Ultraviolet and infrared emission from lightning discharges observed at Aragats (original) (raw)
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Observations of lightning in the stratosphere
Journal of Geophysical Research, 1995
An examination and analysis of video images of lightning, captured by the payload bay TV cameras of the space shuttle, provided a variety of examples of lightning in the stratosphere above thunderstorms. These images were obtained on several recent shuttle flights while conducting the Mesoscale Lightning Experiment (MLE). The images of stratospheric lightning illustrate the variety of filamentary and broad vertical discharges in the stratosphere that may accompany a lightning flash. A typical event is imaged as a single or multiple filament extending 30 to 40 km above a thunderstorm that is illuminated by a series of lightning strokes. Examples are found in temperate and tropical areas, over the oceans, and over the land. 1465 ning. These include the detection of gamma-ray burst of atmospheric origin [Fishman et al., 1994], lightning-induced brightening of the airglow layer [Boeck et al., 1992], and unusual tran-ionospheric pulse pair radio signals detected by the Blackbeard experiment on the ALEXIS satellite [Holden et al.,
Journal of Geophysical Research: Space Physics, 2009
TLEs are optically observed from the U.S. Langmuir Laboratory, while ELF/VLF waveform data are simultaneously recorded on board the Centre National d'Etudes Spatiales microsatellite DEMETER and on the ground at Langmuir. Analyses of ELF/VLF measurements associated with sprite events observed on 28 July 2005 and 3 August 2005 are presented. Conditions to trace back the wave emissions from the satellite to the source region of the parent lightning discharge are discussed. The main results concern: (1) the identification from a low Earth orbit satellite of the 0+ whistler signatures of the TLE causative lightning; (2) the identification of the propagation characteristics of proton whistlers triggered by the 0+ whistlers of the causative lightning, and the potential use of those characteristics; (3) recognition of the difficulty to observe sprite-produced ELF bursts in the presence of proton-whistlers; (4) the use of geographical displays of the average power received by the DEMETER electric field antennas over the U.S. Navy transmitter North West Cape (NWC) located in Western Australia to evaluate VLF transmission cones which explain the presence (28 July events) or the absence (3 August events) of propagation links between sferics observed at ground and 0+ whistlers observed on DEMETER; and (5) owing to electron-collisions, an optimum transfer of energy from the atmosphere to the ionosphere for waves with k vectors antiparallel, or quasi-antiparallel, to Earth's magnetic field direction.
Journal of Geophysical Research, 2008
Abstract[1] Transient luminous events above thunderstorms such as sprites, halos, and elves require large electric fields in the lower ionosphere. Yet very few in situ measurements in this region have been successfully accomplished, since it is typically too low in altitude for rockets and satellites and too high for balloons. In this article, we present some rare examples of lightning-driven electric field changes obtained at 75–130 km altitude during a sounding rocket flight from Wallops Island, Virginia, in 1995. We summarize these electric field changes and present a few detailed case studies. Our measurements are compared directly to a 2D numerical model of lightning-driven electromagnetic fields in the middle and upper atmosphere. We find that the in situ electric field changes are smaller than predicted by the model, and the amplitudes of these fields are insufficient for elve production when extrapolated to a 100 kA peak current stroke. This disagreement could be due to lightning-induced ionospheric conductivity enhancement, or it might be evidence of flaws in the electromagnetic pulse mechanism for elves.
Lightning and middle atmospheric discharges in the atmosphere
Journal of Atmospheric and Solar-Terrestrial Physics, 2015
Recent development in lightning discharges including transient luminous events (TLEs) and global electric circuit are discussed. Role of solar activity, convective available potential energy, surface temperature and difference of land-ocean surfaces on convection process are discussed. Different processes of discharge initiation are discussed. Events like sprites and halos are caused by the upward quasielectrostatic fields associated with intense cloud-to-ground discharges while jets (blue starter, blue jet, gigantic jet) are caused by charge imbalance in thunderstorm during lightning discharges but they are not associated with a particular discharge flash. Elves are generated by the electromagnetic pulse radiated during lightning discharges. The present understanding of global electric circuit is also reviewed. Relation between lightning activity/global electric circuit and climate is discussed.
Radio Frequency Observations of Lightning Discharges by the Forte Satellite
2002
FORTE-observed VHF signatures for different lightning discharges are presented. For in-cloud discharges, a pulse pair is typically recorded and is named a "transionospheric pulse pair" (TIPP). Many intense TIPPs are coherent and polarized, whereas initial and dart leaders do not show a recognizable degree of polarization. TIPPs are optically weaker than cloud-to-ground (CG) strokes, and stronger VHF TIPPs are optically darker. About 10% of CG strokes, mostly over seawater, produce extremely narrow, powerful VHF pulses at the very beginning of the return strokes. These narrow pulses are found to form an upward beam pattern.
