Thunderstorm Activity Research Articles

Lightning activity in India an important cause of increase in fatalities

With Recent increase in deaths due to lightning activity in India we are posed with a question - are these fatalities related to increase in the lightning activity owing to climate change? The IPCC report (2013) projects global warming of 1-5 °C by the end of 21st Century. The global warming is closely related to increased concentration of greenhouse gases. Previous studies have shown that on different temporal and spatial scales small increases in surface temperature leads to increase in thunderstorm and lightning activity. The lightning induced deaths are on the rise especially in the tropical south Asia and Africa but IPCC report does not explicitly deals with lightning activity and its future projection. Studies on this aspect become all the more important as the subgrid scale phenomena such as convective clouds and hence lightning are poorly resolved and taken in to account by climate models. In order to address this issue we have analyzed trends of lightning activity, surface temperature, upper tropospheric water vapour, cloud ice, Convective Available Potential Energy (CAPE) and aerosols. We also present correlation of these parameters with lightning activity using lightning flash rate data of Lightning Imaging Sensor aboard TRMM, TRMM Level -2 Precipitation Radar data, gridded temperature data of IMD, aerosol data acquired by MODIS. The result indicates that upper tropospheric temperature rise is more than surface temperature rise. This imply stable atmosphere with fewer thunderstorms. The increased convection transports additional water vapour into upper troposphere. The water vapour acts as green house has by absorbing infrared radiation emitted by the surface of the Earth. This results in more warming in the upper troposphere than at the surface and stabilizing of the atmosphere. However, results also show that within the thunderstorm the instability measured by CAPE is positively correlated with lightning activity. This paradox of stabilization of global mean atmosphere with increase in lighting activity leads us to conclude that tough thunderstorm activity has subdued but those develop are much more explosive producing more lightning activity and perhaps lead to more fatalities.

Investigation of anomalous lightning activity during the January 15, 2022 Tonga volcano eruption based on measurements of the VLF and ELF electromagnetic fields

An anomalous increase in the level of Very Low Frequency (VLF, 3–30 kHz) and Extremely Low Frequency (ELF, 3–3000 Hz) radio noise and the rate of VLF atmospherics was registered during the explosive eruption of the Tonga volcano on January 15, 2022 at the Akademik Vernadsky station (65.246°S; 64.257°W) about 8870 km from the volcano. At the peak activity around 5 UT, the number of atmospherics in 2-min intervals increased by almost 15 times compared to the period preceding the eruption. At this point, the estimated rate reached 360 VLF atmospherics per second. At the same time, an increase in the power spectral density of the magnetic field by 5–9 times was observed in both the ELF and VLF ranges. After 40 min, only on ELF an increased peak lasting ∼10 min was observed, comparable in magnitude to the main peak. According to the Worldwide Lightning Location Network (WWLLN), increased thunderstorm activity was concentrated very close to the volcano during this period. This discrepancy between the intensities of ELF and VLF radiation suggests a significant difference in the parameters of currents in lightning discharges occurring in the area of the volcano vent and in the area of the volcanic ash plume.

Thunderstorm climatology of Slovakia between 1984–2023

Thunderstorms are among the most extreme meteorological phenomena that can cause widespread destruction and loss of life. Their occurrence varies significantly across different regions and times of the year. Despite various studies on thunderstorm activity across Central Europe, direct analyses based on data from the Slovak territory still need to be made available. Given Slovakia’s diverse natural conditions, there is a need for detailed knowledge about the frequency and spatial distribution of thunderstorms in this region. To address this knowledge gap, we analysed the frequency and spatiotemporal distribution of days with thunderstorm occurrences in Slovakia between 1984 and 2023, utilising climatological data from the Slovak Hydrometeorological Institute. We limited our analysis to data of days with close thunderstorms (thunderstorms occurring within 3 km of the monitoring station). Our findings reveal a significant variation in thunderstorm occurrences across Slovakia, with peak activity in the summer, especially in June and July. However, the spatial distribution of thunderstorms differed significantly across the country, with the highest frequency observed in mountainous regions and the east-central part of Slovakia. We found significant deceasing signals of the thunderstorm activity trends during the studied period, including analyses during the colder part of the year. Furthermore, our results underscore the critical role of synoptic situations in shaping these trends, where changes in certain atmospheric patterns were closely aligned with variations in thunderstorm frequency. The interaction between these synoptic conditions and regional topography was particularly evident, reinforcing the notion that topographical and environmental complexities substantially contribute to the observed thunderstorm distribution.

