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| Titel |
Impact of January 2005 solar proton events on chlorine species |
| VerfasserIn |
A. Damiani, B. Funke, D. R. Marsh, M. López-Puertas, M. L. Santee, L. Froidevaux, S. Wang, C. H. Jackman, T. Clarmann, A. Gardini, R. R. Cordero, M. Storini |
| 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. 9 ; Nr. 12, no. 9 (2012-05-10), S.4159-4179 |
| Datensatznummer |
250011127
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| Publikation (Nr.) |
 copernicus.org/acp-12-4159-2012.pdf |
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| Zusammenfassung |
Sudden changes in stratospheric chlorine species in the polar northern
atmosphere, caused by the Solar Proton Events (SPEs) of 17 and 20 January
2005, have been investigated and compared with version 4 of the Whole
Atmosphere Community Climate Model (WACCM4). We used Aura Microwave Limb
Sounder (MLS) measurements to monitor the variability of ClO, HCl, HOCl and
Michelson Interferometer for Passive Atmospheric Sounder (MIPAS) on ENVISAT
to retrieve ClONO2. SPE-induced chlorine activation has been identified.
HCl decrease occurred at nearly all the investigated altitudes (i.e.,
10–0.5 hPa) with the strongest decrease (of about 0.25 ppbv) on 21
January. HOCl was found to be the main active chlorine species under
nighttime conditions (with increases of more than 0.2 ppbv) whereas both
HOCl and ClO enhancements (about 0.1 ppbv) have been observed at the polar
night terminator. Further, small ClO decreases (of less than 0.1 ppbv) and
ClONO2 enhancements (about 0.2 ppbv) have been observed at higher
latitudes (i.e., at nighttime) roughly above 2 hPa.
While WACCM4 reproduces most of the SPE-induced variability in the chlorine
species fairly well, in some particular regions discrepancies between the
modeled and measured temporal evolution of the abundances of chlorine species
were found. HOCl changes are modelled very well with respect to both
magnitude and geographic distribution. ClO decreases are reproduced at high
latitudes, whereas ClO enhancements in the terminator region are
underestimated and attributed to background variations. WACCM4 also
reproduces the HCl depletion in the mesosphere but it does not show the
observed decrease below about 2 hPa. Finally, WACCM4 simulations indicate
that the observed ClONO2 increase is dominated by background variability,
although SPE-induced production might contribute by 0.1 ppbv. |
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