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| Titel |
A Monte Carlo model of auroral hydrogen emission line profiles |
| VerfasserIn |
J.-C. Gérard, V. I. Shematovich, D. V. Bisikalo, D. Lummerzheim |
| 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 ; 23, no. 4 ; Nr. 23, no. 4 (2005-06-03), S.1473-1480 |
| Datensatznummer |
250015237
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| Publikation (Nr.) |
 copernicus.org/angeo-23-1473-2005.pdf |
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| Zusammenfassung |
| Hydrogen line profiles measured from space-borne or ground-based instruments
provide useful information to study the physical processes occurring in the
proton aurora and to estimate the proton flux characteristics. The line
shape of the hydrogen lines is determined by the velocity distribution of H
atoms along the line-of-sight of the instrument. Calculations of line
profiles of auroral hydrogen emissions were obtained using a Monte Carlo
kinetic model of proton precipitation into the auroral atmosphere. In this
model both processes of energy degradation and scattering angle
redistribution in momentum and charge transfer collisions of the high-energy
proton/hydrogen flux with the ambient atmospheric gas are considered at the
microphysical level. The model is based on measured cross sections and
scattering angle distributions and on a stochastic interpretation of such
collisions. Calculations show that collisional angular redistribution of the
precipitating proton/hydrogen beam is the dominant process leading to the
formation of extended wings and peak shifts in the hydrogen line profiles.
All simulations produce a peak shift from the rest line wavelength
decreasing with increasing proton energy. These model predictions are
confirmed by analysis of ground-based H-β line observations from
Poker Flat, showing an anti-correlation between the magnitude of the peak
shift and the extent of the blue wing of the line. Our results also strongly
suggest that the relative extension of the blue and red wings provides a
much better indicator of the auroral proton characteristic energy than the
position of the peak wavelength. |
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