Axiom expert search, June 14, 2000:
(sprite <in> (Ab,ti) AND lightning <in> (AB, TI))
OR
(mesosphere <in> (Ab,ti) AND lightning <in> (AB, TI))
OR
(vaughan <in> (AU) AND lightning <in> (AB,TI))
OR
(stratosphere <in> (Ab,ti) AND lightning <in> (AB, TI))
OR
(clear air <in> (Ab,ti) AND lightning <in> (AB, TI))


@article{6444829,
author={{Cummer S.A.} and {Stanley M.}},
title={Submillisecond resolution lightning currents and sprite development: observations and implications},
journal={Geophysical Research Letters},
volume={26},
number={20},
pages={3205-8},
year={1999},
abstract={We analyze synchronized high speed video images and ELF-VLF radio
emissions from 11 sprite clusters observed on 6 October 1997. Quantitative
analysis shows that vertical lightning charge moment changes of 150-1100 C.km
occurred before the optical emissions reached their peak with delays of 2-11 ms
from the lightning discharge. This threshold unexpectedly decreases with
increasing delay from parent lightning to peak emissions. We also find that
sprite charge moment change and minimum sprite altitude are not well correlated
with the vertical charge moment change in the parent discharge. These
observations do not agree well with present sprite generation models, and we
suggest that streamer development and horizontal lightning charge motion can
play a significant role in sprite generation}
}
@article{5575048,
author={{Pasko V.P.} and {Inan U.S.} and {Bell T.F.} and {Taranenko Y.N.}},
title={Sprites produced by quasi-electrostatic heating and ionization in the lower ionosphere},
journal={Journal of Geophysical Research},
volume={102},
number={A3},
pages={4529-61},
year={1997},
abstract={Quasi-electrostatic (QE) fields that temporarily exist at high
altitudes following the sudden removal (e.g., by a lightning discharge) of
thundercloud charge at low altitudes lead to ambient electron heating (up to ~5
eV average energy), ionization of neutrals, and excitation of optical emissions
in the mesosphere/lower ionosphere. Model calculations predict the possibility
of significant (several orders of magnitude) modification of the lower
ionospheric conductivity in the form of depletions of electron density due to
dissociative attachment to O/sub 2/ molecules and/or in the form of
enhancements of electron density due to breakdown ionization. Results indicate
that the optical emission intensities of the 1st positive band of N/sub 2/
corresponding to fast (~1 ms) removal of 100-300 degrees C of thundercloud
charge from 10 km altitude are in good agreement with observations of the upper
part ("head" and "hair" [Sentman et al., 1995]) of the sprites. The typical
region of brightest optical emission has horizontal and vertical dimensions ~10
km, centered at altitudes 70 km and is interpreted as the head of the sprite.
The model also shows the formation of low intensity glow ("hair") above this
region due to the excitation of optical emissions at altitudes ~85 km during
~500 mu s at the initial stage of the lightning discharge. Comparison of the
optical emission intensities of the 1st and 2nd positive bands of N/sub 2/,
Meinel and 1st negative bands of N/sub 2//sup +/ and 1st negative band of O/sub
2//sup +/ demonstrates that the 1st positive band of N/sub 2/ is the dominating
optical emission in the altitude range around ~70 km, which accounts for the
observed red color of sprites, in excellent agreement with recent spectroscopic
observations of sprites. Results indicate that the optical emission levels are
predominantly defined by the lightning discharge duration and the conductivity
properties of the atmosphere/lower ionosphere (i.e., relaxation time of
electric field in the conducting medium). The model demonstrates that for low
ambient conductivities the lightning discharge duration can be significantly
extended with no loss in production of optical emissions. The peak intensity of
optical emissions is determined primarily by the value of the removed
thundercloud charge and its altitude. The preexisting inhomogeneities in the
mesospheric conductivity and the neutral density may contribute to the
formation of a vertically striated fine structure of sprites and explain why
sprites often repeatedly occur in the same place in the sky as well as their
clustering. Comparison of the model results for different types of lightning
discharges indicates that positive cloud to ground discharges lead to the
largest electric fields and optical emissions at ionospheric altitudes since
they are associated with the removal of larger amounts of charge from higher
altitudes}
}
@article{4698179,
author={{Kotamarthi V.R.} and {Ko M.K.W.} and {Weisenstein D.K.} and {Rodriguez J.M.} and {Sze N.D.}},
title={Effect of lightning on the concentration of odd nitrogen species in the lower stratosphere: an update},
journal={Journal of Geophysical Research},
volume={99},
number={D4},
pages={8167-73},
year={1994},
abstract={Revised model estimates of the effect of lightning on the lower
stratospheric NO/sub y/ are presented. Several changes in the Atmospheric and
Environmental Research Incorporated model were made since the last evaluation
of the impact of lightning. Improvements were made in the model circulation and
location of tropopause in the tropics, which is now calculated from the
National Meteorological Center temperature data. Changes in model circulation
reduced the mass flux from the troposphere to the tropical stratosphere. The
calculated mass fluxes are found to agree better with recent estimates. The
circulation changes also reduced the advective mass flux from the tropical
lower stratosphere to the midlatitudes. The change in circulation and the
change in the tropopause height lead to increases in the calculated
concentration of N/sub 2/O, O/sub 3/ and NO/sub y/ in the tropical lower
stratosphere. The effect of lightning is to increase the calculated
concentration of NO/sub y/ around 64 mbar by a factor of 2, compared to a
factor of 10 enhancement in the previous calculations. Comparison with the
Stratosphere Troposphere Exchange Project 1987 data indicates that the
inclusion of a lightning source brings the model results in closer agreement
with the observations}
}
@article{5808725,
author={{Taranenko Y.} and {Roussel-Dupre R.} and {Yukhimuk V.} and {Symbalisty E.}},
title={Generation of elves by sprites and jets},
journal={Proceedings XXIII International Conference on Phenomena in Ionized Gases (ICPIG)},
volume={},
number={},
pages={8-9 vol.3},
year={1997},
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}},
}
@article{6485375,
author={{Barrington-Leigh C.P.} and {Inan U.S.} and {Stanley M.} and {Cummer S.A.}},
title={Sprites triggered by negative lightning discharges},
journal={Geophysical Research Letters},
volume={26},
number={24},
pages={3605-8},
year={1999},
abstract={High altitude air breakdown, manifested as "red sprites", is reported
in close association with negative cloud-to-ground lightning (-CG) on at least
two occasions above an unusual storm on August 29, 1998. Data from high speed
photometry, low-light-level video, and receivers of lightning electromagnetic
signatures in the frequency range 10 Hz to 20 kHz are used to establish the
association and indicate that the causative -CG discharges effected unusually
large vertical charge moment changes ( Delta M/sub Qv/) of up to 1550 C.km in 5
ms. The existence of sprites caused by -CG events, rather than the regularly
associated +CG events, has immediate implications for sprite models and
observations}
}
@article{6349305,
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},
pages={16943-64},
year={1999},
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}
}
@article{6121879,
author={{Fullekrug M.} and {Reising S.C.}},
title={Excitation of Earth-ionosphere cavity resonances by sprite-associated lightning flashes},
journal={Geophysical Research Letters},
volume={25},
number={22},
pages={4145-8},
year={1998},
abstract={Simultaneously recorded discrete excitations of Earth-ionosphere
cavity resonances at Silberborn, Germany, and Hollister, California, ~9.1 Mm
apart, are used to triangulate source locations of lightning flashes in the
continental United States with an accuracy of ~0.8 Mm, as verified by the
National Lightning Detection Network. The identified lightning flashes are
mainly associated with positive cloud-to-ground discharges with first return
stroke peak currents ~20-70 kA. 80% of these particular lightning flashes are
associated with sprites, as verified by simultaneous low-light level TV camera
observations at Yucca Ridge, Colorado. This high probability of sprite
detection is attributed to particularly large cloud-to-ground lightning
currents, simultaneously exciting both Earth-ionosphere cavity resonances and
sprites}
}
@article{6114066,
author={{Armstrong R.A.} and {Shorter J.A.} and {Taylor M.J.} and {Suszcynsky D.M.} and {Lyons W.A.} and {Jeong L.S.}},
title={Photometric measurements in the SPRITES '95 and '96 campaigns of nitrogen second positive (399.8 nm) and first negative (427.8 nm) emissions},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={787-99},
year={1998},
abstract={{The authors have obtained blue photometric measurements of the N/sub
2/ second positive 399.8 nm and the N/sub 2//sup +/ first negative 427.8 nm
emission from sprites elves and lightning along with supporting video images.
The pulse width and intensity results for sprites are consistent with those of
Suszcynsky et al. (1998). The red emission from sprites has been independently
and unambiguously identified by Hampton et al. (1996) and Mende et al. (1995)
as the nitrogen first positive band. The source has been attributed to electron
impact excitation from low energy electrons ( approximately=1 eV) in the
sprite. The short pulse width of the 427.8 nm and 399.8 nm photometer time
traces obtained in this investigation are probably not from the same source
that produces the red emission. The results indicate an initial energetic
ionizing event sufficient to ionize and excite nitrogen followed by secondary
electron processes which give rise to the dominant red emission. The photometer
results for elves are consistent with the EMP mechanism suggested by Inan et
al. (1996). The photometer traces obtained for lightning indicate emissions
consistent with a `continuing current' as the charge redistributes within the
thunderstorm cloud. The authors find that the ratio of the intensity of the
399.8 nm N/sub 2/ (2P) emission to that of 427.8 nm N/sub 2//sup +/ (1N)
emission can be used to discriminate among sprites elves and lightning}},
}
@article{5789806,
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},
pages={2973-6},
year={1997},
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 ~3 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]}
}
@article{4907900,
author={{Boeck W.L.} and {Vaughan O.H. Jr.} and {Blakeslee R.J.} and {Vonnegut B.} and {Brook M.} and {McKune J.}},
title={Observations of lightning in the stratosphere},
journal={Journal of Geophysical Research},
volume={100},
number={D1},
pages={1465-75},
year={1995},
abstract={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 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}
}
@article{6539786,
author={{Zhang R.} and {Sanger N.T.} and {Orville R.E.} and {Xuexi Tie} and {Randel W.} and {Williams E.R.}},
title={Enhanced NO/sub x/ by lightning in the upper troposphere and lower stratosphere inferred from the UARS global NO/sub 2/ measurements},
journal={Geophysical Research Letters},
volume={27},
number={5},
pages={685-8},
year={2000},
abstract={This paper reveals a possible connection between lightning activity
and the UARS NO/sub 2/ data on a global scale. NO/sub 2/ measured by the
Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research
Satellite (UARS) is analyzed for the entire year of 1993 and compared to the
seasonal and global lightning distributions inferred from the Optical Transient
Detector (OTD). The results suggest a link between lightning activity and
observed high levels of NO/sub 2/ in the upper troposphere and lower
stratosphere. Enhanced NO/sub 2/ mixing ratios significantly above the
background level are consistently found in areas of elevated lightning
activity. This relation is strongest in the tropical regions during the summer
and spring months of the Northern and Southern Hemispheres. Moreover, the
results show that background levels of NO/sub 2/ mixing ratios generally
correspond to areas of little or no lightning activity}
}
@article{6435805,
author={{Lehtinen N.G.} and {Bell T.F.} and {Inan U.S.}},
title={Monte Carlo simulation of runaway MeV electron breakdown with application to red sprites and terrestrial gamma ray flashes},
journal={Journal of Geophysical Research},
volume={104},
number={A11},
pages={24699-712},
year={1999},
abstract={{A three-dimensional Monte Carlo model of the uniform relativistic
runaway electron breakdown in air in the presence of static electric and
magnetic fields is used to calculate electron distribution functions avalanche
rates and the direction and velocity of avalanche propagation. The authors also
derive the conditions required for an electron with a given momentum to start
an avalanche in the absence of a magnetic field. The results are compared to
previously developed kinetic and analytical models and their own analytical
estimates and it is concluded that the rates used in many early models [e.g.
Lehtinen et al. 1997} and {Taranenko and Roussel-Dupre 1996} and {Yukhimuk et
al. 1998} and {Roussel-Dupre et al. 1998] are overestimated by a factor of ~10.
The Monte Carlo simulation results are applied to a fluid model of runaway
electron beams in the middle atmosphere accelerated by quasi-electrostatic
fields following a positive lightning stroke. In particular the authors
consider the case of lightning discharges which drain positive charge from
remote regions of a laterally extensive (>100 km) thundercloud using a
Cartesian two-dimensional model. The resulting optical emission intensities in
red sprites associated with the runaway electrons are found to be negligible
compared to the emissions from thermal electrons heated in the conventional
type of breakdown. The calculated gamma ray flux is of the same order as the
terrestrial gamma ray flashes observed by the Burst and Transient Source
Experiment detector on the Compton Gamma Ray Observatory}},
}
@article{6348519,
author={{Pasko V.P.} and {Inan U.S.} and {Bell T.F.}},
title={Mesospheric electric field transients due to tropospheric lightning discharges},
journal={Geophysical Research Letters},
volume={26},
number={9},
pages={1247-50},
year={1999},
abstract={A physical picture and quantitative two-dimensional electromagnetic
modeling of mesospheric electric field transients produced by cloud-to-ground
(CG) lightning discharges with short duration currents (<0.5 ms) are presented.
The range of applicability of existing quasi-electrostatic models of sprites
and the physical conditions under which relatively weak CG lightning discharges
(thundercloud charge moment changes less than 50 C *10 km) may initiate sprites
are discussed in the context of experimental findings}
}
@article{6146242,
author={{Valdivia J.A.} and {Milikh G.M.} and {Papadopoulos K.}},
title={Model of red sprites due to intracloud fractal lightning discharges},
journal={Radio Science},
volume={33},
number={6},
pages={1655-68},
year={1998},
abstract={A new and improved model of red sprites is presented. Emphasis is
placed on accounting for the puzzling observation of the spatial structure in
the emissions. The model relies on the electromagnetic pulse (EMP) fields
created by a horizontal lightning discharge and includes the observed fractal
structure of such discharges in the computation of the EMP power density. It is
shown that the model can account for the observed spatial structure of the red
sprites while reducing the typical charge required to approximately 100 C}
}
@article{6114076,
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},
pages={917-40},
year={1998},
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 ~300 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}
}
@article{6114065,
author={{Marshall L.H.} and {Hale L.C.} and {Croskey C.L.} and {Lyons W.A.}},
title={Electromagnetics of sprite- and elve-associated sferics},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={771-86},
year={1998},
abstract={Electromagnetic data recorded in conjunction with the Sprites '95
campaign are presented. The primary data set consists of electric and magnetic
field waveforms related to visually identified sprites and elves recorded on
the night of 24-25 July 1995. The data were collected near State College, PA,
from a mesoscale convective system (MCS) located about 2100 km away near
Lubbock, TX. The optical events were visually identified from an observation
station in Fort Collins, CO. Presented are the waveforms of the sferics, a
description of the measurement system, and a discussion of the signature traits
of optical event-producing sferics. All of the sferics recorded which were
related to visually identified events exhibited primarily unipolar `slow tail'
electromagnetic signatures of order one millisecond duration in the direction
indicating positive lightning. Similar waveforms of opposite polarity,
indicating ordinary negative lightning, were not accompanied by any observed
high altitude optical events}
}
@article{6114057,
author={{Gomes C.} and {Cooray V.}},
title={Long impulse currents associated with positive return strokes},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={693-9},
year={1998},
abstract={{Long distant electric fields (400-500 km) generated by 26 positive
cloud-to-ground flashes were analysed. These flashes consist of well detectable
long impulse fields subsequent to the initial peak. These hook-shaped slow
fields are of considerable amplitude and have a mean duration of 1.24 ms. The
amplitude of the long impulse field and the initial peak of the field show an
approximately linear relationship. The long impulse current pertinent to
positive return strokes which give rise to the measured long impulse fields
were estimated. Flashes with these slow fields lower a mean charge of 50 C
within the first 3 ms (excluding the first 100 mu s which contains the initial
peak) whereas the maximum charge lowered is 124 C. The mean of the ratio
between the peak of the long impulse field and the initial peak is 41%. The
authors also estimated the fields that will be generated by the long impulse
currents at distances of 1000 km 3000 km and 5000 km from the strike. The
estimated peak magnetic fields at 5000 km have a mean of 52 pT. The peak
magnetic fields observed at distances of about 5000 km from positive lightning
flashes which were associated with red sprites are in the same range as the
peak magnetic fields that the authors have calculated for the above 26 flashes.
