field experiments. Today, widely available networks for lightning detection offer a chance to assess alleged BL reports with located lightning and its physical parameters. This assessment was realized with BL case data and EUCLID lightning data for Germany, Austria, the Czech Republic, and Switzerland. According to the initial flash hypothesis, the electromagnetic pulse of a detected stroke near the geocoded BL position could be the triggering event of the BL process. The lightning location system (LLS) provides stroke location, time, polarity (positive/negative), and peak current in kA. In this assessment, 34 BL case reports over the period from 1994 to 2016 suggested a physical link of the stroke with maximum peak current in kA to the subsequent BL process. No electromagnetic field values for individual strokes can be computed with the kA peak current. As a first step in this analysis, geocoded distances of less than 1 km between stroke location and BL observation site were called \quotedblbase close event`` (CE) and distances 1-10 km \quotedblbase distant event`` (DE). For cloud-ground (CG) strokes the stroke-to-BL distance values were obtained. LLS-provided coordinates for intra-cloud (CC) strokes were also used to obtain a distance, although CC do not have a defined striking point. 28 BL cases occurred in the summer months, 6 cases in winter. Their time pattern follows the diurnal thunderstorm frequency in Central Europe. 19 cases were from Germany, 10 from Austria, 3 from the Czech Republic and 2 from Switzerland. 19 of the correlated EUCLID strokes were positive and 15 negative. Positive strokes ranged from 4 to 370 kA, negative from -3 to -37 kA. 28 were classified by the LLS as CG, 6 as CC strokes. The mean value of the semi-major axis of the EUCLID location confidence ellipse was 0.45 km. The BL-to- stroke distance in km for CG events had a mean of 0.42 km and a range of 0.0-0.8 km for CE cases, and a mean of 5.7 km and a range of 1.4-10 km for DE cases. The case statistics of this sample showed smaller BL-stroke distances for higher kA peak currents for both negative and positive CG events. This result leads to the interpretation that most DE strokes are uncorrelated with BL since their physical effects are marginal. Replications with more BL cases will show whether the pattern holds.

This paper is focused on the Power Spectrum Density analysis of the lightning electric field signatures collected in Subcarpathian part of Poland, in 2014. Lightning records were carried out in two different ways. The slow electric field sensor (TLF-ELF), the mill, was used for observation of lightning activity during entire thunderstorm lifetime. The second recording mode was the acquisition of fast electric field changes (0.3 Hz to 3 MHz) associated with different types of cloud-to-ground (CG) and inter-, intra-cloud (IC) type discharges. The registration process was synchronized with microsecond time precision. This allowed to relate lightning stroke detections to these reported by the LINET, the commercial lightning location system. Different lightning stroke components, as e.g. the preliminary breakdown (PB), the return stroke (RS) and the continuing current (CC) were identified with application of the Short-Time Fourier Transform. The spectral analysis might be adapted to improve in future some detection algorithms used in lightning location systems. Such lightning CG stroke discrimination is not applied as yet by any lightning location system routinely operated in Europe. Streszczenie.W artykule skupiono sie na analizie spektrogramow widmowej gestości mocy wyznaczonych dla roznych przebiegow piorunowego pola elektrycznego zebranych w poludniowo-wschodniej cześci Polski w 2014 roku. Dane zostaly zebrane z wykorzystaniem dwoch sensorow pola elektrycznego. Sensor pola elektrycznego pracujący w zakresie TLF-ELF umozliwil obserwacje aktywności burzowej w dlugofalowym okresie czasu. Drugi typ rejestracji obejmowal akwizycje szybkich zmian pola elektrycznego (0.3 Hz do 3 MHz) pochodzących of roznych typow wyladowan doziemnych oraz wewnątrz-, miedzy-chmurowych. Proces rejestracji zostal zsynchronizowany z mikrosekundową precyzją. Pozwolilo to na porownanie wlasnych rejestracji z detekcjami LINET-u - komercyjnego systemu lokalizacji wyladowan. Rozne skladowe wyladowania takie jak wyladowania wstepne, udar glowny oraz prąd dlugotrwaly zostaly zidentyfikowane z wykorzystaniem krotkoczasowej transformaty Fouriera. Analiza spektralna moze w przyszlości zostac wykorzystana w usprawnieniu algorytmow detekcji wyladowan. Taki rodzaj identyfikacji wyladowan doziemnych nie zostal jak dotąd zaimplementowany w zadnym systemie lokalizacji wyladowan atmosferycznych pracującym regularnie w obszarze Europy. (Czasowa oraz widmowa analiza roznych skladowych wyladowania atmosferycznego w oparciu o przebiegi pola elektrycznego zebrane w poludniowo-wschodniej cześci Polski w 2014 roku).