Total lightning signatures in a tornadic thunderstorm over the Pearl River Delta of Southern China

Tornado rises rotating air columns extending from the bottom of cumulonimbus clouds to the ground, often accompanied by strong convection with thunderstorms, hail, and short-term heavy precipitation, which seriously threaten people's lives and property safety. Studying the characteristics of thunderstorm activity during a tornado is crucial for comprehending the atmospheric electrical mechanisms involved in its generation process and developing cooperative methods for tornado warning and forecasting. Based on the VLF/LF total lightning location system and radar echo data, this paper analyzes the spatial-temporal evolution, frequency, polarity, and height of total lightning during a strong tornado (EF3) in the Pearl River Delta region on June 3, 2014. The lightning activity lasted for about 3.5 h, with a total of 41,117 total lightning flashes, of which intra-cloud (IC) flashes accounted for 74.7%, cloud-to-ground (CG) flashes accounted for 21.6%, and narrow bipolar events (NBEs) accounted for 3.7%. Connected-Component Labeling (CCL) algorithm was used to divide the thunderstorm into four stages: initiation, development, maturation, and dissipation, and it was observed that the occurrence of tornadoes was closely related to total lightning activities. The observed characteristics of lightning activity in the tornado are summarized through comparison with other studies.

Аномальный грозовой процесс на территории Ростовской области

The work examines the anomalous thunderstorm process that occurred on the territory of the Rostov region on June 27, 2023. This thunderstorm process was observed in other regions of the North Caucasus, but the greatest intensity of thunderstorm activity was observed in the territory of the Rostov region, where the thunderstorm lasted more than a day. The analysis of thunderstorm activity was carried out using data from the lightning direction network of the Federal State Budgetary Institution "High Mountain Geophysical Institute". During the day, about 60,000 lightning strikes were recorded in this territory, of which 7,635 were ground strikes. Of the registered 7635 ground-based lightning discharges in the Rostov region, negative lightning amounted to 6625, and positive lightning – 1010. The share of negative lightning discharges from the total number of ground-based lightning discharges in the specified territory was 87 %. The largest number of negative lightning (more than 70 %) had values up to 20 kA. More than 50 % of positive lightning discharges had values from 21 to 40 kA. The average value of the negative polarity currents was -19.19 kA, and the positive polarity was +39.7 kA. Such a large-scale thunderstorm process is a consequence of regional climate change. When carrying out lightning protection measures for facilities in the Rostov region, it is recommended to take into account abnormal values of thunderstorm activity.

Thunderstorm total lightning activity behavior associated with transmission line trip events of power system

High-voltage transmission lines are susceptible targets for lightning strikes. It is an interesting topic how the trip event of transmission line is related to the area, location, and intensity of thunderstorms occurring at that time and that place. Based on total lightning observation containing intra-cloud and cloud-to-ground lightning, and transmission line trip information from relaying system of power system, 8 thunderstorms associated with the lightning strike trip of local transmission lines were selected in the Pearl River Delta (PRD) region. Analysis was conducted on the total lightning activity of each thunderstorm process, including the characteristics of total lightning counts and density, followed by the variations in total lightning activity before and after lightning strike trips. Further, our investigation encompassed the spatial and temporal evolution, charge structure, and kinematic parameters of thunderstorms. It was revealed that almost all lightning trips in this area emerged in close proximity to bodies of water, accompanied by a discernible reduction in thunderstorm cloud altitude during line trip occurrences. This paper aims to enhance the understanding of total lightning and thunderstorm activity behavior, thereby providing valuable insights for lightning disaster prevention and mitigation in the meteorological bureau and power system.