Hence the authors conclude that the observed Q-bursts which coincide with the
occurrence of red sprites are due to the long impulse currents of positive
return strokes. This slow field variation is rarely observed in connection with
negative return strokes. Even when it is present in the event of a negative
return stroke the amplitude and the duration of the tail are much less than
those of its counterpart in positive return strokes. This explains why
ionospheric lightning is predominantly associated with positive return strokes
but not with negative return strokes}},
}
@article{6114056,
author={{Williams E.R.}},
title={The positive charge reservoir for sprite-producing lightning},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={689-92},
year={1998},
abstract={The close association of mesospheric sprites with positive ground
flashes has led to the frequent assumption that positive charge is transferred
from the top of a thunderstorm with positive-over-negative charge structure,
from an altitude of 10 km or higher. Electrical and meteorological observations
are reviewed which support a different picture: sprites are produced by
laterally extensive mesoscale convective systems (MCS) in which the positive
charge reservoir predominates in the 4-6 km ranges of altitude. The behaviour
of the surface electric field during the End-of-Storm Oscillation and the
behaviour of the vertical electric field above MCS during positive ground
flashes both suggest a predominant in-cloud dipole moment with opposite
polarity to that of the ordinary thundercloud. Lightning charge transfers of a
few hundred Coulombs from the 4-6 km height range may be required for
consistency with theories for sprite optical intensity and to account for ELF
Q-burst intensity}
}
@article{6114055,
author={{Winckler J.R.}},
title={Optical and VLF radio observations of sprites over a frontal storm viewed from O'Brien Observatory of the University of Minnesota},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={679-88},
year={1998},
abstract={Video images, and photometric and VLF data, were obtained by the
University of Minnesota SKYFLASH system of 38 `sprite' events associated with a
strong frontal system located in the upper midwest, U.S.A., on 20-21 June 1996.
Besides two image-intensified TV cameras, the SKYFLASH system included
telescopic photometers sensitive to Rayleigh scattered lightning flashes by
viewing the zenith over the station (O'Brien Observatory, University of
Minnesota, about 40 km NE of Minneapolis-St Paul) and also several VLF channels
with 300 Hz to 10 kHz bandwidth for recording the electromagnetic `sferics'.
The sprites covered a wide range of sizes, from small kilometer-size filaments
to huge luminous objects 50-60 km in lateral dimension. All the sprites
appeared to consist of bundles of filaments, and always followed-within several
ms-a `trigger' could-ground discharge which, in 35 of the 38 events, was
positive. It is difficult to find physical mechanisms that explain this
positive stroke preference. The larger events reached from 80 km almost to
cloud tops, but the small events were localized near 60 km altitude, which is
the `bright' region of sprite luminosity, a fact also not well explained
theoretically. The filamentary structure of sprites also presents challenges to
explain. Of about a dozen lightning storms observed with SKYFLASH in the period
from 1993 to 1996 in the upper midwest, only two had an appreciable number of
sprites}
}
@article{6106680,
author={{Pasko V.P.} and {Inan U.S.} and {Bell T.F.} and {Reising S.C.}},
title={Mechanism of ELF radiation from sprites},
journal={Geophysical Research Letters},
volume={25},
number={18},
pages={3493-6},
year={1998},
abstract={Charge and current systems associated with sprites constitute a part
of the large scale atmospheric electric circuit, providing a context for
physical understanding of recently discovered ELF radiation originating from
currents flowing within the body of sprites. It is shown that the impulse of
the electric current driven in the conducting body of the sprite by lightning
generated transient quasi-electrostatic fields produces significant
electromagnetic radiation in the ELF range of frequencies, comparable to that
radiated by the causative lightning discharge}
}
@article{6022086,
author={{Lyons W.A.} and {Uliasz M.} and {Nelson T.E.}},
title={Large peak current cloud-to-ground lightning flashes during the summer months in the contiguous United States},
journal={Monthly Weather Review},
volume={126},
number={8},
pages={2217-33},
year={1998},
abstract={A clear association between large peak current cloud-to-ground (CG)
lightning flashes of positive polarity and sprites and elves in the
stratosphere and mesosphere has been previously demonstrated. This paper
reports on the first climatology of large peak current CG (LPCCG) lightning
flashes compiled from the U.S. National Lightning Detection Network. Analysis
of almost 60 million CG flashes from 14 boreal summer months (1991-95) reveals
distinct geographic differences in the distribution of positive and negative
polarity LPCCGs, arbitrarily defined as flashes with peak currents >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}
}
@article{5811449,
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},
pages={3169-72},
year={1997},
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}
}
@article{5549063,
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},
pages={29653-62},
year={1996},
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}
}
@article{5420972,
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},
pages={2157-60},
year={1996},
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 ~100-300 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}},
}
@article{5331447,
author={{Inan U.S.} and {Reising S.C.} and {Fishman G.J.} and {Horack J.M.}},
title={On the association of terrestrial gamma-ray bursts with lightning and implications for sprites},
journal={Geophysical Research Letters},
volume={23},
number={9},
pages={1017-20},
year={1996},
abstract={Measurements of ELF/VLF radio atmospherics (sterics) at Palmer
Station, Antarctica, provide evidence of active thunderstorms near the inferred
source regions of two different gamma-ray bursts of terrestrial origin (Fishman
et al., 1994). In one case, a relatively intense steric occurring within
+or-1.5 ms of the time of the gamma-ray burst provides the first indication of
a direct association of this burst with a lightning discharge. This steric and
many others launched by positive cloud-to-ground (CG) discharges and observed
at Palmer during the periods studied exhibit `slow tail' waveforms, indicative
of continuing currents in the causative lightning discharges. The slow tails of
these sterics are similar to those of sterics originating in positive CG
discharges that are associated with sprites}
}
@article{5312514,
author={{Pasko V.P.} and {Inan U.S.} and {Bell T.F.}},
title={Sprites as luminous columns of ionization produced by quasi-electrostatic thundercloud fields},
journal={Geophysical Research Letters},
volume={23},
number={6},
pages={649-52},
year={1996},
abstract={Quasi-electrostatic (QE) fields which exist above thunderclouds after
lightning discharges can lead to the formation of columnar channels of
breakdown ionization and carrot-like vertical luminous structures with typical
transverse dimension ~5-10 km spanning an altitude range from ~80 km to well
below ~50 km. The carrot-like forms closely resemble those observed in sprites.
Results indicate that the appearance of optical emissions can be significantly
delayed in time (~1-20 ms) with respect to the causative lightning discharge}
}
@article{5234948,
author={{Baginski M.E.} and {Hodel A.S.} and {Lankford M.}},
title={An investigation of the reconfiguration of the electric field in the stratosphere following a lightning event},
journal={Journal of Electrostatics},
volume={36},
number={4},
pages={331-47},
year={1996},
abstract={Baginski and Hodel (1994) and Baginski and Jarriel (1994) discussed
some peculiarities in the late-time electric field and Maxwell current density
signatures following a lightning event. In the present paper we extend the
analysis to investigate the temporal relationship between the vertical and
horizontal electric field in the stratosphere (altitudes 30-50 km) and consider
how a quasi-planar region can be defined by introducing the angular orientation
( theta =tan/sup -1/(E/sub z//E/sub y/)) between the respective field
components. The geometry, constitutive parameters and assumptions used in the
earlier modeling are employed also. Special attention is given to two
dimensional graphical representations of the behavior of the electric field
that clearly illustrate that a relatively thin segregated region can be defined
between a time-varying upper and lower region where the maximum rate of change
of the orientation of the field occurs at z/sub p/(t)=h/sub s/log( tau (z)/t).
The research reinforces the model presented by Greifinger and Greifinger
(1976). An empirical model is also derived from previous research that is in
good overall agreement with the simulations}
}
@article{3498784,
author={{Legrand M.R.} and {Stordal F.} and {Isaksen I.S.A.} and {Rognerud B.}},
title={A model study of the stratospheric budget of odd nitrogen, including effects of solar cycle variations},
journal={Tellus, Series B (Chemical and Physical Meteorology)},
volume={41B},
number={4},
pages={413-26},
year={1989},
abstract={{A two-dimensional diabatic circulation model of the stratosphere and
the troposphere is used to study the budget of total odd nitrogen (NO/sub y/)
and to simulate the response of odd oxygen and nitrogen species to the 11-year
solar cycle variations. The results are discussed in terms of the various
NO/sub y/ production processes including surface sources (anthropogenic sources
soil exhalation) lightning N/sub 2/O oxidation Galactic cosmic rays (GCRs) and
high-latitude input from the thermosphere and mesosphere. Although N/sub 2/O
oxidation is the dominant odd nitrogen source throughout the stratosphere
NO/sub y/ produced within the thermosphere and transported through the
stratopause at high latitude during winter may affect NO/sub y/ distribution
particularly during periods of large solar activity. In the lower stratosphere
the lightning contribution becomes significant. The authors find less than 4%
variations in NO/sub y/ at 19 km in the winter hemisphere where the main effect
from solar cycle variations stems from changes in photon fluxes}},
}
@article{3291372,
author={{Borucki W.J.} and {Giver L.P.} and {McKay C.P.} and {Scattergood T.} and {Parris J.E.}},
title={Lightning production of hydrocarbons and HCN on Titan: laboratory measurements},
journal={Icarus},
volume={76},
number={1},
pages={125-34},
year={1988},
abstract={Many hydrocarbon species have been detected in the atmosphere of
Titan. It is possible that lightning activity is occurring in the troposphere
and that it contributes to the hydro-carbon inventory. Measurements of the
chemical yields of hydrogen cyanide, acetylene, ethylene, ethane, and propane
from simulated lightning discharges are reported. A comparison of the
experimental results with those based on thermodynamic equilibrium assumptions
shows significant disagreement and implies that theories based solely on
thermodynamic equilibrium are inadequate. Although photochemistry and charged
particle chemistry occurring in the stratosphere can account for many of the
observed hydrocarbon species, the predicted abundance of ethylene is too low by
a factor of 10 to 40. While some ethylene will be produced by charged-particle
chemistry, the production of ethylene by lightning and its subsequent diffusion
into the stratosphere appears to be an adequate source}
}
@article{2700244,
author={{Ko M.K.W.} and {McElroy M.B.} and {Weisenstein D.K.} and {Nien Dak Sze}},
title={Lightning: a possible source of stratospheric odd nitrogen},
journal={Journal of Geophysical Research},
volume={91},
number={D5},
pages={5395-404},
year={1986},
abstract={It is argued on the basis of a two-dimensional stratospheric model
that upward transport of oxides of nitrogen produced by lightning in the
tropical troposphere can significantly enhance the concentrations of NOY, the
composite of all forms of odd nitrogen, in the lower stratosphere. The impact
can be as large as a factor of 10 at 22 km near the equator, dropping to less
than 50% above 30 km. Inclusion of the lightning source of NOY in the model
results in improved agreement with available satellite data for the sum of
NO/sub 2/ and HNO/sub 3/. Lightning is important even if only 5% of the
nitrogen oxides produced enters the stratosphere}
}
@article{2085640,
author={{Levine J.S.} and {Shaw E.F. Jr.}},
title={In situ aircraft measurements of enhanced levels of N/sub 2/O associated with thunderstorm lightning},
journal={Nature},
volume={303},
number={5915},
pages={312-14},
year={1983},
abstract={Reports the first series of measurements of enhanced levels of
atmospheric N/sub 2/O associated with thunderstorm lightning. N/sub 2/O is an
environmentally significant species since its reaction with excited oxygen
(O(/sup 1/D)) in the stratosphere produces NO which through the catalytic
NO/sub x/ cycle is responsible for about 65% of the total global destruction of
ozone (O/sub 3/) in the stratosphere. In addition, due to its absorption at 7.8
mu m in the atmospheric window, N/sub 2/O absorbs and then re-emits
Earth-emitted IR radiation which leads to an enhancement of the surface
temperature, and, hence, has important implications for climate considerations}
}
@article{1912151,
author={{Rust W.D.} and {Doviak R.J.}},
title={Radar research on thunderstorms and lightning},
journal={Nature},
volume={297},
number={5866},
pages={461-8},
year={1982},
abstract={Weather radars can resolve many phenomena related to thunderstorms.
Echoes from clear air, water and ice condensate, and ionized lightning channels
can all be identified. Radial velocity data from two Doppler-radars are
synthesized to show a storm mesocyclone with updraft speeds as large as 40
ms/sup -1/, moist boundary layer air flowing into the storm, and outflow into
the upper troposphere. Maximum wind speeds in tornadoes can be remotely
measured using Doppler spectra obtained with a high PRF radar. Doppler radars
can detect thunderstorm gusts even when they are in the clear air many tens of
kilometres away from the storm, and radar detection of the ionized channels
caused by lightning opens new avenues into thunderstorm research}
}
@article{6585207,
author={{Nunn D.} and {Strangeways H.J.}},
title={Trimpi perturbations from large ionisation enhancement patches},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={62},
number={3},
pages={189-206},
year={2000},
abstract={A number of increasingly sophisticated and realistic models have been
developed in order to investigate the interaction between sub-ionospherically
propagating VLF waves and regions of ionisation enhancement (LIE') in the
D-region caused by lightning-induced electron precipitation enhancements (LEP).
This LEP-produced LIE can result in phase and amplitude perturbations on
received VLF radio signals that are referred to as Trimpis or more precisely,
classic Trimpis, to distinguish them from "early/fast Trimpis" or "VLF sprites"
which are not caused by LEP and are not considered. It is important, for
comparison with experimentally observed Trimpi effects, that the spatial extent
of the D-region electron density (N/sub c/) perturbation is modeled accurately.
It is argued that most previous modeling has used patch (LIE) sizes that are
typically up to 100 km in both latitudinal and longitudinal extent, which are
generally smaller than those that actually occur for real lightning induced
electron precipitation events. It would also appear that maximum Delta V/sub
2/, values assumed have often been too large, and the patches (LIEs) have been
incorrectly modelled as circular rather than elliptical in horizontal extent.
Consequently, in the present work, Trimpi perturbations are determined for LIEs
with smaller maximum Delta N/sub e/, larger spatial extent and elliptical
shape. Calculations of VLF Trimpis have been made as a function of the
horizontal coordinates of the LIE centre, over the whole rectangular corridor
linking transmitter and receiver. The Trimpi modelling program is fully 3D, and
takes account of modal mixing at the LIE. The underlying theory assumes weak
Born scattering, but the code calculates a non-Born skin depth attenuation
function for the LIE in question}
}
@article{6554895,
author={{Schumann U.} and {Schlager H.} and {Arnold F.} and {Ovarlez J.} and {Kelder H.} and {Hov O.} and {Hayman G.} and {Isaksen I.S.A.} and {Staehelin J.} and {Whitefield P.D.}},
title={Pollution from aircraft emissions in the North Atlantic flight corridor: overview on the POLINAT projects},
journal={Journal of Geophysical Research},
volume={105},
number={D3},
pages={3605-31},
year={2000},
abstract={The Pollution From Aircraft Emissions in the North Atlantic Flight
Corridor (POLINAT) projects were undertaken to investigate the impact of
aircraft engine exhaust emissions on the state of the atmosphere in the North
Atlantic flight corridor. Changes in the composition of the lower stratosphere
and upper troposphere from aircraft emissions are identified from combined
measurements and model analyses. Measurements were performed using the
Deutsches Zentrum fur Luft- und Raumfahrt Falcon research aircraft and a
Swissair B-747 over the North Atlantic covering the altitude range 6 to 13 km
in November 1994 and June/July 1995 and from August to November 1997. The
measurements include those of nitrogen oxides, nitrous and nitric acids, sulfur
dioxide, sulfuric acid, acetone, carbon dioxide, ozone, water vapor, carbon
monoxide, aerosols, and meteorological parameters. The atmospheric composition
was found to be highly variable, and emissions from sources at the surface or
from lightning discharges also contribute strongly to the nitrogen oxides
abundance and ozone formation. Contributions from aircraft emissions have been
measured and identified in single and multiple plumes of several hours ages,
and accumulation of such nitrogen oxides and particles emissions can be
identified under certain conditions in and downstream of the flight corridor
region. Acetone was found at high mixing ratios. The global and regional models
predict ozone increases of 3 to 6% by current air traffic at the flight
corridor altitude north of 30 degrees N, in agreement with previous model
analyses but too small to be measurable. In autumn, the upper troposphere is
often humid with water vapor concentration far above ice saturation, providing
conditions for persistent contrails}
}
@article{6539739,
author={{Pasko V.P.} and {Inan U.S.} and {Bell T.F.}},
title={Fractal structure of sprites},
journal={Geophysical Research Letters},
volume={27},
number={4},
pages={497-500},
year={2000},
abstract={A large scale model of sprites based on a phenomenological
probabilistic approach to modeling of streamer corona discharges is developed.
