Version 4: 2000 July 6: Inspec search: Find SUBJECT ELVES or TITLE LIGHTNING INDUCED AIRGLOW or SUBJECT LIGHTNING OPTICAL EMP OR SUBJECT ELECTROMAGNETIC PULSES LIGHTNING IONOSPHERE OR TITLE PHYSICS HIGH ALTITUDE LIGHTNING OR TITLE OPTICAL EMISSION IONOSPHERE SIMULATION or TITLE LIGHTNING RADIO EMISSION STRATOSPHERE %OR subject optical lighting induced heating Result: 53 citations I then had to add the "Jul" to the Taranenko97 conference, since it has no month. I also changed "Mengu Cho" to "Cho, M" in Cho and Rycroft, 98. -> ChoMay98 /usr/tmp/citation.tmp.3068 @ARTICLE{HuangJul99, author={Huang, E. and Williams, E. and Boldi, R. and Heckman, S. and Lyons, W. and Taylor, M. and Nelson, T. and Wong, C.}, title={ Criteria for sprites and elves based on Schumann resonance observations }, journal={Journal of Geophysical Research}, volume={104}, number={D14}, year={1999}, month={Jul}, pages={16943-64}, abstract={ Ground flashes with positive polarity associated with both sprites and elves excite the Earth's Schumann resonances to amplitudes several times greater than the background resonances. Theoretical predictions for dielectric breakdown in the mesosphere are tested using ELF methods to evaluate vertical charge moments of positive ground flashes. Comparisons of the measured time constants for lightning charge transfer with the electrostatic relaxation time at altitudes of nighttime sprite initiation (50-70 km) generally validate the electrostatic assumption in predictions made initially by Wilson (1925). The measured charge moments (QdS=200-2000 C-km) are large in comparison with ordinary negative lightning but are generally insufficient to account for conventional air breakdown at sprite altitudes. The measured charge moments, however, are sufficient to account for electron runaway breakdown, and the long avalanche length in this mechanism also accounts for the exclusive association of sprites with ground flashes of positive polarity. The association of elves with large peak currents (50-200 kA) measured by the National Lightning Detection Network in a band pass beyond the Schumann resonance range is consistent with an electromagnetic pulse mechanism for these events }, keywords={ Earth-ionosphere waveguide lightning mesosphere sprites elves Schumann resonance observations mesospheric dielectric breakdown ELF methods vertical charge moments positive ground flashes measured time constants lightning charge transfer electrostatic relaxation time nighttime sprite initiation air breakdown electron runaway breakdown avalanche length peak currents National Lightning Detection Network EM pulse mechanism }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @CONFERENCE{Nickolaenko98, author={Nickolaenko, A.P.}, title={ Spectra and waveforms of natural electromagnetic pulses in the ELF range }, booktitle={Fourteenth International Wroclaw Symposium and Exhibition. ElectromagneticCompatibility 1998}, volume={}, number={}, year={1998}, month={}, pages={557-60}, abstract={ Electromagnetic waves are studied in the extremely low frequency range where single zero-order radio wave propagates. The authors apply the well known solution for the spherical Earth-ionosphere cavity. Relevant time domain fields are obtained using the FTT algorithm. The field distribution had been obtained in both the frequency-distance and time-distance domains. Relief of the amplitude of the natural radio signal over the frequency-distance plane is a system of summits and depressions. The maximum energy lies at hundreds of Hz when the source-observer distance is small. This explains an effectiveness of the nearby discharge location using the slow tail atmospheric technique. The high frequency signal rapidly decays when the distance grows, and from some megameter distance, amplitude reaches its maximum in the Schumann resonance (SR) frequence band. This is why the global lightning location is a success based on the SR techniques. Natural ELF pulse travels within the Earth-ionosphere guiding system with a constant velocity and bounces' from the source and its antipode. The pulse width gradually increases along the propagation path due to natural filtration of the high frequency components. Meanwhile, distance dependence of the pulse amplitude depends on both the geometrical focusing of the signal in a spherical cavity and the high frequency absorption }, keywords={ electromagnetic pulse fast Fourier transforms radiowave propagation time-domain analysis ELF range natural electromagnetic pulses single zero-order radio wave propagation spherical Earth-ionosphere cavity time domain fields FTT algorithm field distribution frequency-distance domain time-distance domain slow tail atmospheric technique high frequency signal Schumann resonance frequence band pulse width high frequency components }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @CONFERENCE{Nickolaenko98, author={Nickolaenko, A.P. and Hayakawa, M.}, title={ Electric fields from model lightning discharges }, booktitle={Fourteenth International Wroclaw Symposium and Exhibition. ElectromagneticCompatibility 1998}, volume={}, number={}, year={1998}, month={}, pages={553-6}, abstract={ Time domain electric field from the model lightning discharges in the neutral atmosphere is computed and its modifications due to geometrical changes of the stroke are examined. A standard model of the return stroke is used as a basic one. The current wave-form at the stroke base is a sum of four exponential terms. Current wave moves upward with an exponential decaying velocity. Static, induction and radiation field components were computed. The model was modified then to describe the electric fields from: (i) the powerful vertical return stroke, (ii) the positive stroke that initiates from the ground or from the cloud, (iii) the broken' discharge, and (iv) the spider' stroke. The combined effect of the motion of the current wave and the tortuosity of the lightning channel results in multiple pulses. The vector of the electric field acquires transient vertical, inward/outward and sideways components. The relevant field scans' the sky. Disturbances above the storm may lead to the air density and temperature fluctuations that facilitate modification of the plasma in the lower ionosphere }, keywords={ atmospheric temperature electric fields ionosphere lightning model lightning discharges electric fields time domain electric field neutral atmosphere current wave-form exponential terms current wave exponential decaying velocity radiation field components induction field components static field components vertical return stroke positive stroke ground stroke cloud stroke broken discharge spider stroke lightning channel tortuosity air density temperature fluctuations lower ionosphere plasma }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{VeronisJun99, author={Veronis, G. and Pasko, V.P. and Inan, U.S.}, title={ Characteristics of mesospheric optical emissions produced by lightning discharges }, journal={Journal of Geophysical Research}, volume={104}, number={A6}, year={1999}, month={Jun}, pages={12645-56}, abstract={ A new 2D cylindrically symmetric EM model of the lightning-ionosphere interaction includes effects of both the lightning radiated EM pulses (EMP) and the quasi-electrostatic (QE) fields, thus allowing effective studies of lightning-ionosphere interactions on time scales ranging from several microseconds to tens of milliseconds. The temporal and spatial evolution of the electric field, lower ionospheric electron density, and optical emissions calculated with the new model are used to investigate theoretically the effects of the lightning return stroke current waveform and of the observational geometry on the optical signals observed with a photometer. For typical lightning discharges of À100 mu s duration the ionospheric response is dominated by the EMP-induced heating leading to the highly transient and laterally expanding optical flashes known as elves. The optical signal characteristics are found to be highly sensitive to both the observational geometry and the current waveform. The onset delay with respect to the lightning discharge, the duration, and the peak magnitude of optical emissions are highly dependent on the elevation and azimuth angles of field of view of individual photometric pixels. The shape of the optical signal clearly reflects the source current waveform. For a waveshape with risetime of À50 mu s or longer a double-pulse shape of the photometric signal is observed. For cloud to ground lightning discharges of À1 ms duration removing substantial amount of charge, heating and ionization changes induced by the QE field lead to the mesospheric luminous glows with lateral extent <100 km, referred to as sprites }, keywords={ atmospheric radiation atmospheric temperature electromagnetic pulse electron density ionospheric disturbances lightning mesosphere mesospheric optical emissions lightning discharges 2D cylindrically symmetric electromagnetic model lightning-ionosphere interaction EM pulses quasi-electrostatic fields time scales temporal evolution spatial evolution lower ionospheric electron density lightning return stroke current waveform observational geometry EMP-induced heating optical flashes elves onset delay duration source current waveform risetime double-pulse shape photometric signal ionization changes }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{Nickolaenko, author={Nickolaenko, A.P.}, title={ Natural ELF electromagnetic pulses }, journal={Telecommunications and Radio Engineering}, volume={}, number={}, year={}, month={}, pages={25-34}, abstract={ Interest in monitoring natural electromagnetic pulse radio signals has re-appeared recently stimulated by attempts at location of distant powerful lightning strokes that cause optical emissions in the upper atmosphere. Such a luminous structure over a thunderstorm cell may reach 95 km altitude. The goal of the present study is an analysis of the model solution within the whole extremely low frequency (ELF) band. We apply a well-known frequency domain solution for a wave travelling in the spherical Earth-ionosphere cavity. The time-dependent field components are obtained with the numerical Fourier transform. Within such an approach, any further development of the known theory is unnecessary, and the field distribution over the frequency-distance plane is obtained from the unified positions. We describe ELF spectral components of an electromagnetic wave using the mode theory developed for the spherical Earth-ionosphere waveguide }, keywords={ Earth-ionosphere waveguide electromagnetic pulse Fourier transforms frequency-domain analysis lightning radiowave propagation spectral analysis thunderstorms natural ELF pulses electromagnetic pulse radio signals thunderstorm lightning strokes extremely low frequency band frequency domain solution spherical Earth-ionosphere cavity time-dependent field components numerical Fourier transform field distribution spectral components electromagnetic wave mode theory }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{Barrington-LeighMar99, author={Barrington-Leigh, C.P. and Inan, U.S.