Lightning Events Research Articles

Measurement and characterization of infrasound waves from the March 25, 2023 thunderstorm at the near equatorial

<abstract> <p>Thunderstorm activity on March 25, 2023 provided a unique opportunity to study the mechanism of lightning events on changes in air pressure. In particular, this event made it possible to study changes in air pressure during thunderstorms using various instruments. This paper presented comprehensive results of infrasound, satellite data, weather radar and weather measurements at the ground during the storm. Observations of lightning events were confirmed using observational data from the International Space Station's Lightning Imaging Sensor (ISS LIS). This work estimated three spectral percentile values on infrasonic sensor data, time series interpolation of standard meteorology profiles, weather radar reflectivity and total radiant energy of lightning from ISS LIS observations during the day and night periods. As a result, during the investigation, it was seen that the recorded infrasound signal in the 0.6–0.8 Hertz (Hz) range was contaminated by background environmental noise, but in the 1–3 Hz band range it was consistent with the appearance of storms that produce high energy blows. Infrasound detection and electromagnetic lightning detection show good correlation up to a distance of 100 km from the infrasonic station. During a thunderstorm, the ISS LIS flight directly above the observation site detected more than 2,000 lightning events. In addition, the application of lightning detection from several independent instruments can provide a complete picture of the observed event.</p> </abstract>

Effect of lightning mast placement on underground power cable jacket stress within high voltage substations

This study aims to investigate the impact of lightning masts placement on underground cables within high voltage substations. While the subject of lightning discharges near to underground cables has been covered with open cable runs and wind farms in many papers, this study focuses on lightning events within high voltage substations considering the associated effective zones, which were not covered in the available literature. Substations built within areas prone to high lightning activity experience frequent discharges that cause the potential rise of the earthing system into hundreds of kilovolts. The potentials propagating within the soil and the earthing grid affect underground cables jackets terminated within the substation. The numerical analysis of the problem is carried out using Current Distribution, Electromagnetic fields, Grounding and Soil structure analysis (CDEGS) software engine for different configurations of lightning mast placements with varied separation, electrode placement and length, soil resistivity, and lightning current. Study findings indicate that provision of lightning masts/down conductors as far as possible or at least twice the effective zone radius from cable termination/route electrodes ensures relatively lower stress voltages. Electrodes with effective zone radius length placed as close as possible to lightning masts further reduce the attainable jacket stress voltages.

Book review. Weather – Hurricanes, Tornadoes, Ice, Lightning and Other Dramatic Weather Events in Photographs

Book review. Weather – Hurricanes, Tornadoes, Ice, Lightning and Other Dramatic Weather Events in Photographs

Synoptic climatology of pre-monsoon frequent lightning events in Bangladesh

Synoptic climatology of pre-monsoon frequent lightning events in Bangladesh

A New Method for Modeling and Parameter Identification of Positively Charged Downward Lightning Leader Based on Remote Lightning Electric Field Signatures Recorded in the ELF/MF Range and 3D Doppler Radar Scanning Data

The aim of this paper is modeling and parameter identification of the leader stage preceding the positive stroke of natural cloud-to-ground lightning. This research is based on electric field and 3D Doppler radar data recorded during thunderstorms in Poland, as supplied by database information from long range lightning location systems. The numerical simulation performed in the MATLAB platform showed that a high number of assumed model parameters, such as non-uniform leader tip speed and lightning channel charge density, allowed us to obtain greater compliance between simulated and measured electric field signatures than in the classical approach. The proposed model can be implemented in lightning location systems and forest fire warning systems, operating globally to reduce the risk of damages caused by positive cloud-to-ground flashes being one of the most dangerous type of lightning events. An alternative application of the model can be for research, including ground-based lightning data supplementation for the corresponding satellite and airborne registrations.

