ICAE International Commission on Atmospheric Electricity

ICAE 2003 Versailles

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Wednesday 11th June



Session E2 Middle Atmosphere Electrical Events II (poster)

  S. Clodman, Y. Yair
TLE Detection by Instrument and by Proposed Human Vision System for Space-Based Missions

W. M. Farrell, R. A. Goldberg, M. D. Desch, J. G. Houser, J. D. Mitchell, C. L. Croskey, R. J. Blakeslee, D. M. Mach, and J.C. Bailey
Aces : A unique platform for electrodynamic studies of upward currents into the middle atmosphere

Y. Goto, Y. Sato, and Y. Ohba
The optical and spectral measurements of low pressure air discharges as sprite models
  L. Hale
Some Lightning Interactions with the Earth and Ionosphere


TLE Detection by Instrument and by Proposed Human Vision System for Space-Based Missions

Stephen Clodman
10 Tangreen Court, apt 1207, Toronto, Ontario, Canada, M2M 4B9
Phone: (416) 223-8368

Yoav Yair
Open University of Israel, 16 Klauzner St., Ramat Aviv, Tel Aviv, Israel, 61392
Phone: 972-3-646-5579


This study, on both instrument and human detection of TLEs (transient luminous events), was made to help prepare for the MEIDEX Sprite mission. First, we made estimates, based on current scientific knowledge, of the apparent brightness and other features of sprites, elves, and jets, as they might be viewed by a space-based instrument. From the TLE brightness and spectra, the number of photons received by the instrument at different wavelengths was estimated in order to evaluate TLE detectability and select the best filter band. Lightning interference with the TLE detection was also considered. Storm-finding tactics for TLEs were recommended.

It was found that sprites, jets, and elves should all be detectable, but care is needed to minimize lightning interference. Space-based detection should be especially advantageous for finding jets and elves. Known red to near-IR bands are suitable for sprites and elves. Blue to near-UV wavelengths are suitable for jets, but the choice of emission band is somewhat uncertain. (Early MEIDEX Sprite data, discussed in a separate ICAE conference paper, confirms some of these conclusions.)

Second, it is useful, and we think feasible, when studying TLEs from a manned space platform, to have the crew search for TLEs by eye. This would increase the value of on-board or ground-based instrument studies, by helping to select target storms. Human observation could be used even in the absence of an optical instrument.

However, the astronaut should be equipped with a suitable viewing system, the design of which we outline here. The design should consider the eye's sensitivity and dark adaptation at different wavelengths. The system should also help find the storms and use the observations. The most important part of the system is a viewer with a filter which will admit as much as possible of the narrow blue or red TLE emission spectrum, while blocking lightning light at other wavelengths.


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ACES: A Unique Platform for Electrodynamic Studies of Upward Currents into the Middle Atmosphere

W. M. Farrell, R. A. Goldberg, M. D. Desch and J. G. Houser
NASA Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A.

J. D. Mitchell and C. L. Croskey
Department of Electrical Engineering, The Pennsylvania State University, University Park, PA, 16802, U.S.A.

R. J. Blakeslee
NASA Marshall Space Flight Center, Huntsville, AL 35812, U.S.A.

D. M. Mach
University of Alabama in Huntsville, Huntsville, AL 35899, U.S.A.

J.C. Bailey
Raytheon ITSS, Huntsville, AL 35805, U.S.A.


Recent research has helped identify, define, and describe the occurrence of transient electrical bursts such as jets and sprites (~10-20 ms duration) in the stratosphere and mesosphere during tropospheric electrical storms. However, it is critical to make in situ measurements within the active electrical region for the primary purpose of understanding the currents responsible for the luminous events, to develop a proper understanding of their cause(s), and of their impact on the atmospheric electromagnetic environment. The transfer of significant quantities of energy between the lower and upper atmosphere during tropospheric electrical storms has long been suspected but never verified until the identification of these type phenomena. It has become important to develop measuring system which can be used to determine the mechanisms responsible for generating these events, to make a better appraisal of their role and importance in the electrical structure of the atmosphere. The use of unmanned aerial vehicles (UAV) such as ALTUS provides a unique and valuable approach for obtaining the desired information. An important objective of The ALTUS Cumulus Electrification Study (ACES) was to monitor the electromagnetic state of the atmosphere during electrically active (thunderstorm) periods. The program involved several flights of a payload designed to continuously measure for extended periods the electromagnetic structure near and above thunderstorms. It was conducted at the Naval Air Station in Key West, FL during August, 2002.The payload contained instrumentation to measure the time varying and steady state three dimensional vectors for electric (slow antenna and field mills) and magnetic fields (search coils and magnetometer), as well as a Gerdien probe to measure electrical conductivity. The data acquisition system aboard the payload permitted acquisition of short-term bursts with a few microsecond resolution.


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The Optical and Spectral Measurements of Low Pressure Air Discharges as Sprite Models

Department of Electrical Engineering, Tohoku Gakuin University, 1-13-1, Chuo, Tagajo, Miyagi, 985-8537,JAPAN


Air-filled cold cathode glass tube with a variety of gas pressures from 0.04Torr to 7Torr have been excited with capacitor discharges. To overcome the Paschen minimum in the laboratory at gas pressures appropriate for sprites in the meso-sphere(0.04Torr at 70km altitude), a very long(1.5m) discharge tube has been used. The current and pressure dependence of light intensity from the discharges have been measured by a head-on type photo-multiplier 7102(light sensibility: S1). Moreover, the pressure dependence of spectral distribution from the discharges have been measured with Hamamatsu Photonic multi-channel analyzer PMA 11(band width of wave length: 300-800nm).

As the measured results, total light intensity from the discharges increased with the air pressure and the intensity P is directly proportional to discharge current I at air pressure 0.04Torr constant. For the pressure dependence of the spectral distribution, H-alpha line(656.2nm) intensity decreased with air pressure, otherwise O1 line(777.6nm) intensity increased with air pressure.


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Some Lightning Interactions with Earth, Ionosphere, and Magnetosphere

Les Hale
Communications and Space Sciences Laboratory, Penn State University, Univerityy Park, PA, 16802, USA.


Lightning fields occurring in free space might be treated by "dipole moments," but when the presence of the earth and ionosphere are included, it is necessary to consider all the currents and charges in the lightning and in these two "boundaries." In the case of the earth alone, a ground reflection produces the double pulse phenomena known as TIPPS and SIPPS. At HF and below the ionosphere must be considered, and in general it is not a sharp boundary. An illuminating contribution to this problem was made by Carl and Phyllis Greifinger (JGR, 1976). Realizing that the curl E=0 "relaxation time" solution frequently used can result in errors of many orders of magnitude, they developed the concept of an ionospheric boundary moving downward after the stroke, from which ULF fields can be calculated. (This model has been effectively used by V. Pasko and the Stanford group to treat the development of "red sprites.") The ELF solution is more difficult, generally requiring a computer model for the transient solution of the complete Maxwell's equations to one or more "Wilson monopoles," (eg Hale and Baginsky, Nature, 1987). A result of that calculation was the generation of a "slow tail," of about one millisecond duration, not due to continuing currents, controlled by the round trip delay between the earth and ionosphere, and containing enormous energy. These slow tails propagate in the earth-ionosphere cavity, and have been recently used by Hale to explain the large "DC" mesospheric fields (volts/meter), observed by Russian and US groups, as due to polarization of the magnetosphere along magnetic field lines by the "slow tails," as they propagate globally. Another effect not included in the dipole moment formulation is the field due to charges moving in the lightning channel.


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