TROPOSPHERIC LIGHTNING AS A SOURCE OF HIGH ALTITUDE LIGHTNING (HAL) DISCHARGES
International Journal of Current Research and Review, 2012
High altitude lightning (HAL) discharges are a family of short lived electrical-breakdown phenomena that occur at altitudes ranging from cloud tops to the ionosphere. HAL discharges include mainly blue starters, blue jets, red sprites and elves. In this paper, it is described that the tropospheric cloud-to-ground (CG) lightning discharges pave the way of HAL discharges. The electric field, generated due to CG lightning discharge in the upper atmosphere is calculated. This electric field deposits the heat energy in the ambient space which comes in the form of HAL discharges. An altitude profile of heat energy density, deposited in the body of HAL discharges is also calculated. The HAL generating electric field deposits huge amount of energy at lower altitudes as compared to the higher altitudes. The energy loss at an altitude of 20 km where blue starters/jets initiate comes out to be of the order of 10-4 Jm-3. Similarly the energy loss at sprite initiating altitude (70 km) comes out to be of the order of 10-8 Jm-3. This shows that the blue starters/jets are more luminous as compared to the red sprites, which is in conformity with the experimental observations.
Multispectral Optical Diagnostics of Lightning from Space
Remote Sensing
We present spectroscopic diagnostic methods that allow us to estimate the gas and the electron temperature in emerged lightning stroke channels (from thunderclouds) observed by the photometers and cameras of the Atmosphere Space Interaction Monitor (ASIM). We identify the species (molecules, atoms and ions) producing light emission in different wavelengths, and how the blue (337 ± 2 nm), red (777.4 ± 2.5 nm) and ultraviolet (180–230 nm) optical emissions captured by ASIM photometers change as a function of the temperature in the lightning stroke channel. We find good agreement between the light curves of the emerged lightning observed by ASIM and the synthetic ones obtained from calculated spectra. Our results suggest that (i) early stage (high temperature > 20,000 K) emerged lightning strokes at high altitude can contribute to the optical signals measured by the PH2 photometer (180–230 nm), (ii) intermediate stage (mid temperatures, 6000–21,000 K) emerged lightning strokes can p...
Optical observations of terrestrial lightning by the FORTE satellite photodiode detector
Journal of Geophysical Research, 2001
We review data from observations of terrestrial lightning obtained by the FORTE satellite between September 1997 and January 2000. A silicon photodiode detector (PDD) records the intensity-time history of transient optical events occurring within its 80Њ circular field of view. This field of view corresponds to a circle on the Earth's surface having an approximate diameter of 1200 km. We describe the instrument, present examples of the data, explain how the data are screened for false triggers, and review, within the context of previous measurements, the general statistics of peak irradiance, pulse width, and energy associated with the data. We compare the FORTE data with National Lightning Detection Network (NLDN) reported cloud-to-ground (CG) strokes and find that the PDD detection efficiency for these CG strokes is ϳ6%. Moreover, we infer that FORTE preferentially detects the in-cloud portion of optical lightning signals. Events having inferred peak powers between 10 8 and 10 12 W and optical energy outputs between 10 3 and 10 9 J are observed. From a population of nearly 700,000 events we find that the median peak power and median detected optical energy at the source are estimated to be ϳ1 ϫ 10 9 W and 4.5 ϫ 10 5 J, respectively. These values of source peak power and energy are comparable to previous space-based measurements and consistent with aircraft-based and ground-based measurements. The observed median effective pulse width is about 590 microseconds. Further, the pulse widths for CG strokes, reported by NLDN, are inversely proportional to pulse peak power. This paper is not subject to U.S.
Physics of lightning: new model approaches and prospects of the satellite observations
Physics-Uspekhi, 2018
Contents 1. Question of lightning initiation and evolution and new observation possibilities 766 2. Satellites as unique instruments for detecting lightning discharge radiation 769 3. New approaches in the lightning discharge theory 772 3.1 Lightning initiation as a noise-induced kinetic transition; 3.2 Lightning discharge as a fractal dissipative structure; 3.3 Compact intracloud discharge model as an example of applying a new approach for describing discharge phenomena 4. Conclusions 776 References 778
Chapter 13: Space- and Ground-Based Studies of Lightning Signatures
2009
This article provides a brief survey of the space-and ground-based studies of lightning performed by investigators at Los Alamos National Laboratory (LANL). The primary goal of these studies was to further understand unique lightning signatures known as Narrow Bipolar Events (NBEs). First, an overview is presented of the Fast On-orbit Recording of Transient Events (FORTE) satellite and of the ground-based Los Alamos Sferic Array (LASA). This is followed by a summary of the phenomenology, physics, and meteorological context of NBEs and NBE-related discharges. This article also discusses additional radio frequency and optical observations of lightning made by the FORTE satellite and concludes with an outlook on LANL's growing interest in the use of lightning observations in the study of severe weather and hurricane intensification.