Lightning Incidence Research Articles

Investigation of Upward Leader Development Characteristics by Two Kinds of Charge Density Models in Wind Turbines

ABSTRACTThe upward discharge is a significant factor threatening the operation of wind farms. This paper investigates the inception and development of upward leaders of wind turbines' tip, where blade rotation prevents charge accumulation, using charge density models from laboratory discharges and artificially triggered lightning. The results indicate that larger return stroke currents create higher spatial potentials, and slower downward leader speeds allow for longer development time, favoring the development of upward leaders. As wind turbine sizes increase, the rotation of the blade tips resembles artificially triggered lightning, and the long air gap discharge model may underestimate the development of upward leaders. Calculations from the artificially triggered lightning model reveal improved upward leader formation when further laterally away from the downward leader within a certain distance, elucidating why multiple upward leaders are frequently observed around turbines. The striking distance and attractive radius are largely determined by the development of upward leaders. The absence of corona charge shielding at blade tips means upward leader inception is independent of downward leader velocity, emphasizing downward leaders' significant influence on turbines. Thus, the formula for estimating a wind turbine's lightning incidence requires integrating the return stroke current and velocity of the downward leader.

Accelerating Stochastic Lightning Attachment Simulations for the Estimation of Lightning Incidence to Overhead Lines

Lightning attachment can be modeled through a stochastic approach adopting a detailed representation of the lightning phenomenon. A fractal-based modeling technique can be used for this purpose, considering lightning discharge branched and tortuous behavior, as well as physical properties associated with downward and upward leaders’ inception and propagation. However, fractal-based simulations require substantial computational resources, especially for the accurate calculation of the electric field at all points of the discretized simulation domain at each simulation step. Thus, the considerable computational cost inhibits the extensive application of stochastic simulations for estimating lightning incidence to common structures and power systems. This work investigates optimization techniques for fractal-based simulations regarding total simulation time; these are applicable to both high-performance computing and personal computers. The proposed techniques consist of a C-MATLAB integration methodology, as well as a multi-color ordering algorithm enabling parallel execution using CPU and GPU programming. Applications associated with lightning incidence to overhead transmission lines are presented. The total simulation time is substantially reduced with respect to the original code. A reduction of up to 98% is achieved, enhancing the applicability of stochastic modeling to lightning incidence estimation problems.

Evidence of a link between Amazon fires and lightning

The number of fires in the Amazon region increased dramatically at the beginning of 2022 compared to 2021. Considering that this period is also characterized by a large incidence of cloud-to-ground (CG) lightning in this region, we investigated if these phenomena may be related to each other. Two regions of Brazil were considered in the analysis: Mato Grosso state, on the border of the Amazon region where most of the deforestation occurs, and Amazonas state, in the interior of the Amazon region. In the first four months of 2022, 26,554 fires and approximately 3 million CG lightning flashes in Mato Grosso and 2468 fires and about 3.4 million CG lightning flashes in Amazonas were recorded. By comparison, in 2021, 16,844 fires and approximately 2.7 million CG lightning flashes in Mato Grosso and 1258 fires and about 3.2 million CG lightning flashes in Amazonas were recorded. In this study, we examined whether these phenomena were linked on a 2 to 9-day timescale, utilizing wavelet coherence analysis of both fire and lightning data. Our results indicate that these phenomena are linked (p < 0.05) for several weeks in both regions in both years. Additionally, correlations for 2022 were notably higher (above 0.90 versus 0.80) when the incidence of fires and lightning was higher, lending support to the notion of a relationship between these two events. Considering the periodicity characteristics of our results and that most fires in these regions are human-induced, we conclude that anthropogenic fires may affect lightning activity through aerosol-cloud particle interactions, with additional and not previously documented implications for climate change. Assuming the same is happening in other regions of the planet, we may face a new aspect not considered in the present global climate model projections.

