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| Titel |
Diurnal variations of reactive chlorine and nitrogen oxides observed by MIPAS-B in the Arctic in January 2010 and March 2011 |
| VerfasserIn |
G. Wetzel, H. Oelhaf, F. Friedl-Vallon, O. Kirner, A. Kleinert, G. Maucher, H. Nordmeyer, J. Orphal, R. Ruhnke |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062115
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| Zusammenfassung |
| Arctic winters 2009/2010 and 2010/2011 were characterized by strong vortices with
extremely cold temperatures in the lower stratosphere above northern Scandinavia. Hence,
the occurrence of widespread polar stratospheric clouds enabled a strong activation of
chlorine compounds (ClOx) which rapidly destroyed ozone when sunlight returned after
winter solstice.
MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) balloon
measurements obtained in northern Sweden on 24 January 2010 and 31 March 2011 inside
the polar vortices have provided the first time diurnal variations of chlorine species over the
whole altitude range in which chlorine is undergoing activation and deactivation. The first
flight was carried out in very cold chlorine-activated air with widespread polar stratospheric
clouds. The second one was performed at the end of the winter during the last phase of ClOx
deactivation. Around sunrise, several fast sequences of spectra (in time steps of about 10
min.) were measured to allow the retrieval of chlorine- and nitrogen-containing species which
change quickly their concentration around the terminator between night and day. For
this purpose the line of sight of the instrument was aligned perpendicular to the
azimuth direction of the sun to allow for a symmetric illumination of the sounded
air mass before and beyond the tangent point. Mixing ratios of species like ClO,
NO2, and N2O5 show significant changes under twilight conditions. Observations
are compared and discussed with calculations performed with the 3-dimensional
Chemistry Climate Model EMAC (ECHAM5/MESSy Atmospheric Chemistry). |
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