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| Titel |
Latitudinal extent of the January 2005 solar proton event in the Northern Hemisphere from satellite observations of hydroxyl |
| VerfasserIn |
P. T. Verronen, C. J. Rodger, M. A. Clilverd, H. M. Pickett, E. Turunen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 25, no. 10 ; Nr. 25, no. 10 (2007-11-06), S.2203-2215 |
| Datensatznummer |
250015935
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| Publikation (Nr.) |
 copernicus.org/angeo-25-2203-2007.pdf |
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| Zusammenfassung |
| We utilise hydroxyl observations from the MLS/Aura satellite instrument to
study the latitudinal extent of particle forcing in the northern polar region
during the January 2005 solar proton event.
MLS is the first satellite instrument to observe HOx changes during
such an event.
We also predict the hydroxyl changes with respect to the magnetic latitude by
the Sodankylä Ion and Neutral Chemistry model, estimating the variable
magnetic cutoff energies for protons using a parameterisation based on
magnetosphere modelling and the planetary magnetic index Kp.
In the middle and lower mesosphere, HOx species are good indicators
of the changes in the atmosphere during solar proton events, because they
respond rapidly to both increases and decreases in proton forcing. Also,
atmospheric transport has a negligible effect on HOx because
of its short chemical lifetime.
The observations indicate the boundary of the proton forcing and a
transition region, from none to the "full" effect, which ranges from about 57
to 64 degrees of magnetic latitude.
When saturating the rigidity cutoff Kp at 6 in the model, as suggested by earlier studies
using observations of cosmic radio noise absorption, the equatorward boundary
of the transition region is offset by ≈2 degrees polewards compared
with the data, thus the latitudinal extent of the proton forcing in the
atmosphere is underestimated. However, the model predictions are in reasonable
agreement with the MLS measurements when the Kp index is allowed to vary
within its nominal range, i.e., from 1 to 9 in the cutoff calculation. |
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