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| Titel |
Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations |
| VerfasserIn |
A. V. Pavlov |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 15, no. 8 ; Nr. 15, no. 8, S.984-998 |
| Datensatznummer |
250012906
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| Publikation (Nr.) |
 copernicus.org/angeo-15-984-1997.pdf |
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| Zusammenfassung |
| This study compares the OV1-10 satellite
measurements of the integral airglow intensities at 630 nm in the SAR arc
regions observed in the northern and southern hemisphere as a conjugate
phenomenon, with the model results obtained using the time-dependent
one-dimensional mathematical model of the Earth ionosphere and plasmasphere (the
IZMIRAN model) during the geomagnetic storm of the period 15–17 February 1967.
The major enhancements to the IZMIRAN model developed in this study are the
inclusion of He+ ions (three major ions: O+, H+,
and He+, and three ion temperatures), the updated photochemistry and
energy balance equations for ions and electrons, the diffusion of NO+
and O2+ ions and O(1D) and the revised electron
cooling rates arising from their collisions with unexcited N2, O2
molecules and N2 molecules at the first vibrational level. The
updated model includes the option to use the models of the Boltzmann or non-Boltzmann
distributions of vibrationally excited molecular nitrogen. Deviations from the
Boltzmann distribution for the first five vibrational levels of N2
were calculated. The calculated distribution is highly non-Boltzmann at
vibrational levels v > 2 and leads to a decrease in the calculated
electron density and integral intensity at 630 nm in the northern and southern
hemispheres in comparison with the electron density and integral intensity
calculated using the Boltzmann vibrational distribution of N2. It is
found that the intensity at 630 nm is very sensitive to the oxygen number
densities. Good agreement between the modelled and measured intensities is
obtained provided that at all altitudes of the southern hemisphere a reduction
of about factor 1.35 in MSIS-86 atomic oxygen densities is included in the
IZMIRAN model with the non-Boltzmann vibrational distribution of N2.
The effect of using of the O(1D) diffusion results in the decrease of
4–6% in the calculated integral intensity of the northern hemisphere and 7–13%
in the calculated integral intensity of the southern hemisphere. It is found
that the modelled intensities of the southern hemisphere are more sensitive to
the assumed values of the rate coefficients of O+(4S) ions
with the vibrationally excited nitrogen molecules and quenching of O+(2D)
by atomic oxygen than the modelled intensities of the northern hemisphere. |
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