}, title={ Elves triggered by positive and negative lightning discharges }, journal={Geophysical Research Letters}, volume={26}, number={6}, year={1999}, month={Mar}, pages={683-6}, abstract={ Optical flashes in the lower ionosphere due to the transient heating caused by lightning electromagnetic pulses (EMP) are unambiguously identified with the Fly's Eye photometric array. Data from a thunderstorm over Mexico recorded at Langmuir Laboratory on August 27 1997 demonstrate that relatively common negative cloud-to-ground lightning is a previously unrecognized major cause of elves. The spatial extent of the transient heating is shown optically to be typically at least 200-700 km laterally, indicating the possibility for accumulation of ionization effects produced by successive flashes within large nighttime thunderstorm systems. One especially bright event suggests that temporal fine-structure in the causative very low frequency EMP can manifest itself in the photometric record of elves }, keywords={ ionosphere lightning mesosphere thermosphere elf elves optical emission upper atmosphere thermosphere middle atmosphere mesosphere lightning triggered negative lightning discharge positive lightning lightning electric discharge optical flash lower ionosphere transient heating lightning electromagnetic pulse EMP thunderstorm storm Mexico AD 1997 08 27 negative cloud-to-ground lightning cause spatial extent ionization effec temporal fine-structure }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{RakovNov98, author={Rakov, V.A. and Uman, M.A.}, title={ Review and evaluation of lightning return stroke models including some aspects of their application }, journal={IEEE Transactions on Electromagnetic Compatibility}, volume={40}, number={4}, year={1998}, month={Nov}, pages={403-26}, abstract={ Four classes of models of the lightning return stroke are reviewed. These four classes are: (1) the gas dynamic models; (2) the electromagnetic models; (3) the distributed-circuit models; and (4) the "engineering" models. Validation of the reviewed models is discussed. For the gas dynamic models, validation is based on observations of the optical power and spectral output from natural lightning. The electromagnetic, distributed-circuit, and "engineering" models are most conveniently validated using measured electric and magnetic fields from natural and triggered lightning. Based on the entirety of the validation results and on mathematical simplicity, we rank the "engineering" models in the following descending order: MTLL, DU, MTLE, BG, and TL. When only the initial peak values of the channel-base current and remote electric or magnetic field are concerned, the TL model is preferred. Additionally discussed are several issues in lightning return-stroke modeling that either have been ignored to keep the modeling straightforward or have not been recognized, such as the treatment of the upper, in-cloud portion of the lightning channel, the boundary conditions at the ground, including the presence of a vertically extended strike object, the return-stroke speed at early times, the initial bi-directional extension of the return stroke channel, and the relation between leader and return stroke models. Various aspects of the calculation of lightning electric and magnetic fields in which return stroke models are used to specify the source are considered, including equations for fields and channel-base current, as well as a discussion of channel tortuosity and branches }, keywords={ electric current electric fields electromagnetic pulse lightning magnetic fields reviews lightning return stroke models gas dynamic models electromagnetic models distributed-circuit models engineering models optical power spectral output natural lightning measured electric fields measured magnetic fields triggered lightning channel-base current lightning channel boundary conditions ground vertically extended strike object return stroke speed early times leader models source equations channel tortuosity lightning EMP channel branches }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{TsunodaMay98, author={Tsunoda, R.T. and Livingston, R.C. and Buonocore, J.J. and Lyons, W.A. and Nelson, T.E. and Kelley, M.C.}, title={ Evidence of a high-altitude discharge process responsible for radar echoes at 24.4 MHz }, journal={Journal of Atmospheric and Solar-Terrestrial Physics}, volume={60}, number={7-9}, year={1998}, month={May}, pages={957-64}, abstract={ Presents preliminary evidence of a high-altitude, electrical discharge process that can produce radar echoes at 24.38 MHz. This conclusion is drawn from pulsed-radar observations of near time-coincident occurrences of impulsive electromagnetic radiation with radar echoes that originated at altitudes well above those of mesoscale convective systems }, keywords={ atmospheric electricity atmospheric electromagnetic wave propagation remote sensing by radar thunderstorms radar echoes HF high-altitude electrical discharge process pulsed-radar observations impulsive EM radiation red sprites blue jets elves upper stratosphere mesosphere 24.38 MHz }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{Roussel-DupreMay98, author={Roussel-Dupre, R. and Symbalisty, E. and Taranenko, Y. and Yukhimuk, V.}, title={ Simulations of high-altitude discharges initiated by runaway breakdown }, journal={Journal of Atmospheric and Solar-Terrestrial Physics}, volume={60}, number={7-9}, year={1998}, month={May}, pages={917-40}, abstract={ Detailed 2D hydrodynamic and quasi-electrostatic simulations of high-altitude discharges driven by runaway air breakdown are presented for four cases, corresponding to sprites initiated by positive cloud-to-ground lightning strikes in which 200 C of charge is neutralized at an altitude of 11.5 km in 10, 7, 5 and 3 ms. We find that the computed optical emissions agree well with low-light level camera images of sprites, both in terms of the overall intensity and spatial distribution of the emissions. Our results show the presence of blue emissions extending down to 40 km (blue tendrils) and red sprite tops extending from 50 to 77 km. Simulated spectra show that N/sub 2/ 1st positive emissions dominate in the wavelength range from 550 to 850 nm, in good agreement with observations. Strong radio pulses with durations of À300 mu s and peak electric field amplitudes ranging from 20 to 75 V/m at an altitude of 80 km and an approximate distance from the discharge of 50 km were computed. The magnitude and duration of these pulses is sufficient to cause breakdown and heating of the lower ionosphere (80-95 km) and leads us to suggest that sprites may also launch the EMP responsible for the production of elves. The computed values for the gamma -ray fluxes are in agreement with observations of gamma -ray bursts of atmospheric origin and the peak secondary electron densities which we obtain are in good agreement with HF echoes at mesospheric heights and associated with lightning }, keywords={ airglow atmospheric electricity atmospheric radiation atmospheric temperature ionospheric disturbances lightning thunderstorms high-altitude discharges runaway breakdown 2D hydrodynamic simulations quasi-electrostatic simulations sprites positive cloud-to-ground lightning strikes optical emissions blue emissions N/sub 2/ 1st positive emissions radio pulses electric field heating gamma -ray fluxes secondary electron densities mesospheric heights 40 to 80 km 550 to 850 nm 11.5 km N/sub 2/ }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{ChoMay98, author={Cho, M and Rycroft, M.J.}, title={ Computer simulation of the electric field structure and optical emission from cloud-top to the ionosphere }, journal={Journal of Atmospheric and Solar-Terrestrial Physics}, volume={60}, number={7-9}, year={1998}, month={May}, pages={871-88}, abstract={ Computer simulations are carried out to study the sprite' onset mechanism. Both electrostatic and electromagnetic codes are developed to calculate the electric field structure and optical emission intensity between the top of the thundercloud and the ionosphere. The optical emission is composed of two structures. One peaks at 70 km height and its lateral dimension is 50-60 km; the other peaks at 90 km height and the lateral dimension extends beyond 200 km. It is found that the nitrogen first positive band, which has a red colour, dominates over the nitrogen second positive band except at the bottom of the optical emission. The upper part of the optical emission is caused by a horizontally travelling electromagnetic pulse induced by a lightning discharge current. The lower structure is caused by electrostatic effects induced by the unneutralized charge left after the lightning discharge current flows. The electromagnetic codes developed can simulate the self-consistent response of the upper atmosphere to the lightning discharge current. The electrostatic treatment can predict only the optical emission at heights less than À80 km. The optical emission intensity has a strong nonlinear dependence on the electric field strength through the enhanced electron density, and is increased for a long discharge path, a large current, and a short pulse. Also, the higher the lightning discharge is initiated, the brighter the optical emission is, because the electrostatic field is stronger for high altitude lightning }, keywords={ airglow atmospheric electricity atmospheric radiation ionospheric disturbances lightning electric field structure optical emission cloud-top ionosphere sprite electrostatic codes electromagnetic codes optical emission intensity thundercloud lateral dimension first positive band horizontally travelling electromagnetic pulse electrostatic effects unneutralized charge lightning discharge current self-consistent response electrostatic treatment nonlinear dependence electric field strength enhanced electron density discharge path current short pulse 0 to 120 km }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{RowlandMay98, author={Rowland, H.L.