World Wide Lightning Location Network Research Articles

Machine Learning–Based Lightning Parameterizations for the CONUS

Abstract The diversity in the lightning parameterizations for numerical weather and climate models causes considerable uncertainty in lightning prediction. In this study, we take a data-driven approach to address the lightning parameterization problem, by combining machine learning (ML) techniques with the rich lightning observations from the World Wide Lightning Location Network. Three ML algorithms are trained over the contiguous United States (CONUS) to predict lightning stroke density in a 1° box based on the information about the atmospheric variables in the same grid (local) or over the entire CONUS (nonlocal). The performance of the ML-based lightning schemes is examined and compared with that of a simple, conventional lightning parameterization scheme of Romps et al. We find that all ML-based lightning schemes exhibit a performance that is superior to that of the conventional scheme in the regions and in the seasons with climatologically higher lightning stroke density. To the west of the Rocky Mountains, the nonlocal ML lightning scheme achieves the best overall performance, with lightning stroke density predictions being 70% more accurate than the conventional scheme. Our results suggest that the ML-based approaches have the potential to improve the representation of lightning and other types of extreme weather events in the weather and climate models.

Influence of the Super El Niño event during 2015/2016 on the aerosol properties and lightning activity in subtropical South America

This work investigates the impact of ENSO on aerosols and lightning activity in subtropical South America (SSA). An analysis of the interannual variability of Aerosol Optical Depth (AOD), Ångström Exponent (AE) and different cloud parameters using MODIS satellite datasets and the lightning activity based on the lightning observations from the World Wide Lightning Location Network was performed. High positive AE, AOD anomalies and high lightning activity were found in the northeastern region of SSA during the Super El Niño event during 2015/2016 in latter spring and summer. The Pearson correlation coefficients between these aerosol parameters and monthly discharges were higher than 0.7 in the northeastern region during the Super El Niño. These positive correlations, which have been widely reported in previous studies, were explained considering the vegetation cover, consisting mainly of subtropical forests in the northeastern region of SSA, and the increase in rainfall during El Niño in this area in spring and summer. The increases in AOD and AE during latter spring and summer in the northeastern region were therefore related to the release of biological aerosols and to aerosols emission mechanisms independent of the background aerosol concentration, respectively. The increase in lightning activity was related to the role of these released aerosols as ice nuclei particles and/or as cloud condensation nuclei, affecting cloud properties and thus the lightning activity. The results reported in this work show the effect of the Super El Niño on aerosol and lightning activity and, in this way on aerosol-cloud interactions.

Lightning Stroke Strength and Its Correlation with Cloud Macro- and Microphysics over the Tibetan Plateau

Lightning stroke strength, characterized by energy and peak currents, over the Tibetan Plateau (TP), is investigated by utilizing datasets from the World Wide Lightning Location Network and the Chinese Cloud-to-Ground Lightning Location System during 2016–2019. Focused on the south-central (SC) and southeast (SE) of the TP, it reveals that SE-TP experiences strokes with larger average energy and peak currents. Strong strokes (energy ≥ 100 kJ or peak currents ≥ |100| kA), exhibiting bimodal distribution in winter and summer, are more frequent and have larger average values over the SE-TP than the SC-TP, with diurnal distribution indicating peaks in energy and positive strokes in the middle of the night and negative strokes peaking in the morning. Utilizing the ECMWF/ERA-5 and MERRA-2 reanalysis, we find that stronger strokes correlate with thinner charge zone depths and larger CIWCFs but stable warm cloud depths and zero-degree levels over the SC-TP. Over the SE-TP, stronger strokes are associated with smaller CIWCFs and show turning points for warm cloud depths and zero-degree levels. Thicker charge zone depths correlate with stronger negative strokes but weaker positive strokes. Generating strokes of similar strength over the SC-TP requires larger CIWCFs, thinner warm cloud depths, and lower zero-degree levels than over the SE-TP.