BiLSTM‐based thunderstorm prediction for IoT applications

AbstractAlthough the market demand for smart devices (SDs) in the Internet of Things (IoT) era is surging, the corresponding thunderstorm protection measures have rarely attracted attention. This paper presents a thunderstorm prediction method with elevation correction, to reduce the thunderstorm damage to SDs by visually tracking thunderstorm activities. First, a self‐made three‐dimensional atmospheric electric field apparatus (3DAEFA) deployed in IoT is developed to collect real‐time AEF data. A 3DAEFA‐based localization model is established, and the localization formula after correction is derived. AEF data predicted by the bi‐directional long short‐term memory (BiLSTM) model are input to this formula to obtain thunderstorm point charge localization results. Then, the localization skill is evaluated. Finally, the proposed method is assessed in experiments, under single and multiple point charge conditions. There are significant reductions of at least 33.1% and 8.8% in ranging and elevation angle errors, respectively. Particularly, this post‐prediction correction reduces the deviation of fitted point charge moving paths by at most 0.189 km, demonstrating excellent application effects. Comparisons with radar charts and existing methods testify that this method can effectively predict thunderstorms.

A Study of Lightning Activities and Their Impact in the Ionosphere Over Nepal

The ionosphere is a system that can experience dynamical perturbation due to external influences from solar dynamics and activities: geomagnetic storms, solar radiation and lower atmospheric events such as thunderstorms and gravity waves. In this study we have analyzed the changes in the Total Electron Content (TEC) in relation with the thunderstorm activities taking into account of the lightning stroke density as a perturbing factor. The data pertaining to TEC have been obtained from GNSS whereas the lightning stroke data have been obtained from VAISALA’s GLD 360. Analyzing the data from 2015 to 2018 the variation of TEC in association with stroke density during the pre-monsoon season was found to be significant for the period of study (pre-monsoon period). This implies that thunderstorms play a significant role in the ionospheric perturbation that may result in the disruption in communication. The outcome of this study can lay the foundation on the work to investigate the extent of perturbation and hence the communication disruption being emanated by thunderstorms.

Impact of Thunderstorm Activities on Tropospheric NOx Over Koshi Province of Nepal and Their Possible Role in Climate Change

Lightning, a natural atmospheric phenomenon, plays a significant role in altering atmospheric chemistry and air quality by generating nitrogen oxides (NOX). This research aims to explore the correlation between lightning stroke density and atmospheric NOX over Koshi Province of Nepal by using observational data. Over the course of three year (2018, 2019 and 2020), sessional (lightning pre-dominant; pre-monsoon and post-monsoon) measurements of lightning activity (lightning stroke density) were obtained from Global Lightning Dataset (GLD 360) and NOX data acquired from NASA’s Ozone Monitoring Instrument (OMI). The computation was conducted by using programming language PYTHON. Correlation analysis was performed to examine the relationship between lightning stroke density and NOX concentrations by considering lightning stroke density as independent variable and average NOX as dependent variable. Our analysis shows a notable positive correlation between lightning stroke density and average NOX over Koshi Province of Nepal. The values of correlation coefficient (R) was found 0.625, 0.630 and 0.511 in pre-monsoon of years 2018, 2019 and 20120 respectively and 0.654, 0.605 and 0.370 respectively in post-monsoon. Increased lightning activity corresponded to heightened NOX concentrations, especially during pre-monsoon and post-monsoon. These results indicate that lightning significantly contributes to NOX emissions in Koshi Province. Understanding the relationship between lightning and NOX is essential for study atmospheric chemistry and assessing the impact of lightning on atmosphere.

Study on corona discharge on the grounding wire of ±1100 kV transmission line during the downward lightning flash

The atmospheric space electrical field has nonlinear distribution characteristics during thunderstorm activity, which influences the ground surface electric corona of UHV transmission lines. In this paper, the corona discharge model of ground wire of ±1100 kV UHVDC transmission line is established considering the combined effect of ground lightning process and working voltage. With the combined action of thundercloud electrical field and DC voltage, the positive conductor suppresses the electric corona of the upper shied wire, and the negative conductor enhances the discharge of the upper shied wire. The corona current of the right shied wire is 54.7 μA/m larger than that of the left shied wire. When the down leader develops, the leader voltage, the line operating voltage and the thundercloud voltage work together, and the electric corona on the surface of the conductor and shied wire of the transmission line increases rapidly. The corona current increases 102 times on the left shied wire's surface and 103 times on the right shied wire's. Considering the environmental factors and the development of the downgoing leader at the same time, the degree of electric corona on the surface of the shied wire is weakened when the humidity in the space increases, but the overall value of the corona current is much higher than the thundercloud electrical field. When the wind speed increases, the degree of electric corona on the surface of the shied wire is aggravated. The corona current on the surface of the left shied wire is 37.13 μA/m, and the one of the right shied wire is 109.33 μA/m. The corona current value of ground surface increases with the increase of wind direction.