}, title={ Theories and simulations of elves, sprites and blue jets }, journal={Journal of Atmospheric and Solar-Terrestrial Physics}, volume={60}, number={7-9}, year={1998}, month={May}, pages={831-44}, abstract={ This review considers the different models that have been developed to explain a class of phenomena that occur above lightning storms. These phenomena have been named elves, red sprites and blue jets. The elves appear between 90 and 70 km altitude and extend over several 100 km horizontally. They are visible for less than 0.1 ms. Red sprites cover a range of altitudes from 80 to 55 km with narrow tendrils extending below 55 km. Horizontally they are 20-30 km wide. Their visible lifetime is from a few to some tens of ms. Blue jets propagate from cloud tops (15 km) to an altitude of 40 km with a velocity of 100 km/s which gives a lifetime of 300 ms. In all of the models, the energy source is the electric fields associated with the lightning-the quasistatic fields due to the original charge distribution, the electromagnetic pulse due to the propagation of the return stroke or the quasistatic fields due to the charge redistribution by the currents. There are two different models to explain the heating of the neutral atmosphere by these electric fields. These models accelerate either the ambient thermal electrons (or=75 kA. Large peak current positive CGs (LPC+CGs) are concentrated in the High Plains and upper Midwest, the region in which a large majority of optical sprite and elves observations have been obtained. By contrast, large peak current negative CGs (LPC-CGs) preferentially occur over the coastal waters of the Gulf of Mexico and the southeastern United States. A total of 1.46 million LPCCGs were found, of which only 13.7% were +CGs. Almost 70% of the LPC+CGs, however, occurred in the central United Stares (30 degrees -50 degrees N, 88 degrees -110 degrees W). The percentage of all LPCCGs that were positive approached 30% in the central United States compared to 4.5% for the remainder of the country. Over a half million negative CGs and over 1000 positive CGs were found with multiplicity }, keywords={ lightning mesosphere stratosphere large peak current cloud-to-ground lightning flashes boreal summer months contiguous United States positive polarity sprites elves stratosphere mesosphere US National Lightning Detection Network AD 1991 to 1995 geographic distribution peak currents High Plains Midwest Gulf of Mexico multiplicity USA }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @CONFERENCE{Francis97, author={Francis, N.P.}, title={ Biological effects of EMI from domestic appliance }, booktitle={Proceedings of the International Conference on Electromagnetic Interferenceand Compatibility '97 (IEEE Cat. No.97TH8310)}, volume={}, number={}, year={1997}, month={}, pages={289-93}, abstract={ Electromagnetic fields have an adverse effect on human health. Low frequency, radio frequency and microwave frequency may cause a flow of current through the human body. This flow of current generates heat and produce thermal injury. Natural low frequency fields are static electric fields between the ionosphere and Earth, and static electromagnetic pulses due to lightning. These fields have been keeping living beings in an invisible cage of EM wave and pulses. The health effects that might originate from EM radiations are almost certainly the most complicated and difficult to understand of all the effects of EM radiations. In domestic appliances a controlled environment is created where the radiated E&H fields are reduced below safe values by different means viz. shields, gaskets. The average specific adsorption rate (SAR), is 0.08 W/kg for a person's entire body and the peak SAR is 1.6 W/kg. This paper analyses and presents the biological effects of EMI on people working within the vicinity of radiation emitted by domestic appliances }, keywords={ biological effects of fields domestic appliances electromagnetic compatibility electromagnetic interference domestic appliances biological effects EMI electromagnetic fields human health microwave frequency low frequency radio frequency current flow thermal injury low frequency fields static electric fields ionosphere Earth static electromagnetic pulses lightning EM waves EM pulses health effects EM radiation average specific adsorption rate peak SAR EMC }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{BuselliNov96, author={Buselli, G. and Cameron, M.}, title={ Robust statistical methods for reducing sferics noise contaminating transient electromagnetic measurements }, journal={Geophysics}, volume={61}, number={6}, year={1996}, month={Nov}, pages={1633-46}, abstract={ The transient electromagnetic (TEM) method is used extensively for mineral exploration and other applications such as geothermal soundings, oil exploration, groundwater pollution, soil salinity and geological mapping. Sferics pulses produced by lightning strokes propagating in the ionosphere-Earth waveguide cavity induce noise in a bandwidth of a few Hz to tens of kHz. The usual method of stacking and calculating the mean of a given stack cannot effectively reduce the spike-like noise induced by high-amplitude sferics pulses. To reduce this type of noise, a number of different ways of stacking data were investigated and compared. Noise data were stacked by using robust estimators such as the median, trimmed mean, and a range of M-estimators. Since storage of all the samples of a given stack can take up a prohibitively large amount of microprocessor memory, recursive algorithms for the M-estimators and their standard error were developed for the real-time reduction of sferics pulses. The recursive algorithms have been demonstrated to work effectively on windowed data, and thus the memory normally required to obtain the mean is sufficient for calculation of the M-estimate. In the recursive calculation of the robust estimate of the transient response, the spread of the background noise distribution (known as the scale of the data) needs to be known or calculated. In the algorithm that has been developed, the scale of the data is derived from a noise run carried out before pulsing the transmitter loop with current. It has been assumed that the presence of a signal does not change the scale of the data. This value of the scale of the data has been used to obtain a robust estimate of the transient response itself. To allow for possible changes in the background noise level during a given survey, the estimate of the scale of the data is updated throughout the survey }, keywords={ atmospherics geophysical prospecting geophysical signal processing geophysical techniques statistical analysis terrestrial electricity geophysical measurement technique prospecting exploration terrestrial electricity geoelectric method robust statistical method noise sferics reduction atmospherics sferics noise transient electromagnetic measurement transient EM method EM method M-estimator recursive algorithm real-time reduction }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{MendeAug97, author={Mende, S.B. and Sentman, D.D. and Wescott, E.M.}, title={ Lightning between Earth and space }, journal={Scientific American (International Edition)}, volume={277}, number={2}, year={1997}, month={Aug}, pages={56-9}, abstract={ Once dismissed as figments of pilots' imaginations, strange flashes appearing above thunderstorms have been confirmed as entirely new forms of lightning. Known as sprites, elves, blue jets and gamma-ray events, these high-altitude phenomena arise through a physics all their own. Their features and origin are discussed }, keywords={ lightning mesosphere thermosphere thunderstorms flashes thunderstorms lightning sprites elves blue jets gamma-ray events high-altitude phenomena origin 50 to 90 km }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{ValdiviaDec97, author={Valdivia, J.A. and Milikh, G. and Papadopoulos, K.}, title={ Red sprites: lightning as a fractal antenna }, journal={Geophysical Research Letters}, volume={24}, number={24}, year={1997}, month={Dec}, pages={3169-72}, abstract={ A new and improved model of red sprites is presented. Emphasis is placed in accounting for the puzzling observation of the spatial structure in the red sprite's optical emissions. The model relies upon a horizontal fractal lightning discharge, which generates the EMPs that excites the optical emissions in the lower ionosphere. It is shown that the fractal model may account for the observed sprite's spatially structured optical pattern, while reducing the typical charge threshold to approximately 100 C }, keywords={ atmospheric electricity fractals lightning mesosphere nightglow thermosphere upper atmosphere middle atmosphere mesosphere upper atmosphere thermosphere lightning nightglow stratosphere red sprite fractal antenna model spatial structure optical emission horizontal fractal lightning discharge electric discharge EMP electromagnetic pulse }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{ZuelsdorfDec97, author={Zuelsdorf, R.S. and Strangeway, R.J. and Russell, C.T. and Casler, C. and Christian, H.J. and Franz, R.C.}, title={ Trans-ionospheric pulse pairs (TIPPs): their geographic distributions and seasonal variations }, journal={Geophysical Research Letters}, volume={24}, number={24}, year={1997}, month={Dec}, pages={3165-8}, abstract={ Since November 1993 the Blackbeard instrument aboard the ALEXIS satellite has detected pairs of pulses in the VHF band, known as trans-ionospheric pulse pairs (TIPPs). These pulses exhibit dispersion consistent with a source of sub-ionospheric origin. As of January 1997 over 850 TIPPs have been detected. The source of these emissions still remains a mystery, although it is believed that TIPPs are in some way related to thunderstorms as such storms provide a strong sub-ionospheric source and produce radiation in the same frequencies observed by Blackbeard. In an attempt to establish this connection the authors compare the geographic occurrence of TIPPs to that of lightning flashes observed from space by the Optical Transient Detector (OTD) on the Microlab-1 spacecraft. TIPP data run from 2 November 1993 to 19 November 1996. OTD data run from 1 May 1995 to 30 November 1996. The geographical occurrence of TIPPs and that of lightning flashes is strongly correlated. TIPPs occur less frequently during the winter months and their region of production moves southward in the North American sector similar in behaviour to lightning activity }, keywords={ atmospheric radiation ionosphere ionospheric electromagnetic wave propagation ionoshere radiowave propagation transionospheric propagation season occurrence trans-ionospheric pulse pair TIPP geographic distribution seasonal variation AD 1995 AD 1996 winter production region VHF dispersion sub-ionospheric origin thunderstorm lightning Optical Transient Detector OTD Microlab-1 }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @CONFERENCE{Symbalisty97, author={Symbalisty, E. and Roussel-Dupre, R. and Yukhimuk, V. and Taranenko, Y.