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Evidence for continuing current in sprite-producing cloud-to-ground lightning

Authors:
  • FMA Research, Inc.

Abstract

Radio atmospherics launched by sprite-producing positive cloud-to-ground lightning flashes and observed at Palmer Station, Antarctica, exhibit large ELF slow tails following the initial VLF portion, indicating the presence of continuing currents in the source lightning flashes. One-to-one correlation of sferics with NLDN lightning data in both time and arrival azimuth, measured with an accuracy of ±1° at ∼12,000 km range, allows unambiguous identification of lightning flashes originating in the storm of interest. Slow-tail measurements at Palmer can potentially be used to measure continuing currents in lightning flashes over nearly half of the Earth's surface.
... The physical mechanisms responsible for sprites and elves initiation are independent of the polarity of the lightning flash [127,128,[131][132][133][134]; however the vast majority of sprites are initiated by positive cloud-to-ground (CG) flashes [27,29,135,136]. These powerful positive flashes emit strong electromagnetic energy in the ELF range, indicative of continuing currents lasting over time scales of at least a few milliseconds [135], and thus can be detected in the SR band. ...
... The physical mechanisms responsible for sprites and elves initiation are independent of the polarity of the lightning flash [127,128,[131][132][133][134]; however the vast majority of sprites are initiated by positive cloud-to-ground (CG) flashes [27,29,135,136]. These powerful positive flashes emit strong electromagnetic energy in the ELF range, indicative of continuing currents lasting over time scales of at least a few milliseconds [135], and thus can be detected in the SR band. Recent observations [27][28][29][30]91,137] reveal that occurrences of sprites and transient SR are highly correlated ( Figure 10). ...
... The physical mechanisms responsible for sprites and elves initiation are independent of the polarity of the lightning flash [127,128,[131][132][133][134]; however the vast majority of sprites are initiated by positive cloudto-ground (CG) flashes [27,29,135,136]. These powerful positive flashes emit strong electromagnetic energy in the ELF range, indicative of continuing currents lasting over time scales of at least a few milliseconds [135], and thus can be detected in the SR band. ...
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Lightning produces electromagnetic fields and waves in all frequency ranges. In the extremely low frequency (ELF) range below 100 Hz, the global Schumann Resonances (SR) are excited at frequencies of 8 Hz, 14 Hz, 20 Hz, etc. This review is aimed at the reader generally unfamiliar with the Schumann Resonances. First some historical context to SR research is given, followed by some theoretical background and examples of the extensive use of Schumann resonances in a variety of lightning-related studies in recent years, ranging from estimates of the spatial and temporal variations in global lighting activity, connections to global climate change, transient luminous events and extraterrestrial lightning. Both theoretical and experimental results of the global resonance phenomenon are presented. It is our hope that this review will increase the interest in SR among researchers previously unfamiliar with this phenomenon.
... Later, analysis of ELF/VLF broadband data from Palmer station, Antarctica indicated that majority of TGF events (76%) are associated with lightning discharges and the peak VLF intensity of the TGF associated lightning discharges is found among the most intense in the same storm 57 . Since the peak VLF power of a radio atmospheric is directly proportional to the intensity of lightning, 92 therefore TGFs should be produced by EMPs generated by intense lightning. The electric field of EMPs radiated by return stroke propagating upwards with velocity vr and current I is given by Krider: 60 ...
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Extraordinarily bright events with highly energetic radiation in the form of bursts of hard X-rays and γ-rays of short durations have been detected in our atmosphere by scientific community routinely during strong thunderstorms and lightning activity. Terrestrial Gamma-ray Flashes (TGFs) are very short (< 1 ms) bursts of highly energetic gamma-ray photons which are generated during powerful thunderstorms and have been detected by both airborne as well as ground based experiments. TGFs driven source has been an active area of research since their accidental discovery by Burst and Transient Source Experiment detector, on board the Compton Gamma-ray Observatory in 1994. These gamma-rays bursts originate in deep atmosphere within thunderclouds typically at altitude ranging from 10-20 km. It is found that certain meteorological conditions like high convective available potential energy (CAPE) values, high cloud tops, high lightning stroke occurrence and vigorous electrically active storms play important role for TGF production. It is believed that rapid production of relativistic runaway electrons which are accelerated in the strong thundercloud/lightning electric field causes TGFs via bremsstrahlung emission. Gamma-ray glows or Thunderstorm Ground Enhancements (TGEs) and TGF afterglow are also some other high energy atmospheric phenomena which are related to TGFs. In this study, we will discuss about the characteristics of TGFs, Gamma-ray glows or Thunderstorm Ground Enhancements (TGEs) and TGF afterglow including energy spectrum, time profile, their correlation with lightning and their production mechanisms.