The model utilizes the experimentally documented macroscopic properties of
positive and negative streamer coronas in air and allows a realistic
determination of the propagation of multiple breakdown branches in a
self-consistent electric field. The model results reproduce the large scale
volumetric shapes of sprites, agree with the experimentally documented
thundercloud charge moment changes in sprites producing cloud to ground
lightning discharges (CGs), and demonstrate fundamental asymmetries between
sprites generated by CGs of positive and negative polarity}
}
@article{6456665,
author={{Levy H. II} and {Moxim W.J.} and {Klonecki A.A.} and {Kasibhatla P.S.}},
title={Simulated tropospheric NO/sub x/: its evaluation, global distribution and individual source contributions},
journal={Journal of Geophysical Research},
volume={104},
number={D21},
pages={26279-306},
year={1999},
abstract={Using the 11-level Geophysical Fluid Dynamics Laboratory global
chemical transport model, we simulate global tropospheric fields of NO/sub x/,
peroxyacetyl nitrate (PAN), HNO/sub 3/, and NO/sub y/, as well as the
deposition of nitrate, extensively evaluate them against available observations
of individual natural and anthropogenic sources. The patterns and magnitudes of
simulated and observed HNO/sub 3/ wet deposition are generally in good
agreement around the globe. Scatterplots of model simulations versus aircraft
observations for NO/sub x/ and NO/sub y/ find ~50% of the points within
+or-25%, find ~75% within +or-50%, and show no systematic global biases. Both
simulated and observed vertical profiles have similar shapes with high levels
(~1 ppbv or greater) in the polluted boundary layer (BL), very low values in
the remote BL, and values increasing from the middle to the upper troposphere.
Simulated NO/sub y/, HNO/sub 3/, and NO/sub x/+PAN are also in good agreement
with extensive lower free tropospheric (FT) observations made at Mauna Loa
Observatory. In general, the level of agreement between simulation and
observation is as good as the agreement between separate, but simultaneous,
observations of NO, NO/sub x/ or NO/sub y/. As previous studies have shown,
fossil fuel combustion and biomass burning control NO/sub x/ levels in most of
the lower half of the troposphere with a significant contribution from biogenic
emissions. The exceptions are the remote low-NO/sub x/ regions where BL and FT
sources make comparable contributions. Unlike most previous studies, we find
that the much smaller in situ FT sources generally dominate in the upper half
of the troposphere. Lightning dominates in the tropics and summertime
midlatitudes, and stratospheric injection is the major source in the summer
high latitudes. The exception is transported emissions from fossil fuel
combustion, which dominate in winter high latitudes. Though seldom dominant,
aircraft emissions do have significant impact on the upper troposphere and
lower stratosphere of the northern hemisphere extratropics}
}
@article{6444796,
author={{Thompson A.M.} and {Sparling L.C.} and {Kondo Y.} and {Anderson B.E.} and {Gregory G.L.} and {Sachse G.W.}},
title={Perspectives on NO, NO/sub y/ and fine aerosol sources and variability during SONEX},
journal={Geophysical Research Letters},
volume={26},
number={20},
pages={3073-6},
year={1999},
abstract={Distributions of upper tropospheric tracer data on each of the 14
science flights of SONEX (SASS [Subsonics Assessment] Ozone and Nitrogen Oxides
Experiment) provide a statistical overview of NO, NO/sub y/ and fine aerosol
variability during SONEX (an aircraft mission conducted in October and November
1997). The wide range of variability of NO from all sources provides a
perspective on the aircraft perturbation. Background distributions of NO/sub y/
are somewhat elevated inside flight corridors relative to outside; fine aerosol
and NO/NO/sub y/ in and out of corridors are similar. The potential vorticity
of air sampled during SONEX is low relative to the NAFC (North Atlantic Flight
Corridor) as a whole, due either to advection of lower latitude air into the
corridor or biases in sampling to avoid the stratosphere. High NO/NO/sub y/
(>0.4) from fresh lightning and aircraft sources was usually associated with pv
much lower than the NAFC as a whole. Air masses identified as tropospheric by a
low ozone criterion nevertheless have high pv, a marker for stratospheric air.
Thus, stratospheric and surface sources also contribute to overall variability.
A statistically robust assessment of the relative aircraft NO contribution
during SONEX, based on data alone, is unlikely, given the mixture of other NO
sources within which the aircraft signal is embedded. This underscores the need
for more data and modeling studies}
}
@article{6375016,
author={{Rodger C.J.}},
title={Red sprite, upward lightning, and VLF perturbations},
journal={Reviews of Geophysics},
volume={37},
number={3},
pages={317-36},
year={1999},
abstract={In the last decade there has been a great deal of interest in the
detection and understanding of phenomena occurring above active thunderstorms.
The discovery of the optical phenomena now termed "red sprites" is discussed,
along with the properties that have been experimentally determined. Areas of
disagreement between experimentalists are pointed out. Other optical and
electromagnetic phenomena associated with red sprites are presented. These
include blue jets, transionospheric pulse pairs, and gamma ray flashes.
Particular attention is given to the work on perturbations on very
low-frequency radio wave transmissions ("VLF sprites"), which has provided
estimates of the electrical properties of sprites. Research into activity above
thunderstorms will continue to lead to a greater understanding of the coupling
between thunderstorms in the troposphere to the stratosphere, mesosphere,
ionosphere, and beyond}
}
@article{6361095,
author={{Liu S.C.} and {Yu H.} and {Ridley B.} and {Wang Y.} and {Davis D.D.} and {Kondo Y.} and {Koike M.} and {Anderson B.E.} and {Vay S.A.} and {Sachse G.W.} and {Gregory G.L.} and {Fuelburg H.} and {Thompson A.} and {Singh H.}},
title={Sources of reactive nitrogen in the upper troposphere during SONEX},
journal={Geophysical Research Letters},
volume={26},
number={16},
pages={2441-4},
year={1999},
abstract={The relationship among NO/sub y/, O/sub 3/, N/sub 2/O, ultra-fine
condensation nuclei (CN), and other trace gases in the upper troposphere (UT)
and lower stratosphere (LS) observed during SONEX are analyzed with the goal to
identify and quantify the sources of NO/sub y/ in the UT. We use N/sub 2/O to
separate upper tropospheric air from stratospheric influenced air and focus our
analysis on the former. The distributions of NO/sub y/ and O/sub 3/ show
remarkable similarity when they are plotted as a function of N/sub 2/O. The
only difference between NO/sub y/ and O/sub 3/ is found in upper tropospheric
air where a large number of data points have high values of both NO/sub y/ and
the NO/sub y//O/sub 3/ ratio. Major sources contributing to these high NO/sub
y/ values are found to be emissions from lightning and surface sources
transported to the UT by convection}
}
@article{6331133,
author={{Bartlett E.J.} and {Vaughan M.} and {Moore P.J.}},
title={Investigations into electromagnetic emissions from power system arcs},
journal={Proceedings of Electromagnetic Compatibility},
volume={},
number={},
pages={47-52},
year={1999},
abstract={Impulsive electromagnetic radiation can originate from many diverse
sources in power systems when arcing occurs. The emission of radio wave energy
in the form of a power system sferic in a similar way to lightning induced
sferics is related to the non-linear properties of the plasma arc. This paper
describes research work investigating the electromagnetic emissions in the very
low frequency (VLF) and very high frequency (VHF) frequency bands from power
system arcing events. Sources of power system sferics and the inducing
mechanism are detailed. The characterisation of different types of power system
arcing events recorded during experimentation are also discussed. The
principles allowing power system arcing fault induced sferics to be
discriminated from other impulsive noise sources and the location of the
sferic's origin are outlined. Finally the practical implementation of a
real-time fault monitoring system and recorded results are presented}
}
@article{6291550,
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},
pages={12645-56},
year={1999},
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 ~100 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 ~50 mu s or
longer a double-pulse shape of the photometric signal is observed. For cloud to
ground lightning discharges of ~1 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}
}
@article{6211493,
author={{Milikh G.} and {Valdivia J.A.}},
title={Model of gamma ray flashes due to fractal lightning},
journal={Geophysical Research Letters},
volume={26},
number={4},
pages={525-8},
year={1999},
abstract={A model of gamma -ray flashes is presented. The model relies upon a
horizontal fractal lightning discharge, which generates the electromagnetic
pulses that produce the stochastic electron runaway discharge in the
stratosphere. The model computes the flux and energy spectrum of the gamma
-rays generated by the runaway discharge. The results of the computations are
compared with the GRO observations after including the gamma -ray attenuation
in the atmosphere}
}
@article{6146293,
author={{Lyons W.A.} and {Nelson T.E.} and {Williams E.R.} and {Cramer J.A.} and {Turner T.R.}},
title={Enhanced positive cloud-to-ground lightning in thunderstorms ingesting smoke from fires},
journal={Science},
volume={282},
number={5386},
pages={77-80},
year={1998},
abstract={Smoke from forest fires in southern Mexico was advected into the U.S.
southern plains from April to June 1998. Cloud-to-ground lightning (CG) flash
data from the National Lightning Detection Network matched against
satellite-mapped aerosol plumes imply that thunderstorms forming in
smoke-contaminated air masses generated large amounts of lightning with
positive polarity (+CGs). During 2 months, nearly half a million flashes in the
southern plains exhibited +CG percentages that were triple the climatological
norm. The peak currents in these +CGs were double the expected value. These
thunderstorms also produced abnormally high numbers of mesospheric optical
sprites}
}
@article{6123834,
author={{Raizer Yu.P.} and {Milikh G.M.} and {Shneider M.N.} and {Novakovski S.V.}},
title={Long streamer in the upper atmosphere above thundercloud},
journal={Journal of Physics D (Applied Physics)},
volume={31},
number={22},
pages={3255-64},
year={1998},
abstract={It has been suggested that optical flashes observed in the upper
atmosphere above giant thunderstorms (red sprites) are due to streamers. Such
streamers are initiated in the lower ionosphere by electron patches caused by
electromagnetic radiation from horizontal intracloud lightning and then develop
downward in the static electric field due to the thundercloud. The triggering
conditions of streamer development are analysed. Using similarity relations,
known characteristics of streamer tips obtained earlier in laboratory
conditions are extended to a description of streamers in rare air. Streamer
growth in the nonuniform atmosphere is calculated. It is shown that streamers
first appear at a height of about 80 km and then grow downward to slightly
below 50 km, where they are terminated. This is in agreement with red sprite
observations. An altitude distribution of the streamer generated plasma is
obtained. The simple models of streamer development presented in this paper
could be applied for computations of streamers growing in other conditions}
}
@article{6114075,
author={{Milikh G.} and {Valdivia J.A.} and {Papadopoulos K.}},
title={Spectrum of red sprites},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={907-15},
year={1998},
abstract={A synthetic spectrum of red sprites due to electron energization by
the electric field from lightning is presented. It is computed by using the
electron distribution function obtained from a Fokker-Planck code, which
includes various inelastic losses. The model also includes the atmospheric
attenuation of the optical emissions. The results are compared with observed
red sprite spectra. Some implications of the results to models of red sprites
are discussed}
}
@article{6114074,
author={{Milikh G.M.} and {Usikov D.A.} and {Valdivia J.A.}},
title={Model of infrared emission from sprites},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={895-905},
year={1998},
abstract={A model of the 4.26 mu m infrared emission due to red sprites is
presented. The model considers the generation of nitrogen `vibrons' due to the
collisions of the nitrogen molecules with the electrons energized by the
electric field from lightning, followed by the transition of the nitrogen
vibrons to the CO/sub 2/(001) vibrational level, with a lifetime much shorter
than that of nitrogen. The infrared photons of wavelength lambda =4.26 mu m
radiated by the CO/sub 2/(001) propagate through the optically thick
atmosphere; therefore, this emission could best be observed from space. The
model computes the infrared radiance of sprites, as well as the energy
collected by a state-of-the-art space infrared detector, and estimates the
signal to background ratio}
}
@article{6114073,
author={{Rycroft M.J.} and {Cho M.}},
title={Modelling electric and magnetic fields due to thunderclouds and lightning from cloud-tops to the ionosphere},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={889-93},
year={1998},
abstract={Following some lightning flashes from energetic thunderclouds, blue
jets and red sprites are observed in the atmosphere above the cloud and into
the ionosphere. In order to understand the physical processes leading to these
and associated phenomena, both the temporal and spatial evolution of the
electric (and magnetic) fields due to the thundercloud and the lightning
discharge are modelled. These numerical simulations are carried out either
using a quasi-electrostatic code or an EM code, with appropriate boundary
conditions and grids. The redistribution of electric charge and the EM pulse
due to the lightning, can accelerate electrons, which collide with neutrals and
ions, heating them, and also ionising the atmosphere. Runaway electrons and/or
electrical breakdown of the atmosphere can also occur. The first and second
positive bands of molecular nitrogen are excited appreciably if sufficient
energy is produced. The situation is strongly nonlinear. The results show the
temporal and spatial development of (a) the electric field divided by the
neutral gas density, and (b) the energy density of optical emissions (up to
10/sup 13/ photons m/sup -3/ s/sup -1/). They show that energy propagates up to
the ionosphere in 0.3 ms, at the speed of light. A ring of optical emissions is
created, the outer rim of which propagates horizontally in the ionosphere at an
altitude ~90 km, reaching a radial distance of 280 km in a further 0.7 ms. At
the same time, the intense electric field at >07 km altitude above the
thundercloud creates a much enhanced (~10/sup 3/ x) electron density (with a
radius up to 25 km) which lasts for several ms. This heated region modifies the
amplitude and phase characteristics of VLF radio waves propagating in the
Earth-ionosphere waveguide}
}
@article{6114069,
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},
pages={831-44},
year={1998},
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 (<eV) or high energy,
cosmic-ray-generated MeV electrons. These electrons in turn collisionally heat
the neutrals and produce the heating, ionization and optical emissions}
}
@article{6114062,
author={{Dowden R.L.} and {Hardman S.F.} and {Rodger C.J.} and {Brundell J.B.}},
title={Logarithmic decay and Doppler shift of plasma associated with sprites},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={741-53},
year={1998},
abstract={VLF phase and amplitude perturbations in `early/fast Trimpis' have
been observed simultaneously on two or more transmitters at two or more
receiver sites and simultaneously with sprites observed optically in Colorado.