Lightning incidence study on an FPSO-type oil platform: A risk analysis approach based on the Monte Carlo method

Lightning incidence study on an FPSO-type oil platform: A risk analysis approach based on the Monte Carlo method

First comparisons of ball-lightning report website data with lightning-location-network data

Ball lightning (BL) is known primarily through observations of untrained eyewitnesses who see it fortuitously. Because this mode appears to be the primary source of data on ball lightning up to now, we established a website in June of 2020 designed to collect detailed reports of ball lightning sightings from eyewitnesses. As a first step toward reinforcing such reports with objective instrumented data, we have performed successful correlations of selected reports of ball lightning with lightning-location-network (LLN) data provided by Earth Networks. We linked ball lightning cases to an Earth Networks database of cloud-to-ground (CG) strokes by selecting strokes that were close, both geographically and in time, to the ball lightning incidents. The seven individual cases presented fit the previously established characteristics of ball lightning well, including demonstrating that BL does not necessarily form at the lightning ground strike location. Reports also emphasize certain features which are not always considered in theoretical treatments of ball lightning, e. g. its ability to pass through closed glass windows. We conclude with recommendations for both theorists and observational scientists.

Mapping main risk areas of lightning fatalities between 2000 and 2020 over Odisha state (India): A diagnostic approach to reduce lightning fatalities using statistical and spatiotemporal analyses

This study analyzes the spatiotemporal variation of lightning flashes and lightning strike deaths from 2001 to 2020 among all 30 districts of Odisha State, India. Lightning flash data for the study area were acquired from Lightning Imaging Sensor (LIS) installed aboard the Tropical Rainfall Measuring Mission (TRMM) for the 2001–2014 period and from International Space Station for the 2017–2020 period. Deaths by lightning flashes were acquired from the annual report of natural calamities for the 2001–2020 period from the Revenue and Disaster Management Department, Government of Odisha. In this study, the spatial pattern of lightning flashes based on LIS data and resultant deaths were assessed using spatiotemporal statistical analysis, including the interpolation method and Sen's slope estimator. The geospatial heat maps of lightning strikes and deaths highlight the spatiotemporal heterogeneity of lightning strikes and induced deaths in Odisha State. Furthermore, statistical analyses demonstrate an apparent increase in lightning strikes in the state as a whole, with particular attention to the Mayurbhanj, Sundargarh, and Keonjhar districts, which had the highest incidence of lightning. Odisha State was hit by more than 10,000 lightning strikes every year between 2000 and 2020, excluding 2001, 2017, and 2018. The results show a moderate correlation (R = 0.61) between lightning strikes and lightning deaths in Odisha State during the analyzed period, which further needs to be investigated with respect to the seasonality of lightning, the locational vulnerability, and temporal risk.

Retrospective study of lightning fatalities in Raigarh, Chhattisgarh

is a massive electrostatic discharge caused by the circulation of warm moisture-filled air through unbalanced electric field in the atmosphere, accompanied by the loud sound of thunder.: The present study was conducted to ascertain the pattern of lightning cases along with distribution of cases based on age, sex, season, location, activity of the victim and injury pattern in the corpse.: The present cross sectional retrospective study was carried out in the department of Forensic Medicine at Govt. Medical College, Raigarh, CG. All autopsy cases of lightning deaths from 2018 to 2019 (two years) were considered for the study.: Most of the deceased were in the age group of 31-40 years. All incidents happened in open field. High incidence of lightning deaths occurred during monsoon season and peak incidence in evening hours. In most cases arborescent mark was found as pathognomonic finding.: Lightning incidents are always accidental in nature. They are fatal and need prompt resuscitative measures. Lightning injuries have bizarre presentation in the body, therefore the autopsy surgeon needs meticulous and detailed methodical approach during autopsy.

Uma Análise Visual da Espacialização das Descargas Elétricas Atmosféricas e do Comportamento das Mortes Causadas por Raios no Estado da Bahia