... In order to satisfy the rate of 2−3 sprites per minute globally and the (2014) is not coupled to the meteorological conditions that favor their inception (Lang et al., 2016). Sprites are triggered by high CMC strokes frequently followed by a long continuing current phase (Reising et al., 1996) that can be detected using Extremely Low Frequency (ELF) and optical measurements (Adachi et al., 2009;Bitzer, 2017). For instance, Sato and Fukunishi (2003) J o u r n a l P r e -p r o o f estimated locations and rates of sprite occurrences (720 events per day or 1 every two minutes) on average on a global scale using 1-−100 Hz ELF magnetic field waveform data obtained at Syowa station in Antarctica and Onagawa observatory in Japan, and the empirical sprite initiation probability reported by Hu et al. (2002). ...
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Atmospheric electricity has been intensively studied during the last 30 years after the discovery in 1989 of different forms of upper atmospheric electrical discharges (so–called Transient Luminous Events) triggered by lightning in the troposphere. In spite of the significant number of investigations that led to important new results unveiling how lightning produces a zoo of transient electrical discharges from the upper troposphere to the mesosphere, there is still no clear understanding about how all sort of TLEs – including those that occur inside thunderclouds – can contribute to the chemistry of the atmosphere both at the local and global scale. This review paper aims at presenting a perspective on the TLE atmospheric chemistry research done in the past, in the present as well as to describe some of the challenges that await ahead to find the true scientific importance of the non-equilibrium atmospheric chemistry triggered by TLEs. This review comes to conclude that while the global chemical impact of elves and halos are almost negligible, the large scale chemical impact of sprites, blue jets and blue starters and that of impulsive cloud corona discharges might be non–negligible in terms of their possibly measurable contribution to important greenhouse gases such as ozone and nitrous oxide (N2O). Being the third strongest greenhouse gas (after carbon dioxide and methane) and by having the ability to deplete ozone, precise determination of atmospheric N2O sources is of increasing and pressing demand. A new era in atmospheric electricity is just emerging in which dedicated scientific space missions (ISS–LIS, ASIM) together with geostationary lightning sensors (since 2016) and new micro–scale and parameterizations of TLEs in general atmospheric chemistry circulation models will hopefully help to start clarifying the full role of TLEs in the chemistry of the atmosphere.
... The morphological properties of optical sprite observations are commonly attributed to the specific characteristics of the sprite producing lightning discharges. For example, the vast majority of sprites are caused by intense positive lightning discharges (Boccippio et al., 1995;Pasko, 2010, and references therein) followed by a lightning continuing current (Cummer et al., 1998;Pasko et al., 1998;Reising et al., 1996) with a large charge moment change (Cummer & Stanley, 1999;Cummer & Füllekrug, 2001). On occasion, sprites are initiated by negative lightning discharges (Barrington-Leigh & Inan, 1999) as confirmed by detailed experimental observations Chen et al., 2019;Lu et al., 2012) and supported by corresponding theoretical studies Qin et al., 2012). ...
Article
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Sprites are composed of numerous streamers which exhibit transient luminosities in the upper middle atmosphere above thunderclouds after initiation by an intense positive lightning discharge, often followed by lightning continuing current. Here we report the discovery of a sprite which exhibits its main luminosity near the stratopause. This novel phenomenon is attributed to a sudden surge of intracloud lightning leader activity, based on a rigorous analysis of our observed electromagnetic waveforms. Each lightning leader discharge causes an additional electric field that generates a small amount of electromagnetic energy near the stratopause and thereby contributes to the overall sprite luminosity morphology. The observation of sprite streamers near the stratopause is important because it is relevant for the ongoing assessment of the lightning impact on N2 and CO2 with emissions from the near to far infrared part of the spectrum.