}, title={ High altitude atmospheric discharges according to the runaway air breakdown mechanism }, booktitle={XXIII International Conference on Phenomena in Ionized Gases, ICPIGProceedings. Contributed Papers}, volume={}, number={}, year={1997}, month={}, pages={12-13 vol.3}, abstract={ High altitude optical transients-red sprites, blue jets, and elves-are modeled in the context of the relativistic electron runaway air breakdown mechanism. These emissions are usually with large mesoscale convective systems (hereafter MCS). In thunderstorms cloud electrification proceeds over time scale long enough to permit the conducting atmosphere above the cloud to polarize and short out the thunderstorm electric field. When a lightning strike rapidly neutralizes a cloud charge layer runaway driving fields can develop in the stratosphere and mesosphere. According to the authors' simulations of the full runaway process the variety of observed optical emissions are due to the nature of the normal lightning event in the MCS that kick starts the runaway avalanche. The authors describe some details of the model, present the results of the evolution of the primary electron population, and summarize the initial conditions necessary for different types of discharges. Two companion papers present: (a) the predicted optical, gamma ray, and radio emissions caused by these electrical discharges, and (b) the time evolution of the secondary electron population and its implications in terms of observables }, keywords={ atmospheric electricity atmospheric ionisation lightning mesosphere stratosphere mesosphere middle atmosphere lightning electric discharge high altitude atmospheric discharge runaway air breakdown mechanism optical transient red sprite red sprites blue jets blue jet elf elves relativistic electron runaway air breakdown mechanism thunderstorm cloud electrification electric field stratosphere }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @CONFERENCE{Roussel-Dupre97, author={Roussel-Dupre, R. and Fitzgerald, T.J. and Symbalisty, E. and Blanc, E.}, title={ HF echoes from ionization potentially produced by high-altitude discharges }, booktitle={XXIII International Conference on Phenomena in Ionized Gases, ICPIGProceedings. Contributed Papers}, volume={}, number={}, year={1997}, month={}, pages={10-11 vol.3}, abstract={ The authors report on recent radar measurements taken during the month of October 1994 with the LDG HF radar in the Ivory Coast, Africa as part of the International Equatorial Electrojet Year. The purpose of this experimental effort in part was to study the effects of thunderstorms on the ionosphere. At the same time, they decided to carry out a set of experiments of an exploratory nature to look for echoes that could potentially arise from ionization produced in the mesosphere. The two leading candidates for producing transient ionization in the mesosphere are meteors and high-altitude discharges. Each is discussed in the context of their measurements }, keywords={ airglow atmospheric ionisation ionosphere lightning mesosphere radar observations HF echo ionization high-altitude discharge electric discharge sprite jet elves elf sprites lightning middle atmosphere AD 1994 10 mesosphere ionosphere meteor Ivory Coast West Africa thunderstorm transient ionization }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @CONFERENCE{TaranenkoJul97, author={Taranenko, Y. and Roussel-Dupre, R. and Yukhimuk, V. and Symbalisty, E.}, title={ Generation of elves by sprites and jets }, booktitle={XXIII International Conference on Phenomena in Ionized Gases, ICPIGProceedings. Contributed Papers}, volume={}, number={}, year={1997}, month={}, pages={8-9 vol.3}, abstract={ Recent years of observations of the upper atmosphere and the lower ionosphere brought a fascinating collection of new phenomena including optical, radio, and gamma-ray emissions originating in the 20 to 90 km altitude range. Up to now, the most diverse phenomenology has emerged from the optical observations which have led to the identification of red sprites, blue jets, blue starters and elves. Most of the previous studies have concentrated on relating such phenomena in the upper atmosphere to regular lightning discharges in the troposphere. For example, sprites and jets are believed to be optical manifestations of electrical discharges in the upper atmosphere caused by quasi-electrostatic fields penetrating to high altitudes during a regular lightning discharge. The sprite/jet discharge itself can be caused by the runaway air breakdown or regular air breakdown. The standard theory for optical airglow transients in the lower ionosphere above the thunderstorms also known as elves suggests that they are produced during interaction of electromagnetic pulses (EMP) from lightning with the lower ionosphere. Heating of the ambient electrons by the EMP in the D-region can result in excitation of optical emissions once the optical excitation thresholds are reached. In this paper the authors suggest that in addition to this mechanism elves can be caused by an EMP generated by sprites and jets. If sprites and jets are indeed accompanied by electrical discharges then some energy of their EMPs reaches to the ionosphere and heats ambient electrons there that in turn stimulates optical emissions similar to EMPs from regular lightning }, keywords={ airglow ionosphere lightning mesosphere stratosphere mesosphere middle atmosphere lightning stratosphere ionosphere generation formation model elves sprite jet elf red sprite blue jet blue starters electrical discharge EM pulse runaway air breakdown theory airglow electromagnetic pulse EMP D-region }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{IkeyaJun97, author={Ikeya, M. and Takaki, S. and Matsumoto, H. and Tani, A. and Komatsu, T.}, title={ Pulsed charge model of fault behavior producing seismic electric signals (SES) }, journal={Journal of Circuits, Systems and Computers}, volume={7}, number={3}, year={1997}, month={Jun}, pages={153-64}, abstract={ The electromagnetic (EM) behavior of a geological fault is postulated to follow the mathematical model of a fault in seismology that illustrates seismic EM anomalies. Charge densities, +q and -q in C/m/sup 2/ are generated at a fault zone by the change in seismic stress, sigma as dq/dt=- alpha d sigma /dt-q/ epsilon rho , where sigma , epsilon and rho are the charge generation constants measured in C/N, dielectric constant and resistivity of bedrocks, respectively. A fault of length, 2a, plane area, A and the displacement or rupture time, tau gives pulsed charge densities, +q(t) and -q(t), or a dipole moment of p(t)=2aAq(t)= alpha M/sub 0/[ epsilon rho /( tau - epsilon rho )][exp(-t/ tau )-exp(-t/ epsilon rho )] using the earthquake moment M/sub 0/. Maxwell's equations for this dipole in a conductive Earth give power spectra of EM waves at different distances. Seismic electric signals including the DC VAN method can be explained as EM waves. Electrons with density n in the atmosphere are accelerated by the electric field and travel a distance l, resulting in the excitation and ionization of atmospheric molecules leading to earthquake lightning. They also polarize the ionosphere by disturbing the transmission of EM waves. Preliminary results of pulsed electric field measurements are presented for lightning, prior to an earthquake and artificial electronic noises. The same pulsed field surprised eels and hamsters, suggesting seismic anomalous animal behavior as electro-physiological responses to the stimuli of electric pulses }, keywords={ earthquakes faulting lightning terrestrial electricity seismic anomalous animal behaviour pulsed charge model seismic electric signals EM behaviour geological fault behaviour mathematical model seismology seismic EM anomalies electrophysiological responses fault zone seismic stress charge generation dielectric constant resistivity bedrock pulsed charge densities dipole moment earthquake moment Maxwell equations conductive Earth EM waves earthquake lightning }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{FukunishiDec97, author={Fukunishi, H. and Takahashi, Y. and Sato, M. and Shone, A. and Fujito, M. and Watanabe, Y.}, title={ Ground-based observations of ULF transients excited by strong lightning discharges producing elves and sprites }, journal={Geophysical Research Letters}, volume={24}, number={23}, year={1997}, month={Dec}, pages={2973-6}, abstract={ Optical and search coil magnetometer data obtained from the SPRITES'96 campaign carried out at Yucca Ridge Field Station, Colorado in July 1996 have presented clear evidence for the excitation of ULF transients with their dominant power at 1-2 Hz by strong lightning discharges producing elves and sprites. The most striking feature is that the ULF transients exhibit different wave forms in the case of sprites without preceding elves and the case of sprites with preceding elves. In the former case damped, quasi-sinusoidal oscillations commence impulsively at the onset of sprites, while in the latter case quasi-sinusoidal wavelets with a duration of À3 s are excited, and elves and sprites occur within each wavelet. It is likely that these ULF transients are due to the nonlinear excitation of the ionospheric Alfven resonator by strong lightning discharge, as proposed by Sukhorukov and Stubbe [1997] }, keywords={ Earth-ionosphere waveguide lightning Earth ionosphere waveguide Earth ionosphere cavity radiowave propagation ground-based observations ULF transients ULF transient strong lightning discharge elves sprites sprite elf EM wave propagation excitation AD 1996 07 damped quasi-sinusoidal oscillation quasi-sinusoidal wavelet nonlinear excitation ionospheric Alfven resonator 1 to 2 Hz }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{YukhimukDec97, author={Yukhimuk, V. and Roussel-Dupre, R.