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On the detection of the solar signal in the tropical stratosphere

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Chiodo, Gabriel and Marsh, D.R. and García Herrera, Ricardo and Calvo Fernández, Natalia and García, J.A. (2014) On the detection of the solar signal in the tropical stratosphere. Atmospheric chemistry and physics, 14 (11). pp. 5251-5269. ISSN 1680-7316

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Official URL: http://dx.doi.org/10.5194/acp-14-5251-2014




Abstract

We investigate the relative role of volcanic eruptions, El Niño–Southern Oscillation (ENSO), and the quasibiennial oscillation (QBO) in the quasi-decadal signal in the tropical stratosphere with regard to temperature and ozone commonly attributed to the 11 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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© Author(s) 2014. The authors thank J. Añel, K. Matthes, and J. Richter for performing two of the simulations. The authors are grateful for the support with high-performance computing from Yellowstone (ark:/85065/d7wd3xhc), provided by NCAR’s Computational and Information System Laboratory, sponsored by the National Science Foundation. Computing resources were also provided by the Barcelona Supercomputing Center (BSC), Centro Extremeño de Investigación, Innovación Tecnológica y Supercomputación (CENITS), and Centro de Supercomputación de Galicia (CESGA). The authors thankfully acknowledge the technical expertise and assistance provided by BSC, CENITS, and CESGA for carrying out the model simulations in the MareNostrum, Lusitania, and Finisterrae supercomputers. The authors also acknowledge the European COST Action ES1005. G. Chiodo was supported by the Spanish Ministry of Education in the framework of the FPU doctoral fellowship (grant AP2009-0064).This work was also supported by the Spanish Ministry of Science and Innovation (MCINN) through the CONSOLIDER (CSD2007- 00050-II-PR4/07) and MATRES (CGL2012-34221) projects. The National Center for Atmospheric Research is operated by the University Corporation for Atmospheric Research with sponsorship of the National Science Foundation.

Uncontrolled Keywords:Quasi-biennial oscillation; Ozone; Cycle; Temperature; Variability; Pinatubo; Eruption; Climate; Dataset; Aerosol.
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
Sciences > Physics > Atmospheric physics
ID Code:29707
Deposited On:22 Apr 2015 12:20
Last Modified:10 Dec 2018 15:05

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