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| Titel |
Impact of geomagnetic excursions on atmospheric chemistry and dynamics |
| VerfasserIn |
I. Suter, R. Zech, J. G. Anet, T. Peter |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 3 ; Nr. 10, no. 3 (2014-06-19), S.1183-1194 |
| Datensatznummer |
250116985
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| Publikation (Nr.) |
 copernicus.org/cp-10-1183-2014.pdf |
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| Zusammenfassung |
| Geomagnetic excursions, i.e. short periods in time with much weaker
geomagnetic fields and substantial changes in the position of the geomagnetic
pole, occurred repeatedly in the Earth's history, e.g. the Laschamp event
about 41 kyr ago. Although the next such excursion is certain to come,
little is known about the timing and possible consequences for the state of
the atmosphere and the ecosystems. Here we use the global chemistry climate
model SOCOL-MPIOM to simulate the effects of geomagnetic excursions on
atmospheric ionization, chemistry and dynamics. Our simulations show
significantly increased concentrations of nitrogen oxides (NOx)
in the entire stratosphere, especially over Antarctica (+15%), due to
enhanced ionization by galactic cosmic rays. Hydrogen oxides
(HOx) are also produced in greater amounts (up to +40%) in
the tropical and subtropical lower stratosphere, while their destruction by
reactions with enhanced NOx prevails over the poles and in high
altitudes (by −5%). Stratospheric ozone concentrations decrease globally
above 20 km by 1–2% and at the northern hemispheric tropopause by up to
5% owing to the accelerated NOx-induced destruction. A 5%
increase is found in the southern lower stratosphere and troposphere. In
response to these changes in ozone and the concomitant changes in atmospheric
heating rates, the Arctic vortex intensifies in boreal winter, while the
Antarctic vortex weakens in austral winter and spring. Surface wind anomalies
show significant intensification of the southern westerlies at their poleward
edge during austral winter and a pronounced northward shift in spring. Major
impacts on the global climate seem unlikely. |
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