Numerical simulation of a widespread lightning event over north India using an ensemble of WRF modeling configurations

Widespread event of lightning occurred in two states of eastern India on June 25, 2020, killing 83 people in Bihar and 24 people in Uttar Pradesh (UP). Lightning event is studied using ground-based lightning observational data and Weather Research and Forecasting (WRF) model. A Specialized forecast system for lightning and thunderstorm is needed to minimize the loss of lives. The updraft and ice particle concentration play essential roles in the initialization of lightning inside the thundercloud. The charge generation and separation inside the clouds play an essential role in the severity of lightning. The Lightning Potential Index (LPI) measures the potential of charge generation and separation inside the clouds. It plays a significant role in determining lightning-prone zones.As the monsoon intensified over the Indo Gangetic Plains, lightning simulation is carried out using an ensemble of different WRF model configurations. The model has been integrated from 24th June 0000 UTC to 26th June 0600 UTC with an ensemble of 9 members. 8 members are simulated with a single domain (3 km resolution), and only the second member is simulated with a triple nested domain (9, 3, and 1 km resolution) over Bihar. The ensemble consists of 1 control +8 members with different configurations of the WRF model. LPI is calculated using the model-derived parameters. Furthermore, the model explicitly simulated lightning flash count using a lightning parameterization scheme. The results are analyzed using the Indian Institute of Tropical Meteorology (IITM) ground-based observation data. Every ensemble member's results are distinct from each other. This shows the sensitivity of every configuration. Member 2 (M2) is the triple nested member; it uses the same physics option as member 1 (M1). Moreover, M2 shows comparatively good results towards the observation. Simulated radar reflectivity is compared and analyzed using Indian National Satellite System (INSAT-3D) 3D Brightness Temperature (BT). To check the results of all ensemble members model skill score has been calculated. Ensemble probability is calculated to measure the spatial pattern and threat of lightning based on LPI, and it recorded the high lightning threat (90–100) % probability over northwest Bihar (Gopalganj), and it also recorded the heavy rainfall (300 mm). The skill scores of simulated lightning flash count in M2, M8, and M9 showed reasonably good POD values (0.6, 0.5, and 0.69, respectively).

Environmental Analysis of Warm-Season First Cloud-To-Ground Lightning Events over the Western Florida Peninsula

Abstract Florida annually leads the United States in lightning-caused fatalities. While many studies have examined the lightning frequency maximum near Cape Canaveral, relatively little attention has been paid to the western Florida peninsula, which features a similar warm-season lightning event density. Of particular concern are first cloud-to-ground (FCG) lightning events in developing thunderstorms, which are difficult to predict with sufficient lead time and can catch people off guard. This study performs an environmental analysis of warm-season (May–September) FCG events (2014–21) across the western Florida peninsula using high-resolution model analysis data, including a comparison to null (No CG) days. FCG events and No CG days are first identified from ground-based lightning data and partitioned into nine synoptic-scale flow regimes. Next, spatiotemporal distributions of FCG events are elucidated for the western Florida peninsula. An ingredients-based analysis shows that the convective environment one hour before FCG events during strong south-southeast flow features the largest amounts of moisture, but the smallest instability values and weak midtropospheric lapse rates, primarily due to warm advection and moisture transport from the Atlantic Ocean. Environments one hour before FCG events in all nine flow regimes feature markedly greater instability values, larger relative humidity values, and steeper midtropospheric lapse rates than do No CG days. Results emphasize that instability and moisture are the key ingredients for warm-season FCG events in the region. Convective parameter statistical distributions and composite soundings populate an online dashboard that can be used by regional forecasters to better predict FCG events and increase alert lead times. Significance Statement Florida annually leads the United States in lightning fatalities. Of particular concern are first cloud-to-ground (FCG) lightning events, which are difficult to forecast and can catch people off guard especially during outdoor recreational activities and labor. We investigate the environmental characteristics of warm-season FCG events across the western Florida peninsula. Among nine regional flow patterns, some are associated with a less moist and more unstable atmosphere one hour before an FCG event, while other regimes exhibit a more moist and less unstable atmosphere. However, regardless of flow pattern, FCG events consistently feature substantially greater instability and moisture than do null events. Key findings are displayed on an online dashboard, to better inform regional forecasters.