}, title={ Magnetic field pulses produced via whistler mode wave decay in the ionosphere }, journal={Physics of Plasmas}, volume={4}, number={12}, year={1997}, month={Dec}, pages={4388-93}, abstract={ The nonlinear ionospheric effects of very low-frequency (VLF) electromagnetic radiation produced by lightning discharges are considered. Electric and magnetic field measurements by a rocket in the ionosphere reported by Kelly et al. (1990) show the simultaneous presence of powerful electromagnetic whistler wave bursts along with electrostatic waves and a magnetic pulse with duration about 20 ms. The parametric decay of whistler mode waves into electrostatic waves and ultralow-frequency (ULF) electromagnetic waves is proposed as a possible explanation for the observed phenomenon. The evolution of whistler mode wave decay instabilities in time and two spatial dimensions is studied. The nonlinear dispersion equation is obtained, and solved numerically. Two-fluid magnetohydrodynamics is used to describe the three-wave interaction. The theoretical results are compared with observational data }, keywords={ ionospheric electromagnetic wave propagation magnetic fields whistlers magnetic field pulse durations whistler mode wave decay ionosphere nonlinear ionospheric effects very low-frequency electromagnetic radiation VLF radiation lightning discharges electric field measurements magnetic field measurements rocket electromagnetic whistler wave bursts electrostatic waves three-wave interaction parametric decay ultralow-frequency electromagnetic waves ULF waves decay instabilities spatial dimensions nonlinear dispersion equation two-fluid magnetohydrodynamics time evolution }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{MiyamuraMay97, author={Miyamura, K. and Nagano, I. and Yagitani, S.}, title={ Full-wave calculation of VLF waveforms induced by lightning discharge }, journal={Transactions of the Institute of Electronics, Information and CommunicationEngineers B-II}, volume={J80B-II}, number={5}, year={1997}, month={May}, pages={387-96}, abstract={ A numerical technique has been developed to calculate VLF electromagnetic waveforms in the region of free space up to the lower ionosphere induced by a cloud-to-ground lightning discharge, by using a full-wave (multi-layered) method, expansion of a spherical wave into plane waves, and Fourier transform in the time domain. We can obtain the time evolution of reflection, penetration and coupling into a whistler mode wave in the lower ionosphere of electromagnetic pulses radiated from the lightning discharge. Calculated results suggest that an electrostatic component may cause a luminous emission "red sprites" in the lower ionosphere associated with a cloud-to-ground lightning discharge }, keywords={ electromagnetic pulse electromagnetic wave reflection Fourier transforms ionospheric disturbances ionospheric electromagnetic wave propagation lightning radiowave propagation time-domain analysis whistlers lightning discharge VLF electromagnetic waveforms lower ionosphere full-wave calculation plane waves Fourier transform time domain reflection penetration coupling whistler mode wave electromagnetic pulses electrostatic component luminous emission red sprites }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{SukhorukovApr97, author={Sukhorukov, A.I. and Stubbe, P.}, title={ Excitation of the ionospheric Alfven resonator by strong lightning discharges }, journal={Geophysical Research Letters}, volume={24}, number={8}, year={1997}, month={Apr}, pages={829-32}, abstract={ A mechanism for the nonlinear excitation of the ionospheric Alfven resonator by elves- or/and sprites-produced lightning discharge is proposed. The source of the time-varying nonlinear current, located at altitudes below 95 km, is due to the large impulse electron heating and breakdown of the atmosphere by a strong tropospheric discharge. The discussed mechanism may be responsible for anomalously large ULF events observed onboard the satellites above atmospheric weather systems }, keywords={ ionospheric disturbances lightning ionospheric Alfven resonator excitation strong lightning discharges nonlinear excitation mechanism elves sprites time-varying nonlinear current source impulse electron heating atmospheric breakdown tropospheric discharge anomalously large ULF events satellite observations atmospheric weather systems 95 km }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{InanMar97, author={Inan, U.S. and Barrington-Leigh, C. and Hansen, S. and Glukhov, V.S. and Bell, T.F. and Rairden, R.}, title={ Rapid lateral expansion of optical luminosity in lightning-induced ionospheric flashes referred to as elves' }, journal={Geophysical Research Letters}, volume={24}, number={5}, year={1997}, month={Mar}, pages={583-6}, abstract={ Data acquired by a new array of horizontally spaced photometers boresighted with a low-light-level camera provide the first measurement of the rapid lateral expansion of optical luminosity in lightning-induced ionospheric flashes referred to as elves', occurring over time scales substantially less than 1 ms. The narrow individual fields-of-view of (2.2 degrees *1.1 degrees ) provide a spatial resolution of \20-km at a range of 500 km, enabling the documentation of expansion occurring over a horizontal range of 200 km with a time resolution of \30 mu s. The observed dynamic features of elves are consistent with a model in which the optical output is produced as a result of heating by the electromagnetic pulse (EMP) from a lightning discharge }, keywords={ atmospheric radiation atmospheric temperature ionospheric disturbances lightning plasma radiofrequency heating rapid lateral expansion optical luminosity lightning-induced ionospheric flashes elves dynamic features heating electromagnetic pulse lightning discharge }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{FernslerDec96, author={Fernsler, R.F. and Rowland, H.L.}, title={ Models of lightning-produced sprites and elves }, journal={Journal of Geophysical Research}, volume={101}, number={D23}, year={1996}, month={Dec}, pages={29653-62}, abstract={ Three different types of optical phenomena have been observed at high altitude above thunderstorms: an enhanced airglow ("elves") at roughly \90 km; a reddish glow ("sprites") from 50 to 90 km; and an upward moving, bluish emission ("jets") below 40 km. A likely explanation for some or all of these phenomena is gas breakdown caused by the electromagnetic fields of lightning discharges. This paper examines the connection between these fields and breakdown at high altitude, using both analytic models and numerical simulations. Included in the calculations are the radiation fields from the lightning return stroke and the quasi-static fields from the continuing current. The different nature of the two fields is shown to produce two distinct types of breakdown, with characteristics similar to those of elves and sprites. Also mentioned is a third breakdown mechanism which may account for blue jets }, keywords={ atmospheric electricity electromagnetic fields lightning thunderstorms lightning-produced sprites elves blue jets models optical phenomena high altitude thunderstorms enhanced airglow reddish glow upward moving bluish emission gas breakdown EM fields lightning discharges analytic models numerical simulations radiation fields lightning return stroke quasistatic fields continuing current breakdown mechanism 40 to 90 km }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{LyonsDec96, author={Lyons, W.A.}, title={ Sprite observations above the U.S. High Plains in relation to their parent thunderstorm systems }, journal={Journal of Geophysical Research}, volume={101}, number={D23}, year={1996}, month={Dec}, pages={29641-52}, abstract={ Transient luminous events (sprites, blue jets, elves) above large mesoscale convective systems (MCSs) over the U.S. High Plains have been routinely monitored from the Yucca Ridge Field Station near Fort Collins, Colorado using ground-based low-light video systems. The author analyzed 36 sprites above the Nebraska MCS of August 6, 1994. The results lend further support to the hypothesis that sprites are almost uniquely associated with positive cloud-to-ground lightning flashes (+CGs). Sprite-associated +CGs also averaged substantially larger peak currents than the remaining +CG population (81 kA versus 30 kA in this storm system). There is some evidence that sprite-associated +CGs also have higher stroke multiplicity. This study yields no evidence of sprites associated with negative CG events. In the central United States an additional requirement appears to be that the parent MCS has a contiguous radar reflectivity area exceeding 20-25,000 km/sup 2/. The majority of the sprites occur above the large stratiform precipitation region and not the high-reflectivity convective core of the MCS. Triangulation of a limited number of paired images (from September 7, 1994) suggests that the sprite is generally centered within 50 km of the parent +CG. Assuming the +CG provides the range, single-image photogrammetric analyses provide estimates of the maximum vertical extent of the sprites. For this storm the sprite tops averaged 77 km with a maximum of 88 km. The bases averaged 50 km but with a few sprite tendrils extending as low as 31 km }, keywords={ lightning thunderstorms sprite observations US High Plains thunderstorm systems transient luminous events blue jets elves large mesoscale convective systems Yucca Ridge Field Station Fort Collins Colorado USA ground-based low-light video systems Nebraska AD 1994 08 06 positive cloud-to-ground lightning flashes peak currents stroke multiplicity central United States radar reflectivity area stratiform precipitation region AD 1994 09 07 single-image photogrammetric analyses maximum vertical extent sprite tendrils sprite top heights 81 kA 77 to 88 km }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{SukhorukovOct96, author={Sukhorukov, A.I. and Rudenchik, E.A. and Stubbe, P.