In all cases the early/fast Trimpis could apparently be resolved into two
components: the RORD (rapid onset, rapid decay) component coincident with the
sprite and a `classic Trimpi' component having the slower onset and decay of
Trimpis generally thought to be caused by whistler-induced electron
precipitation from the radiation belts. The phase and amplitude perturbations
can decay at very different rates, and even change in sign from positive to
negative perturbation (`overshoot') during decay. This implies a spatial
separation between the rapid decay plasma responsible for the RORD and the slow
decay plasma responsible for the classic Trimpi component of up to a few tens
of km. This is much less than the expected separation of sprite plasma and
electron precipitation plasma induced by the same cloud-ground lightning. The
discovery of very strong early/fast Trimpis in the tropics (Darwin, Australia),
where electron precipitation is unlikely, which showed similar effects like
overshoot but much more clearly, caused an examination of recent Colorado data
of high resolution. The Colorado Trimpis, which are clearly associated with
sprites, show the same features as the Darwin Trimpis where optically detected
sprites were not available. Both can be explained in terms of sprite plasma
decaying from the bottom up without recourse to electron precipitation}
}
@article{6114061,
author={{Wescott E.M.} and {Sentman D.D.} and {Heavner M.J.} and {Hampton D.L.} and {Lyons W.A.} and {Nelson T.}},
title={Observations of `columniform' sprites},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={733-40},
year={1998},
abstract={{This paper reports observations of a distinctive form of sprites
associated with positive CG flashes carrying currents of 23 or less to about
100 kA in mesoscale thunderstorms. The sprites are characterized by long
vertical columns about 10 km long less than 1 km in diameter and show virtually
no variation in brightness along their length. Three dimensional triangulation
of what the authors define as a `columniform' sprite (c-sprite) event on the
evening of 19 June 1995 showed that the individual elements had an average
terminal altitude of 86.7 km and an average bottom of 76.2 km. Some show faint
diffuse `hair' or tendrils extending above and below the column. The sprite
columns are nearly vertical in video imagery. On some evenings c-sprites are
the dominant form of sprite activity above thunderstorms but on other nights
with many sprites they may not be observed at all. Comparison of c-sprite forms
vs National Lightning Detection Network (NLDN) positive cloud-to-ground current
shows a progression from simple thin vertical forms to brighter and more
complicated forms. Theoretical explanations which predict the form and vertical
structure of the classical sprites do not at present account for these
different forms}},
}
@article{6114059,
author={{Wescott E.M.} and {Sentman D.D.} and {Heavner M.J.} and {Hampton D.L.} and {Vaughan O.H. Jr.}},
title={Blue jets: their relationship to lightning and very large hailfall, and their physical mechanisms for their production},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={713-24},
year={1998},
abstract={{Blue jets are narrow cones of blue light that appear to propagate
upward from the cloud tops at speeds of about 100 km/s to terminal altitudes of
about 40 km (Wescott et al. 1995). The present authors give the results of a
refined analysis of these optical phenomena and their relationship to
cloud-to-ground (CG) and intracloud lightning and to very large hailfall their
apparent color and possible mechanisms for their production. In a thunderstorm
where more than 50 of these events were observed from aircraft on the night of
1 July 1994 about half of the blue jets occurred in a cluster near Foreman
Arkansas and the rest in an area near Texarkana (Texas/Arkansas). Hail 7 cm in
diameter fell in those two storm cells at the time of the blue jet occurrences.
One other blue jet was observed over an intense multi cell storm in Kansas on
the night of 3 July 1994. Comparison to cloud-to-ground (CG) lightning strokes
revealed that blue jets were not coincident with either positive or negative CG
strokes but they occurred in the same general area as negative CG strokes and
large hail and that cumulative distributions of the negative CG strokes in
+or-5 s before and after the jet and within a radius of 15 km showed a
significant reduction in the flash rate for 2 s following the event. From an
analysis of color TV signal levels and calculations of quenching and
atmospheric transmission the authors conclude that significant ionization is
present in the jets. Theoretical work by others suggests that the mechanism for
their production is a streamer but there remain discrepancies between these
theories and the observations}},
}
@article{6114058,
author={{Boccippio D.J.} and {Wong C.} and {Williams E.R.} and {Boldi R.} and {Christian H.J.} and {Goodman S.J.}},
title={Global validation of single-station Schumann resonance lightning location},
journal={Journal of Atmospheric and Solar-Terrestrial Physics},
volume={60},
number={7-9},
pages={701-12},
year={1998},
abstract={Global measurements of large, optically bright lightning events from
the Optical Transient Detector (OTD) satellite are used to validate estimates
of lightning location from single-station Schumann resonance (SR) data. Bearing
estimates are obtained through conventional magnetic direction-finding
techniques, while source range is estimated from the range-dependent impedance
spectrum of individual SR transients. An analysis of 40 such transients
suggests that single-station techniques can locate lightning globally with an
accuracy of 1-2 Mm. This is confirmed by further validation at dose ranges from
flashes detected by the National Lightning Detection Network (NLDN).
Observations with both OTD and SR systems may be useful for globally locating
lightning with necessary, if not sufficient, characteristics to trigger
mesospheric sprites}
}
@article{6100182,
author={{Penner J.E.} and {Bergmann D.J.} and {Walton J.J.} and {Kinnison D.} and {Prather M.J.} and {Rotman D.} and {Price C.} and {Pickering K.E.} and {Baughcum S.L.}},
title={An evaluation of upper troposphere NO/sub x/ with two models},
journal={Journal of Geophysical Research},
volume={103},
number={D17},
pages={22097-113},
year={1998},
abstract={{Upper tropospheric NO/sub x/ controls in part the distribution of
ozone in this greenhouse-sensitive region of the atmosphere. Many factors
control NO/sub x/ in this region. As a result it is difficult to assess
uncertainties in anthropogenic perturbations to NO from aircraft for example
without understanding the role of the other major NO/sub x/ sources in the
upper troposphere. These include in situ sources (lightning aircraft)
convection from the surface (biomass burning fossil fuels soils) stratospheric
intrusions and photochemical recycling from HNO/sub 3/. This work examines the
separate contribution to upper tropospheric "primary" NO/sub x/ from each
source category and uses two different chemical transport models to represent a
range of possible atmospheric transport. Because aircraft emissions are tied to
particular pressure altitudes it is important to understand whether those
emissions are placed in the model stratosphere or troposphere and to assess
whether the models can adequately differentiate stratospheric air from
tropospheric air. The authors examine these issues by defining a point-by-point
"tracer tropopause" in order to differentiate stratosphere from troposphere in
terms of NO/sub x/ perturbations}},
}
@article{6096693,
author={{Vaughan M.} and {Moore P.J.} and {Johns A.T.} and {Ormondroyd R.F.}},
title={Condition monitoring of power systems utilising arcing fault noise in the very low frequency spectrum},
journal={Proceedings of 1998 Universities Power Engineering Conference},
volume={},
number={},
pages={851-4 vol.2},
year={1998},
abstract={This paper describes research being conducted at the University of
Bath (UK) into a novel monitoring technique that uses the electromagnetic
radiation energy present in a power system arcing fault. The technique utilises
the propagation effects of very low frequency (VLF) radio waves, together with
the electromagnetic energy dissipated in a power system arcing fault. The paper
describes an intelligent monitoring VLF detector station which can discriminate
between power system arcing fault noise and other noise sources in the VLF
region, which include lightning discharges and navigational signals}
}
@article{5974998,
author={{Ernstmeyer J.} and {Chang T.}},
title={Lightning-induced electron heating in the mesosphere},
journal={Geophysical Research Letters},
volume={25},
number={13},
pages={2389-92},
year={1998},
abstract={A multiple-fluid, quasi-electrostatic simulation model is used to
examine the effects of lightning on the atmosphere between 20 km and 90 km
altitude. Two principal new results are obtained; (1) first, significant space
charge is found in the altitude range 20 to 40 km during a positive, but not
negative, cloud-to-ground (CG) discharge. (2) Second, a lightning flash is
shown to increase total conductivity in the altitude range of 20 to 40 km by at
least an order of magnitude, 10 s after the discharge. This is due to the
lingering effects of the ion and electron redistribution caused by the
lightning discharge}
}
@article{5914908,
author={{Bell T.F.} and {Reising S.C.} and {Inan U.S.}},
title={Intense continuing currents following positive cloud-to-ground lightning associated with red sprites},
journal={Geophysical Research Letters},
volume={25},
number={8},
pages={1285-8},
year={1998},
abstract={{In July-August 1996 Stanford University carried out broadband
ELF/VLF measurements of the magnetic field radiated by positive cloud-to-ground
(CG) discharges associated with Red Sprites. The authors report these
measurements for 17 sprite associated discharges that occurred during a 15
minute period on August 1 1996. The current and charge moments for each of the
events are deduced and it is found that in every case intense continuing
currents of ~1 ms duration are responsible for most of the positive charge
transfer to ground that precedes the appearance of the sprite. The time delay
between the causative positive discharge and the video field in which the
sprite first appeared varied from 0 to 15 ms for the larger events to as much
as 100 ms for the smaller events. The authors suggest that in the smaller
events the removal of significant positive charge during this delay interval is
accomplished through a horizontal intracloud discharge}},
}
@article{5914907,
author={{Cummer S.A.} and {Inan U.S.} and {Bell T.F.} and {Barrington-Leigh C.P.}},
title={ELF radiation produced by electrical currents in sprites},
journal={Geophysical Research Letters},
volume={25},
number={8},
pages={1281-4},
year={1998},
abstract={Measurements of ELF-radiating currents associated with
sprite-producing lightning discharges exhibit a second current peak
simultaneous in time with sprite luminosity, suggesting that the observed ELF
radiation is produced by intense electrical currents flowing in the body of the
sprite}
}
@article{5897451,
author={{Wauben W.M.F.} and {Fortuin J.P.F.} and {van Velthoven P.F.J.} and {Kelder H.M.}},
title={Comparison of modeled ozone distributions with sonde and satellite observations},
journal={Journal of Geophysical Research},
volume={103},
number={D3},
pages={3511-30},
year={1998},
abstract={The global distribution of ozone in the troposphere and lower
stratosphere calculated with a three-dimensional chemistry transport model
driven by European Centre for Medium-Range Weather Forecasts (ECMWF)-analyzed
meteorological fields has been compared with observed ozonesonde profiles. This
comparison is presented in a new graphical format, which shows in a single
panel the vertical and seasonal dependence. The modeled ozone profiles compare
reasonably well with climatological ozonesonde data for various stations all
over the world, especially if the variability of the ozone concentrations is
taken into account. However, the ozone mixing ratios in the upper troposphere
and lower stratosphere at midlatitudes are generally overestimated by the
model. This is probably caused by a combination of an overestimation of the
stratosphere-troposphere exchange and the absence of heterogeneous reactions in
the lower stratosphere which reduce ozone. The latitudinal dependence and
seasonal dependence of the observations are reproduced by the model
calculations, except for the ozone concentrations at the surface. This might be
due to the neglect of nonmethane hydrocarbons, which give rise to photochemical
ozone production during summer, although other factors such as emissions and
deposition cannot be ruled out. The ozone column density obtained by combining
calculated ozone distributions up to 50 hPa with climatological zonal mean data
for ozone above 50 hPa compares reasonably well with total ozone mapping
spectrometer (TOMS) observations. In this study a methane and carbon monoxide
oxidation chemistry scheme has been employed without stratospheric chemistry.
Furthermore, the comparison of TOMS total ozone observations in the tropics
with model calculations seems to suggest that the treatment of ozone precursors
such as the NO, emissions by lightning and biomass burning needs to be
improved}
}
@article{5876248,
author={{Kraus A.B.}},
title={Global distribution of tropospheric NO/sub x/: a three-dimensional model study},
journal={},
volume={},
number={},
pages={},
year={1997},
abstract={The nitrogen oxides NO and NO/sub 2/, which are lumped into NO/sub
X/, play a dual role in tropospheric chemistry. On the one hand they are the
most important species with respect to the net tropospheric ozone production,
on the other hand they control the concentration of the hydroxyl radical. Thus,
the distribution of NO/sub X/ must be known before distributions of these two
species can be calculated. However, because of the short chemical lifetime and
the resulting high temporal and spatial variability of NO/sub X/, this
distribution is difficult to determine by measurements, at least on a global
scale. In the present study an existing three-dimensional chemical tracer model
was extended in order to characterize the global distribution of tropospheric
NO/sub X/. This was done by implementing a known, linear NO/sub X/ chemistry
scheme and emission scenarios for the following six sources of tropospheric
NO/sub X/: fossil fuel combustion, soil microbial activity, lightning
discharges, biomass burning, downward transport from the stratosphere, and
aircraft emissions. Since the uncertainty of each of these sources is a factor
of 2 at least, the resulting global NO/sub X/ distributions are associated with
corresponding uncertainties as well. A new parametrization was developed for
the lightning source in which the relative distribution of global lightning
activity is derived from the convection statistics included in the present
model. Two parameters are used to weight individual convection convection
events according to observed monthly mean relative lightning distributions. The
relative distributions are scaled by an absolute emission rate derived from
global estimates}
}
@article{5833926,
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},
pages={56-9},
year={1997},
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}
}
@article{5823846,
author={{Orville R.E.} and {Silver A.C.}},
title={Lightning ground flash density in the contiguous United States: 1992-95},
journal={Monthly Weather Review},
volume={125},
number={4},
pages={631-8},
year={1997},
abstract={Cloud-to-ground lightning data for the years 1992-95 have been
analyzed for geographical distribution of total flashes, positive flashes, and
the percentage of flashes that lower positive charge to ground. In the
contiguous United States the measured total cloud-to-ground lightning flash
counts were 16.3 million (1992), 24.2 million (in both 1993 and 1994), and 22.3
million in 1995. The maximum flash densities occurred in Florida in 1992 (9-11
flashes per square kilometer) and in the Midwest in 1993 (11-13 flashes per
square kilometer), coinciding with the storms and floods that dominated the
summer of 1993 in the Midwest. In 1994, the area of maximum flash density was
again in Florida (11-13 flashes per square kilometer). In 1995, the flash
density maxima (911 km/sup -2/) were in southern Louisiana and near the
Kentucky-Illinois border. Positive flash densities had maxima in the Midwest in
all four years with values of 0.4 (1992), 1.0 (1993), 0.7 (1994), and 1.8
flashes per square kilometer (1995). The annual mean percentage of flashes that
lowered positive charge to ground was between 4% and 5% for the three years,
1992-94, but increased to 9.3% in 1995. The monthly values of the percentage of
positive flashes ranged from 3% (August 1992) to 258 (December 1993). The
positive flash maxima in the Midwest appear to be near the geographical areas
in which cloud-ionosphere discharges (sprites) have been reported}
}
@article{5808746,
author={{Yukhimuk V.} and {Roussel-Dupre R.} and {Symbalisty E.} and {Taranenko Y.}},
title={Optical, radio and X-ray radiation of red sprites produced by runaway air breakdown},
journal={Proceedings XXIII International Conference on Phenomena in Ionized Gases (ICPIG)},
volume={},
number={},
pages={52-3 vol.3},
year={1997},
abstract={We use the runaway air breakdown model of upward discharges to
calculate optical, radio, and X-ray radiation generated by red sprites. Red
sprites are high altitude (up to 90 km) lightning discharges. Aircraft based
observations (Sentman et al., 1995) show that sprites are predominantly red in
color at altitudes above ~55 km with faint blue tendrils, which extend downward
to an altitude of 40 km; the duration of a single sprite is less than 17 ms,
their maximum brightness is about 600 kR, and estimated total optical energy is
about 1-5 kJ per event. The ground based observations show similar results, and
provide some additional information on spatial and temporal structure of
sprites (Winckler et al., 1996), and on sprite locations (Lyons et al., 1996).
One difference between aircraft and ground-based observations is that blue
tendrils are rarely observed from the ground. Sprites usually occur above the
anvils of large mesoscale convective systems and correlate with strong positive
cloud to ground discharge (Boccipicio et al., 1995). Upward discharges are the
most probable source of X-ray emission observed above large thunderstorm
complexes by the Compton Gamma-ray Observatory (Fishman et al., 1994). To
escape the atmosphere these gamma -rays must originate above 25 km altitude.