The impacts of shipping emissions on lightning: roles of aerosol-radiation-interactions and aerosol-cloud-interactions

Long-term (2005–2021) observations from the World Wide Lightning Location Network reveal significantly larger flash counts over heavily trafficked shipping lanes in the northeastern Indian Ocean compared to nearby regions. Here, we use the online coupled meteorology-chemistry model WRF-Chem to examine the impact of aerosols from shipping emissions on lightning activity over one of the world’s busiest shipping lanes (5–7° N, 82–92° E). We conduct three case simulations in January 2013, 2015, and 2018 when frequent lightning activities were recorded. The WRF-Chem model with lightning parameterized based on convective cloud-top height captures the temporal evolution of lightning activities but overestimates the magnitude of lightning counts. We find that all three cases consistently show enhanced lightning flash counts due to shipping-induced aerosols by 6.2%–22.3%, accompanied by increased cloud droplet number, cloud water concentration, radar reflectivity, and cloud-top height. Sensitivity simulations show that aerosol-cloud-interactions from shipping aerosols consistently enhance the strength of convection and lightning frequency in all three cases, by increasing cloud condensation nuclei and cloud droplet numbers, delaying precipitation of cloud water, allowing the lift and accumulation of water vapor, increasing release of latent heat, and finally invigorating convections. In comparison, aerosol-radiation-interactions show inconsistent contributions to convection and lightning, which enhance lightning frequency in the 2013 and 2015 cases but decrease lightning frequency in the 2018 case. This inconsistency may be attributed to differences in the number and vertical structure of shipping aerosols and cloud droplet in the three cases. Our study thus approves the certain but complicated anthropogenic impacts on lightning activities through shipping-induced aerosols, which has important implications for understanding future trends in lightning and its impact on atmospheric chemistry and climate.

Энергия и суточный ход молниевой активности в локациях пожаров от гроз на территории Республики Алтай

The article presents the results of a study of the thunderstorm activity diurnal rate and the energy parameters of lightning discharges in locations of thunderstorm fires. The Altai Republic territory serves as the region of research, fire data were obtained from the Ministry of Natural Resources, Ecology and Tourism of the Altai Republic and the Altai State Nature Biosphere, data on thunderstorm activity were provided by the World Wide Lightning Location Network (WWLLN). The study period covers May to October from 2016 to 2020. It was found that the maximum thunderstorm activity shifts from the second half of the day (15-16 hours) to the evening (18-19 and 21 hours) in the days preceding fires. Regularities in hourly dynamics of discharge energy for the territory of the republic were identified - median values gradually increasing from the first half of the day to the evening and decreasing at night and in the morning. It was also established that in the days preceding fires, there is an increase in median discharge energy (by 13 % from the usual value), as well as an increase in values of the first quartile of discharge energy (by 27 % from the usual value).

Characteristics of the Blitzortung.org Lightning Location Catalog in Japan

We evaluated the detection efficiency and location accuracy of lightning discharges in Japan using Blitzortung.org, a volunteer-based network for locating lightning discharges from sferics measured by very low frequency (VLF) electromagnetic receivers that have been deployed worldwide in recent years. A comparison of the flash rate (the detected lightning rate per area and period) from Blitzortung.org with that from the satellite-based OTD/LIS and the ground-based World Wide Lightning Location Network (WWLLN) observations showed that Blitzortung.org clearly observed intense lightning activity in and around the Kanto area, including Tokyo, in summer, which is typical of Japanese lightning activity. However, it did not clearly observe lightning activity in and around the Nansei Islands, including Okinawa. Conversely, Blitzortung.org observed winter lightning activity in the Hokuriku area and off the Kanto. In addition, event studies have compared the detection efficiency and location accuracy of Blitzortung.org with those of the Japanese Lightning Location Network (JLDN) to infer their absolute values. The latest detection efficiency of Blitzortung.org in the Kanto area was estimated at roughly 90%. The mean location accuracy was estimated at up to 5.6 km.