}, title={ Simulation of the strong lightning pulse penetration into the lower ionosphere }, journal={Geophysical Research Letters}, volume={23}, number={21}, year={1996}, month={Oct}, pages={2911-14}, abstract={ Lightning electromagnetic pulse penetration into the night-time lower ionosphere and plasma modification are simulated using the large particle method. The collisions of the electrons with the neutral species, both elastic and related to the excitation, ionization of and attachment to the neutrals are modeled using a Monte-Carlo technique. The dynamics of the impulse electron heating and breakdown in the lower ionosphere above the strong lightning discharge are analysed. The level of the induced ionization strongly depends on the amplitude, form and duration of the incident pulses. The self-consistent fields on the time scale of 10/sup 2/ mu s are subjected to strongly nonlinear damping during the passage through the D-region of the ionosphere }, keywords={ atmospherics ionospheric disturbances ionospheric electromagnetic wave propagation lightning ionospheric disturbance strong lightning pulse penetration lower ionosphere EM wave EM pulse electromagnetic pulse nighttime plasma modification Monte-Carlo model impulse electron heating breakdown induced ionization amplitude duration self-consistent fields nonlinear damping D-region atmospherics }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{FukunishiAug96, author={Fukunishi, H. and Takahashi, Y. and Kubota, M. and Sakanoi, K. and Inan, U.S. and Lyons, W.A.}, title={ Elves: lightning-induced transient luminous events in the lower ionosphere }, journal={Geophysical Research Letters}, volume={23}, number={16}, year={1996}, month={Aug}, pages={2157-60}, abstract={ Observations of optical phenomena at high altitude above thunderstorms using a multichannel high-speed photometer and image intensified CCD cameras were carried but at Yucca Ridge Field Station (40 degrees 40' N, 104 degrees 56' W), Colorado as part of the SPRITES'95 campaign from 15 June to August 6, 1995. These new measurements indicate that diffuse optical flashes with a duration of <1 ms and a horizontal scale of À100-300 km occur at 75-105 km altitude in the lower ionosphere just after the onset of cloud-to-ground lightning discharges, but preceding the onset of sprites. Here we designate these events as "elves" to distinguish them from "red sprites". This finding is consistent with the production of diffuse optical emissions due to the heating of the lower ionosphere by electromagnetic pulses generated by lightning discharges as suggested by several authors }, keywords={ atmospheric radiation atmospheric temperature electromagnetic pulse ionospheric disturbances lightning thunderstorms lightning-induced transient luminous events lower ionosphere thunderstorms SPRITES'95 campaign diffuse optical flashes cloud-to-ground lightning discharges elves heating electromagnetic pulses AD 1995 06 15 to 08 06 75 to 105 km }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{GlukhovAug96, author={Glukhov, V.S. and Inan, U.S.}, title={ Particle simulation of the time-dependent interaction with the ionosphere of rapidly varying lightning EMP }, journal={Geophysical Research Letters}, volume={23}, number={16}, year={1996}, month={Aug}, pages={2193-6}, abstract={ The interaction with the lower ionosphere of rapidly varying electromagnetic pulses (EMPs) produced by lightning discharges is studied. The nonlinear heating, ionization and optical emission production are modeled using the Monte Carlo technique, which allows for consideration of realistic lightning EMPs with a few mu s rise times. Results indicate that the electron distribution function is highly anisotropic during the first few mu s of the interaction, but subsequently develops into a near-isotropic quasi-stationary state. The peak optical emissions intensities are found to be highly dependent on the EMP waveform, while the altitude range at which the emissions occur is relatively independent of pulse shape. Results of the particle simulation are used to assess the range of applicability of the quasi-stationary models [Taranenko et al., 1993; Inan et al., 1996] }, keywords={ electromagnetic pulse ionospheric disturbances ionospheric electromagnetic wave propagation lightning EM pulse radiowave propagation ionospheric disturbance particle simulation time-dependent interaction ionosphere rapidly varying lightning EMP rapidly varying electromagnetic pulse nonlinear heating ionization optical emission Monte Carlo method anisotropic electron distribution function EMP waveform quasistationary model }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{RowlandApr96, author={Rowland, H.L. and Fernsler, R.F. and Bernhardt, P.A.}, title={ Breakdown of the neutral atmosphere in the D region due to lightning driven electromagnetic pulses }, journal={Journal of Geophysical Research}, volume={101}, number={A4}, year={1996}, month={Apr}, pages={7935-45}, abstract={ Electromagnetic pulses (EMPs) driven by lightning can cause breakdown of the neutral atmosphere in the lower D-region. Using a computer simulation model, the authors study the dependence of the breakdown on the pulse strength, the orientation of the lightning discharge, the ambient plasma density, the ionization model, and the neutral density. For a discharge along a straight line the EMP is strongest in the plane perpendicular to the current so that for a given current, horizontal discharges will radiate the D-region more strongly than a vertical discharge. For horizontal currents, breakdown occurs for E/sub 100/>20 V/m (I>55 kA) in a low-density, nighttime ionosphere, where E/sub 100/ is the amplitude of the pulse normalized to 100 km from the discharge and I is the discharge current. Vertical strokes require E/sub 100/>50 V/m (I>140 kA). Discharges with higher currents and fields form ionization patches which are larger in volume, larger in degree of ionization, and lower in altitude. The ionization is most sensitive to the pulse strength, pulse orientation, ambient plasma density, and neutral gas density at breakdown threshold. Higher ambient plasma densities reduce the ionization, but for large EMPs, breakdown can occur even with high daytime densities. The breakdown increases the plasma density which acts to limit the EMP and ionization. This feedback reduces the sensitivity of the breakdown to the ionization model. Neutral density variations, such as caused by atmospheric gravity waves, can cause spatial variations in the ionization density }, keywords={ atmospheric electricity D-region electromagnetic pulse lightning neutral atmosphere breakdown lower D-region lightning driven EM pulses computer simulation model pulse strength dependence lightning discharge orientation ambient plasma density ionization model horizontal discharges vertical discharges horizontal currents discharge current ionization patches pulse strength pulse orientation neutral gas density breakdown threshold }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{InanJan96, author={Inan, U.S. and Sampson, W.A. and Taranenko, Y.N.}, title={ Space-time structure of optical flashes and ionization changes produced by lightning-EMP }, journal={Geophysical Research Letters}, volume={23}, number={2}, year={1996}, month={Jan}, pages={133-6}, abstract={ Intense electromagnetic pulses (EMPs) released by lightning discharges produce bright optical emissions at 80-95 km altitudes emitted in a thin (À30 km) cylindrical shell expanding to radial distances of up to >150 km, lasting for À400 mu s, and appearing in limb-view as a thin layer with À400 km lateral extent }, keywords={ airglow atmospheric ionisation atmospheric optics atmospheric radiation lightning upper atmosphere airglow optical emission thermosphere spatial structure temporal structure optical flash light ionization change lightning EMP electromagnetic pulse EM pulse thin cylindrical shell 80 to 95 km }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{RowlandFeb95, author={Rowland, H.L. and Fernsler, R.F. and Huba, J.D. and Bernhardt, P.A.}, title={ Lightning driven EMP in the upper atmosphere }, journal={Geophysical Research Letters}, volume={22}, number={4}, year={1995}, month={Feb}, pages={361-4}, abstract={ Large lightning discharges can drive electromagnetic pulses (EMP) that cause breakdown of the neutral atmosphere between 80 and 95 km leading to order of magnitude increases in the plasma density. The increase in the plasma density leads to increased reflection and absorption, and limits the pulse strength that propagates higher into the ionosphere }, keywords={ electromagnetic pulse ionosphere lightning upper atmosphere lightning discharge driven EM pulses model upper atmosphere neutral atmosphere breakdown plasma density increase reflection absorption pulse strength ionosphere 80 to 95 km }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{MilikhJan95, author={Milikh, G.M. and Papadopoulos, K. and Chang, C.L.}, title={ On the physics of high altitude lightning }, journal={Geophysical Research Letters}, volume={22}, number={2}, year={1995}, month={Jan}, pages={85-8}, abstract={ Past and recent observations indicate the presence of lightning at altitudes in excess of 30 km. The phenomenon is manifested as a high altitude optical flash, correlated with the presence of giant thunderstorms in the atmosphere below. This letter presents the first physical model of the process. The model is based on low frequency RF breakdown of the upper atmosphere, ignited by the upward propagating electromagnetic pulses due to conventional low altitude lightning. Horizontal intercloud lightning strokes form the optimal configuration. Horizontal lightning discharges with cloud-to-cloud moment charge approximately 6000-8000 C-km account for the observed level of optimal emissions }, keywords={ lightning mesosphere stratosphere electric breakdown stratosphere middle atmosphere mesosphere high altitude lightning optical flash giant thunderstorms physical model frequency RF breakdown upper atmosphere 30 to 80 km }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{TaranenkoDec93, author={Taranenko, Y.N. and Inan, U.S. and Bell, T.F.