Red sprites are usually observed at altitudes higher than 50 km, and are
therefore a likely source of this X-ray emission}
}
@article{5808727,
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},
journal={Proceedings XXIII International Conference on Phenomena in Ionized Gases (ICPIG)},
volume={},
number={},
pages={12-13 vol.3},
year={1997},
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}},
}
@article{5807430,
author={{Hocking W.K.}},
title={Recent advances in radar instrumentation and techniques for studies of the mesosphere, stratosphere, and troposphere},
journal={Radio Science},
volume={32},
number={6},
pages={2241-70},
year={1997},
abstract={There have been significant advances in
mesosphere-stratosphere-troposphere (MST) radar studies. This is true with
respect to studies ranging from MF through VHF and up to UHF. These advances
have been in each of the areas of equipment, techniques, and general radar
theory. In this paper we highlight some of these advances and discuss their
significance in the longer-term application of MST radar techniques. We
concentrate primarily on discussion about instrumentation and the raw products
(powers, radial velocities, and spectral widths) produced by the systems, with
some reference to the nature of the radio wave scattering entities. Quantities
which are derived from the measurements of these raw quantities like gravity
wave fluxes, tidal studies, and so forth will not generally be considered in
any detail. Sample advances include new methods of data analysis (both on-line
and post-collection), lightning detection, rainfall measurement, and
temperature determination. Other interesting applications include simultaneous
application of MST techniques with other procedures such as in radio acoustic
sounding (RASS) and the artificial periodic inhomogeneity (API) method. Areas
of advance in terms of understanding scattering mechanisms include new insights
into the controversy about the nature of aspect-sensitive scattering (specular
reflection compared with anisotropic turbulence) and improvements and
refinements in our measurements of turbulence with these radars. The paper will
concentrate on radars which can employ clear-air scattering}
}
@article{5776779,
author={{Lehtinen N.G.} and {Bell T.F.} and {Pasko V.P.} and {Inan U.S.}},
title={A two-dimensional model of runaway electron beams driven by quasi-electrostatic thundercloud fields},
journal={Geophysical Research Letters},
volume={24},
number={21},
pages={2639-42},
year={1997},
abstract={Intense, transient quasi-electrostatic (QE) fields, which exist above
thunderclouds following a positive cloud-to-ground lightning discharge, can
produce an upward travelling runaway electron (REL) beam. A new two-dimensional
(2D) REL-QE model is developed, expanding the previously reported 1D model
[Bell et al., 1995] and incorporating the QE [Pasko et al., 1997] and the
electrostatic heating (ESH) [Pasko et al., 1997] models. The new model gives
the lateral electron distribution in the beam and allows us to determine the
ionospheric effects and the optical luminosities resulting from the
simultaneous action of the QE fields on the ambient electrons and the runaway
electrons. The model is self-consistent and includes the changes in space
charge and conductivity due to the REL. Optical emissions and gamma -ray
emissions [Lehtinen et al., 1996] are calculated and compared to experimental
observations of sprites and terrestrial gamma -ray flashes (TGF). It is shown
that the structure of the electric field and the optical emissions can be
significantly affected by the REL}
}
@article{5770968,
author={{Flatoy F.} and {Hov O.}},
title={NO/sub x/ from lightning and the calculated chemical composition of the free troposphere},
journal={Journal of Geophysical Research},
volume={102},
number={D17},
pages={21373-81},
year={1997},
abstract={In the free troposphere, injection from the stratosphere, emissions
at the surface transported upward by dynamic processes, aircraft emissions and
production in lightning strokes are the main sources of oxides of nitrogen
(NO/sub x/). The global source of NO/sub x/ production by lightning is not well
known and estimates vary from 3 to 650 Mt NO/sub 2//yr. In this paper the role
of regional and episodic emissions of NO/sub x/ from lightning is examined with
a three-dimensional chemistry transport model, and a parameterization of the
emissions is proposed, linking it to the intensity of latent heat generation in
convection calculated in a numerical weather prediction model. The
parameterization is scaled to give an annual global emission of 16 MtNO/sub
2//yr. The resulting distribution of the concentration of NO/sub x/, ozone, OH
and nonmethane hydrocarbons is compared for the free troposphere over the
northern hemisphere with the results of a calculation where the total NO/sub x/
emissions from lightning were about the same but were fixed in time and space
over the 18 day calculation (June 18 to July 5, 1995). The maximum differences
in the free tropospheric concentrations are significant: for NO/sub x/, OH and
nonmethane hydrocarbon of the same order of magnitude as the concentrations
themselves, for ozone 1 order of magnitude less than the ozone concentration.
This means that NO/sub x/ emissions from lightning may cause a variability in
free tropospheric composition which makes it quite difficult to distinguish the
importance of other sources of free tropospheric NO/sub x/ from that of
lightning in periods when lightning occurs}
}
@article{5727373,
author={{Jenkins G.S.} and {Mohr K.} and {Morris V.R.} and {Arino O.}},
title={The role of convective processes over the Zaire-Congo Basin to the southern hemispheric ozone maximum},
journal={Journal of Geophysical Research},
volume={102},
number={D15},
pages={18963-80},
year={1997},
abstract={During October, satellite measurements show that there is a region of
elevated tropospheric ozone over the tropical southern Atlantic Ocean. The
cause of the high ozone concentrations has been related to biomass burning in
South America and Africa. In this paper, we present evidence from satellite
sources, European Center for Medium-Range Weather Forecast analyses, and a
mesoscale simulation during October, suggesting that afternoon and evening deep
convection in central Africa is responsible for some of the abnormally high
concentrations of ozone in the tropical South Atlantic which extend southeast
over southern Africa into the Indian Ocean. The mechanisms for enhancing
tropospheric O/sub 3/ includes (1) the removal of ozone, NO/sub x/, and
hydrocarbon rich air from fires in eastern Africa within the planetary boundary
layer to the middle and upper troposphere by deep convection; (2) the
production of NO/sub x/ from lightning associated with mesoscale convective
systems and the subsequent photochemical production of O/sub 3/, and (3) the
entrainment of O/sub 3/ rich air from the lower stratosphere into the upper
troposphere by deep convection. During the next few years an international
field campaign in central Africa (the experiment for regional sources and sinks
of oxidants-EXPRESSO), global lightning data, and the launch of the Tropical
Rainfall Measuring Mission (TRMM) will help to identify the relative importance
of each of the processes over central Africa that could be responsible for high
O/sub 3/ concentrations over the tropical south Atlantic}
}
@article{5661080,
author={{Cummer S.A.} and {Inan U.S.}},
title={Measurement of charge transfer in sprite-producing lightning using ELF radio atmospherics},
journal={Geophysical Research Letters},
volume={24},
number={14},
pages={1731-4},
year={1997},
abstract={{Transient high altitude optical emissions referred to as "sprites"
are believed to occur as a result of the transfer of large amounts of charge
(~100-300 C) from cloud altitudes of 5-10 km to the ground. Using a general
subionospheric ELF propagation model the authors quantitatively interpret
magnetic field waveforms of ELF radio atmospherics originating in mid-western
U.S. lightning discharges and observed at Stanford (~1800 km range) to
determine the temporal variation of the lightning current and thereby measure
the charge transfer during the stroke. For 6 sprite-producing lightning current
waveforms observed on July 24 1996 the authors find that 25 to 325 coulombs of
charge was transferred during the first 5 ms of the discharges assuming a 10 km
altitude for the initial charge}},
}
@article{5627014,
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 Communication Engineers B-II},
volume={J80B-II},
number={5},
pages={387-96},
year={1997},
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}
}
@article{5626094,
author={{Nemiroff R.J.} and {Bonnell J.T.} and {Norris J.P.}},
title={Temporal and spectral characteristics of terrestrial gamma flashes},
journal={Journal of Geophysical Research},
volume={102},
number={A5},
pages={9659-65},
year={1997},
abstract={{The authors have analyzed the Burst and Transient Source Experiment
(BATSE) high-resolution timing data for 13 terrestrial gamma flashes (TGFs) to
better characterize this newly identified phenomenon which may be related to
atmospheric lightning. They find that the minimum timescale for TGF variability
is ~25-250 mu s with 50 mu s near typical. In general TGFs are spectrally much
harder than cosmic gamma ray bursts (GRBs). They additionally find that as with
GRBs individual pulses within a TGF tend to peak earlier at higher energies.
This time-asymmetry rules out models such as sweeping beams. They also find
that different pulses can have different spectra with spectra typically
softening as a pulse progresses. Event-averaged spectra for the TGFs were
examined and found to be better fit in the 25-500 keV range by a power law than
by a blackbody model. However in general even a power law is not a perfect fit.
They find correlation between minimum TGF timescale and the power law spectral
index with rapidly varying TGFs appearing softer. From empirical comparisons of
timescales and structures they speculate that if TGFs are somehow related to
known high-atmospheric lightning events then they are more probably related to
red sprites than to blue jets or transionospheric pulse pairs}},
}
@article{5608394,
author={{Rodger C.J.} and {Wait J.R.} and {Dowden R.L.}},
title={Electromagnetic scattering from a group of thin conducting cylinders},
journal={Radio Science},
volume={32},
number={3},
pages={907-12},
year={1997},
abstract={Solutions are given for the problem of scattering of plane waves from
an arbitrary number of vertical columns that are thin in terms of the incident
wavelength. The electric properties of the cylinders are taken as homogenous
and isotropic but otherwise arbitrary, and the incident electric field vector
is taken to be parallel to the axis of the cylinders. The scattering solution
for individual columns is described, which is used to introduce that for
multiple columns under the Born approximation. A more general approach is
presented that leads to a solution which includes multiple scattering
(coupling) between the cylinders. Comparison is made between this solution for
a ring of cylindrical elements and one that treats the scattering from the ring
as a whole. The theory described here is being extended and applied to the
scattering from vertical ionized columns known as "sprites". These are
associated with lightning discharges between the ionosphere and cloud tops}
}
@article{5602399,
author={{Miyamura K.} and {Nagano I.} and {Yagitani S.} and {Murakami Y.}},
title={Full wave calculation of 3D VLF/LF wave fields radiated from a lightning discharge},
journal={Proceedings of ISAP'96 - International Symposium on Antennas and Propagation},
volume={},
number={},
pages={701-4 vol.3},
year={1996},
abstract={Recently new types of luminous phenomena in the lower ionosphere
associated with strong lightning discharges called blue jets and sprites have
been discovered. A hypothesis that VLF/LF electromagnetic waves radiated from
the lightning discharge might trigger those phenomena was proposed by some
investigators. We discuss the frequency dependence of electromagnetic wave
structures in the lower ionosphere radiated from a lightning discharge by the
full wave method. A huge calculation is carried out with parallel virtual
machine (PVM) software using a few tens of workstations connected by a network.
These results can be also extended to a time domain transient analysis of wave
propagation from a pulse current of a lightning discharge}
}
@article{5580211,
author={{Milikh G.M.} and {Valdivia J.A.} and {Papadopoulos K.}},
title={Model of red sprite optical spectra},
journal={Geophysical Research Letters},
volume={24},
number={8},
pages={833-6},
year={1997},
abstract={A synthetic spectrum of red sprites due to electron energization by
the electric field from lightning is computed by using the electron energy
spectrum obtained from a Fokker-Planck code, which includes various inelastic
losses. The results are compared with observed sprite spectra. Implications to
models of red sprites are presented}
}
@article{5578444,
author={{Nemiroff R.J.} and {Bonnell J.T.} and {Norris J.P.}},
title={Temporal and spectral characteristics of terrestrial gamma flashes},
journal={AIP Conference Proceedings},
volume={},
number={384},
pages={990-4},
year={1996},
abstract={{Analyzes the BATSE high time resolution data for several terrestrial
gamma flashes (TGFs) to characterize this newly identified phenomenon which may
be related to atmospheric lightning. The minimum timescale for TGF variability
is 40-250 mu s. In general TGFs are spectrally much harder than cosmic
gamma-ray bursts (GRBs) but as in GRBs pulses within a TGF tend to peak earlier
at higher energies and can have different spectra. Spectra for several TGFs
were examined and found to be better fit in the 25-500 keV range by a power-law
than a black body model. From empirical comparisons the authors speculate that
if TGFs are related to known high-atmospheric lightning events then they are
more probably related to red sprites than to blue jets or trans-ionospheric
pulse pairs}},
}
@article{5549062,
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},
pages={29641-52},
year={1996},
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 20-25000 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}},
}
@article{5542297,
author={{Wescott E.M.} and {Sentman D.D.} and {Heavner M.J.} and {Hallinan T.J.} and {Hampton D.L.} and {Osborne D.L.}},
title={The optical spectrum of aircraft St. Elmo's fire},
journal={Geophysical Research Letters},
volume={23},
number={25},
pages={3687-90},
year={1996},
abstract={On February 26, 1995, during a NASA sponsored mission to Peru to
study red sprites and blue jets, the instrumented Westwind 2 jet aircraft
encountered spectacular St. Elmo's fire from the wing pods, tail and nose while
flying through a cloud at an altitude of 13.83 km (45376 ft). The phenomenon
was captured on low light level monochromatic and color television systems
aboard the aircraft, and its spectrum was recorded on a low light level TV
spectrograph with response from 395.0 to 750.0 nm. The cameras and spectrograph
also recorded scattered intra-cloud lightning and a possible lightning
discharge near, or to, the aircraft. The spectrum of St. Elmo's fire was
primarily the second (2nd) positive bands of N/sub 2/. The data were consistent
with a population of electrons having relatively low energy (<18 eV)}
}
@article{5516509,
author={{Zheng J.} and {Weinheimer A.J.} and {Ridley B.A.} and {Liu S.C.} and {Sachse G.W.} and {Anderson B.H.} and {Collins J.H. Jr.}},
title={Analysis of small- and large-scale increases of reactive nitrogen observed during the Second Airborne Arctic Stratospheric Expedition},
journal={Journal of Geophysical Research},
volume={101},
number={D22},
pages={28805-16},
year={1996},
abstract={{An analysis of the data obtained during AASE II was made to
characterize small- ( delta x<24 km) and large-scale (30< delta x<260 km)
increases of reactive nitrogen species. By using the NO/sub x//NO/sub y/ ratio
the increases were classified into fresh emissions and aged air parcels. The
sources of the NO/sub y/ increases were then assessed by the freshness of the
increases and by examining the correlation (or absence thereof) between NO/sub
y/ and other trace species including tracers of various NO/sub x/ sources: for
example aircraft emissions lightning the stratospheric source and sources in
the boundary layer. The authors found that the majority (43%) of NO/sub y/
increases in the upper troposphere and lower stratosphere were due to
displacement of constant mixing ratio surfaces relative to isobaric flight
paths. Aircraft emissions were the second most abundant (17%). The next
significant contributor was surface emissions including fossil fuel combustion
and biomass burning. Only two lightning spikes were found apparently due to the
winter season and emphasis on high latitudes in the AASE II experiment. The
relative contribution from each source to the increases (or positive
variability) represents a measure of the relative source strength. However it
is important to note that the authors' findings on the relative contribution of
each source to the increases should not be applied directly to estimating the
relative source strength of the ambient or background NO/sub y/ abundance.
Knowledge of the detailed temporal and spatial distribution of the relative
contribution of each source is needed. This requires a substantially higher
precision for the instruments of tracer gases than those used in this study}},
}
@article{5469047,
author={{Jacob D.J.} and {Heikes B.G.} and {Fan S.-M.} and {Logan J.A.} and {Mauzerall D.L.} and {Bradshaw J.D.} and {Singh H.B.} and {Gregory G.L.} and {Talbot R.W.} and {Blake D.R.} and {Sachse G.W.}},
title={Origin of ozone and NO/sub x/ in the tropical troposphere: a photochemical analysis of aircraft observations over the South Atlantic basin},
journal={Journal of Geophysical Research},
volume={101},
number={D19},
pages={24235-50},
year={1996},
abstract={The photochemistry of the troposphere over the South Atlantic basin
is examined by modeling of aircraft observations up to 12-km altitude taken
during the TRACE A expedition in September-October 1992. A close balance is
found in the 0 to 12-km column between photochemical production and loss of
O/sub 3/, with net production at high altitudes compensating for weak net loss
at low altitudes. This balance implies that O/sub 3/ concentrations in the 0-12
km column can be explained solely by in situ photochemistry; influx from the
stratosphere is negligible. Simulation of H/sub 2/O/sub 2/, CH/sub 3/OOH, and
CH/sub 2/O concentrations measured aboard the aircraft lends confidence in the
computations of O/sub 3/ production and loss rates, although there appears to
be a major gap in current understanding of CH/sub 2/O chemistry in the marine
boundary layer. The primary sources of NO/sub x/ over the South Atlantic Basin
appear to be continental (biomass burning, lightning, soils). There is evidence
that NO/sub x/ throughout the 0 to 12-km column is recycled from its oxidation
products rather than directly transported from its primary sources. There is
also evidence for rapid conversion of HNO/sub 3/ to NO/sub x/ in the upper
troposphere by a mechanism not included in current models. A general
representation of the O/sub 3/ budget in the tropical troposphere is proposed
that couples the large-scale Walker circulation and in situ photochemistry.
