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| Titel |
Middle atmospheric changes caused by the January and March 2012 solar proton events |
| VerfasserIn |
C. H. Jackman, C. E. Randall, V. L. Harvey, S. Wang, E. L. Fleming, M. López-Puertas, B. Funke, P. F. Bernath |
| 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 ; 14, no. 2 ; Nr. 14, no. 2 (2014-01-29), S.1025-1038 |
| Datensatznummer |
250118319
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| Publikation (Nr.) |
 copernicus.org/acp-14-1025-2014.pdf |
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| Zusammenfassung |
| The recent 23–30 January and 7–11 March 2012 solar proton event (SPE)
periods were substantial and caused significant impacts on the middle
atmosphere. These were the two largest SPE periods of solar cycle 24 so far.
The highly energetic solar protons produced considerable ionization of the
neutral atmosphere as well as HOx (H, OH, HO2) and
NOx (N, NO, NO2). We compute a NOx production of 1.9
and 2.1 Gigamoles due to these SPE periods in January and March 2012,
respectively, which places these SPE periods among the 12 largest in the past
50 yr. Aura Microwave Limb Sounder (MLS) observations of the peroxy radical,
HO2, show significant enhancements of > 0.9 ppbv in the
northern polar mesosphere as a result of these SPE periods. Both MLS
measurements and Goddard Space Flight Center (GSFC) two-dimensional (2-D)
model predictions indicated middle mesospheric ozone decreases of
> 20% for several days in the northern polar region with
maximum depletions > 60% over 1–2 days as a result of the
HOx produced in both the January and March 2012 SPE periods. The
SCISAT-1 Atmospheric Chemistry Experiment Fourier Transform Spectrometer
(ACE) and the Envisat Michelson Interferometer for Passive Atmospheric
Sounding (MIPAS) instruments measured NO and NO2
(~ NOx), which indicated enhancements of over 20 ppbv in
most of the northern polar mesosphere for several days as a result of these
SPE periods. The GSFC 2-D model and the Global Modeling Initiative
three-dimensional chemistry and transport model were used to predict the
medium-term (~ months) influence and showed that the polar middle
atmospheric ozone was most affected by these solar events in the Southern
Hemisphere due to the increased downward motion in the fall and early winter.
The downward transport moved the SPE-produced NOy to lower
altitudes and led to predicted modest destruction of ozone (5–13%) in
the upper stratosphere days to weeks after the March 2012 event. Polar total
ozone reductions were predicted to be a maximum of 1.5% in 2012 due to
these SPEs. |
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