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| Titel |
The H Lyman-a actinic flux in the middle atmosphere |
| VerfasserIn |
T. Reddmann, R. Uhl |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 3, no. 1 ; Nr. 3, no. 1 (2003-02-20), S.225-231 |
| Datensatznummer |
250000721
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| Publikation (Nr.) |
 copernicus.org/acp-3-225-2003.pdf |
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| Zusammenfassung |
| The penetration of solar H
Lyman-a radiation into the
terrestrial middle atmosphere is studied in detail. The Lyman-a
actinic flux is calculated with a Monte Carlo approach including multiple resonance scattering of
Lyman-a
photons within the terrestrial atmosphere and a temperature dependent absorption cross section of molecular oxygen. The
dependence of the actinic flux on the temperature profile is significant for
O2 column densities greater than about 1024 m-2. For column densities greater than about
5 · 1024 m-2 resonance scattering becomes important at solar zenith angles
> 60°. The O(1D) quantum yield of the O2 dissociation by
Lyman-a
photons is found to decrease from 0.58 in the lower thermosphere to 0.48 in
the lower mesosphere. Parameterisations for Lyman-a
actinic flux, mean O2 absorption cross section and O(1D)
quantum yield including temperature dependence and resonance scattering are given valid up to a
O2 column density of about 1025 m-2. |
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