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| Titel |
Impacts of solar particle events on middle atmospheric chlorine compounds |
| VerfasserIn |
Holger Winkler, Miriam Sinnhuber, Jan-Maik Wissing, May-Britt Kallenrode, Gabrielle Stiller, Thomas von Clarmann, Bernd Funke |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038789
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| Zusammenfassung |
| Solar particle events (SPEs) are well known sources of chemical perturbations in the middle
atmosphere. A well-understood effect is the release of reactive NOx and HOx, and the
subsequent destruction of ozone. Satellite measurements (HALOE, MIPAS, AURA-MLS)
have shown that there is also chlorine activation in the stratosphere and mesosphere, and an
increase of chlorine nitrate in the lower and middle stratosphere during SPEs. This cannot be
explained by the NOx and HOx increase alone. Atmospheric models with standard
parametrizations of NOx and HOx production due to SPEs fail to reproduce the magnitude of
the observed chlorine disturbances.
Numerical simulations using the University of Bremen ion chemistry (UBIC) model show a
much better agreement with measurements if full negative ion chemistry is considered
additionally to the NOx and HOx production. The UBIC results in combination with
atmospheric models indicate that reactions of negative cluster ions can have a significant
impact on the middle atmosphere’s chlorine chemistry during SPEs. There is a transformation
of HCl into active chlorine via anion cluster chemistry. Additionally, the release of
O(1D) through N(2D) + O2 - NO + O(1D) has a considerable impact on chlorine
species.
Results of UBIC simulations for different SPEs (July 2000, October 2003, January 2005) are
presented. They are compared with the observed changes of chlorine compounds – HCl,
HOCl, ClO and ClONO2 – from the satellite instruments HALOE, MIPAS and AURA-MLS. |
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