Deep convection in the rising branches of the Walker circulation injects NO/sub
x/ from combustion, soils, and lightning to the upper troposphere, leading to
O/sub 3/ production; eventually, the air subsides and net O/sub 3/ loss takes
place in the lower troposphere, closing the O/sub 3/ cycle. This scheme implies
a great sensitivity of the oxidizing power of the atmosphere to NO/sub x/
emissions in the tropics}
}
@article{5468955,
author={{Kraus A.B.} and {Rohrer F.} and {Grobler E.S.} and {Ehhalt D.H.}},
title={The global tropospheric distribution of NO/sub x/ estimated by a three-dimensional chemical tracer model},
journal={Journal of Geophysical Research},
volume={101},
number={D13},
pages={18587-604},
year={1996},
abstract={The global distribution of NO/sub x/ in the troposphere is calculated
using a simple three-dimensional chemical tracer model. This model includes a
simplified chemistry scheme for the tracers NO/sub x/ identical to NO+NO/sub 2/
and HNO/sub 3/, which are redistributed by advection, dry and wet convection,
and large-scale diffusion. The sources of NO/sub x/ considered are fossil fuel
combustion, emissions from soil microbial activity, biomass burning, lightning
discharges, emissions by aircraft, and downward transport from the
stratosphere. Dry and wet deposition act as final sinks. At northern middle and
high latitudes the calculated tropospheric NO/sub x/ content is dominated by
the surface sources, fossil fuel combustion in particular. In the tropical free
troposphere, lightning discharges provide about 80% of the total NO/sub x/
throughout the year. The zonally averaged fractional contribution of aircraft
emissions strongly depends on the season. The largest contribution of this
source, over 60%, occurs during January in the upper troposphere between 45
degrees N and 60 degrees N. The NO mixing ratios determined by the model show
good overall agreement with vertical profiles measured during the Stratospheric
Ozone Experiment (STRATOZ) III aircraft campaign}
}
@article{5414331,
author={{Wescott E.M.} and {Sentman D.D.} and {Heavner M.J.} and {Hampton D.L.} and {Osborne D.L.} and {Vaughan O.H. Jr.}},
title={Blue starters: brief upward discharges from an intense Arkansas thunderstorm},
journal={Geophysical Research Letters},
volume={23},
number={16},
pages={2153-6},
year={1996},
abstract={{Documents the first observations of a new stratospheric electrical
phenomenon associated with thunderstorms. On the night of 30 June (UT 1 July)
1994 30 examples of these events which the authors have called "blue starters"
were observed in a 6 m 44 s interval above the very energetic Arkansas
thunderstorm where blue jets were first observed. The blue starters are
distinguished from blue jets by a much lower terminal altitude. They are bright
and blue in color and protrude upward from the cloud top (17-18 km) to a
maximum 25.5 km (83655 ft.) in altitude. All blue starters events were recorded
from two small areas near Texarkana Texas/Arkansas where hail 7.0 cm in
diameter was falling. Comparison to cloud-to-ground (CG) lightning flashes
revealed: 1. Blue starters were not observed to be coincident with either
positive or negative CG flashes but they do occur in the same general area as
negative CG flashes} and {2. Cumulative distributions of the negative CG
flashes in +or-5 s before and after the starter and within a radius of 50 km
shows a significant reduction for about 3 s following the event in the two
cells where starters and jets were observed. The energy deficit is
approximately 10/sup 9/ J. It is possible that blue starters are a short-lived
streamer phenomenon}},
}
@article{5340467,
author={{Kohler I.} and {Sausen R.} and {Reinberger R.}},
title={Contributions of aircraft emissions to the atmospheric NO/sub x/ content},
journal={},
volume={},
number={},
pages={},
year={1996},
abstract={The relative contribution of aircraft emissions to the total
atmospheric NO/sub x/ content is studied by means of the atmosphere general
circulation model ECHAM, which was extended by a simplified (linear) NO/sub x/
chemistry module with NO/sub x/ and HNO/sub 3/ as prognostic variables. NO/sub
x/ originates from fossil fuel combustion, biomass burning, soil microbial
activity, lightning, degradation of N/sub 2/O in the stratosphere, and aircraft
emissions. NO/sub 2/ and HNO/sub 3/ are removed by dry deposition, HNO/sub 3/
additionally by wet deposition. A simulation in seasonal cycle mode was
performed. Both, the resulting January and July mean distributions of NO/sub x/
and the relative contributions of the different sources to the total
atmospheric NO/sub x/ burden are analysed, including their uncertainty ranges.
NO/sub x/ emissions from aircraft cause a significant change to the background
NO/sub x/ concentration. During January more than 60% of the NO/sub x/
emissions found in the region between 30 degrees N and 60 degrees N, and 175
hPa to 325 hPa arise from aircraft. The maximum value in the North Atlantic
flight corridor is found to be larger than 85%. During July aircraft emissions
contribute only about 20% to the NO/sub x/ burden in this region. In January
and July the uncertainty ranges of these contributions are 42% to 80% and 10%
to 37%, respectively}
}
@article{5300202,
author={{Inan U.S.} and {Slingeland A.} and {Pasko V.P.} and {Rodriguez J.V.}},
title={VLF and LF signatures of mesospheric/lower ionospheric response to lightning discharges},
journal={Journal of Geophysical Research},
volume={101},
number={A3},
pages={5219-38},
year={1996},
abstract={{New evidence is presented of disturbances of the electrical
conductivity of the nighttime mesosphere and the lower ionosphere in
association with lightning discharges. In addition to extensive documentation
of the characteristics of a class of events heretofore referred to as
early/fast VLF events Inan et al. (1993) the present authors` data reveal a new
feature of these events consisting of a postonset peak that typically lasts for
1-2 s. They also report the observation of short-duration VLF or LF
perturbations in which the amplitude of the subionospheric signal exhibits a
sudden change within 20 ms of the causative lightning discharge and recovers
back to its original level in <3 s. These short-duration events have
characteristics similar to the previously observed rapid onset rapid decay VLF
signatures Doulden et al. (1994). Both the typical and rapidly recovering
events are observed primarily when the causative lightning discharge is within
+or-50 km of the VLF or LF great circle propagation path indicating that the
scattering from the localized disturbance is highly collimated in the forward
direction. The latter in turn implies that for the parameters in hand the
transverse extent of the disturbance must be at least ~100-150 km. The measured
VLF signatures are compared with the predictions of a three-dimensional model
of subionospheric VLF propagation and scattering in the presence of localized
ionospheric disturbances produced by electromagnetic impulses and
quasi-electrostatic QE fields produced by lightning discharges. The rapidly
recovering or short-duration events are consistent with the heating of the
ambient electrons by quasi-static electric fields in cases when heating is not
intense enough to exceed-the attachment or ionization thresholds. When no
significant electron density changes occur the conductivity changes due to
heating alone last only as long as the QE fields typically less than a few
seconds. When heating is intense enough so that attachment or ionization
thresholds are exceeded reductions or enhancements in electron density can
respectively occur in which case the medium would relax back to the ambient
conditions with the time scales of the local D-region chemistry typically
10-100 s}},
}
@article{5294479,
author={{Marshall T.C.} and {Stolzenburg M.} and {Rust W.D.}},
title={Electric field measurements above mesoscale convective systems},
journal={Journal of Geophysical Research},
volume={101},
number={D3},
pages={6979-96},
year={1996},
abstract={{The authors show that electric field discontinuities occur above the
stratiform clouds associated with mesoscale convective systems. Above cloud top
12 discontinuities were observed at altitudes between 10 and 16 km. The field
changes of the discontinuities ranged from -1.1 to -4.0 kV m/sup -1/. The data
suggest that the electric field discontinuities were caused by coincident
positive cloud-to-ground lightning flashes. The coincident ground flashes
included both single and multiple return stroke flashes with first-stroke peak
currents between 20 and 154 kA. The authors modeled the electric field change
that would occur if lightning discharged a horizontally extensive positive
charge layer within the stratiform cloud. In the model disks with charge
densities of 1 and 3 nC m/sup -3/ a thickness of 400 m and diameters ranging
from 20 to 200 km were discharged and produced field changes similar to the
observed above-cloud field discontinuities. The authors` results support the
idea that sprites may be initiated by above-cloud field changes caused by
positive cloud-to-ground lightning flashes that discharge a horizontally
extensive charge region in the stratiform cloud of a mesoscale convective
system. During the time between the electric field discontinuities the electric
field above the stratiform clouds was -0.5 to -1.0 kV m/sup -1/} and {this
field may be important in the global electrical circuit because the stratiform
clouds have large horizontal extents (~10/sup 4/ km/sup 2/)}},
}
@article{5294472,
author={{Poulida O.} and {Dickerson R.R.} and {Heymsfield A.}},
title={Stratosphere-troposphere exchange in a midlatitude mesoscale convective complex. 1. Observations},
journal={Journal of Geophysical Research},
volume={101},
number={D3},
pages={6823-36},
year={1996},
abstract={{On June 28 1989 a severe thunderstorm over North Dakota developed
into a squall line and then into a mesoscale convective complex (MCC) with
overshooting tops as high as ~14 km and a cirrus anvil that covered more than
3*10/sup 5/ km/sup 2/. The authors describe the trace gas concentrations prior
to in and around the storm. The anvil outflow sampled at altitudes of 10.8 to
12.2 km extended well into what used to be the stratosphere. Air inside the
anvil was characterized by notably low concentrations of O/sub 3/ and high CO
relative to the out-of-cloud environment. Elevated concentrations of NO and
NO/sub y/ due to lightning and upward transport were observed in the anvil. A
tongue of air with tropospheric characteristics lay above stratospheric air
showing that extensive stratosphere-troposphere exchange had occurred. The
authors estimate a minimum flux of 2*10/sup 10/ g of O/sub 3/ into the
troposphere and a maximum flux of 3-7*10/sup 13/ g of H/sub 2/O into the
stratosphere. This is a greater flux of water than the stratospheric water
budget can support and thus most of this water must return to the troposphere}
and {the ice crystals were of sufficient size to have substantial settling
velocity. If however even a small fraction of the mass of such anvils remains
in the stratosphere then convective transport of reactive tropospheric trace
species such as NO/sub y/ CO and non-methane hydrocarbons may dominate the
chemistry of the lower stratosphere in this midlatitude region}},
}
@article{5259375,
author={{Brasseur G.P.} and {Muller J.-F.} and {Granier C.}},
title={Atmospheric impact of NO/sub x/ emissions by subsonic aircraft: a three-dimensional model study},
journal={Journal of Geophysical Research},
volume={101},
number={D1},
pages={1423-8},
year={1996},
abstract={{Three-dimensional model calculations suggest that the world`s fleet
of subsonic aircraft has enhanced the abundance of nitrogen oxides in the upper
troposphere by up to 20-35% and has produced a significant increase in the
ozone concentration in this region of the atmosphere (4% in summer and 1% in
winter). In year 2050 on the basis of current scenarios for growth in aviation
the concentration of NO/sub x/ at 10 km could increase by 30-60% at
midlatitudes and the concentration of ozone could be enhanced by 7% and 2% in
summer and winter respectively (relative to a situation without aircraft
effects). The perturbation is not limited to the flight corridors but affects
the entire northern hemisphere. The magnitude (and even the sign) of the ozone
change depends on the level of background atmospheric NO/sub x/ and hence on
NO/sub x/ sources (lightning intrusion from the stratosphere and convective
transport from the polluted boundary layer) and sinks which are poorly
quantified in this region of the atmosphere. On the basis of the authors` model
estimates 20% of the NO/sub x/ found at 10 km (midlatitudes) is produced by
aircraft engines 25% originates from the surface (combustion and soils) and
approximately 50% is produced by lightning. For a lightning source enhanced in
the model by a factor of 2 the increase in NO/sub x/ and ozone at 10 km due to
aircraft emissions is reduced by a factor of 2. The magnitude of aircraft
perturbations in NO/sub x/ is considerably smaller than the uncertainties in
other NO/sub x/ sources}},
}
@article{5221615,
author={{Rairden R.L.} and {Mende S.B.}},
title={Time resolved sprite imagery},
journal={Geophysical Research Letters},
volume={22},
number={24},
pages={3465-8},
year={1995},
abstract={Fleeting columns of luminosity occurring above large thunderstorms at
50-90 km altitude, presently known as sprites, were imaged with an intensified
video charge coupled device (CCD) camera during a July 1995 ground-based
campaign near Fort Collins, Colorado. These unfiltered intensified images
reveal detailed spatial structure within the sprite envelope. The temporal
resolution of standard interlaced video imagery is limited by the 60 fields per
second acquisition rate (16 ms). The specific CCD used, however, is subject to
bright events leaking into the readout registers, allowing time-resolution on
the order of the linescan rate (63 mu s). Typical sprite onset is found to
follow the associated cloud lightning by 1.5 to 4 ms. The onsets of the
individual sprites within a cluster are generally, but not always, simultaneous
to within 1 ms. Sprites tend to have a bright localized core, less than 2 km in
horizontal dimension, which rises to peak intensity within 0.3 ms and maintains
this level for 5 to 10 ms before fading over an additional 10 ms}
}
@article{5186324,
author={{Feldman W.C.} and {Symbalisty E.M.D.} and {Roussel-Dupre R.A.}},
title={Association of discrete hard X-ray enhancements with eruption of Mount Pinatubo},
journal={Journal of Geophysical Research},
volume={100},
number={A12},
pages={23829-34},
year={1995},
abstract={Hard X-ray fluxes in the energy range between 50 keV and 140 keV
measured using the Army Background Experiment are found to be associated with
the injection by Mount Pinatubo of a massive aerosol into the stratosphere June
14-15, 1991. Discrete X-ray enhancement events are observed to increase from an
average of 1.8 per month to 20 during a 1-month interval beginning 12 days
after the Mount Pinatubo eruption. Systematics of these enhancements suggests a
mechanism that requires a strong coupling between magnetospheric and
atmospheric processes, perhaps associated with upward lightning}
}
@article{5069293,
author={{Winckler J.R.}},
title={Further observations of cloud-ionosphere electrical discharges above thunderstorms},
journal={Journal of Geophysical Research},
volume={100},
number={D7},
pages={14335-45},
year={1995},
abstract={During the night of 9-10 August 1993 more than 150 luminous
cloud-ionosphere discharges (CIs) were observed above a thunderstorm complex
moving SE across the state of Iowa. Images of the CIs were obtained through
clear air by intensified CCD TV cameras at the O'Brien Observatory of the
University of Minnesota located about 60 km NE of Minneapolis and 250-500 km
from the storm center. The discharges consisted of bright vertical striations
extending from 50-80 km altitude, often covering tens of kilometers laterally,
with tendrils of decreasing intensity visible for the brighter events down to
cloud tops below 20 km altitude. All the more intense CIs were coincident with
a VLF sferic in the 300 Hz-12 kHz range, but small events often did not yield a
detectable sferic. There is no unambiguous evidence that CIs were sources of
sferics. Some of the CIs were observed to be coincident with a cloud
brightening and with a cloud-ground stroke recorded by the National Lightning
Detection Network. The duration of the images was generally less than one TV
field (<16.7 ms). Many of these discharges have now been observed by the space
shuttle, by aircraft-borne TV cameras and a large number by a ground-based
camera observations in Colorado. The present results are compared with these
observations and recent theoretical ideas related to the CI events are
discussed. It is proposed that CIs arise from intense bursts of cloud
electrification and may follow the preexisting paths of cloud-to-ionosphere
thunderstorm currents}
}
@article{5063357,
author={{Boccippio D.J.} and {Williams E.R.} and {Heckman S.J.} and {Lyons W.A.} and {Baker I.T.} and {Boldi R.}},