Exploring Spatio-Temporal Precipitation Variations in Istanbul: Trends and Patterns from Five Stations across Two Continents

This study aims to reveal the long-term station-based characteristics of precipitation in Istanbul, a mega city located on the continents of Europe and Asia, with complex topography and coastline along the Marmara and Black Seas. Using data from five different stations, three located in the European continent and two in the Asian continent, with measurement periods ranging from 72 to 93 years, wet and dry days have been identified, statistics on precipitation conditions during the warm and cold seasons have been generated, categorization based on precipitation intensities has been performed, and analyses have been conducted using extreme precipitation indices. At stations located in the northern part of the city, higher annual total precipitation has been observed compared to those in the south. A similar situation applies to the number of wet days. While during the cold season, the wet and dry day counts are nearly the same across all stations, this condition exhibits significant differences in favor of dry days during the warm season. Apart from dry conditions, “moderate” precipitation is the most frequently observed type across all stations. However, “extreme” events occur significantly more often (6%) during the warm season compared to the cold season (2%). Long-term anomalies in terms of annual precipitation totals have shown similarity between stations in the north and south, which has also been observed in longitudinally close stations. Despite the longer duration of the cold season and stronger temperature gradients, extreme rainfall events are more frequent during the warm season, primarily due to thunderstorm activity. While trend analyses revealed limited significant trends in precipitation intensity categories and extreme indices, the study highlights the importance of comprehensive examination of extreme rainfall events on both station-based and regional levels, shedding light on potential implications for regional climate change. Lastly, during the cold season, the inter-station correlation in terms of annual total precipitation amounts has been considerably higher compared to the warm season.

Мониторинг ежемесячной динамики грозовой активности в Ираке

The article presents the study results of the monthly variability thunderstorm activity at three meteorological stations located in Iraq over a ten-year period from 2000 to 2009. This is a study based on archived data from daily meteorological observations. The study of fronts for six months a year and for ten years showed that thunderstorms most often occur in March and April, accounting for about 47.42% of all thunderstorms. Moreover, 22.3% of them are in the northern mountainous region of Iraq. 67 baroclinic and 63 barotropic cases were registered at Khanaqin Station; 42 baroclinic and 47 barotropic cases were recorded at Baghdad Airport Station; and 21 baroclinic and 27 barotropic cases were listed at Basra Airport Station. Whenever there is a change in the horizontal temperature, potential energy becomes available. Low-pressure systems usually cause sudden weather changes, including strong winds, heavy rain, thunderstorms, and other possible meteorological phenomena. This low-pressure system, which includes the Mediterranean low-pressure system and occurs in regions with predominantly westerly and reverse winds, leads to increased winds and increases the likelihood of thunderstorms and heavy rainfall. When the depression of the Red Sea connects with the depression of the Mediterranean Sea, deep cumulonimbus clouds will form, and the weather will be very bad with rain and thunderstorms (rain, thunder, lightning, maybe even hail).

