R. Said

Vaisala (United States)

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U. S. Inan

Stanford University

M. B. Cohen

Georgia Institute of Technology

Earle Williams

Massachusetts Institute of Technology

Chris Vagasky

Vaisala (United States)

Yakun Liu

Dalian University of Technology

Gabriella Sátori

HUN-REN Institute of Earth Physics and Space Science

Tamás Bozóki

HUN-REN Institute of Earth Physics and Space Science

R. H. Holzworth

Earth and Space Research

Michael Atkinson

Johns Hopkins University Applied Physics Laboratory

Péter Steinbach

Eötvös Loránd University

Cooperative Institutions

National Oceanic and Atmospheric Administration

University of Colorado Boulder

Goddard Space Flight Center

Cooperative Institute for Research in Environmental Sciences

University of East Anglia

Centre National de la Recherche Scientifique

NOAA National Environmental Satellite Data and Information Service

National Centre for Atmospheric Science

Royal Netherlands Meteorological Institute

NOAA Earth System Research Laboratory

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Climatological diurnal variation of negative CG lightning peak current over the continental United States

Journal of Geophysical Research Atmospheres (2014)

Themis Chronis Kenneth L. Cummins R. Said William J. Koshak Eugene W. McCaul

Abstract This study provides an 11 year climatology of the diurnal variability of the cloud‐to‐ground (CG) lightning peak current. The local diurnal variation of peak current for negative polarity CG (−CG) flashes exhibits a highly consistent behavior, with increasing magnitudes between the late night to early morning hours and decreasing magnitudes during the afternoon. Over most regions, an inverse relationship exists between the −CG peak current and the corresponding −CG activity, although specific details can depend on region and time of day. Overall, the diurnal variation of the −CG peak current appears to reflect fundamental differences between morning and afternoon storms, but additional studies are required to clearly identify the primary cause(s).

Diurnal temperature variation

Lightning

Variation (astronomy)

Time of day

Local time

10.1002/2014jd022547

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Citations (33)

Empirical Parameterization of Broadband VLF Attenuation in the Earth‐Ionosphere Waveguide

Journal of Geophysical Research Space Physics (2023)

R. Said Mark Gołkowski Vijay Harid

Abstract The Earth‐ionosphere waveguide (EIW) determines the propagation of Very Low Frequency (VLF; ∼3−30 kHz) waves. Characterizing the waveguide is a longstanding challenge due to its large spatial scale and the complex variability of the lower ionosphere. Here we apply a novel linear basis function regression technique to characterize attenuation in the EIW using broadband measurements of lightning‐generated radio waves. The process begins with defining a basis function set, which ideally encompasses a feature set that can predict the variability seen in VLF attenuation properties. With this basis set defined, a system of linear equations is then constructed using sensor pair observations to eliminate the dependency on source amplitude in each observation. Using this formalism, an empirical attenuation model for broadband signals from lightning is constructed and the dependence on attenuation properties with the boundary conditions is explored. The empirically derived results show attenuation rates over ice that are 12 dB/Mm higher compared to paths over saltwater. Well‐known east/west attenuation rate asymmetry stemming from anisotropic reflection coefficients of the ionosphere is also demonstrated and investigated. For example, under a daytime ionosphere, westward‐propagating waves suffer up to 2.8 dB/Mm greater attenuation compared to eastward‐propagating waves. The trained model is used for propagation corrections in a global lightning locating system (LLS), but this technique can be expanded to further study VLF attenuation rates by employing different sets of basis functions.

Earth–ionosphere waveguide

Waveguide

10.1029/2022ja030742

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Citations (3)

International Journal of Disaster Risk Reduction (2019)

Ronald L. Holle Ashraf Dewan R. Said William A. Brooks Md. Faruk Hossain

Lightning

Case fatality rate

Vulnerability

10.1016/j.ijdrr.2019.101264

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Citations (69)

Empirical Parameterization of Broadband VLF Attenuation in the Earth-Ionosphere Waveguide

Zenodo (CERN European Organization for Nuclear Research) (2023)

R. Said Mark Gołkowski Vijay Harid

Earth–ionosphere waveguide

Waveguide

10.5281/zenodo.7671994

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Citations (0)

Volcanic Lightning as a Monitoring Tool during the 2016-2017 Eruption of Bogoslof Volcano, AK

Cassandra M. Smith Alexa R. Van Eaton R. Said R. H. Holzworth

Lightning

Vulcanian eruption

Volcanic Gases

Phreatic eruption

Source

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Citations (4)

Whistler Observations on DEMETER Compared with Full Electromagnetic Wave Simulations

AGU Fall Meeting Abstracts (2014)

A. J. Compston Mylan C. Cohen N. G. Lehtinen U. S. Inan I. R. Linscott

Whistler

Source

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Lightning stroke rates, atmospheric electric potential gradient data, and Schumann resonance data corresponding to the eruption of the Hunga Tonga - Hunga Ha'apai volcano on January 15, 2022