title={Sprites, ELF transients, and positive ground strokes},
journal={Science},
volume={269},
number={5227},
pages={1088-91},
year={1995},
abstract={In two summertime mesoscale convective systems (MCSs), mesospheric
optical sprite phenomena were often coincident with both large-amplitude
positive cloud-to-ground lightning and transient Schumann resonance excitations
of the entire Earth-ionosphere cavity. These observations, together with
earlier studies of MCS electrification, suggest that sprites are triggered when
the rapid removal of large quantities of positive charge from an areally
extensive charge layer stresses the mesosphere to dielectric breakdown}
}
@article{5023594,
author={{Sentman D.D.} and {Wescott E.M.}},
title={Red sprites and blue jets: thunderstorm-excited optical emissions in the stratosphere, mesosphere, and ionosphere},
journal={Physics of Plasmas},
volume={2},
number={6},
pages={2514-22},
year={1995},
abstract={Low light level monochrome television observations obtained from the
ground and from the space Shuttle, and low light level color and monochrome
television images obtained from aboard jet aircraft, have shown that intense
lightning in mesoscale thunderstorm systems may excite at least two distinct
types of optical emissions that together span the space between the tops of
some thunderstorms and the ionosphere. The first of these emissions, dubbed
"sprites," are luminous red structures that typically span the altitude range
60-90 km, often with faint bluish tendrils dangling below. A second, rarer,
type of luminous emission are "blue jets" that appear to spurt upward out of
the anvil top in narrow cones to altitudes of 40-50 km at speeds of
approximately 100 km/s. In the paper the principal observational
characteristics of sprites and jets are presented, and several proposed
production mechanisms are reviewed}
}
@article{4976048,
author={{Pasko V.P.} and {Inan U.S.} and {Taranenko Y.N.} and {Bell T.F.}},
title={Heating, ionization and upward discharges in the mesosphere due to intense quasi-electrostatic thundercloud fields},
journal={Geophysical Research Letters},
volume={22},
number={4},
pages={365-8},
year={1995},
abstract={Quasi-electrostatic fields that temporarily exist at high altitudes
following the sudden removal (e.g. by a lightning discharge) of thundercloud
charge at low altitudes are found to significantly heat mesospheric electrons
and produce ionization and light. The intensity, spatial extent, duration and
spectra of optical emissions produced are consistent with the observed features
of the red sprite type of upward discharges}
}
@article{4749869,
author={{Lelieveld J.} and {Crutzen P.J.}},
title={Role of deep cloud convection in the ozone budget of the troposphere},
journal={Science},
volume={264},
number={5166},
pages={1759-61},
year={1994},
abstract={Convective updrafts in thunderstorms prolong the lifetime of ozone
(O/sub 3/) and its anthropogenic precursor NO/sub x/ (nitric oxide
(NO)+nitrogen dioxide (NO/sub 2/)) by carrying these gases rapidly upward from
the boundary layer into a regime where the O/sub 3/ production efficiency is
higher, chemical destruction is slower, and surface deposition is absent. On
the other hand, the upper troposphere is relatively rich in O/sub 3/ and NO/sub
x/ from natural sources such as downward transport from the stratosphere and
lightning; convective overturning conveys the O/sub 3/ and NO/sub x/ toward the
Earth's surface where these components are more efficiently removed from the
atmosphere. Simulations with a three-dimensional global model suggest that the
net result of these counteractive processes is a 20 percent overall reduction
in total tropospheric O/sub 3/. However, the net atmospheric oxidation
efficiency is enhanced by 10 to 20 percent}
}
@article{4733310,
author={{Uman M.A.}},
title={Natural lightning},
journal={IEEE Transactions on Industry Applications},
volume={30},
number={3},
pages={785-90},
year={1994},
abstract={{The present understanding of natural lightning is reviewed. Research
on lightning has been motivated in part by the need to protect advanced
ground-based and airborne systems that utilize low voltage solid-state
electronics} and {by the desire to prevent spectacular accidents such as
occurred in 1969 during the launch of Apollo 12 and in 1987 during the launch
of Atlas-Centaur 67} and {and by the desire to elucidate the physics of one of
nature's most impressive phenomena. The author discusses lightning sources
natural lightning negative and positive cloud-to-ground lightning upward
lightning cloud discharges top-of-the cloud and clear air lightning lightning
avoidance and lightning protection}},
}
@article{4690747,
author={{Uman M.A.}},
title={Natural lightning},
journal={Proceedings of IEEE/IAS Industrial and Commercial Power Systems Annual Technical Conference (I&CPS)},
volume={},
number={},
pages={1-7},
year={1993},
abstract={The present understanding of natural lightning is reviewed. Specific
topics addressed include: sources of lightning; negative cloud-to-ground
lightning; positive cloud-to-ground lightning; upward lightning cloud
discharges; top-of-the-cloud and clear air lightning; and lightning avoidance
and protection}
}
@article{4250118,
author={{Vaughan O.H. Jr.} and {Blakeslee R.} and {Boeck W.L.} and {Vonnegut B.} and {Brook M.} and {McKune J. Jr.}},
title={A cloud-to-space lightning as recorded by the Space Shuttle payload-bay TV cameras},
journal={Monthly Weather Review},
volume={120},
number={7},
pages={1459-61},
year={1992},
abstract={Video images from space showing a single upward luminous discharge
into the clear night air above a thunderstorm were recorded for the first time
during the Space Shuttle STS-32 mission, and later during the STS-31 mission
and other missions using the Shuttle's payload-bay TV cameras. The upward
luminous discharge was seen to move out of the top of a single thunderstorm
during the flight of STS-31. This video image was taken at 0335:59 UTC 28 April
1990 while the shuttle was passing over Mauritania, northwest Africa. The storm
that had the luminous discharge was located at approximately 7.5 degrees N, 4.0
degrees E, and was about 2000 km from the shuttle's position. The lightning
discharge was determined to be at least 31 km long. This discharge is of
interest because it is probably caused by an electric-field concentration in
the upper part of the thunderstorm and appears to be a discharge that was
predicted by Wilson (1925)}
}
@article{4214527,
author={{}},
title={Proceedings. Symposium on Titan (ESA SP-338)},
journal={},
volume={},
number={},
pages={},
year={1992},
abstract={The following topics were dealt with: Saturn, formation, satellites,
Titan, atmosphere, interior, thermal structure, composition, UV albedo,
meteorology, circulation, planetary boundary layer, gravity tide, meteoric
ionisation, lightning sferics, photochemistry, exobiology, organic chemistry,
unsaturated nitriles, organic haze, clouds, aerosols, near-IR, middle-IR,
Cassini VIMS, Cassini CIRS, Huygens ACP, Huygens ASI, surface models, solar
wind interaction, plasma, mass loading, comets, magnetosphere, ionosphere,
spectra, ocean, refractive index, liquid gas mixtures, thermal conductivity,
waves, HCP, HCN, gas chromatography, pyrolysis-GC, Huygens REF, 3 Sgr
occultation of 1989 July 3, stratosphere, intensity, polarisation, transmitted
light, dielectric constant, surface science package, benzene, butadiyne, and
cyanoacetylene}
}
@article{4162392,
author={{Ehhalt D.H.} and {Rohrer F.} and {Wahner A.}},
title={Sources and distribution of NO/sub x/ in the upper troposphere at northern mid-latitudes},
journal={Journal of Geophysical Research},
volume={97},
number={D4},
pages={3725-38},
year={1992},
abstract={A simple quasi-two-dimensional model is used to study the zonal
distribution of NO/sub x/. The model includes vertical transport in the form of
eddy diffusion and deep convection, zonal transport by a vertically uniform
wind, and a simplified chemistry of NO, NO/sub 2/, and HNO/sub 3/. The NO/sub
x/ sources considered are surface emissions (mostly from the combustion of
fossil fuel), lightning, aircraft emissions, and downward transport from the
stratosphere. The model is applied to the latitude band of 40 degrees to 50
degrees N during the month of June; the contributions to the zonal NO/sub x/
distribution from the individual sources and transport processes are
investigated. The model predicted NO/sub x/ concentration in the upper
troposphere is dominated by air lofted from the polluted planetary boundary
layer over the large industrial areas of eastern North America and Europe.
Aircraft emissions are also important and contribute on average 30%.
Stratospheric input is minor about 10%, less even than that by lightning}
}
@article{4146067,
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},
pages={99-102},
year={1992},
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}
}
@article{3921070,
author={{Penner J.E.} and {Atherton C.S.} and {Dignon J.} and {Ghan S.J.} and {Walton J.J.} and {Hameed S.}},
title={Tropospheric nitrogen: a three-dimensional study of sources, distributions, and deposition},
journal={Journal of Geophysical Research},
volume={96},
number={D1},
pages={959-90},
year={1991},
abstract={Simulates the global cycle of reactive nitrogen in a
three-dimensional model of chemistry, transport, and deposition. The model is
based on the Lagrangian tracer model described by Walton et al. (1988) and uses
winds and precipitation fields calculated by the Livermore version of the NCAR
Community Climate Model. The model includes the basic chemical reactions of NO,
NO/sub 2/, and HNO/sub 3/. For this study, prescribed OH and O/sub 3/
concentrations are used. The concentrations of NO, NO/sub 2/, and HNO/sub 3/
for a perpetual January and a perpetual July are calculated. The sources of
reactive nitrogen due to fossil-fuel combustion, lightning discharges, soil
microbial activity, biomass burning and the oxidation of N/sub 2/O in the
stratosphere are included. Model-predicted concentrations of NO, NO/sub 2/, and
HNO/sub 3/ are compared to available measurements}
}
@article{3709826,
author={{}},
title={1987 AGU Spring Meeting},
journal={EOS Transactions of the American Geophysical Union},
volume={68},
number={1-26},
pages={},
year={1987},
abstract={The following topics were dealt with: geophysics in 19th century,
Earth as system, ocean drilling, acid rain, atmosphere O/sub 3/, troposphere,
chemistry; dynamics, radiation, climate, meteorology, lightning detection
system, expert systems, geodesy, gravity, Global Positioning System, crust,
VLBI, laser ranging, errors, geodynamics, geodetic networks, palaeomagnetism,
geomagnetism, plate tectonics, geomagnetic variation, apparent polar wander,
rock magnetism, sediments, porous media, hydrology, groundwater, surface water,
rainfall, water quality, vadose zone, wetlands, hazardous waste, ocean,
palaeooceanography, estuaries, biology, coast regions, circulation, techniques,
instrumentation, Venus, impact fluxes, material alteration, seismology,
propagation, earthquakes, seismicity, mantle, core, lithosphere, ionosphere,
thermosphere, dayglow, aurora, plasma, middle atmosphere, mesosphere,
stratosphere, airglow, aerosols, cosmic rays, comets, solar activity, Sun,
solar wind, magnetosphere, reconnection, pulsations, magnetotail, planets,
magnetic storms, Mercury, equations of state, faults, convection, rocks,
minerals, volcanology, geochemistry, petrology, geochronology, and remote
sensing}
}
@article{3630675,
author={{Legrand M.R.} and {Kirchner S.}},
title={Origins and variations of nitrate in south polar precipitation},
journal={Journal of Geophysical Research},
volume={95},
number={D4},
pages={3493-507},
year={1990},
abstract={{South polar firm cores spanning the last millennium have been
analyzed to determine the nitrate background level of high-latitude
precipitation and its temporal variations. The resulting data reveal no
evidence of a positive correlation between solar activity (11-year solar cycle
low solar activity time periods and solar proton events) and the NO/sub 3/
content of south polar snow. These data therefore suggest that NO/sub x/
production in the upper stratosphere mesosphere and thermosphere does not
contribute significantly to the antarctic NO/sub 3/ budget. This study of the
NO/sub 3/ content of high latitude precipitation suggests a major contribution
by lightning (from a third to a half of the total) and by NO/sub x/ produced in
the lower stratosphere (approximately a third from N/sub 2/O oxidation and to a
lesser extent galactic cosmic rays) to the NO/sub 3/ budget of this background
atmosphere the remaining portion being related to the present NO/sub x/ surface
sources of the southern hemisphere. For the first time the authors' data point
to a decrease of NO/sub 3/ content when very large amounts of sulfuric acid are
present in South Pole snow layers}},
}
@article{3606660,
author={{Saha A.K.} and {Lohar D.}},
title={Tropospheric ozone and tropical thunderstorms},
journal={Indian Journal of Radio & Space Physics},
volume={18},
number={5-6},
pages={218-19},
year={1989},
abstract={Height distributions of tropospheric ozone, with altered shapes
during tropical thunderstorms, are considered in the light of photochemical
processes. The hypothesis of increase of ozone in the lower troposphere by
lightning discharges in thunderstorms appears to be a reasonable one. Decrease
of ozone in the upper troposphere, associated with the storms is, however,
found to be more likely due to updraft of air from thunderstorms obstructing
the normal downward diffusion of ozone from the stratosphere}
}
@article{3570218,
author={{Vonnegut B.} and {Vaughan O.H. Jr.} and {Brook M.}},
title={Nocturnal photographs taken from a U-2 airplane looking down on tops of clouds illuminated by lightning},
journal={Bulletin of the American Meteorological Society},
volume={70},
number={10},
pages={1263-71},
year={1989},
abstract={Photographs have been taken at night from an airplane at an altitude
of 20 km looking directly down on the tops of thunderclouds illuminated by
lightning. The hard, cauliflower-like appearance of the clouds gives evidence
that strong convective activity is present. In one case a well-organized system
of convective structures is evident whose deepest folds, apparently caused by
downdrafts, are estimated to extend into the cloud for depths of as much as
several kilometers. Often the whole cloud top, approximately 10 km across, is
diffusely illuminated by lightning that is occurring lower in the cloud. In
most of these cases no lightning channels can be seen, but occasionally a few
segments of channels are visible bridging the folds between the convective
protuberances. A few photographs show thin, weak, lightning channels that come
out of the top of the cloud, proceed horizontally for several hundred meters,
and then terminate in the clear air above the cloud. When such channels can be
seen, the background is usually quite dark, indicating that not much lightning
activity is taking place elsewhere in the cloud at that time}
}
@article{3382817,
author={{}},
title={American Geophysical Union Fall Meeting and American Society of Limnology and Oceanography Winter Meeting},
journal={EOS Transactions of the American Geophysical Union},
volume={67},
number={26-52},
pages={},
year={1986},
abstract={The following topics were dealt with: biogeochemical cycles, climate,
western water, fractals, spectral analysis, mesoscale convective systems, upper
atmosphere chemistry, troposphere, polar O/sub 3/ variations, meteorology,
lightning detection, electric fields, boundary layer, data management, toxic
pollutant, cloud, Asian dust, Arctic, aerosol, Western Atlantic Ocean
Experiment, earthquakes, Pacific-North American plate boundary deformation, GPS
shootout, geodesy, core, mantle, Earth rotation, geopotential, sea surface, sea
floor, baselines, geomagnetic variations, magnetic storms, magnetotelluric
sounding, crust, Magsat, tectonics, palaeomagnetism, grains, rock,
stratigraphy, rain, runoff, acid precipitation, agriculture, hydrology,
groundwater, glaciers, rivers, water quality, ocean, limnology, biology, lakes,
waves, sea ice, dynamics, circulation, hydrothermal activity, geochemistry,
sediment, remote sensing, volcanoes, planet rings, atmospheres, seismicity,
faults, geology, thermosphere, ionosphere, mesosphere, magnetosphere, aurora,
airglow, solar wind, cosmic rays, comets, plasma, geochronology and magma}
}
@article{2857836,
author={{Legrand M.R.} and {Delmas R.J.}},
title={Relative contributions of tropospheric and stratospheric sources to nitrate in Antarctic snow},
journal={Tellus, Series B (Chemical and Physical Meteorology)},
volume={38B},
number={3-4},
pages={236-49},
year={1986},
abstract={The nitrate contents of nearly 500 firn samples collected at various
sites on the Antarctic ice sheet are reported. Additional chemical measurements
of all major ions, in particular protons, have also been performed so that new
conclusions regarding the most probable form and origin of nitrate in the
Antarctic can now be drawn. It is shown that nitrate is deposited as gaseous
HNO/sub 3/ and that tropospheric sources dominate in this remote region.
