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| Titel |
On the dependence of the OH* Meinel emission altitude on vibrational level: SCIAMACHY observations and model simulations |
| VerfasserIn |
C. Savigny, I. C. McDade, K.-U. Eichmann, J. P. Burrows |
| 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 ; 12, no. 18 ; Nr. 12, no. 18 (2012-09-28), S.8813-8828 |
| Datensatznummer |
250011480
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| Publikation (Nr.) |
 copernicus.org/acp-12-8813-2012.pdf |
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| Zusammenfassung |
Measurements of the OH Meinel emissions in the terrestrial
nightglow are one of the standard ground-based techniques to
retrieve upper mesospheric temperatures. It is often assumed that
the emission peak altitudes are not strongly dependent on the
vibrational level, although this assumption is not based on
convincing experimental evidence. In this study we use
Envisat/SCIAMACHY (Scanning Imaging Absorption spectroMeter for
Atmospheric CHartographY) observations in the near-IR spectral
range to retrieve vertical volume emission rate profiles of the
OH(3-1), OH(6-2) and OH(8-3) Meinel bands in order to investigate
whether systematic differences in emission peak altitudes can be
observed between the different OH Meinel bands. The results
indicate that the emission peak altitudes are different for the
different vibrational levels, with bands originating from higher
vibrational levels having higher emission peak altitudes. It is
shown that this finding is consistent with the majority of the
previously published results. The SCIAMACHY observations yield
differences in emission peak altitudes of up to about 4 km
between the OH(3-1) and the OH(8-3) band.
The observations are complemented by model simulations of the
fractional population of the different vibrational levels and of
the vibrational level dependence of the emission peak altitude.
The model simulations reproduce the observed vibrational level
dependence of the emission peak altitude well – both
qualitatively and quantitatively – if quenching by atomic oxygen
as well as multi-quantum collisional relaxation by O2 is
considered. If a linear relationship between emission peak
altitude and vibrational level is assumed, then a peak altitude
difference of roughly 0.5 km per vibrational level is inferred
from both the SCIAMACHY observations and the model simulations. |
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