... The morphological properties of optical sprite observations are commonly attributed to the specific characteristics of the sprite producing lightning discharges. For example, the vast majority of sprites are caused by intense positive lightning discharges (Boccippio et al., 1995;Pasko, 2010, and references therein) followed by a lightning continuing current (Cummer et al., 1998;Pasko et al., 1998;Reising et al., 1996) with a large charge moment change (Cummer & Stanley, 1999;Cummer & Füllekrug, 2001). On occasion, sprites are initiated by negative lightning discharges (Barrington-Leigh & Inan, 1999) as confirmed by detailed experimental observations Chen et al., 2019;Lu et al., 2012) and supported by corresponding theoretical studies Qin et al., 2012). ...
Article
Full-text available
Sprites are composed of numerous streamers which exhibit transient luminosities in the upper middle atmosphere above thunderclouds after initiation by an intense positive lightning discharge, often followed by lightning continuing current. Here we report the discovery of a sprite which exhibits its main luminosity near the stratopause. This novel phenomenon is attributed to a sudden surge of intracloud lightning leader activity, based on a rigorous analysis of our observed electromagnetic waveforms. Each lightning leader discharge causes an additional electric field that generates a small amount of electromagnetic energy near the stratopause and thereby contributes to the overall sprite luminosity morphology. The observation of sprite streamers near the stratopause is important because it is relevant for the ongoing assessment of the lightning impact on N2 and CO2 with emissions from the near to far infrared part of the spectrum.
... Mlynarczyk et al. (2016) analyzed strong lighting discharges at the distances of up to 12 Mm using two ELF receivers, one located in Poland and the other in Colorado, USA. Some other studies related to lighting location that the reader might be interested in include Reising et al. (1996) and Füllekrug and Constable (2000). ...
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In this work, we study the accuracy of direction finding in the extremely low frequency (ELF) range using a newly installed broadband receiver equipped with two active magnetic antennas. The main natural source of ELF radio waves is lightning. In this work, we analyzed 1000 atmospheric discharges at distances of up to 5000 km from the receiver. We identified the most important factors influencing the accuracy of the angle of arrival: the deviation of the radio waves propagating through the day-night terminator zone and the signal-to-noise ratio resulting from local electromagnetic noise and Schumann resonance background. The obtained results clearly show that the accuracy of estimating the direction of arrival is very high (an average error of 0.1° with the standard deviation of 2.3°) when the signal-to-noise ratio is large (the amplitude of the magnetic field component above 100 pT), except for short periods in the local morning and evening, when the day-night terminator is present on the propagation path of the direct wave. For the day-night propagation paths, the refraction angle was larger than the incidence angle, and for the night-day propagation paths, the refraction angle was smaller than the incidence angle, which is consistent with theory. Using our analytical ELF radio propagation model allowed us to explain the obtained results.
... Note that delayed arrival of the ELF signals can be explained partly by the difference between the time of production of the VLF and ELF radiation in the discharge process. While the VLF band radiation is dominantly produced by the return stroke, the most intense electromagnetic waves in the ELF band may originate from the subsequent continuing current phase of the lightning discharge [Hepburn, 1957;Wait, 1960b;Reising et al., 1996]. ...
Article
Q-bursts are globally detectable extremely low frequency (ELF, 3-3000Hz) band wave packets produced by intense lightning discharges. Q-bursts recorded in the Széchenyi István Geophysical Observatory (NCK, 16.7°E, 47.6°N), Hungary, on 1 and 2 August 2012 have been analyzed to find azimuths of their sources. The location of parent lightning strokes of 320 and 205 Q-bursts on the 2days, respectively, have been identified in the records of the World Wide Lightning Location Network (WWLLN) using the detection times at NCK. ELF data-based source azimuths were found to differ systematically from source azimuths obtained from WWLLN lightning locations. The difference between the corresponding azimuth values depends on the azimuth of the source. This variation of the source azimuth error mirrors the symmetry of the conductance of the Earth's crust inferred from magnetotelluric measurements around NCK. After correction for the azimuthal dependence, the variation of the residual error shows a diurnal pattern with positive azimuth deviations occurring near midnight, local time. Füllekrug and Sukhorukov (1999) suggested that the anisotropic conductivity in the Earth's crust below the observatory and the different daytime and nighttime conductivities in the lower ionosphere, respectively, may cause the identified error terms. Our results emphasize the substantial effect of anisotropic conductivity in the Earth's crust around the recording station on the accuracy of ELF direction finding. The need for theoretical approach and more measurements is pointed in understanding the underlying mechanisms quantitatively and in investigating whether ELF observations can be used in geophysical prospecting.
