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| Titel |
On the detection of the solar signal in the tropical stratosphere |
| VerfasserIn |
G. Chiodo, D. R. Marsh, R. Garcia-Herrera, N. Calvo, J. A. García |
| 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. 11 ; Nr. 14, no. 11 (2014-06-02), S.5251-5269 |
| Datensatznummer |
250118758
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| Publikation (Nr.) |
 copernicus.org/acp-14-5251-2014.pdf |
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| Zusammenfassung |
| We investigate the relative role of volcanic eruptions, El Niño–Southern
Oscillation (ENSO), and the quasi-biennial oscillation (QBO)
in the quasi-decadal signal in the tropical stratosphere with regard to
temperature and ozone commonly attributed to the 11 \unit{yr} solar
cycle. For this purpose, we perform transient simulations with the
Whole Atmosphere Community Climate Model forced from 1960 to 2004
with an 11 yr solar cycle in irradiance and different
combinations of other forcings. An improved multiple linear regression
technique is used to diagnose the 11 yr solar signal in the
simulations. One set of simulations includes all observed forcings,
and is thereby aimed at closely reproducing observations. Three
idealized sets exclude ENSO variability, volcanic aerosol forcing,
and QBO in tropical stratospheric winds, respectively. Differences
in the derived solar response in the tropical stratosphere in the
four sets quantify the impact of ENSO, volcanic events and the QBO
in attributing quasi-decadal changes to the solar cycle in the model
simulations. The novel regression approach shows that most of
the apparent solar-induced lower-stratospheric temperature and ozone increase
diagnosed in the simulations with all observed forcings is due to two major volcanic
eruptions (i.e., El Chichón in 1982 and Mt. Pinatubo in 1991). This
is caused by the alignment of these eruptions with periods of high solar activity.
While it is feasible to detect a robust solar signal in the middle and
upper tropical stratosphere, this is not the case in the tropical lower
stratosphere, at least in a 45 yr simulation.
The present results suggest that in the tropical lower stratosphere,
the portion of decadal variability that can be unambiguously linked to the solar
cycle may be smaller than previously thought. |
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