Analysis of lightning activity characteristics and its relationship with precipitation in a strong convective weather process in Jiangsu Province

Based on multi-source observation data such as lightning locator, atmospheric electric field instrument and hourly precipitation data from automatic stations, the lightning characteristics of the strong convective weather process under the influence of the northeast cold vortex in Nanjing Jiangsu Province on 15 June 2020 was analyzed in depth, and the relationship between the lightning activity and the precipitation was obtained. The results show that this strong convective weather process is formed by the cold air from the back of the northeast cold vortex along the front of the high-pressure ridge and the back of the transverse through southward to the middle and lower reaches of the Yangtze River, which makes the cold and warm air currents converge along the south of the Yangtze River to form the heavy precipitation, and is accompanied by the strong lightning activity in the process of this heavy precipitation. The local thunderstorm electric field in Nanjing is mainly characterized by negative increasing type, positive and negative alternating type, and multi-single thunderstorm electric field, and the thunderstorm activity is mainly dominated by negative ground flashes. During this strong thunderstorm, the stronger precipitation periods corresponded to the stronger lightning frequency periods, and the lightning and precipitation fallout areas showed a consistent spatial distribution. The correlation between the lightning activity and precipitation was analyzed by linear fitting, and the correlation between them is 0.946.

Evaluating the Influence of the Shillong Plateau Topography on Thunderstorm Activity Over Northeast India

Evaluating the Influence of the Shillong Plateau Topography on Thunderstorm Activity Over Northeast India

New Method for Determining Azimuths of ELF Signals Associated With the Global Thunderstorm Activity and the Hunga Tonga Volcano Eruption

AbstractA new method is proposed for deriving extremely low frequency (ELF) wave arrival azimuths using the wide range of signal amplitudes, contrary to previously applied high amplitude impulses only. The method is applied to observations from our new magnetic sensor in the Hylaty station with an 18 bit dynamic range and a 3 kHz sampling frequency. We analyzed a day of 15 January 2022, to test the procedure against the ability to extract ELF signals generated during the Hunga Tonga volcano eruption. With complementary filtering of power line 50 Hz signatures, precise azimuth information can be extracted for waves from a multitude of thunderstorms on Earth varying during the day at different azimuths. A phenomenon of successive regular variation—decay or activation—of thunderstorms activity with varying azimuth is observed, possibly due to passing over the solar (day/night) terminator, and signatures of azimuth direction change during this passage can be noted. We also show that the erupting Hunga Tonga volcano associated impulses dispersed due to a long propagation path are clearly revealed in the azimuth distribution with analysis using parameters fitted to measure slowly varying signals, but not for fast varying impulses. We show that the Hunga Tonga related signals arrive from the azimuth ≈10° smaller than the geographic great circle path. The discrepancy is believed to be due to propagation through the polar region and in the vicinity of the solar terminator.

Spatiotemporal Distributions of the Thunderstorm and Lightning Structures over the Qinghai–Tibet Plateau

Utilizing data from the Tropical Rainfall Measuring Mission (TRMM) satellite’s precipitation radar (PR) and lightning imaging sensor (LIS), this study explores the spatiotemporal distributions of thunderstorm and lightning structures over the Qinghai–Tibet Plateau (QTP), an aspect that has not been explored previously. The structural aspects are crucial when considering the impact of thunderstorm and lightning activity in the atmospheric processes. Thunderstorms over the QTP show clear spatial variations in both vertical height and horizontal extension. In the southern region, the average heights of 20 dBZ and 30 dBZ echo tops typically exceed 11.2 and 9.3 km, respectively. Meanwhile, in the eastern part, the average coverage areas for reflectivity greater than 20 dBZ and 30 dBZ consistently surpass 1000 and 180 km2, respectively. The spatial distribution of thunderstorm vertical development height relative to the surface aligns more closely with the horizontal extension, indicating stronger convection in the eastern QTP. The thunderstorm flash rate shows an eastward and northward prevalence, while the thunderstorm flash density peaks in the western and northeastern QTP, with a minimum in the southeast. Furthermore, in the eastern QTP, lightning duration, spatial expansion, and radiance are more pronounced, with the average values typically exceeding 0.22 s, 14.5 km, and 0.50 J m−2 sr−1 μm−1, respectively. Monthly variations reveal heightened values during the summer season for thunderstorm vertical extension, areas with reflectivity greater than 30 dBZ, and lightning frequency. Diurnal variations highlight an afternoon increase in thunderstorm vertical and horizontal extension, lightning frequency, duration, and spatial scale. From a statistical perspective, under weak convective conditions, lightning length exhibits a positive correlation with thunderstorm convection intensity, contrasting with the opposite relationship suggested by previous studies. This article further analyzes and discusses the correlations between various thunderstorm and lightning structural parameters, enhancing our understanding of the distinctive features of thunderstorm and lightning activities in the QTP.

