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Changes in Zonal Surface Temperature Gradients and Walker Circulations in a Wide Range of Climates

Merlis, Timothy M. and Schneider, Tapio (2011) Changes in Zonal Surface Temperature Gradients and Walker Circulations in a Wide Range of Climates. Journal of Climate, 24 (17). pp. 4757-4768. ISSN 0894-8755. https://resolver.caltech.edu/CaltechAUTHORS:20111012-074304154

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Abstract

Variations in zonal surface temperature gradients and zonally asymmetric tropical overturning circulations (Walker circulations) are examined over a wide range of climates simulated with an idealized atmospheric general circulation model (GCM). The asymmetry in the tropical climate is generated by an imposed ocean energy flux, which does not vary with climate. The range of climates is simulated by modifying the optical thickness of an idealized longwave absorber (representing greenhouse gases). The zonal surface temperature gradient in low latitudes generally decreases as the climate warms in the idealized GCM simulations. A scaling relationship based on a two-term balance in the surface energy budget accounts for the changes in the zonally asymmetric component of the GCM-simulated surface temperature. The Walker circulation weakens as the climate warms in the idealized simulations, as it does in comprehensive simulations of climate change. The wide range of climates allows a systematic test of energetic arguments that have been proposed to account for these changes in the tropical circulation. The analysis shows that a scaling estimate based on changes in the hydrological cycle (precipitation rate and saturation specific humidity) accounts for the simulated changes in the Walker circulation. However, it must be evaluated locally, with local precipitation rates. If global-mean quantities are used, the scaling estimate does not generally account for changes in the Walker circulation, and the extent to which it does is the result of compensating errors in changes in precipitation and saturation specific humidity that enter the scaling estimate.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1175/2011JCLI4042.1 DOIUNSPECIFIED
http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI4042.1PublisherUNSPECIFIED
ORCID:
AuthorORCID
Schneider, Tapio0000-0001-5687-2287
Additional Information:© 2011 American Meteorological Society. Manuscript received 30 August 2010, in final form 9 March 2011. We thank Simona Bordoni, Isaac Held, Yohai Kaspi, Xavier Levine, and Paul O’Gorman for helpful discussions and technical assistance. The comments of two anonymous reviewers helped clarify the presentation of our work. This work was supported by a National Defense Science and Engineering Graduate Fellowship, a National Science Foundation Graduate Research Fellowship, and a David and Lucile Packard Fellowship. The GCM simulations were performed on Caltech’s Division of Geological and Planetary Sciences Dell cluster. The program code for the simulations, based on the Flexible Modeling System of the Geophysical Fluid Dynamics Laboratory, as well as the simulation results themselves are available from the authors upon request.
Funders:
Funding AgencyGrant Number
National Defense Science and Engineering Graduate FellowshipUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
David and Lucile Packard FellowshipUNSPECIFIED
Subject Keywords:Atmospheric circulation, General circulation models, Surface temperature, Tropics, Walker circulation
Issue or Number:17
Record Number:CaltechAUTHORS:20111012-074304154
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20111012-074304154
Official Citation:Merlis, Timothy M., Tapio Schneider, 2011: Changes in zonal surface temperature gradients and walker circulations in a wide range of climates. J. Climate, 24, 4757–4768. doi: 10.1175/2011JCLI4042.1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:27174
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:12 Oct 2011 14:58
Last Modified:03 Oct 2019 03:21

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