Performance of Lightning Potential Index, Lightning Threat Index, and the Product of CAPE and Precipitation in the WRF Model

AbstractLightning is a naturally occurring phenomenon with significant socioeconomic and environmental impacts, underlining the need for the application of advanced methods to predict it. This study aims to evaluate the performance of the Weather Research and Forecasting (WRF) model in the prediction of the lightning potential index (LPI), the lightning threat index (LTI), and the product of convective available potential energy (CAPE) and precipitation (CAPE × P). Based on the intensity of convection and the number of lightning flashes, we simulated seven thundercloud events that occurred in Tehran between 2008 and 2013. The simulated LPI, LTI, and CAPE × P values are compared both qualitatively and quantitatively against ground‐based lighting data obtained from the world wide lightning location network (WWLLN). LPI, LTI, and CAPE × P predict the location of lightning with relatively good accuracy, although LPI outperforms LTI and CAPE × P. We also compared the simulated area‐averaged LPI, LTI, and CAPE × P against the number of lightning flashes from the WWLLN data, based on which LPI shows a better performance. Overall, LPI can be used as an effective index for the prediction of lightning. As LPI is based on cloud microphysics and LTI and CAPE × P are thermodynamic‐based methods, a better performance of LPI implies that a method based on the microphysical approach can better predict lightning. The performance of LPI, LTI, and CAPE × P is also sensitive to the horizontal resolution of model simulations, with a considerable improvement in simulations with higher horizontal resolutions.

Characterization of Thunderstorm Cells Producing Observable Terrestrial Gamma‐Ray Flashes

AbstractThe meteorological conditions required for the production of Terrestrial Gamma‐ray Flashes (TGFs) are not well understood. Particularly, the link between TGF production, meteorology, and weather severity is poorly characterized with most works focusing on only a small set of TGF events or isolated storms. This work is a further step toward understanding the general context of the meteorological conditions required for TGF production and if it differs from regular lightning production. We use TGFs observed from AGILE, ASIM, Fermi, and RHESSI to generate the largest catalog of TGFs with associated lightning sferics from either the World Wide Lightning Location Network (WWLLN) or Global Lightning Detection (GLD) combined with geostationary satellite images and meteorological conditions derived from ERA5 reanalysis data. In total we analyze 1582 TGF events and contextualize them in comparison to lightning flashes as characterized by ASIM. In our analysis we consider the proportion of TGFs and lightning coming from systems with overshooting tops as well as the Cloud Top Temperature (CTT) and the Convective Available Potential Energy (CAPE). Our results are consistent with previous studies, finding that TGFs observed from space come from primarily higher cloud tops than regular lightning flashes do. We find that CAPE and the proportion of cells with overshooting tops is similar for both TGF and lightning producing cells. It suggests that TGF observations from space are biased toward systems with higher cloud tops because the attenuation of the gamma‐rays from lower altitude TGFs reduce their intensity below the detection level of LEO instruments.

Seasonal dependence of the equatorial electrojets generated by thunderstorms

A model for the distribution of the ionospheric potential which drives the ionospheric currents closing the electric currents from/to the atmosphere is constructed. It is a part of the global electric circuit (GEC). Only the internal electric fields and currents generated by thunderstorms are studied, and without any magnetospheric or ionospheric generators. The atmospheric conductivity profiles with altitude are empirically determined, and the topography of the Earth’s surface is taken into account. A two-dimensional approximation of the ionospheric conductor is based on high conductivity along the geomagnetic field. The model of the global distribution of thunderstorms obtained from the ground-based World Wide Lightning Location Network is used as a proxy for the electric currents to the ionosphere from the atmosphere above thunderstorm regions. The global distributions of the electric potential in the ionosphere are calculated for twelve months during a year with low solar activity. The designed models contain the equatorial electrojets. There are day-time electrojets, the strengths of which are up to 200 A, and night-time ones (which are up to only half this value), while the total current of the GEC is taken equal between 1.5 and 2.5 kA in our model to satisfy the Carnegie data for the simulated dates and UT. The results are presented as diagrams of the currents in the electrojets depending on the geomagnetic longitude and month for 04 and 18 UT. These times are chosen to be the times of minimum and maximum fair weather electric field in accordance with the Carnegie results. The diagrams could help us to choose optimal conditions for measurements of the magnetic perturbations observed on the ground or by satellites to find the electrojets of the GEC which are obtained in our simulations.