Zenodo (CERN European Organization for Nuclear Research) (2022)

József Bór Michael Atkinson S. A. Behnke Tamás Bozóki Attila Buzás

Lightning

Schumann resonances

10.5281/zenodo.7313474

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Long‐range lightning geolocation using a VLF radio atmospheric waveform bank

Journal of Geophysical Research Atmospheres (2010)

R. Said U. S. Inan Kenneth L. Cummins

Lightning discharges generate broadband electromagnetic pulses with a peak component in the very low frequency (VLF; 3–30 kHz) range. VLF waves propagate through the Earth‐ionosphere waveguide with relatively low attenuation, enabling the detection of these radio atmospherics at great distances from the lightning discharge. A new technique of long‐range (≤6000 km) global lightning geolocation via sferic detection is presented. This new technique catalogs the dominant variation in expected received waveforms in a set of waveform banks, which are then used to estimate the propagation distance and accurately determine the arrival time. Using three sensors in a trial network, this new technique is used to demonstrate a median accuracy of 1–4 km, depending on the time of day. An overall cloud‐to‐ground (CG) stroke detection efficiency between ∼40 and 60% is estimated by correlating individual lightning stroke events to data from the National Lightning Detection Network (NLDN). Additional events reported by the trial network are shown to have a tight spatial clustering to storm clusters identified by NLDN, suggesting that many of the unmatched events correspond to weak cloud‐to‐ground strokes, M components, or cloud pulses. Exploiting an empirical correlation between peak VLF field strength and peak current values reported by NLDN, we also provide unvalidated estimates of the peak current and lightning channel polarity. The trial network does not distinguish between cloud and ground discharges, so these peak current estimates only relate to an Earth‐referenced channel current for the subset of reported events that are return strokes.

Lightning detection

Lightning

Atmospherics

Atmospheric electricity

10.1029/2010jd013863

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Citations (186)

A lightning discharge producing a beam of relativistic electrons into space

Geophysical Research Letters (2010)

M. B. Cohen U. S. Inan R. Said M. S. Briggs G. J. Fishman

Strong electric fields associated with lightning generate brief (∼1 ms) but intense Terrestrial Gamma‐ray Flashes (TGFs), detected by spacecrafts. A few events are thought to be the signature of a relativistic electron beam escaping the atmosphere, which is distinguishable from a TGF since the lightning discharge is along the geomagnetic field line from the spacecraft, rather than below. We refer to this event herein as a ‘Terrestrial Energetic‐electron Flash’ (TEF), and present the first TEF with associated discharge. The TEF was detected by the Gamma‐ray Burst Monitor aboard the Fermi satellite, and is correlated with a lightning discharge detected by three Stanford University AWESOME ELF/VLF receivers, a Duke University ULF receiver, and by the GLD360 lightning geolocation network. The discharge, nearly simultaneous with the generated electrons, was of intense peak current and of positive polarity, and with a modest total charge transfer, similar to TGF‐associated discharges.

Lightning

Upper-atmospheric lightning

10.1029/2010gl044481

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Citations (38)

Day‐To‐Day Quantification of Changes in Global Lightning Activity Based on Schumann Resonances

Journal of Geophysical Research Atmospheres (2023)

Tamás Bozóki Gabriella Sátori Earle Williams Anirban Guha Yakun Liu

Abstract The importance of lightning has long been recognized from the point of view of climate‐related phenomena. However, the detailed investigation of lightning on global scales is currently hindered by the incomplete and spatially uneven detection efficiency of ground‐based global lightning detection networks and by the restricted spatio‐temporal coverage of satellite observations. We are developing different methods for investigating global lightning activity based on Schumann resonance (SR) measurements. SRs are global electromagnetic resonances of the Earth‐ionosphere cavity maintained by the vertical component of lightning. Since charge separation in thunderstorms is gravity‐driven, charge is typically separated vertically in thunderclouds, so every lightning flash contributes to the measured SR field. This circumstance makes SR measurements very suitable for climate‐related investigations. In this study, 19 days of global lightning activity in January 2019 are analyzed based on SR intensity records from 18 SR stations and the results are compared with independent lightning observations provided by ground‐based (WWLLN, GLD360, and ENTLN) and satellite‐based (GLM, LIS/OTD) global lightning detection. Daily average SR intensity records from different stations exhibit strong similarity in the investigated time interval. The inferred intensity of global lightning activity varies by a factor of 2–3 on the time scale of 3–5 days which we attribute to continental‐scale temperature changes related to cold air outbreaks from polar regions. While our results demonstrate that the SR phenomenon is a powerful tool to investigate global lightning, it is also clear that currently available technology limits the detailed quantitative evaluation of lightning activity on continental scales.

Lightning

Schumann resonances

Upper-atmospheric lightning

Polar orbit

10.1029/2023jd038557

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Citations (6)