... Electromagnetic (EM) emissions associated with sprites can provide information about their current characteristics and their specific signatures for their identification [Cummer et al., 1998;Füllekrug et al., 2001]. Reising et al. [1996] showed that sprite-producing +CG lightning flashes produce large extremely low frequency (ELF) tails following the initial VLF portion, indicating the presence of continuing current in the discharge. Radio waveforms in the ELF range (from 3 Hz to 3 kHz) originating in sprite-producing lightning discharges have been used to estimate the charge removed [Cummer and Inan, 1997;Bell et al., 1998]. ...
Article
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During the night of 22-23 October 2012, together with the Hydrology cycle in the Mediterranean eXperiment (HyMeX) Special Observation Period 1 (SOP1) campaign, optical observations of sprite events were performed above a leading stratiform Mesoscale Convective System (MCS) in southeastern France. The total lightning activity of the storm was monitored in three dimensions with the HyMeX Lightning Mapping Array (HyLMA). Broadband Extremely Low Frequency (ELF)/Very Low Frequency (VLF) records and radar observations allowed characterizing the flashes and the regions of the cloud where they propagated. Twelve sprite events occurred over the stratiform region, during the last third of the lightning activity period, and well after the coldest satellite-based cloud top temperature (-62°C) and the maximum total lightning flash rate (11 min-1). The Sprite-Producing positive Cloud-to-Ground (SP+CG) strokes exhibit peak current from 14 to 247 kA, Charge Moment Changes (CMC) from 625 to 3086 C km, and Impulsive CMC (iCMC) between 242 and 1525 C km. The +CG flashes that do not trigger sprites are initiated outside the main convective core, have much lower CMC values, and in average, shorter durations, lower peak currents, and shorter distances of propagation. The CMC appears to be the best sprite predictor. The delay between the parent stroke and the sprite allows classifying the events as short-delayed (< 20 ms) and long-delayed (> 20 ms). All long-delayed sprites, i.e., most of the time carrot sprites, are produced by SP+CG strokes with low iCMC values. All SP+CG flashes initiate close to the convective core and generate leaders in opposite directions. Negative leaders finally propagate towards lower altitudes, within the stratiform region that coincides with the projected location of the sprite elements.
Article
Lightning events could cause ionospheric disturbance on performance of radio signals which could lead to errors. The objective of the study is to investigate the response of vertical total electron content (VTEC) during lightning activity over the Antarctic Peninsula for the year 2017. The lightning data were obtained from the World Wide Lightning Location Network (WWLLN) while the lightning flash data were obtained from the Lightning Detector (LD350) which can detect positive and negative cloud-to-ground (+CG and -CG) flashes. The VTEC data were analyzed from the GPS's ground based station for Carlini (CARL), O'Higgins (OHI2) and Palmer (PALV). The yearly lightning distribution was 117 strikes during low geomagnetic storms. The average ΔVTEC obtained was less than 1 TECU because very low number of lightning activity was detected which contributed to a very low increment of VTEC. The lightning flash per hour was in the range of 1200–1700 in February until April which indicates a very active lightning flash activity. From May until December, less than 200 flashes per hour were detected due to change in season. The lightning distribution for -CG was above 45% and for + CG, it was below 45%. The correlation between lighting flash and VTEC during low geomagnetic activity shows that 19% of the total events was a weak negative and weak positive correlation each as a result of VTEC complexity and thundercloud variation. VTEC enhancement could be contributed by halo film which was involved in ionization and strong sprite that penetrates through the ionosphere.
Chapter
In this chapter the main attention is paid on the atmospheric electricity and on the global lightning activity as a machine supplying the negative charges to the Earth. Here we deal with the electric field and charge distribution in thunderstorm clouds and with the conventional mechanism for air breakdown. Lightning discharge parameters and global thunderstorm activity are discussed. In the remainder of this chapter the main emphasis is on the low frequency effects associated with recently documented evidences of previously unknown forms of upward propagating gigantic electric discharges, also known as transient luminous events (TLEs), which occur above a large thunderstorm system.