FORTE Measurements of Global Lightning Altitudes

AbstractWhile multiple lightning detection systems provide geographical locations of lightning events across the globe, robust lightning altitude measurements on a global scale have proven elusive. Space‐based platforms have an advantageous viewing geometry for making these measurements, but prior studies with the Fast On‐orbit Recording of Transient Events (FORTE) satellite were limited to a few thousand events. In this study, we apply the same technique for calculating source altitude from the previous efforts to a large catalog of hundreds of thousands of global FORTE in‐cloud lightning events that were coincident with flashes geolocated by its lightning imager between 1997 and 2003. We use this new data set to document global variations in lightning altitude. As in previous studies, we find that FORTE primarily resolves sources from the upper (positive) charge layer at ∼11 km altitude in normal thunderstorms. However, sources are also recorded from other charge layers in the storm and from leaders developing between layers. In particular, we note a pronounced increase in source altitude in the first 20 ms of FORTE flashes from the negative leader developing upward into the upper positive charge layer. Regions known for wintertime and/or stratiform lightning have increased contributions from low‐altitude sources, while tropical regions particularly around Panama and the Maritime Continent have the greatest concentrations of high‐altitude sources.

Effects of Convective Mergers on the Evolution of Microphysical and Electrical Activity in a Severe Squall Line Simulated by WRF Coupled With Explicit Electrification Scheme

AbstractTo investigate the process of convective merger (CM) and its effect on thunderstorms evolution and corresponding electrical activity, a severe squall line that took place on 27 July 2015 over the Beijing Metropolitan Region (BMR) is simulated and studied using the Weather Research and Forecasting (WRF) model coupled with an explicit electrification lightning scheme (E‐WRF). The model‐simulated radar reflectivity reasonably captured the whole squall line evolution, including the merging of individual cells and storms. The variation of normalized flash frequency simulated by E‐WRF is highly consistent with the occurrence of a prominent flash rate surge during the CM both in the observation and the simulation. Cloud bridge is one of the regions where lightning events increase most. The upstream anvil and the sinking outflow led to the rapid connection and formation of new convective cells between the two older main storms. Subsequently, the mass of graupel and snow increased substantially at the middle level, and the mass of upper‐level ice was horizontally advected from upstream. During the merger, the in‐cloud charge distribution evolved from a staggered charge pocket structure into a vertically stratified five‐layer structure. This study supports the hypothesized role of CM in enhancing lightning activity, and further expands our understanding of CM effects on microphysics and charge‐redistribution.

End-to-End Prediction of Lightning Events from Geostationary Satellite Images

While thunderstorms can pose severe risks to property and life, forecasting remains challenging, even at short lead times, as these often arise in meta-stable atmospheric conditions. In this paper, we examine the question of how well we could perform short-term (up to 180 min) forecasts using exclusively multi-spectral satellite images and past lighting events as data. We employ representation learning based on deep convolutional neural networks in an “end-to-end” fashion. Here, a crucial problem is handling the imbalance of the positive and negative classes appropriately in order to be able to obtain predictive results (which is not addressed by many previous machine-learning-based approaches). The resulting network outperforms previous methods based on physically based features and optical flow methods (similar to operational prediction models) and generalizes across different years. A closer examination of the classifier performance over time and under masking of input data indicates that the learned model actually draws most information from structures in the visible spectrum, with infrared imaging sustaining some classification performance during the night.

Onboard performance of the level 1 trigger of the mini-EUSO telescope

The Mini-EUSO telescope was launched for the International Space Station on August 22nd, 2019 to observe from the ISS orbit (∼400 km altitude) various phenomena occurring in the Earth’s atmosphere through a UV-transparent window located in the Russian Zvezda Module. Mini-EUSO is based on a set of two Fresnel lenses of 25 cm diameter each and a focal plane of 48×48 pixels, for a total field of view of 44°. Until July 2021, Mini-EUSO performed a total of 41 data acquisition sessions, obtaining UV images of the Earth in the 290 nm – 430 nm band with temporal and spatial resolution on ground of 2.5 μs and 6.3×6.3 km2, respectively. The data acquisition was performed with a 2.5 μs sampling rate, using a dedicated trigger looking for signals with a typical duration of tens of μs.In the present paper the analysis of the performance of the 2.5 μs trigger logic is presented, with a focus on the method used for the analysis and the categories of triggered events. The expected functioning of the trigger logic has been confirmed, with the trigger rate on spurious events that remains within the requirements in nominal background conditions. The trigger logic detected several different phenomena, including lightning strikes, elves, ground-based flashers and events with EAS-like characteristics.