Evaluation of the performance of the World Wide Lightning Location Network (WWLLN) using the lightning detection network (LINET) as a truth

Evaluation of the performance of the World Wide Lightning Location Network (WWLLN) using the lightning detection network (LINET) as a truth

WWLLN Energetic Lightning Events Are Different From Optical Superbolts

AbstractThe most powerful optical emissions from lightning have been described as “superbolts” since the 1970s. Holzworth et al. (2019, https://doi.org/10.1029/2019jd030975) recently applied the superbolt label to the most energetic Radio Frequency emissions recorded by the World Wide Lightning Location Network (WWLLN). We compare the WWLLN energies to optical measurements by the photodiode detector on the Fast On‐orbit Recording of Transient Events satellite and the Geostationary Lightning Mappers on NOAA's Geostationary Operational Environmental Satellites to assess whether these energetic WWLLN events coincide with optical superbolts. We find no overlap between optical and WWLLN superbolts. Moreover, extreme WWLLN events occur in a contrasting meteorological context to optical superbolts. Despite similarities in their overall global patterns of occurrence, WWLLN superbolts correspond to a different phenomenon.

Lightning-Based Tropical Cyclone Rapid Intensification Guidance

Abstract With several seasons of Geostationary Lightning Mapper (GLM) data, this work revisits incorporating lightning observations into operational tropical cyclone rapid intensification guidance. GLM provides freely available, real-time lightning data over the central and eastern North Pacific and North Atlantic Oceans. A long-term lightning dataset is needed to use GLM in a statistical–dynamical operational application to capture the relationship between lightning and the rare occurrence of rapid intensification. This work uses the World Wide Lightning Location Network (WWLLN) dataset from 2005 to 2017 to develop lightning-based predictors for rapid intensification guidance models. The models mimic the operational Statistical Hurricane Intensity Prediction Scheme Rapid Intensification Index and Rapid Intensification Prediction Aid frameworks. The frameworks are averaged to form a consensus as a means to isolate the impact of the lightning predictors. Two configurations for lightning predictors are assessed: a spatial configuration with 0–100-km inner core and 200–300-km rainband area for the preceding 6-h predictors and a temporal configuration with an inner core only for the preceding 0–1, 0–6, and 6–12 h. When tested on the 2018–21 seasons, the temporal configuration adds skill primarily to the 12–48-h forecasts when compared to the no-lightning version and rapid intensification operational consensus. When WWLLN is replaced with GLM, minor changes to the prediction are observed suggesting that this approach is suitable for operational applications and provides a new baseline for tropical cyclone lightning-based rapid intensification aids. Significance Statement The forecasting of rare, yet critical, tropical cyclone rapid intensification events continues to be challenging. The current operational tools to anticipate rapid intensity changes use a combination of numerical weather prediction–derived environmental conditions and satellite-based cloud top temperature variations of deep convection. Here, we use freely available Geostationary Lightning Mapper data, which provide independent information about convection, in similar intensity guidance frameworks using temporal and spatial aspects of lightning variability. Our results show an improvement in short-term (12–48 h) rapid intensification forecasts by using temporal lightning information, and our investigation highlights that users of Geostationary Lightning Mapper lightning information should be cognizant of the influence and impact of land on these observations.

Is Amazon deforestation decreasing the number of thunderstorms over South America?