}, title={ The interaction with the lower ionosphere of electromagnetic pulses from lightning: excitation of optical emissions }, journal={Geophysical Research Letters}, volume={20}, number={23}, year={1993}, month={Dec}, pages={2675-8}, abstract={ A self consistent and fully kinetic simulation of the interaction of lightning radiated electromagnetic (EM) pulses with the nighttime lower ionosphere indicates that optical emissions observable with conventional instruments would be excited. For example, emissions of the 1st and 2nd positive bands of N/sub 2/ occur at rates reaching 7*10/sup 7/ and 10/sup 7/ cm/sup -3/ s/sup -1/ respectively at approximately 92 km altitude for a lightning discharge with an electric field E/sub 100/=20 V/m (normalized to a 100 km distance). The maximum height integrated intensities of these emissions are 4*10/sup 7/ and 6*10/sup 6/ R respectively lasting for approximately 50 mu s }, keywords={ atmospherics D-region lightning nightglow nitrogen plasma thermosphere lower ionosphere electromagnetic pulses lightning optical emissions excitation kinetic simulation nighttime 2nd positive band 1st positive band electric field maximum height integrated intensities 92 km N/sub 2/ }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{TaranenkoAug93, author={Taranenko, Y.N. and Inan, U.S. and Bell, T.F.}, title={ Interaction with the lower ionosphere of electromagnetic pulses from lightning: heating, attachment, and ionization }, journal={Geophysical Research Letters}, volume={20}, number={15}, year={1993}, month={Aug}, pages={1539-42}, abstract={ A Boltzmann formulation of the electron distribution function and Maxwell's equations for the electromagnetic (EM) fields are used to simulate the interaction of lightning radiated EM pulses with the lower ionosphere. Ionization and dissociative attachment induced by the heated electrons cause significant changes in the local electron density (N/sub e/). Due to 'slow' field changes of typical lightning EM pulses over time scales of tens of mu s, the distribution function follows the quasi-equilibrium solution of the Boltzmann equation in the altitude range of interest (70 to 100 km). The EM pulse is simulated as a planar 100 mu s-long single period oscillation of a 10-kHz wave injected at 70 km. Under nighttime conditions, individual pulses of intensity 10-20 V/m (normalized to 100 km horizontal distance) produce changes in N/sub e/ of 1-30% while a sequence of pulses leads to strong modification of N/sub e/ at altitudes <95 km. The N/sub e/ changes produce a 'sharpening' of the lower ionospheric boundary by causing a reduction in electron density at 75-85 km (due to attachment) and a substantial increase at 85-95 km (due to ionization) (e.g. the scale height decreases by a factor of approximately 2 at approximately 85 km for a single 20 V/m EM pulse). No substantial N/sub e/ changes occur during daytime }, keywords={ atmospheric ionisation electromagnetic pulse electron attachment ionospheric electromagnetic wave propagation lightning plasma heating lower ionosphere lightning radiated EM pulses heating VLF perturbations ionization Boltzmann equation Maxwell equations dissociative attachment heated electrons local electron density oscillation nighttime conditions modification 70 to 100 km 100 mus 10 kHz }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{RodriguezOct92, author={Rodriguez, J.V. and Inan, U.S. and Bell, T.F.}, title={ D region disturbances caused by electromagnetic pulses from lightning }, journal={Geophysical Research Letters}, volume={19}, number={20}, year={1992}, month={Oct}, pages={2067-70}, abstract={ Electromagnetic pulses from weak lightning discharges (E/sub 100/=1 V/m, where E/sub 100/ is the field strength in the radiation pattern maximum at 100 km) may substantially heat D region electrons, while only pulses with E/sub 100/>or=20 V/m may create electron density enhancements >or=10% of ambient. A E/sub 100/=20 V/m pulse from a horizontal radiator at 5 km altitude (e.g. the cloud discharge at the stepped-leader onset) increases the electron temperature by a factor of approximately 400 maximum and the electron density (in one ionization cycle) by approximately 230 cm/sup 3/ maximum; the widths at half-maximum of the heated and ionized regions are 200 km and 90 km. A E/sub 100/=40 V/m pulse from a vertical radiator at 0 km altitude (e.g. the vertical return stroke channel) increases the electron temperature by a factor of approximately 350 maximum and the electron density by approximately 80 cm/sup 3/ maximum }, keywords={ D-region lightning electron heating modification EM pulse EM radiation disturbance radiowave emission D-region ionosphere electromagnetic pulses lightning electron temperature }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{FarrellApr92, author={Farrell, W.M. and Desch, M.D.}, title={ Cloud-to-stratosphere lightning discharges: a radio emission model }, journal={Geophysical Research Letters}, volume={19}, number={7}, year={1992}, month={Apr}, pages={665-8}, abstract={ Observations of rare cloud-to-stratospheric lightning discharges suggest the events are inherently 'slow-rising', with the emitted energy reaching peak values in about 10 milliseconds. Applying a dipole radiation model, the authors demonstrate that the emitted radio wave energy from such slow-rising events is strongest below about 50 Hz, and possesses a significant rolloff at higher frequencies. In the analysis, various current distributions are considered in order to determine the effect on the radio spectrum. Near 10 kHz, the emission from cloud-to-stratospheric lightning is significantly reduced as compared to the typical cloud-to-ground return stroke, with amplitudes as much as 50 dB lower. This result may explain the lack of detection of VLF signals from recently observed long-lasting discharge events }, keywords={ atmospheric radiation atmospherics lightning stratosphere radio emission model cloud-to-stratospheric lightning discharges dipole radiation model emitted radio wave energy slow-rising events current distributions }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{BoeckJan92, author={Boeck, W.L. and Vaughan, O.H., Jr. and Blakeslee, R. and Vonnegut, B. and Brook, M.}, title={ Lightning induced brightening in the airglow layer }, journal={Geophysical Research Letters}, volume={19}, number={2}, year={1992}, month={Jan}, pages={99-102}, abstract={ The report describes a transient luminosity observed at the altitude of the airglow layer (about 95 km) in coincidence with a lightning flash in a tropical oceanic thunderstorm directly beneath it. This event provides new evidence of direct coupling between lightning and ionospheric events. This luminous event in the ionosphere was the only one of its kind observed during an examination of several thousand images of lightning recorded under suitable viewing conditions with Space Shuttle cameras. Several possible mechanisms and interpretations are discussed briefly }, keywords={ D-region lightning nightglow thunderstorms Atlantic Ocean D-region ionosphere nightglow lightning induced brightening airglow layer transient luminosity lightning flash tropical oceanic thunderstorm 95 km }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{InanApr91, author={Inan, U.S. and Bell, T.F. and Rodriguez, J.V.}, title={ Heating and ionization of the lower ionosphere by lightning }, journal={Geophysical Research Letters}, volume={18}, number={4}, year={1991}, month={Apr}, pages={705-8}, abstract={ Nighttime ionospheric electrons at 90-95 km altitude are heated by a factor of 100-500 during the upward passage of short (<100 mu s) pulses of intense (5-20 V/m at 100 km distance) electromagnetic radiation from lightning. Heated electrons with average energy of 4-20 eV in turn produce secondary ionization, of up to 400 cm/sup -3/ at approximately 95 km altitude in a single ionization cycle ( approximately 3 mu s). With the time constant of heating being 5-10 mu s, a number of such ionization cycles can occur during a 50 mu s radiation pulse, leading to even higher density enhancements. This effect can account for observations of 'early' or 'fast' subionospheric VLF perturbations }, keywords={ atmospheric ionisation atmospheric radiation atmospheric temperature atmospheric thermodynamics D-region electron density ionosphere ionospheric electromagnetic wave propagation lightning nighttime ionospheric electrons heating aeronomy short intense EM radiation pulses ionosphere ionisation D-region ionisation hot electrons energy ionisation cycle time EM pulse duration ionosphere heating time constant fast VLF perturbations ionisation bubbles lower ionosphere lightning secondary ionization single ionization cycle density enhancements subionospheric VLF perturbations 90 to 95 km 3000 ns 100 km 5 to 10 mus 50 mus 4 to 20 eV }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{KelleyNov90, author={Kelley, M.C. and Ding, J.G. and Holzworth, R.H.}, title={ Intense ionospheric electric and magnetic field pulses generated by lightning }, journal={Geophysical Research Letters}, volume={17}, number={12}, year={1990}, month={Nov}, pages={2221-4}, abstract={ Electric and magnetic field measurements have been made in the ionosphere over an active thunderstorm and an optical detector onboard the same rocket yielded an excellent time base for the study of waves radiated into space from the discharge. In addition to detection of intense, but generally well understood whistler mode waves, very unusual electric and magnetic field pulses preceded the 1-10 kHz component of the radiated signal. These pulses lasted several ms and had a significant electric field component parallel to the magnetic field. The authors have investigated and rejected an explanation based on an anomalous skin depth effect. Although only a hypothesis at this time, the authors are pursuing a more promising explanation involving the generation of the pulse via a nonlinear decay of whistler mode waves in the frequency range 10-80 kHz }, keywords={ atmospheric electricity geomagnetism ionospheric electromagnetic wave propagation lightning radiowave propagation whistlers radiowave propagation VLF LF magnetic field pulses lightning ionosphere active thunderstorm whistler mode waves electric field component anomalous skin depth effect nonlinear decay 10 to 80 kHz }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{StarkMay88, author={Stark, A.