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New observations of sprites (cloud-ionosphere luminous discharges above thunderstorms) were made from the Yucca Ridge Field Station 20 km northeast of Fort Collins, Colorado, on the night of July 11-12, 1994, as part of a summer 1994 observing campaign. The sprites appeared above a moderate mesoscale convective complex mostly over Kansas at a range of about 270 km. The sprites were observed with both wide-field and telescopic image-intensified CCD TV cameras, a telescopic photometer system, and a 1- to 50-kHz band VLF sferics receiver. This paper is based on five 1-s data intervals containing bright sprites, smaller sprites, and cloud and sky flashes. Telescopic TV images of bright sprites had a fan-shaped upper plume with very fine features not well resolved by the TV, but dendritic (upward forked) and vertically striated forms adjacent to these plumes and bright points of luminosity around the plume-shaped regions. Many sprites consisted entirely of groups of vertically aligned striations which sometimes appeared to diverge from a common point of origin at cloud tops. All sprites in the present data sample were preceded by a cloud to ground (CG) stroke with a coincident sferic and sky flash. All CG strokes associated with sprites were positive, and most were 100 kA or more inferred peak current. From the photometer, the duration of the CG- induced sky flashes was about 3 ms and the additional sprite total light curve was also about 3 ms. The puzzling feature that the total duration of TV images of sprites was often longer than the photometric values is discussed and an explanation given. The sprites were attributed to strong negative charging, following the positive CG stroke, of a localized cloud top region which produced an intense electric field and a luminous discharge in the cloud-ionosphere region. The concept of "break-even" electric fields suggested by McCarthy and Parks may explain discharge initiation with moderate field strengths.
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In two summertime mesoscale convective systems (MCSs), mesospheric optical sprite phenomena were often coincident with both large-amplitude positive cloud-to-ground lightning and transient Schumann resonance excitations of the entire Earth-ionosphere cavity. These observations, together with earlier studies of MCS electrification, suggest that sprites are triggered when the rapid removal of large quantities of positive charge from an areally extensive charge layer stresses the mesosphere to dielectric breakdown.
Article
Measurements of ELF/VLF radio atmospherics (sferics) at Palmer Station, Antarctica, provide evidence of active thunderstorms near the inferred source regions of two different gamma-ray bursts of terrestrial origin [Fishman et al., 1994]. In one case, a relatively intense sferic occurring within +/-1.5 ms of the time of the gamma-ray burst provides the first indication of a direct association of this burst with a lightning discharge. This sferic and many others launched by positive cloud-to-ground (CG) discharges and observed at Palmer during the periods studied exhibit `slow tail' waveforms, indicative of continuing currents in the causative lightning discharges. The slow tails of these sferics are similar to those of sferics originating in positive CG discharges that are associated with sprites.
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Extensive observations arc described of the form, magnitude, quasi-period, and delay relative to the high-frequency component of the slow tails of atmospheric waveforms and the variations with time of day and propagation distance. Theoretical considerations of possible source conditions and propagation characteristics fit the observations. They show that the observed linear dependence of the temporal parameters on distance can yield a constant height and conductivity of the equivalent homogeneous ionospheric layer independent of distance, but with different values for day and night.
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Slow-tail portions of atmospherics were recorded simultaneously in Japan and the United States from sources located in the Pacific Ocean area. The amplitude and phase spectra of forty pairs of selected atmospherics were computed, and propagation parameters for the zero-order wave-guide mode were calculated for nighttime conditions only. Attenuation rates for W-E propagation extended from about 0.5 db/Mm at 20 Hz to 2.0 db/Mm at 300 Hz and for E-W propagation from 0.8 db/Mm at 20 Hz to about 2.8 db/Mm at 300 Hz. The phase velocities extended from about 0.7 and 0.8 the velocity of light for W-E and E-W propagation, respectively, at 20 Hz to about 0.93 the velocity of light for either direction at 300 Hz.
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A theoretical treatment is given of the problem of the excitation of ELF pulses by lightning discharges in the Earth-ionosphere waveguide. This is done for the Greifinger and Greifinger [(1978) Radio Sci.13, 831 and (1979) Radio Sci.14, 998] approximation of ELF wave propagation. We have obtained characteristic waveforms of the pulses excited by various model sources under different conditions. The dependence of ELF pulse delay on propagation distance is investigated; this is found to be close to linear at distances 10,000 km. Peculiarities of the form of the ELF pulse excited by a horizontal, or nearly horizontal, lightning discharge have also been analyzed.