Estudos divulgados pelo Grupo de Eletricidade Atmosférica do Instituto Nacional de Pesquisas Espaciais colocam o Brasil como o país com maior incidência de descargas atmosféricas no mundo, sendo, em média, 77,8 milhões todos os anos. No período de 2000 a 2019 foram registados 2.194 óbitos causados por raios no país, sendo que a cada 50 mortes por raios no mundo, uma é no Brasil. Este trabalho se propõe a realizar uma análise visual do comportamento das descargas atmosféricas no estado da Bahia, relacionando- a ao número de mortes causadas por raios em cada município. Para tal, foram consultados os dados de densidade de descargas atmosféricas e número de mortes causados por raios divulgados pelo INPE e Ministério da Saúde, respectivamente. Também foram utilizados os dados referentes ao número de habitantes disponibilizados pelo IBGE em cada município do estado da Bahia. A análise visual foi realizada com a utilização da ferramenta VYR. Os resultados mostraram uma maior incidência de descargas na região Oeste do estado. Quanto ao número de mortes, verificou-se uma distribuição homogênea no estado, com uma aparente relação com a área e número de habitantes dos municípios. Observou-se uma redução no número de mortes nos últimos dez anos, provavelmente relacionada com o aumento do grau de instrução da população. A Visual Analysis of the Spatialization of Atmospheric Electric Discharges and Behavior of Deaths by Rays in the State of Bahia A B S T R A C TStudies released by the Atmospheric Electricity Group of the National Institute for Space Research place Brazil as the country with the highest incidence of lightning in the world, with an average of 77.8 million every year. In the period from 2000 to 2019, 2,194 deaths from lightning were recorded in the country, with every 50 deaths from lightning in the world, one is in Brazil. The objective of this work is to carry out a visual analysis of the behavior of lightning strikes in the state of Bahia, relating it to the number of deaths caused by lightning in each municipality. The goal is to investigate whether there is any relationship between the number of deaths, the region and the population.To this end, data on lightning density density and number of deaths caused by lightning were published by INPE and the Ministry of Health, respectively. The number of inhabitants provided by IBGE in each municipality in the state of Bahia was also used. Visual analysis was performed using the VYR tool. The results showed a higher incidence of discharges in the western region of the state. As for the number of deaths, there was a homogeneous distribution in the state, with an apparent relationship with the number of inhabitants of the municipalities. There was a reduction in the number of deaths in the last ten years, probably related to the increase in the education level of the population.Keywords: Visual analysis, lightning strikes, lightning deaths and the state of Bahia

Reducing Costs of Preventive Lightning Systems by Locational Optimization

The installation of lightning detection sensor systems involves a large volume of resources. However, the absence of these systems can lead to irreparable damage, such as the death of a person. How to reduce the costs of implementing these systems to protect workers and citizens or even public and private equipment? Usually, this problem is not solved on a formal level, but based on the intuition of the involved specialists, without applying optimization techniques. Taking this into account, this research explores the theoretical structure of locational optimization methods to propose a simplified heuristic method that does not require any programming skills for its application. Specifically, its use directly demonstrated by reducing costs of preventive lightning systems in an area containing 41 mines. All mines must be covered by the sensor system which has a coverage radius of 10 km. The experimental results demonstrate that the application of this method generates more effective results than those obtained using known methods of locational optimization. The method proposed in this research contributes directly to reduce costs of preventive lightning systems and indirectly to protect workers in mining areas as well as to protect populations in urban areas where the frequency and incidence of lightning is especially high.

Performance Analysis Among Predictive Models of Lightning Occurrence Using Artificial Neural Networks and SMOTE

Lightning represent a potential threat to various society activities, such as damage to telecommunication systems and the distribution of electric power, as well as injury or death of humans beings. Predicting the occurrence of lightning can help in making decisions about the actions that must be taken to minimize the risks of this natural phenomenon. In this study, data from air temperature profiles, dew point temperature and historical lightning data were used to obtain two predictive models of lightning occurrence. The models were obtained by using an artificial neural network. The first model was obtained through unbalanced data and the second one with data balanced with Synthetic Minority Over-sampling Technique (SMOTE). The model performance was tested in five different classes of lightning predictions: ABSENCE, LOW, MODERATE, VERY and SEVERE, considering five prediction periods: case 1 (one hour), case 2 (two hours), case 3 (three hours), case 4 (four hours) and case 5 (five hours). It was observed that the use of the Synthetic Minority Over-sampling Technique improved accuracy in the recognition of atmospheric patterns that lead to the incidence of lightning in the five classes used in the five prediction cases.

Short-Term Lightning Response to Ground Level Enhancements

Cosmic rays (CRs) are considered the primary energetic particle source of atmospheric ionization on Earth. Under the modulation of severe solar eruption events, CR variations are further speculated to impact the Earth’s lightning activities. Previous researches show that CR intensity and lightning incidence are positively correlated on the time scale of several days to decades. However, to our knowledge, the global lightning response to short-term CR variation has not been studied in the literature. Ground level enhancements (GLEs) provide the opportunity to study such a possible link. As a small fraction of solar energetic particle events that could reach the energy level of several GeVs, GLEs can thus generate atmospheric cascades that could be recorded by ground-based neutron monitors. Furthermore, as GLEs generally take place within several ten minutes to an hour, the lightning variations caused by potential meteorological factors could be maximally diminished in such a short time. During the operational period of the World Wide Lightning Location Network (Aug 2004 to now), three typical GLEs with the intensity greater than 15% are analyzed from the International GLE Database, namely #69 (Jan 20, 2005), #70 (Dec 13, 2006), and #71 (May 17, 2012). For each GLE event, the global lightning incidence presents a positive response to GLE, i.e., a significant enhancement within 20 minutes right after the GLE onset. Meanwhile, the relative amplitude of lightning response seems to be in direct proportion to GLE intensity, i.e., the more intensive the GLE is, the more obvious the increase in the lightning incidence is, which is further verified to be statistically significant by Monte Carlo test. By comparing lightning responses in different latitudinal zones, we find that more intensive lightning responses to GLEs seem to be at higher latitudes.

