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Ishimoto et al. 1994
Ishimoto, M., Romick, G.J. and Meng, C.-I. (1994). Model calculation of atmospheric emission caused by energetic O+ precipitation. Journal of Geophysical Research 99: doi: 10.1029/93JA01148. issn: 0148-0227.

Some anomalous auroral emissions, typically observed below 60¿ geomagnetic latitude during large geomagnetic storms have distinctive spectral characteristics, that have been attributed to energetic ion/neutral particle precipitation. Mass spectrometers on satellites have observed energetic (keV) ion and neutral precipitation (up to 30 erg cm-2 s-1) below 60¿ geomagnetic latitude. In this study we used a model to calculate emissions with the characteristics of the incident O+ energy spectra observed from satellites and compared the emission intensities and intensity ratios of the model calculation to those from the anomalous auroral emission spectra. Using an oxygen transport model with estimated emission cross sections, we calculated the emission altitude distributions, vertically integrated column emission intensities and the spectral profile of atomic oxygen line emissions. The calculated emissions were for the N+2 and O+2 first negative(1N), N2 second positive(2P), and N2 Lyman-Birge-Hopfield (LBH) bands; the N i lines at 1493 ¿, 1744 ¿, and 8680 ¿; the N ii line at 5005 ¿, and the O I lines at 1304 ¿, 1356 ¿, and 6300 ¿. Most atomic oxygen line emissions are from primary oxygen atoms traveling downward at a speed of 107 and 108 cm s-1. Because of the high speed at which the atoms travel, most 1D is quenched before emission. Atomic oxygen line spectra at 1304 ¿ and 1356 ¿ display a 1 ¿ Doppler shift and some broadening if viewed from above or below. The emission altitudes and intensities are most sensitive to the choice of elastic scattering cross sections and emission cross sections, respectively. The emission intensity ratios of both the N+21N to N22P band and the N2LBH bands to the atomic lines, and the Doppler shift of atomic O lines strongly depend on the energy spectrum of incident O+. Seasonal and latitudinal model atmospheric differences have least impact. With an energy spectrum of incident O+, the general model results agree with the observed anomalous auroral emission spectra that were interpreted as being caused by O+ precipitation. ¿ American Geophysical Union 1994

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Abstract

Keywords
Atmospheric Composition and Structure, Airglow and aurora, Atmospheric Composition and Structure, Thermosphere—composition and chemistry, Ionosphere, Auroral ionosphere, Ionosphere, Particle precipitation
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
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American Geophysical Union
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