Exploiting radar polarimetry for nowcasting thunderstorm hazards using deep learning

Abstract. This work presents the importance of polarimetric variables as an additional data source for nowcasting thunderstorm hazards using an existing neural network architecture with recurrent-convolutional layers. The model can be trained to predict different target variables, which enables nowcasting of hail, lightning, and heavy rainfall for lead times up to 60 min with a 5 min resolution, in particular. The exceedance probabilities of Swiss thunderstorm warning thresholds are predicted. This study is based on observations from the Swiss operational radar network, which consists of five operational polarimetric C-band radars. The study area of the Alpine region is topographically complex and has a comparatively very high thunderstorm activity. Different model runs using combinations of single- and dual-polarimetric radar observations and radar quality indices are compared to the reference run using only single-polarimetric observations. Two case studies illustrate the performance difference when using all predictors compared to the reference model. The importance of the predictors is quantified by investigating the final training loss of the model, with skill scores such as critical success index (CSI), precision, recall, precision–recall area under the curve, and the Shapley value. Results indicate that single-polarization radar data are the most important data source. Adding polarimetric observations improves the model performance compared to reference model in term of the training loss for all three target variables. Adding quality indices does so, too. Including both polarimetric variables and quality indices at the same time improves the accuracy of nowcasting heavy precipitation and lightning, with the largest improvement found for heavy precipitation. No improvement could be achieved for nowcasting of the probability of hail in this way.

Аномальный грозовой процесс на территории Ставропольского края

The paper analyzes the dynamics of such anomalous weather phenomenon as a thunderstorm. The thunderstorm process that took place in the North Caucasus on June 27, 2023 is considered. The thunderstorm process under consideration differed significantly from the statistical average, both in duration and in lightning parameters. The analysis was carried out using the example of the Stavropol Krai, although anomalous thunderstorms on June 27, 2023 also occurred in other regions of the North Caucasus. The work used the lightning direction network of the Federal State Budgetary Institution VGI with spatially separated sensors LS8000 and LS7002. To determine the characteristics of thunderstorm activity, the work used long-term data from the specified lightning direction network. Studies of thunderstorm activity were carried out in conjunction with the characteristics of convective clouds determined by MRL-5 weather radars. The Federal State Budgetary Institution VGI has organized the uptake, processing, archiving and transmission to the ASPD network of Roshydromet of radar information from all MRL-5 weather radars of the anti-hail services of the North Caucasus. During the day, about 30,000 lightning strikes were recorded by VGI in this territory. Of these, 3,713 were ground discharges. Of the registered 3,713 ground-based lightning discharges in the Stavropol Krai, negative lightning amounted to 2,901, and the positive one – 812. The share of negative lightning discharges from the total number of ground-based lightning discharges in the specified territory was 78%. The largest number of negative lightning (more than 70%) had values up to 20 kA. More than 40% of positive lightning discharges had values from 21 to 40 kA. The average value of currents of negative polarity was -18.6 kA, and that of positive polarity was +53.2 kA.

Spatio-temporal changes in the pre-monsoon thunderstorm activities of northeast India over the past four decades

Thunderstorms inflict significant danger to both human and environment. Here, we present a thorough examination of recent changes in thunderstorm occurrences in the northeast and eastern regions of India.

Результаты анализа грозовой деятельности на территории Республики Северная Осетия – Алания

The paper presents the results of thunderstorm activity study on the territory of the Republic of North Ossetia-Alania, and in particular, in the area of the all-season tourist complex “Mamison”. The analysis of the average annual factors of thunderstorm and lightning activity in the period from 2012 to 2022 in the warm period of time (May-September) according to the LS8000 thunderstorm direction finding system was performed. The estimation of the number of cloud-earth lightning ratios of positive and negative polarity is made, the influence of the orography of the terrain on the magnitude of lightning currents is investigated, the territorial features of the distribution of cloud-earth lightning currents of different polarity are determined. The resulting expression of the linear trend for the number of thunderstorms shows a decrease in thunderstorm activity in recent years in the study area.