In recent years, lightning and thunderstorm detection techniques have been rapidly developed in many regions of Asia. As the most populous continent, hazards caused by lightning and related phenomena are being paid more and more attentions and lightning observations and detections are booming in many countries. In this paper, we will give a brief review on recent progress of lightning and thunderstorm detection techniques in Asia. First, we will introduce several widely used lightning location systems including VHF interferometers, VHF time-of-arrival systems and LF time-of-arrival systems. As an example, a newly-developed system called BOLT is described and recent observation results are introduced. Second, we will review studies of a special type of intracloud discharge called “narrow bipolar event” (NBE). NBE studies in Asia are flourishing in recent years and are making great contributions to the understanding of various properties of NBE. Finally, we will introduce a fast-scanning phased array radar (PAR) system installed in Osaka University. This radar system has a temporal resolution of 10–30 s, which is much faster than the traditional weather radar and is ideal for observations of fast-evolving storm structures and the analysis of their relationship with lightning activities. Preliminary observation results with PAR are described.

To estimate the detection efficiency of a ground based lightning location system, typically the ground based locations are compared to those seen by satellite. This works well because the detection efficiency of the satellite is relatively uniform with space, and reasonably good. However, this technique does not work for the 2015 or 2016 calendar years because the LIS satellite used is no longer in orbit, and has only recently been replaced by ISS-LIS. In this study, we will investigate applying a machine learning regression algorithm Lasso to lightning parameters determined by ENTLN to see if it is possible to estimate the detection efficiency of the network without satellite data.

In this paper, a method to calculate the probability of lightning attaching in an area-of-interest of any polygonal shape and based on Lightning Location System (LLS) data is described. The calculation is based on previous work in which the equations necessary for calculating the probability of lightning attaching in an area are described. By combining this approach with some of the techniques used in Gaussian smoothed maps, it is possible to make these calculations for areas of any polygonal shape. From this, area-of-interest probability maps can be developed and a case study involving a damaged solar panel is presented as an example.

This paper presents some analysis of lightning activity in Colombia, a country with places with a very high and unusual levels of lighting activity or hotspots. The results presented in this work aim to study the special behavior that seems to be present in Colombia about the relationship between lightning peak current amplitude and Cloud to Ground Lighting Flash Density (CGLFD), using data provided by a Colombian Lightning Location System (LLS) network. 15 years' data analysis is carried out; this is enough information available to obtain some conclusions regarding this subject. A data management in relation with lightning peak current and CGLFD is developed with the aim of making the analysis comparable with other similar studies carried out in different location around the world.

This work compares the classification accuracy (CA) of two algorithms applied to data from the EUCLID lightning location system (lLS). As CA we call the accuracy of a LLS to correctly distinguish between cloud-to-ground (CG) and intra cloud (IC) discharges. The ground-truth data, used for this evaluation, was taken from optical and electric field data measured in various regions in Austria (2012 and 2015) and France (2014). The data set contains CG and IC discharges of positive and negative polarity. The data set was split up into further sub-categories as long as the number of data was still sufficient to give reasonable results. For a coarse overview of the algorithm performances, the total CA was first calculated for each year and country for both polarities. Furthermore, for the class of CG discharges, the CA of first return strokes, the CA of subsequent return strokes (with and without respect to the polarity) as well as the CA of IC events with respect to their polarity was evaluated. Specifically the subdivision into classes of amplitudes of the peak currents for different events can give further insight to the performance of the algorithms. For that reason the total CA, the CA of negative and positive events and CG and IC was analyzed. The evaluation shows that in combination with the new sensor data format LS the new algorithm exhibits an improvement of 2% at the CA. In combination with the old data format IMPACT, the new algorithm performs worse than the old one. In total, IC events have been classified much better by the new algorithm, irrespective of the sensor data format. CG discharges on the other hand show a worse CA throughout all years for the new algorithm.

The Telescope Array (TA) experiment detects air-showers induced by ultra high energy cosmic rays. The TA ground Surface particle Detector array (TASD) observed some short-duration bursts of air-shower like events. As reported at ICRC2015, these events are evidently correlated with lightning. Therefore, we have deployed detectors for lightning discharge in the vicinity of the TASD. We report the status and study of the Telescope Array Lightning Location System (TALLS).

Osaka University, Toshiba and the Osaka Local Government started a new project to develop the Osaka Urban Demonstration Network. The main sensor of the Osaka Network is a 2-node Phased Array Radar Network and lightning location system. Data products that are created both in local high performance computer and Toshiba Computer Cloud, include single and multi-radar data, vector wind, quantitative precipitation estimation, VIL, nowcasting, lightning location and analysis. These new products are transferred to Osaka Local Government in operational mode and evaluated by several section in Osaka Prefecture.

According to the lightning monitoring data recorded by lightning location system of Guangdong power grid in the past 10 years (from 2003 to 2012), we gain the lightning parameters of Shenzhen power grid and fit the lightning current amplitude distribution curve. The research results show that the fitting expression format of the lightning current amplitude distribution gotten from lightning location system adopted by IEEE is better than that adopted by national power industry regulations. And the lightning current in Shenzhen area ranging from 20kA to 40kA shows obvious packing effect. It’s recommended to take anti-accident measures in the weak sections of mountain areas to improve the shielding failure lightning protection performance.