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| Titel |
Variability of NOx in the polar middle atmosphere from October 2003 to March 2004: vertical transport vs. local production by energetic particles |
| VerfasserIn |
M. Sinnhuber, B. Funke, T. von Clarmann, M. López-Puertas, G. P. Stiller, A. Seppälä |
| 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 ; 14, no. 14 ; Nr. 14, no. 14 (2014-07-31), S.7681-7692 |
| Datensatznummer |
250118915
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| Publikation (Nr.) |
 copernicus.org/acp-14-7681-2014.pdf |
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| Zusammenfassung |
| We use NO, NO2 and CO from MIPAS/ENVISAT to investigate the impact of
energetic particle precipitation onto the NOx budget from the
stratosphere to the lower mesosphere in the period from October 2003 to March
2004, a time of high solar and geomagnetic activity. We find that in the
winter hemisphere the indirect effect of auroral electron precipitation due
to downwelling of upper mesospheric/lower thermospheric air into the
stratosphere prevails. Its effect exceeds even the direct impact of the very
large solar proton event in October/November 2003 by nearly 1 order of
magnitude. Correlations of NOx and CO show that the unprecedented
high NOx values observed in the Northern Hemisphere lower
mesosphere and upper stratosphere in late January and early February are
fully consistent with transport from the upper mesosphere/lower thermosphere
and subsequent mixing at lower altitudes. In the polar summer Southern
Hemisphere, we observed an enhanced variability of NO and NO2 on days with
enhanced geomagnetic activity, but this seems to indicate enhanced instrument
noise rather than a direct increase due to electron precipitation. A direct
effect of electron precipitation onto NOx can not be ruled out,
but, if any, it is lower than 3 ppbv in the altitude range 40–56 km and
lower than 6 ppbv in the altitude range 56–64 km. An additional
significant source of NOx due to local production by
precipitating electrons below 70 km exceeding several parts per billion as
discussed in previous publications appears unlikely. |
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