Closed-Form Expressions for the Estimation of the Minimum Backflashover Current of Overhead Transmission Lines

The minimum backflashover current, I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BF</sub> , of typical overhead transmission lines is estimated through ATP-EMTP simulations considering the tower ground resistance and AC voltage phase angle as parameters. Several single- and double-circuit lines are investigated with operating voltage from 66 kV to 765 kV and Basic Insulation Level from 325 kV to 1950 kV. The backflashover rate, BFR, of the investigated lines is obtained using an expression that accurately considers lightning incidence to the line for prospective currents higher than I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BF</sub> ; the relevant CIGRE expression underestimates BFR. BFR can be easily estimated using solely the phase angle values corresponding to zero AC voltage of the phase conductors. Based on the I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BF</sub> and BFR results, simple expressions are introduced for the calculation of an equivalent minimum backflashover current as a function of insulator length and tower ground resistance or impulse impedance. These expressions enable straightforward estimation of BFR without the need for time-consuming simulations or laborious analytical methods adopting simplifying assumptions.

Estimation of Lightning Incidence to Telecommunication Towers

General closed-form expressions for estimating lightning incidence to telecommunication towers are introduced on the basis of several lightning attachment models. The expressions consider the effects of tower height and lightning peak current distribution, as well as orographic and shielding effects. The estimated annual number of lightning strikes to towers, varying considerably among lightning attachment models, increases with tower height according to a power law and it is higher for lightning peak current distributions with high median value and standard deviation. A comparison is made between estimates and field data on lightning incidence; IEC geometric method, which is traditionally used in industry, by exaggerating the effect of tower height, overestimates lightning incidence. Literature lightning attachment models suitable for estimating lightning incidence to telecommunication towers are suggested based also on the observed failure rate of a transformer feeding a GSM base station.

Analysis of the Incidence of Direct Lightning over a HVDC Transmission Line through EFD Model

HVDC systems are becoming more common worldwide, specially in Brazil, since the adoption of such system for Itaipu’s hydroelectric complex in the 1980’s. Today, the country has the Xingu-Estreito bipole, with length of 2375 km. This system crosses a region with high lightning incidence, a phenomenon which causes faults in power systems. The most widely used model for the positioning of the arrestor cables over a transmission line is the electrogeometric model. This model, however, does not take into account the different potentials over the structure’s surface, and therefore presents significant inaccuracies when assessing the risk of lightning strikes on structures such as a HVDC line. This work then used the Electric Field Deflection (EFD) model with the aid finite elements. Four levels of lightning are assessed (I, II, III and IV), with current peaks of 3.9, 5.4, 10.1 and 15.7 kA. It was verified that the positive pole tends to attract most of the lightning with shielding failures width (SFW) of 12, 8, 4 and 0 m. It was then proposed to move the arrestor cables horizontally. The study indicates that this horizontal shifting of the cables in 5 and 8 m toward the side with larger chance of direct incidence reduces the shielding failure widths in 50% for peak current of 3.9 kA and almost eliminates the strikes for lightning with peak currents of 5.4, 10.1 and 15.7 kA.

Design of a UWB biconical antenna with a lightning protection system for surveillance applications

AbstractThis article presents, to the best of our knowledge, the study, software simulation and fabrication of a biconical antenna with a lightning protection system operating in a wide frequency range from 20 MHz to 3 GHz. The purpose of this system is to provide protection against atmospheric electric discharge in regions with a high incidence of lightning.