AbstractLightning activity has been predicted to increase with global warming, though estimates of lightning sensitivity to a change of temperature vary widely. Since lightning is a small‐scale process, it must be represented by parametrizations in climate models. This article uses large‐scale meteorological parameters tied to thunderstorm generation to improve existing empirical models that simulate regional thunderstorm behaviour. The response of the number of thunderstorms (as presented here) to climate change is rarely analysed in global studies. This study focuses on Tropical America, and uses the ERA5 higher‐resolution reanalysis data (ERA5) to develop our empirical model. Thunderstorm data were taken from the World Wide Lightning Location Network (WWLLN) and processed using the clustering algorithm developed by Mezuman et al. (2014). The two meteorological parameters that correlated best with thunderstorm clusters in Tropical America were specific humidity (SH) and convective available potential energy (CAPE). The resulting empirical model was run from 1979 to 2019 using ERA5 reanalysis data as input. This approach approximates the long‐term trends in the behaviour of thunderstorms in the regions, in the absence of a complete historical lightning record. To our surprise, Tropical American thunderstorms exhibited a negative trend over this period, with an 8% decrease in thunderstorm clusters since the 1980s even with a rise of 1 K in temperature over the same period. The regions of largest decreases in thunderstorm activity align well with estimates of deforestation. We estimate that for every 1 Tg C lost due to deforestation, there is a 10% decrease in thunderstorm number.

A dataset of thunderstorm features of the FY-2E full-disc observation area from 2010 to 2018

Thunderstorm clouds yield lightning discharges and are often accompanied by damaging weather; therefore, they are important concerns for weather monitoring and forecasting. At present, the research on the thunderstorm activity in China is deficient; and available thunderstorm cloud datasets with high temporal-spatial resolution and big spatial coverage are rare. We established the thunderstorm feature dataset (TFD) by using the black body temperature (TBB) and the cloud classification (CLC) products from the Fengyun-2E (FY-2E) satellite and the lightning location data from the World-Wide Lightning Location Network (WWLLN). Thunderstorm cloud is defined in accordance with the criterion that at least one WWLLN lightning is in the area with TBB ≤ −32°C or its fitted ellipse. We obtained the parameters including time, location, structure, and lightning activities to prepare the TFD. This dataset extends from 2010 to 2018, with a temporal resolution of 1 hour and wide spatial coverage of the FY-2E full-disc observation area, especially including the mainland and adjacent sea areas of China. This TFD can play an important role in the study of thunderstorm activities.

Ionospheric Perturbations Due to Large Thunderstorms and the Resulting Mechanical and Acoustic Signatures

Perturbations from thunderstorms can play a notable role in the dynamics of the ionosphere. In this work, ionospheric perturbation effects due to thunderstorms were extracted and studied. Thunderstorm-associated lightning activities and their locations were detected by the World-Wide Lightning Location Network (WWLLN). The mechanical components of ionospheric perturbations due to thunderstorms were extracted from the total electron content (TEC), which was measured at selected thunderstorm locations using the polynomial filtering method. Further analyses were conducted using wavelet analysis and Discrete Fourier Transform (DFT) to study the frequency modes and periodicities of TEC deviation. It was revealed that the highest magnitudes of TEC deviations could reach up to ~2.2 TECUs, with dominant modes of frequency in the range of ~0.2 mHz to ~1.2 mHz, falling within the gravity wave range and the second dominant mode in the acoustic range of >1 mHz to <7.5 mHz. Additionally, a 20–60 min time delay was observed between the sprite events, the other high-energy electrical discharges, and the time of occurrence at the highest peak of acoustic-gravity wave perturbations extracted from TEC deviations. The possible mechanism responsible for this phenomenon is further proposed and discussed.

Optimal radii for data of the World Wide Lightning Location Network sampling in climatology of thunderstorm activity

Optimal radii for data of the World Wide Lightning Location Network sampling in climatology of thunderstorm activity

Power flux in the Schumann resonance band linked to the eruption of Tonga volcano on Jan. 15, 2022. (Two point measurements of Umov-Poynting vector)

Observations and model computations are compared of the Umov – Poynting vector (UPV) in the Schumann resonance (SR) band during the eruption of Tonga volcano on Jan. 15, 2022. The volcanogenic SR signals were recorded at the dual site: at the Cumiana observatory (44.96° N and 7.42° E) in the vertical electric field component and at the Sos Enattosobservatory (40.47° N, 9.48° E) in the two orthogonal ELF components of horizontal magnetic field. Initially, we present computations in the update model of the Earth – ionosphere cavity with the global lightning stroke distribution found by the Worldwide Lightning Location Network (WWLLN), which demonstrates the workability of our approach. The hodographs of UPV were obtained in the frequency (formally rigorous) and the time domain during the major phase of eruption. The positions of both of them suitably agree with each other and indicate on the wave arrival from the compact area around volcano during the major phase of Tonga eruption. The UPV magnitude indicates that the contribution from the Tonga volcano has elevated the observed level of ELF power flux by the factor of six relative to the quiet condition.