Continental and anthropogenic nitrates are not significant contributors. It is
suggested that lightning at tropical and/or mid latitudes is the most likely
source of Antarctic nitrate. The formation of HNO/sub 3/ (or its precursors) in
the stratosphere is discussed and the possible evidence for this contribution
in several profiles is carefully investigated. The absence of a convincing
correlation between solar factors and nitrate concentrations in snow confirms
that past solar activity fluctuations cannot be reconstructed from polar ice
cores. The spatial and temporal variations observed in this study are, however,
not fully explained. Finally, emphasis is placed on the necessity of
undertaking HNO/sub 3/ measurements in the Antarctic atmosphere in order to
elucidate the deposition mechanism of this major component of atmospheric
chemistry}
}
@article{2801312,
author={{Barcus J.R.} and {Iversen I.} and {Stauning P.}},
title={Observations of the electric field in the stratosphere over an Arctic storm system},
journal={Journal of Geophysical Research},
volume={91},
number={D9},
pages={9881-92},
year={1986},
abstract={Observations by balloon-borne instrumentation in the stratosphere
(30-35 km) near Sondre Stromfjord, Greenland, have revealed disturbed vertical
electric fields of the order of volts per metre of both polarities above an
Arctic storm system which moved onto the continent from the Davis Strait on
August 11, 1982. This disturbance persisted at the balloon position for more
than 10 hours, exhibiting order of magnitude variations with time scales
ranging from minutes to hours. Simultaneous measurements of the stratospheric
electrical conductivity did not show significant storm-related variations. No
lightning signals were detected. The disturbed field was predominantly downward
(normal fair-weather direction), and estimates of the total current indicate
that at any instant a current of the order of 0.5 A was communicated to the
storm system via the overlying stratosphere}
}
@article{2600972,
author={{Kelley M.C.} and {Siefring C.L.} and {Pfaff R.F.} and {Kinter P.M.} and {Larsen M.} and {Green R.} and {Holzworth R.H.} and {Hale L.C.} and {Mitchell J.D.} and {Le Vine D.}},
title={Electrical measurements in the atmosphere and the ionosphere over an active thunderstorm. I. Campaign overview and initial ionospheric results},
journal={Journal of Geophysical Research},
volume={90},
number={A10},
pages={9815-23},
year={1985},
abstract={The first simultaneous electric field observations performed in the
ionosphere and atmosphere over an active nighttime thunderstorm are reported.
In the stratosphere, typical storm-related DC electric fields were detected
from a horizontal distance of approximately 100 km, and transient electric
fields due to lightning were measured at several different altitudes. In the
ionosphere and mesosphere, lightning-induced transient electric fields in the
range of tens of millivolts per meter were detected with rise times at least as
fast as 0.2 ms and typical duration of 10-20 ms. Copious numbers of whistlers
were generated by the storm and were detected above but not below the base of
the ionosphere. The outline of a new model for direct whistler wave generation
over an active thunderstorm based on these observations is presented}
}
@article{2524600,
author={{Brook M.} and {Rhodes C.} and {Vaughan O.H. Jr.} and {Orville R.E.} and {Vonnegut B.}},
title={Nighttime observations of thunderstorm electrical activity from a high altitude airplane},
journal={Journal of Geophysical Research},
volume={90},
number={D4},
pages={6111-20},
year={1985},
abstract={Two sets of observations from a NASA U-2 airplane looking down on the
tops of nocturnal thunderstorms are reported. Photographs show both diffuse
illumination in the cloud and unobscured segments of lightning channels a
kilometer or longer in clear air around and above the cloud. Multiple images of
lightning channels indicate multiple discharges in the same channel. Lightning
spectra were obtained similar to those observed beneath cloud base. Field
changes correlate with pulses measured with a photocell optical system. Optical
signals corresponding to dart leader, return stroke, and continuing current
events are readily distinguished in the scattered light emerging from the cloud
surface. The implications of these observations for satellite remote sensing of
lightning are discussed}
}
@article{2490604,
author={{Vonnegut B.} and {Vaughan O.H. Jr.} and {Brook M.} and {Krehbiel P.}},
title={Mesoscale observations of lightning from Space Shuttle},
journal={Bulletin of the American Meteorological Society},
volume={66},
number={1},
pages={20-9},
year={1985},
abstract={Motion pictures have been taken at night by astronauts on the Space
Shuttle showing lightning discharges that spread horizontally at speeds on
10/sup 5/ m.s/sup -1/ for distances over 60 km. Tape recordings have been made
of the accompanying optical pulses detected with a photocell optical system.
The observations show that lightning is often a mesoscale phenomenon that can
convey large amounts of electric charge to Earth from an extensive cloud system
via a cloud-to-ground discharge}
}
@article{2328304,
author={{}},
title={Proceedings in Atmospheric Electricity. VIth International Conference},
journal={},
volume={},
number={},
pages={},
year={1983},
abstract={The following topics were dealt with: atmospheric electricity,
thunderstorms, clouds, precipitation, global currents, fair weather
electricity, ions and conductivity, lightning, positive ion reactions,
transport phenomena, aerosols, chemistry, stratosphere, troposphere pollutants,
reactions, condensation nuclei, clusters, whitecap bubbles, ionisation, solar
activity effects, solar wind, rain, charge distribution, coronae at ground
level, riming, ice crystals, seeding effects, EM fields, electrostatic fields,
whistlers, sound waves, spark channels, streamers, positive ground strokes,
superbolts and planetary atmospheres}
}
@article{2217887,
author={{Crutzen P.J.} and {Gidel L.T.}},
title={A two-dimensional photochemical model of the atmosphere. II. The tropospheric budgets of the anthropogenic chlorocarbons CO, CH/sub 4/, CH/sub 3/Cl and the effect of various NO/sub x/ sources on tropospheric ozone},
journal={Journal of Geophysical Research},
volume={88},
number={C11},
pages={6641-61},
year={1983},
abstract={For pt.I see ibid., vol.88, no.C11, p.6622-40 (1983). Presents
two-dimensional photochemical model simulations that show the influence of the
various NO/sub x/ sources from industry, lightning, the stratosphere, and
aircraft on the tropospheric distributions of NO/sub x/, HNO/sub 3/, and O/sub
3/. It was found that, by far, the best agreement with the global observations
is obtained if the industrial sources are included in the calculations.
Industrial activities have led to substantial increases of ozone concentrations
in the lower troposphere of the northern hemisphere. Emissions of NO/sub x/ by
high-flying aircraft have only a small effect on ozone concentrations in the
troposphere. The ability of the model to simulate the global distributions of
the long-lived chlorocarbons CFCl/sub 3/ and CF/sub 2/Cl/sub 2/ indicates that
the interhemispheric exchange is rather well described. The model confirms an
earlier finding that the CF/sub 2/Cl/sub 2/ emission rates estimated by the
Chemical Manufacturers Association may be 35-40% lower for the period 1976
through 1980. Further findings of the model are described}
}
@article{2071075,
author={{Christian H.J.} and {Frost R.L.} and {Gillaspy P.H.} and {Goodman S.J.} and {Vaughan O.H. Jr.} and {Brook M.} and {Vonnegut B.} and {Orville R.E.}},
title={Observations of optical lightning emissions from above thunderstorms using U-2 aircraft},
journal={Bulletin of the American Meteorological Society},
volume={64},
number={2},
pages={120-3},
year={1983},
abstract={In order to determine how to achieve orders of magnitude improvement
in spatial and temporal resolution and in sensitivity of satellite lightning
sensors, better quantitative measurements of the characteristics of the optical
emissions from lightning as observed from above tops of thunderclouds are
required. A number of sensors have been developed and integrated into an
instrument package and flown aboard a NASA U-2 aircraft. The objectives have
been to acquire optical lightning data needed for designing the Lightning
Mapper Sensor, and to study lightning physics and the correlation of lightning
activity with storm characteristics. The instrumentation and observations of
the program are reviewed and their significance for future research is
discussed}
}
@article{2008116,
author={{Yung Y.L.} and {Demore W.B.}},
title={Photochemistry of the stratosphere of Venus: implications for atmospheric evolution},
journal={Icarus},
volume={51},
number={2},
pages={199-247},
year={1982},
abstract={{The photochemistry of the stratosphere of Venus was modeled using an
updated and expanded chemical scheme combined with the results of recent
observations and laboratory studies. The authors examined three models with
H/sub 2/ mixing ratio equal to 2*10/sup -5/ 5*10/sup -7/ and 1*10/sup -13/
respectively. All models satisfactorily account for the observations of CO
O/sub 2/ O/sub 2/(/sup 1/ Delta ) and SO/sub 2/ in the stratosphere but only
the last one may be able to account for the diurnal behavior of mesospheric CO
and the UV albedo. Photolysis of HCl in the upper stratosphere provides a major
source of odd hydrogen and free chlorine radicals essential for the catalytic
oxidation of CO. Oxidation of SO/sub 2/ by O occurs in the lower stratosphere.
It is shown that lightning in the lower atmosphere could provide as much as 30
ppb of NO/sub x/ in the stratosphere. The modeling reveals a number of
intriguing similarities previously unsuspected between the chemistry of the
stratosphere of Venus and that of the Earth}},
}
@article{1825677,
author={{Holzworth R.H.}},
title={High latitude stratospheric electrical measurements in fair and foul weather under various solar conditions},
journal={Journal of Atmospheric and Terrestrial Physics},
volume={43},
number={11},
pages={1115-25},
year={1981},
abstract={Stratospheric electric field and conductivity measurements during a
wide variety of weather and solar conditions are presented. These data are all
from high latitude sites (>50 degrees N GG) in the months of either April or
August. The vector electric field is determined by orthogonal double probes
connected through high impedance inputs to differential electrometers. The
direct conductivity measurement involves determining the relaxation time
constant of the medium after refloating a shorted pair of separated probes.
Vertical electric field data from several balloon flights with average duration
of 18 h at ceiling in fair weather are shown to be well modeled by a simple
exponential altitude dependent equation. Examples of solar flare and
magnetospheric effects on stratospheric electric fields are shown. Data
collected over electrified clouds and thunderstorms are presented along with a
discussion of the thunderstorm related electric currents. Lightning stroke
signatures in the stratosphere during a large thunderstorm are identified in
the electric field data. Current surges through the stratosphere due to DC
currents as well as the sferic are calculated. In nearly 1000 h of balloon data
no direct solar influence is identified in these data except during major
flares. However, variations in all three components of the electric field
during magnetically active conditions are discussed}
}
@article{1675593,
author={{Jackman C.H.} and {Frederick J.E.} and {Stolarski R.S.}},
title={Production of odd nitrogen in the stratosphere and mesosphere: an intercomparison of source strengths},
journal={Journal of Geophysical Research},
volume={85},
number={C12},
pages={7495-505},
year={1980},
abstract={The study intercompares several sources of odd nitrogen (ON) in the
stratosphere and mesosphere (middle atmosphere) so as to place galactic cosmic
rays (GCRs) nuclear explosions, lightning, solar proton events (SPEs),
relativistic electron precipitation, meteors, and the downward diffusion of NO
from the thermosphere in their proper context relative to the oxidation of
nitrous oxide. Use of published measurements of O/sub 3/ and N/sub 2/O show
that the source of ON owing to the reaction of O(/sup 1/D)+N/sub 2/O peaks
between 25 and 35 km and is by far the largest source in an annually, globally
averaged sense with a magnitude of 4.5*10/sup 34/ molecules yr/sup -1/. At
solar minimum the GCRs add about the same amount of ON as N/sub 2/O oxidation
(1.7*10/sup 33/ molecules yr/sup -1/) for geographic latitudes greater than 50
degrees . Nuclear explosions in 1961 and 1962 added 1.1 and 2.2*10/sup 34/ NO
molecules, respectively, to the total global ON content. SPEs produced more ON
at latitudes above 50 degrees than did N/sub 2/O oxidation for the years 1958,
1959, 1960, and 1972. Analysis of available measurements shows the downward
flux of NO from the thermosphere to between 8 and 33% of the integrated N/sub
2/O source. Large variations in measurements of ON should be expected at
geographic latitudes above 50 degrees where the highly variable SPE source of
ON is substantial. Because of the long lifetime of ON in the middle atmosphere,
significant variations in its content may also be expected to occur at
mid-latitudes}
}
@article{1569762,
author={{Waldteufel P.} and {Metzger P.} and {Boulay J.-L.} and {Laroche P.} and {Hubert P.}},
title={Triggered lightning strokes originating in clear air},
journal={Journal of Geophysical Research},
volume={85},
number={C5},
pages={2861-8},
year={1980},
abstract={During the 1978 campaign of the triggered lightning program at
Saint-Privat d'Allier (France), simultaneous data from a movie camera, a
coaxial shunt ammeter, a network of electric field mills and a weather radar,
were collected during the initial phase of a particular triggered event. These
data are shown to exhibit a high degree of consistency, leading to the
conclusion that charges totaling several coulombs were present in cloudfree air
in the vicinity of a stormy area}
}
@article{1563736,
author={{Brook M.} and {Tennis R.} and {Rhodes C.} and {Krehbiel P.} and {Vonnegut B.} and {Vaughan O.H. Jr.}},
title={Simultaneous observations of lightning radiations from above and below clouds},
journal={Geophysical Research Letters},
volume={7},
number={4},
pages={267-70},
year={1980},
abstract={Daytime optical measurements of a lightning flash made simultaneously
from above and below a thundercloud shows nearly identical signals. The optical
pulses are clearly related to electric field changes detected by an E change
meter and to the signals detected by a 2200 MHz receiver. Source power levels
ranging from 10/sup 7/ to 10/sup 10/ W optical were detected at 20 km altitude
from three lightning flashes}
}
@article{1366151,
author={{Vaughan O.H. Jr.} and {Vonnegut B.}},
title={Thunderstorm and lightning observations from Space Shuttle},
journal={Space Instrumentation for Atmospheric Observation. IEEE Region V Annual Conference},
volume={},
number={},
pages={98-101},
year={1979},
abstract={A 16 mm camera equipped with a photocell optical sensor and a
two-channel tape recorder will be used by Shuttle astronauts to obtain
information on thunderstorms and lightning from orbital altitude. The camera
will provide photographs of the lightning at night and of the convective
structure of the storms during the day. The photocell sensor, which is capable
of detecting and recording lightning by day and by night, will give information
on the frequency and characteristics of the lightning that is occurring}
}
@article{1015855,
author={{Tuck A.F.}},
title={Production of nitrogen oxides by lightning discharges},
journal={Quarterly Journal of the Royal Meteorological Society},
volume={102},
number={434},
pages={749-55},
year={1976},
abstract={The annual production of nitric oxide by lightning discharges is
estimated to be 1.8*10/sup 35/ molecules, within rather large limits of
uncertainty. Implications for the global budget of odd nitrogen species are
cursorily examined. More data are needed to decide whether or not
lightning-produced nitrogen oxides are transported in significant quantities to
the stratosphere. Closer studies of the budget of nitrate in rainwater, and of
air trajectories in large cumulonimbus storms, are also indicated}
}
@article{262542,
author={{Illingworth A.J.} and {Wormell T.W.}},
title={Electric field recovery after lightning},
journal={Nature (Physical Science)},
volume={229},
number={7},
pages={213-14},
year={1971},
abstract={Holzer and Saxon (1952) showed that the steady field observed due to
a charge in a thundercloud is greatly modified by the presence of an atmosphere
whose conductivity increases exponentially with height. This effect increases
with distance from the storm and, at a distance of 30 km, the field of the
space charge in the clear air around the storm is about 90% of the Coulomb
field of the pole itself. This article offers an explanation of recovery curves
involving the response of this space charge to the field change caused by the
lightning discharge. On this view, there is no need to suppose a high
conductivity within the cloud}
}