Simultaneous Upward Lightning From Small Structures and From the 150 m High Peissenberg Tower, Germany

In this study, we analyze a lightning event, which occurred on March 20, 2020 at 8:05 pm. Three other-triggered upward lightning developed simultaneously from the 150 m high Peissenberg Tower and from two small structures, a 35 m high mast and a 25 m high Church Tower. The velocity of the upward leaders ranged from 2.1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> to 4.1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> m/s. In addition, to these upward leaders, the total of 51 isolated leaders were observed. These leaders had no contact to the lightning channel or to other leaders or to objects at ground, i.e., most of them did not develop along a path of the decayed channel of a previous leader. Therefore, it is doubtful whether the isolated leaders may be recoil leaders. The lightning to the Peissenberg Tower was a bipolar flash with a current, which contained several (unusual) positive and negative components. The first component was a negative initial continuous current (ICC), followed by a strong negative current component, with a maximum of 4.1 kA and a duration of 40.2 ms. This current component was superimposed by a pulse train of 26 extremely strong current pulses with peak values up to 1.87 kA. The negative current component was followed by a positive current pulse with a peak value of 31 kA, a 10%–90% risetime of 1.80 ms, an action integral of 0.68 MJ/Ω, a full width on half maximum of 0.67 ms and a duration of 15.7 ms. The positive current pulse was superimposed by strong oscillations with the frequency of about 5 kHz and with amplitudes up to 10.2 kA. After its cessation, the positive current pulse turned into a negative continuing current with the duration of 217 ms, the maximum of 245 A, and the transferred charge of 18.0 C. The negative continuing current was followed by a negative return stroke which in turn was followed by a positive continuing current, which lasted 19.7 ms and had a maximum of 173 A. Finally, a second negative return stroke occurred, which was followed by a short negative continuing current with an M-component.

Dependence of lightning current on resistance and radius of discharge plasma channel

The current transmission characteristics of lightning discharge are closely related to lightning hazard mechanisms. The conductive properties of a lightning plasma channel were analyzed based on the spectra of nine negative cloud-to-ground lightning events recorded by a high-speed slit-less spectrograph and the theory of plasma conductivity. Combined with the information of synchronous electric field change caused by lightning, we estimated the peak current and corresponding current-carrying channel radius and further investigated the dependence of the discharge current on the resistance and radius of the discharge plasma channel. The results showed that there was a nonlinear relationship between the peak current and the resistance per unit length of the discharge channel. The radius of the current-carrying channel was positively correlated with the current intensity. Radius was an important parameter that affects the magnitude of the current. The electrical conductivity and the radius of the current-carrying channel have a coupling effect on the current transmission, which is the main factor determining the current transmission feature in the discharge plasma channel.

Analysis of Lightning Events Due to Rainfall and Wind Speed in Pekanbaru City

Quantitative research has been conducted on the effect of rainfall and wind speed on lightning events in Pekanbaru City from August to October 2018. Observation data were obtained from Meteorological Station Class I Sultan Syarif Kasim II Pekanbaru, Riau Province, Indonesia. Observations are made by recording lightning events automatically using a lightning detector which will be analyzed using the Lightning Analysis program version 7.2 and the Google Earth Pro program. The results showed that high rainfall caused frequent thunderstorms, and relatively high wind speeds from late September to October caused the number of lightning strikes to increase due to the ionization process that produces an electric charge.

