The dependence of modeled OI 1,356 and N sub 2 Lyman Birge Hopfield auroral emissions on the neutral atmosphere

Journal Article · Fri Jun 01 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA06p07725· OSTI ID:5268602

Germany, G A; Torr, M R ^[1]; Richards, P G; Torr, D G ^[2]

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1. NASA Marshall Space Flight Center, Huntsville, AL (USA)
2. Univ. of Alabama, Huntsville (USA)

Images of the entire auroral oval at carefully selected wavelengths contain information on the global energy influx due to energetic particles and some information on the characteristic energy of the precipitating particles. In this paper the authors investigate the sensitivity of selected auroral emissions to changes in the neutral atmosphere. In particular, they examine the behavior of OI 1,356 {angstrom} and two Lyman Birge Hopfield (LBH) bands and their ratios to each other with changing atmospheric composition. The two LBH bands are selected so that one lies in the region of strong O{sub 2} absorption (1,464 {angstrom}) and one lies at a wavelength where O{sub 2} absorption is effectively negligible (1,838 {angstrom}). They find that for anticipated average uncertainties in the neutral atmosphere (factor of 2 at auroral altitudes). The resultant change in the modeled intensities is comparable to or less than the uncertainty in the neutral atmosphere. The smallest variations, for example, are for I 1,838 (approximately 10 to 20%) while the largest variation is seen in the OI 1,356 {angstrom} emission which is linear with (O) to within 20%. They have also investigated the dependence of these intensities, and their ratios, to much larger changes in the composition such as might be encountered in large magnetic storms, or over seasonal or solar cycle extremes. They find that the variation in the I 1,356/I 1,838 ratio over the equivalent of a solar cycle is less than 50%. The summer-to-winter changes are approximately a factor of 2. The I 1,356/I 1,838 ratio is a very sensitive indicator of the characteristic energy, showing a change of 13 over the energy range 200 eV to 10 keV. The corresponding change in the LBH long-to-short wavelength ratio is much less (about a factor of 3). However, the latter is insensitive to changes in the neutral atmosphere (<20% changes in LBH emission ratio for large changes in N{sub 2}).

• OSTI ID: 5268602
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:A6; ISSN JGREA; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
&amp; Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
AURORAL OVAL
CHARGED PARTICLES
CHARGED-PARTICLE PRECIPITATION
CHEMICAL COMPOSITION
COMPARATIVE EVALUATIONS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION SPECTRA
ENERGY TRANSFER
EVALUATION
GLOBAL ASPECTS
IMAGES
IONS
LYMAN LINES
MAGNETIC STORMS
NITROGEN
NONMETALS
OXYGEN IONS
RADIATIONS
SEASONAL VARIATIONS
SPECTRA
THERMOSPHERE
ULTRAVIOLET RADIATION
VARIATIONS