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| Titel |
Forcing of stratospheric chemistry and dynamics during the Dalton Minimum |
| VerfasserIn |
J. G. Anet, S. Muthers, E. Rozanov, C. C. Raible, T. Peter, A. Stenke, A. I. Shapiro, J. Beer, F. Steinhilber, S. Brönnimann, F. Arfeuille, Y. Brugnara, W. Schmutz |
| 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 ; 13, no. 21 ; Nr. 13, no. 21 (2013-11-08), S.10951-10967 |
| Datensatznummer |
250085805
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| Publikation (Nr.) |
 copernicus.org/acp-13-10951-2013.pdf |
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| Zusammenfassung |
| The response of atmospheric chemistry and dynamics to volcanic
eruptions and to a decrease in solar activity during the Dalton Minimum
is investigated with the fully coupled atmosphere–ocean chemistry
general circulation model SOCOL-MPIOM (modeling tools for studies of SOlar Climate Ozone Links-Max Planck Institute Ocean Model) covering the time period 1780 to
1840 AD. We carried out several sensitivity ensemble experiments to
separate the effects of (i) reduced solar ultra-violet (UV)
irradiance, (ii) reduced solar visible and near infrared irradiance,
(iii) enhanced galactic cosmic ray intensity as well as less intensive
solar energetic proton events and auroral electron precipitation, and
(iv) volcanic aerosols. The introduced changes of UV irradiance and
volcanic aerosols significantly influence stratospheric dynamics in the
early 19th century, whereas changes in the visible part of the
spectrum and energetic particles have smaller effects. A reduction of
UV irradiance by 15%, which represents the presently discussed highest
estimate of UV irradiance change caused by solar activity changes,
causes global ozone decrease below the
stratopause reaching as much as 8% in the midlatitudes at 5 hPa and
a significant stratospheric cooling of up to 2 °C in the
mid-stratosphere and to 6 °C in the lower mesosphere. Changes in
energetic particle precipitation lead only to minor changes in the
yearly averaged temperature fields in the stratosphere. Volcanic
aerosols heat the tropical lower stratosphere, allowing more water
vapour to enter the tropical stratosphere, which, via HOx reactions,
decreases upper stratospheric and mesospheric ozone by roughly
4%. Conversely, heterogeneous chemistry on aerosols reduces
stratospheric NOx, leading to a 12% ozone increase in the tropics,
whereas a decrease in ozone of up to 5% is found over Antarctica
in boreal winter. The linear superposition of the different
contributions is not equivalent to the response obtained in
a simulation when all forcing factors are applied during the Dalton Minimum (DM) – this
effect is especially well visible for NOx/NOy. Thus,
this study also shows the non-linear behaviour of the coupled
chemistry-climate system. Finally, we conclude that especially UV and
volcanic eruptions dominate the changes in the ozone, temperature and
dynamics while the NOx field is dominated by the energetic particle precipitation. Visible
radiation changes have only very minor effects on both stratospheric
dynamics and chemistry. |
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