}, title={ Antennas protected from electromagnetic pulses }, journal={Mikrowellen Magazin}, volume={14}, number={4}, year={1988}, month={May}, pages={370-4}, abstract={ The effects of electromagnetic pulses caused by lightning (LEMP), nuclear explosion (NEMP), high altitude nuclear explosion (EXO-NEMP) and direct lightning are considered. Maximum magnetic field intensities and their variation around a lightning conductor are discussed. Due to integrated electronic components active antennas seem to be more prone to damage than passive ones. LEMP protection at low frequencies is particularly important because substantial parts of the amplitude spectrum of lightning coincide with the operating range of the antennas. High currents caused by direct lightning can result in thermal and chemical damage of the dielectrics in addition to insulation break-down, mechanical deformation and generation of high voltages by induction. Variation of electrical field intensity as function of time caused by nuclear explosion in high altitudes is shown. The steep rise of the frontal waveform results in an amplitude density in the high frequency end of the spectrum. Special filters are included in installations to reduce the penetration of NEMP via control conductors. After a NEMP event the ionosphere is disturbed for a period of time which makes transmission in the shortwave range impossible. For this situation a surface wave link becomes important }, keywords={ antennas electromagnetic pulse lightning protection thermal damage electromagnetic pulses lightning LEMP nuclear explosion NEMP high altitude nuclear explosion EXO-NEMP direct lightning magnetic field intensities integrated electronic components chemical damage dielectrics electrical field intensity ionosphere }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{Yi-Tie-zhengMay87, author={Yi Tie-zheng}, title={ A simulation of the effective parameters of the lower ionosphere from the spectra of lightning electromagnetic pulses }, journal={Acta Geophysica Sinica}, volume={30}, number={3}, year={1987}, month={May}, pages={236-45}, abstract={ The relation between the spectra of the lightning electromagnetic pulses (LEP) and the structure of the lower ionosphere is discussed by means of the mode theory of the wave propagation in the Earth-lower ionosphere waveguide. The effective parameters of the ionosphere can be deduced by use of the relation between these parameters and the frequencies corresponding to the minimum in the spectra of the LEP. From the measured data of the LEP it can be determined that the effective parameters of the exponential lower ionosphere are beta =0.3 km/sup -1/ and h/sub i/=70 km during the day time, and beta =0.5 km/sup -1/ and h/sub i/=88 km at night. The temporal and geographical variations of the lower ionosphere can also be observed }, keywords={ atmospherics ionosphere ionospheric electromagnetic wave propagation ionospheric techniques electron density electromagnetic pulse spectra disturbance EM pulse atmospherics radiowave sounding method technique LEP Earth ionosphere waveguide effective parameters lower ionosphere lightning electromagnetic pulses structure mode theory wave propagation }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{VollandJan87, author={Volland, H. and Schmolders, M. and Prolss, G.W. and Schafer, J.}, title={ VLF propagation parameters derived from sferics observations at high southern latitudes }, journal={Journal of Atmospheric and Terrestrial Physics}, volume={49}, number={1}, year={1987}, month={Jan}, pages={33-41}, abstract={ Sferics are electromagnetic pulses generated by lightning events. Their maximum spectral energy is in the frequency range below 15 kHz. These powerful natural VLF transmitters can be used to determine the propagation characteristics of the atmospheric wave guide between Earth and ionospheric D layer along virtually every propagation path. A VLF-sferics-analyzer was operating at the German Antarctic von Neumayer Station from January to June 1983. This analyzer recorded sferics from distant lightning events in the frequency range between 5 and 9 kHz. The method of measurement is described. The data are evaluated, and the propagation characteristics of the atmosphere wave guide are determined as a function of azimuth and season. The difference between west-to-east and east-to-west propagation is much smaller than theory predicts, indicating that the ionospheric D layer at high southern latitudes behaves less anisotropic with respect to VLF propagation than at mid-latitudes }, keywords={ atmospherics ionospheric electromagnetic wave propagation radiowave propagation ionosphere high latitude radiowave atmospherics AD 1983 D-region VLF propagation parameters sferics southern atmospheric wave guide azimuth season 5 to 9 kHz }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{PorterAug86, author={Porter, S.}, title={ Pru-Bache broker vies to be one of Wall Street's elves }, journal={Wall Street Computer Review}, volume={3}, number={11}, year={1986}, month={Aug}, pages={28-34}, abstract={ Prudential-Bache veteran John G. Miller states that the most important thing in technical analysis of the stock market is that clients are making more money because of it. Miller says he uses several packages, preferring not to rely on signals produced by any one. He uses a printout of fundamental information on a basket of unlisted issues, provided by Pru-Bache's Branch Office Support System (BOSS) which links brokers to the firms' databases, to show a few issues with decent earnings performance. Miller then adds relative strength studies to come up with some winners which ordinarily might get missed }, keywords={ investment Prudential-Bache technical analysis stock market packages Branch Office Support System }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{Gage84, author={Gage, B. and Greenwell, R. and Summerlin, M. and Zetlen, B.}, title={ Fiber optic aircraft systems electromagnetic pulse (EMP) survivability }, journal={Proc. SPIE - Int. Soc. Opt. Eng. (USA), Proceedings of the SPIE - TheInternational Society for Optical Engineering}, volume={506}, number={}, year={1984}, month={}, pages={109-15}, abstract={ Mitigation of EMP coupling into sensitive, mission critical equipment is essential for aircraft required to operate in adverse nuclear environments. As has been demonstrated in several aircraft test-fix-test programs, traditional hardening can eliminate most EMP problems but generally adds weight, volume, and complexity which impacts system reliability, maintainability and hardness surveillance. Fiber optic technology reduces weight, volume, and complexity while reducing overall life cycle costs and can also mitigate or eliminate many EMP related problems. As requirements for data transfer volume increase, aircraft system expansion utilizing present technology within extended design constraints is hampered by mission requirements for extensive EMI, RFI, EMP, lightning and short circuit shielding and protection. The criticality of excessive weight and space needed for shielding protection is well known and so are the problems of bent pins associated with filter pin connectors. The use of non-metallic composite structural materials for the aircraft skin further exacerbates the traditional shielding and filtering problems. The complete elimination of shielding and filtering is not possible. However, the use of fiber optics paths, complex penetrations and other intentional or inherent inadvertent conductors and thereby greatly simplifies EMP hardening. The inherent dielectric nature of fiber optics makes it relatively resistant or immune to the upset/damage potential of EMP. Fiber optic technology is also capable of electromagnetic interference and cross talk. The vulnerability of fiber optic technology to other significant factors in the operational environment, i.e., ionizing radiation, should also be examined and assessed }, keywords={ aircraft instrumentation crosstalk electromagnetic interference electromagnetic pulse fibre optics optical fibres radiation effects fibre optic aircraft systems EM pulse survivability EMP coupling adverse nuclear environments aircraft test-fix-test programs traditional hardening data transfer volume EMI RFI lightning short circuit shielding excessive weight bent pins filter pin connectors composite structural materials aircraft skin fiber optics paths complex penetrations inadvertent conductors EMP hardening electromagnetic interference cross talk ionizing radiation }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{WellsNov83, author={Wells, J.}, title={ Audio/musical design for animated shows. I. Visual merchandising and display or teaching the hamberger elves to sing }, journal={DB, The Sound Engineering Magazine}, volume={17}, number={10}, year={1983}, month={Nov}, pages={28-32}, abstract={ Discusses how the field of audio/musical design for animated shows is rapidly expanding, bringing with it new challenges for the audio engineer adventuresome enough to try his hand at it. The author examines some of the various engineering solutions necessary to audio/musical design in two market applications }, keywords={ studios audio musical design animated shows }, mynotes={UNREAD}, } /usr/tmp/citation.tmp.3068 @ARTICLE{BetzJul79, author={Betz, R.}, title={ Precision pallet movers surprise even the elves at Keebler }, journal={Material Handling Engineering}, volume={34}, number={7}, year={1979}, month={Jul}, pages={48-53}, abstract={ The clean uncluttered appearance of the Keebler Company's Alsip, III Distribution Center belies the fact that it encompasses one of the highest degrees of automatic control over handling and storage to be found anywhere. The system should work just as well for a wide variety of loads }, keywords={ automatic control materials handling pallet movers automatic control storage Alsip III distribution centre materials handling }, mynotes={UNREAD}, } @ARTICLE{JonesAug70, author={Jones, D.L.}, title={ Propagation of e.l.f. pulses in the Earth-ionosphere cavity and application to 'slow tail' atmospherics }, journal={Radio Science}, volume={5}, number={8-9}, year={1970}, month={Aug}, pages={1153-62}, abstract={ The problem is formulated in the frequency domain; inversion to the time domain is achieved by a numerical evaluation of the Fourier transform. The propagational model employed involves a spherical Earth with a concentric, spherically stratified, inhomogeneous, isotropic ionosphere. The pulse source assumed represents the median return stroke of a lightning discharge. Both short-range propagation and long-range propagation are considered. Particular attention is paid to the nature of the electric- and magnetic-field components of the pulse in the vicinity of the antipode of the source }, keywords={ ionospheric electromagnetic wave propagation lightning radiowave propagation }, mynotes={UNREAD}, }