Global Distribution and Spectral Features of Intense Lightning by the ISUAL Experiment

AbstractDuring the 12 years of the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) experiment onboard the Taiwanese FORMOSAT‐2 satellite (2004/07/01–2016/6/20), 297,349 transient events were recorded, but only 48,414 events (16.3%) were manually classified as transient luminous events (TLEs). Since the main target of ISUAL is to observe TLEs, only the top ∼0.82% of intense lightning can meet the trigger threshold, which means the ISUAL experiment can also serve as a space‐borne intense lightning survey. An autonomous lightning identification algorithm was developed in this work to screen and locate lightning flashes in images, and 292,248 intense lightning discharges were identified successfully. Combining the statistical analysis of lightning events and unique spectral observations of ISUAL, the global distribution of intense lightning with spectral characteristics was constructed. The intense lightning occurrence rate of ISUAL was 1.29 fl s−1, and the land‐to‐ocean ratio 1.27. Intense lightning is most active near the equator, and the bimodal pattern peaks in April and September, different from the typical lightning behavior that occurs in the northern hemisphere during the summertime from July to August. In addition, the spectral statistics show that more than 95% of intense lightning is accompanied by nitrogen band emissions (1PN2, 2PN2, 1NN2+). Far‐ultraviolet photons mainly come from the radiation processes in the mesosphere to the ionosphere, and its radiation flux may correlate with lightning energies. Further, a significant 777.4 nm background enhancement is recognized in South America, which may affect the trigger of space‐borne 777.4 nm lightning surveys.

People Deaths and Injuries Caused by Lightning in Himalayan Region, Nepal

Several natural disasters such as lightning, flood, fire, epidemics, and landslides frequently occur in the Himalayan region, of Nepal. The altitude of this region ranges from 59 m to “8848.86 m”—the height of Mount Everest—along with a distance of just 160 km. As a result, there is a considerable (i.e., nearly 95°C) variation in temperature in the region. Moreover, Nepal has a heterogeneous topography. All these features influence various natural disasters including lightning activity. This paper is aimed at analyzing the variations of lightning within and across the years from January 2011 to December 2021—a total of 11 years. For this, the data were taken from the Disaster Risk Reduction (DRR) portal of the Ministry of Home Affairs (MOHA). The analysis showed that there were no lightning events in November, and the lightning density was higher in the premonsoon period of study in this region. It also showed that the number of injured people is about thrice the death of the people due to the lightning. The null occurrence of lightning in November in the Himalayan region is a contribution novel to this field.

Combined Optical and Radio‐Frequency Perspectives on the Time Evolution of Lightning Measured by the FORTE Satellite

AbstractWe use a cluster feature data set for the Fast On‐orbit Recording of Transient Events (FORTE) satellite that combines detections from its pixelated Lightning Locating System (LLS), photodiode detector (PDD) and Radio‐Frequency (RF) instrumentation to generate statistics describing the frequency and timing of lightning events detected by each instrument during lightning flashes. Coincident observations from the same vantage point allow us to directly compare flash details that can be resolved by the wide Field of View (FOV) instruments relative to the pixelated LLS—whose design is based on NASA's Lightning Imaging Sensor. We find that both the PDD and RF system typically generate more detections than the lightning imager (mean: 1.5 PDD events per LLS group, 2 RF events per LLS group) from pulses that are either not sufficiently bright in the optical band (in the case of RF) or that lack the optical energy density (in the case of the PDD) required to trigger one of the pixels on the LLS imaging array. This includes additional activity before the first LLS group or after the final LLS group. These FORTE results demonstrate that certain lightning processes would be better resolved by wide‐FOV optical and RF instruments than lightning imagers. Current/future space‐based missions that use/plan to use similar instruments will improve our understanding of flash evolution by resolving details missed by lightning imagers.

Predictability analysis and skillful scale verification of the Lightning Potential Index (LPI) in the COSMO-D2 high resolution ensemble system

Abstract. During the last decade, the constant improvement in computational capacity led to the development of the first limited-area, kilometer-scale ensemble prediction systems (L-EPS). The COSMO-D2 EPS (now ICON-D2) was the operational L-EPS at the German weather service (DWD) and has a spatial resolution of around 2.2 km. This grid resolution allows large scale, deep convective processes such as thunderstorms or heavy showers to be handled explicitly, without any physical parametrization. Special parameters involving both clouds microphysics and large scale lifting – such as the Lightning Potential Index, or LPI – have also been developed in order to try to bring the forecasting of deep convection and therefore also of lightning activity to a new level of spatial accuracy. With such high resolution forecasts comes however also a higher error potential, at least for gridpoint-verification. The use of this high resolution setup in an ensemble prediction system might however bring huge benefits in terms of skill and predictability. This work is a preliminary attempt to apply innovative verification approaches such as the dispersion Fractions Skill Score (dFSS) and the ensemble-SAL (eSAL) to the LPI in the COSMO-D2 EPS. Aim of this work is to assess the relationship between the ensemble error and the ensemble dispersion at different spatial scales. For the summer months 2019, the COSMO-D2 EPS shows a general tendency to overestimate the predictability (underestimate the ensemble spread) of the lightning events, though the spread-error relationship varies greatly for different forecast lead times. With the help of the dFSS, one can also express this relationship in terms of skillful scales. On average, the system produces a useful forecast during the afternoon hours for horizontal scales of around 200 km. However, the ensemble members show an average horizontal dispersion that amounts to around half of that value, at more or less 100 km.