Restoring historical fire regimes increases activity of endangered bats

BackgroundFire suppression has altered ecological communities globally. Prescribed fire regimes strive to restore function to these fire-dependent ecosystems by mimicking natural fire regimes. Although fire frequency is a widely acknowledged component of fire regimes, the importance of fire seasonality for biodiversity is less clear but appears to play a critical role for a variety of taxa, particularly in the North American Coastal Plain. In subtropical Florida, USA, fire historically occurred primarily at the transition from the dry to wet season (early wet season: April to June) when dry fuel accumulation coincides with a high incidence of lightning. We investigated the effects of fire frequency and season on endangered Florida bonneted bats (Eumops floridanus [G.M. Allen, 1932]), a species endemic to a region that evolved with frequent fires.ResultsWe surveyed bat activity acoustically in 149 sites in fire-dependent vegetation communities (pine flatwoods and prairies), and evaluated the effects of fire frequency and seasonality, using burn records from the previous 18 years. Variation in bat activity was best explained by both fire frequency and season: bat activity decreased with early wet season (April to June) burn interval and increased with dry season (November to March) burn interval. Bat activity and foraging activity were highest in sites burned at > 3- to 5-year intervals during the early wet season.ConclusionFires during the historic fire season at a moderate frequency (> 3 to 5 yr) appear to optimize habitat for bats in both pine flatwoods and prairies, likely through increases in roosts, flight space, and insect prey availability. It appears that Florida bonneted bats are fire-adapted and benefit from prescribed burn programs that closely mimic historical fire regimes. We encourage consideration of both fire frequency and seasonality when managing ecosystems with fire.

CTR Wilson Meeting 2016

CTR Wilson Meeting 2016

Climatic diagnostics associated with anomalous lightning incidence during the summer 2012/2013 in Southeast Brazil

ABSTRACTThe State of São Paulo in Southeast Brazil experienced during the 2012/2013 summer one of the most severe electrical storm events in recent years, causing various impacts to society, e.g. fires and fatalities. Thus, the objective of this work is to understand which mechanisms and climatic variability modes are associated with the lightning incidence during this summer in this region. The study includes a statistical‐temporal assessment of cloud‐to‐ground (CG) lightning occurrence comprising the 16 years period from 1999 to 2014. The results showed that, for this period of analysis, the lightning incidence was associated with climatic patterns connecting the tropical and extratropical region, through a wave train, from the Indian Ocean to South America, favouring the formation and development of convective storms over Southeast Brazil.

Spatiotemporal variability of lightning activity in Europe and the relation to the North Atlantic Oscillation teleconnection pattern

Abstract. Comprehensive lightning statistics are presented for a large, contiguous domain covering several European countries such as France, Germany, Austria, and Switzerland. Spatiotemporal variability of convective activity is investigated based on a 14-year time series (2001–2014) of lightning data. Based on the binary variable thunderstorm day, the mean spatial patterns of lightning activity and regional peculiarities regarding seasonality are discussed. Diurnal cycles are compared among several regions and evaluated with respect to major seasonal changes. Further analyses are performed regarding interannual variability and the impact of teleconnection patterns on convection. Mean convective activity across central Europe is characterized by a strong northwest-to-southeast gradient with pronounced secondary features superimposed. The zone of maximum values of thunderstorm days propagates southwestward along the southern Alpine range from April to July. Diurnal cycles vary substantially between both different months and regions, particularly regarding the incidence of nighttime lightning. The North Atlantic Oscillation (NAO) is shown to have a significant impact on convective activity in several regions, which is primarily caused by variations of the large-scale lifting pattern in both NAO phases. This dynamical effect is partly compensated for by thermodynamical modifications of the pre-convective environment. The results point to a crucial role of large-scale flow in steering the spatiotemporal patterns of convective activity.

Lightning protection for wind turbines in Vietnam

AbstractWind energy has become increasingly important in the total electrical energy supply mix in Vietnam over the last few years. Small, kW turbines were installed in isolated areas a decade ago, while wind farms of several MW to few hundred MW are now being connected directly to national grid, with many additional projects in planning or under construction to fulfill an objective of 6% of the total installed capacity by 2030 (approximately 6200 MW of wind energy component). The increase in wind farm generation results in increased damage from lightning. In this paper, the annual frequency of lightning strikes to wind turbines in Vietnam is calculated using electrogeometric model. Reported lightning incidents to three major wind farms in Vietnam are summarized. Possible causes of failure are discussed, and an EMTP simulation for each incident was performed accordingly. The simulations suggest the failure mechanisms as well the potential of improved grounding to reduce lightning induced damage in future ...