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| Titel |
Middle atmospheric ion chemistry during energetic particle events, and impacts on the neutral chemistry |
| VerfasserIn |
M. Sinnhuber, H. Winkler, N. Wieters, S. Kazeminejad, J. M. Wissing, M.-B. Kallenrode, G. P. Stiller, T. von Clarmann |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026672
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| Zusammenfassung |
| It is well established that solar proton events (SPEs) are sources of distinct chemical
disturbances in the Earth’s polar atmosphere. While the observed SPE caused production of
NOx, and the subsequent destruction of ozone can be reproduces quite well by
atmospheric models using basic parametrizations for NOx and HOx release as a
function of the particle impact ionisation rate, there are significant differences between
measurements and model predictions concerning several other chemical compounds.
For instance, during the October 2003 SPE, measurements of a number of species
were obtained from the MIPAS instrument on-board the ENVISAT satellite. These
measurements show significant enhancements of HNO3 and N2O5 as well as an increase
of several chlorine species, i.e., ClO, HOCl and ClONO2. Atmospheric models
cannot reproduce these chemical effects if only production of NOx and HOx is
considered.
The impact of positive and negative ion chemistry on the neutral composition of the middle
atmosphere is investigated combining model results from the University of Bremen Ion
Chemistry model UBIC with different neutral stratosphere-mesosphere models,
particularly the new Bremen three-dimensional Chemistry and Transport model of the
middle atmosphere. Focus of the investigation will be the impact of negative ion
chemistry on the activation of chlorine radicals, and on the partitioning of NOy
species.
Model results will be compared to measurement data of different satellite instruments
(HALOE, MIPAS, MLS) for several large SPEs (e.g., the July 2000, Oct/Nov 2003, and
January 2005 events) to show that the observed chlorine activation and the increase of HNO3
can be reproduced much better if full negative ion chemistry is considered additionally to the
NOx and HOx production. |
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