Coherency of Lightning Sferics

AbstractThe amplitudes of lightning sferics are commonly used for data analyses, for example, in lightning location networks. This contribution investigates the coherency of lightning sferics, which is calculated from the phase of the analytic complex signal. The complex signal is obtained from the Hilbert transform with the recorded signal as the input signal. This analytic signal is composed of amplitudes with corresponding phases. Rigorous selection criteria are applied to ensure that consistent events are used to calculate distance‐dependent average sferics waveforms which are summarized in waveform banks for the amplitude and coherency. The impulse response to lightning flashes is derived from an averaged waveform which is used to detect individual lightning events. It is shown that the coherency waveform bank is in general agreement with the amplitude waveform bank, that is, the relative arrival times of the ground and sky waves. The coherency waveform bank exhibits the same number of skywaves on the logarithmic scale, but a less attenuated ground wave when compared to the amplitude waveform bank. The results of this study show that the phase of sferics offers additional information to amplitudes, which could potentially be used for the interferometric lightning location with long‐range lightning detection networks.

Evaluation and Usefulness of Lightning Forecasts Made with Lightning Parameterization Schemes Coupled with the WRF Model

Abstract The evaluation and usefulness of lightning prediction for the Indian subcontinent are demonstrated. Implementation of the lightning parameterizations based on storm parameters, in the Weather Research and Forecasting (WRF) Model, with different microphysics schemes are carried out. With the availability of observed lightning measurements over Maharashtra from the lightning detection network (LDN), lightning cases have been identified during the pre-monsoon season of 2016–18. Lightning parameterization based on cloud top height defined by a reflectivity threshold factor of 20 dBZ is chosen. Initial analysis is carried out for 16 lightning events with four microphysical schemes for the usefulness in lightning prediction. Objective analysis is carried out and quantitative model performance (skill scores) is assessed based on observed data. The skills are evaluated for 10- and 50-km2 boxes from the 1-km domain. There is good POD of 0.86, 0.82, 0.85, and 0.84, and false alarm ratio (FAR) of 0.28, 0.25, 0.29, and 0.26 from WSM6, Thompson, Morrison, and WDM6, respectively. There is an overestimation in lightning flash with a spatial and temporal shift. The fractional skill score is evaluated as a function of spatial scale with neighborhoods from 25 to 250 km. These high skill scores and high degree of correlation between observations and model simulation gives us confidence to use the system for real-time operational forecast over India. The skill for 2019 and 2020 pre-monsoon are calculated to address the predictability of operational lightning prediction over India. Significance Statement A high-resolution model, namely, the Weather Research and Forecasting (WRF) Model, with multiple microphysics parameterization schemes and lightning parameterization is used here. The objective analysis is carried out for the lightning cases over India and the quantitative performance is assessed. The results highlight that there is fairly good probability of detection (POD) of 0.86, 0.82, 0.85, and 0.84 and false alarm ratio (FAR) of 0.28, 0.25, 0.29, and 0.26 from four different microphysical schemes (WSM6, Thompson, Morrison, and WDM6, respectively). These high skill scores and high degree of correlation between observations and model simulation gives us confidence to use the system for real-time operational forecast. The validation of lightning forecast system deployed over India for five pre-monsoon months in real time is carried out, which gives POD of 0.90, FAR of 0.64, hit rate of 0.57, and POFD of 0.50 for the whole Indian region.