Impact of geomagnetic excursions on atmospheric chemistry and dynamics

Suter, I.; Zech, Roland; Anet, J. G.; Peter, T. (2014). Impact of geomagnetic excursions on atmospheric chemistry and dynamics. Climate of the past, 10(3), pp. 1183-1194. Copernicus Publications 10.5194/cp-10-1183-2014

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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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Biogeochemistry and Paleoclimate
08 Faculty of Science > Institute of Geography

UniBE Contributor:

Zech, Roland

Subjects:

900 History > 910 Geography & travel

ISSN:

1814-9324

Publisher:

Copernicus Publications

Language:

English

Submitter:

Monika Wälti-Stampfli

Date Deposited:

12 Sep 2014 16:45

Last Modified:

01 Oct 2015 16:29

Publisher DOI:

10.5194/cp-10-1183-2014

BORIS DOI:

10.7892/boris.58526

URI:

https://boris.unibe.ch/id/eprint/58526

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