Next: Introduction
Sprites, Blue Jets, and Elves: Optical Evidence of Energy
Transport Across the Stratopause
Matthew J Heavner1,
Davis D. Sentman, Dana R. Moudry, and Eugene M. Wescott
Geophysical Institute, University of Alaska Fairbanks
Carl L. Siefring and Jeff S. Morrill
Naval Research Laboratory
Eric J. Bucsela
Raytheon ITSS
1Now at Los Alamos National Labs.
This portion of the web is from the American Geophysical Union Chapman
Conference entitled "Atmospheric Science Across the Stratopause" and
the accompanying monograph. The proper reference for this paper is
Heavner, M.J., D.D. Sentman, D.R. Moudry, E.M. Wescott, C.L Siefring,
J.S. Morrill, and E.J. Bucsela, "Sprites, Blue Jets, and Elves:
Optical Evidence of Energy Transport Across the Stratopause," AGU
Monograph 123 "Atmospheric Science Across the Stratopause," p 69-82,
2000. This paper is available as gzip'ed
postscript.
Abstract:
Sprites, blue jets, blue starters, and elves are recently documented
optical evidence of previously unknown forms of upward electrical
energy transport across the stratopause. These energetic processes
have not been incorporated into most models or descriptions of middle-
and upper-atmospheric dynamics, in part because the details of the
processes themselves are still poorly understood. The earliest (1995)
ground based red spectral observations of neutral molecular nitrogen
emissions from sprites indicate a low energy phenomena compared to the
neutral and ionized emissions observed in lightning or aurora.
However, recent sprite observations of ionized molecular nitrogen
emissions indicate the presence of higher energy processes. In 1998,
the EXL98 aircraft campaign characterized the blue emissions of
sprites, blue jets, and elves. Aircraft measurements include filtered
images, at 427.8 nm (N2+(1NG)) and
340.7 nm (N2(2PG)), as well as NUV/blue
spectral observations between 320-460 nm, while ground based
time-resolved photometric measurements were also made in this
wavelength range. We discuss the filtered and spectral NUV
observations in conjunction with earlier red (640-920 nm) spectral and
filtered photometer observations. The identification of ionized
nitrogen emissions requires processes with electron energies of at
least 18.6 eV to produce these emissions, assuming excitation is
directly from the N2 ground state. This paper provides middle- and
upper-atmospheric scientists an introduction to these recently
discovered phenomena and the current best estimates of the energetic
contributions of these phenomena to the atmosphere above the
tropopause.
Next: Introduction
Matt Heavner
2002-02-13