Transient Luminous Events and Their Relationship to Lightning Strokes Over the Tibetan Plateau and Its Comparison Regions

AbstractThis study investigates the relationship between transient luminous events (TLEs) and lightning strokes, and the characteristics of TLE‐producing thunderstorms over the Tibetan Plateau (TP), and compares them to those over the Yangtze‐River Delta (YRD) and East China Sea (ECS) where at the same latitude during 2005–2015. The data were collected using the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) and the World Wide Lightning Location Network (WWLLN) observations. Elves, sprites and halo (abbreviated as ESHs) were dominantly detected over the southeastern TP (∼88%), mostly in August and September (∼81%). Different from the southeastern TP, the detected sprites and sprite‐to‐lightning stroke ratios over the YRD were larger in spring than those in summer and autumn. Halos were frequently observed in August over all study regions. Blue jets were only detected over the YRD. The density of TLEs over the southeastern TP was three times smaller than those over the YRD and ECS, while the density of elves over the southeastern TP was slightly larger than that over the YRD. The average energy of TLE‐related lightning strokes based on WWLLN was found to be larger over the southeastern TP compared to the YRD and ECS. The ESH‐producing clouds over the southeastern TP had a larger scale with a lower lightning frequency than those over the YRD.

Observational and Model Impact of Tonga Volcano Eruption on Schumann Resonance

AbstractTonga volcano eruption on 15 January 2022 was accompanied by an unprecedentedly high lightning activity in the volcano plume which significantly exceeded the lightning activity level of the whole globe. We compare model computations with the observed effect of the Tonga volcano eruption on the global electromagnetic Schumann resonance (SR). This SR disturbance was detected at many observatories covering the whole globe. SR power spectral density was computed using the updated model of the Earth‐ionosphere cavity, with the global lightning detections recorded by the World Wide Lightning Location Network, as a source. The modeled dynamics of the SR disturbances during Tonga eruption agrees qualitatively and quantitatively with SR recordings from six globally separated observatories. Unprecedentedly high lightning activity during the active phase of eruption caused significant suppression of the global lightning detection rate without noticeable effect on real global thunderstorm activity.

Trends and Features of Thunderstorms and Lightning Activity in the Upper Volga Region

An increase in the frequency of atmospheric hazards in a changing climate has attracted interest in the study of regional features of mesoscale convective systems and trends of lightning activity. Severe convective storms are the most destructive weather events causing substantial damage and fatalities. In this paper, we analyze general trends in the lightning activity in the Upper Volga region and identify the particular features of a severe thunderstorm on 13–14 July 2020. The analysis of the annual variability of the lightning activity in the Upper Volga region, carried out according to the World-Wide Lightning Location Network (WWLLN) data, has shown that the total number of discharges during the convective seasons of 2016–2021 increased. For the convective season of 2020, the daily number of discharges in the neighborhood of Nizhny Novgorod (the center of the region) is calculated according to the WWLLN data and the electric field mill (EFM) measurements. It is revealed that the most powerful (per convective season) thunderstorms have a number of similarities both according to observations and numerical simulation. The thunderstorm on 13–14 July was numerically simulated using the Weather Research and Forecasting (WRF) model in combination with calculations of the electric parameters (such as electric potential and intracloud electric field). The simulations were carried out using two parametrizations of microphysical processes to reveal the features associated with allowance for aerosol particles. The data from the meteorological radar and WWLLN were used to validate the radar reflectivity simulation results of the WRF model. Some features of the thunderstorm evolution characteristic for each of the microphysical parametrizations were identified. In general, the non-aerosol parametrization gives a more correct description of the development of severe thunderstorms in the Upper Volga region (with the exception of the final stage of the convective system development). For a convective event to have the required duration (more than 6 h), aerosol particles should be taken into account.