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Quantifying Eddy Feedbacks and Forcings in the Tropospheric Response to Stratospheric Sudden Warmings

Published version
Peer-reviewed

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Type

Article

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Authors

Hitchcock, Peter 
Simpson, Isla R 

Abstract

jats:titleAbstract</jats:title> jats:pThe equatorward shift of the zonal-mean midlatitude tropospheric jet following a stratospheric sudden warming in a comprehensive stratosphere-resolving model is found to be well quantified by the simple model of tropospheric eddy feedbacks proposed by Lorenz and Hartmann. This permits a decomposition of the shift into a component driven by the stratospheric anomalies and a component driven by tropospheric feedbacks.</jats:p> jats:pThis is done by extending the simple model to include three effective forcing mechanisms by which the stratosphere may influence the tropospheric jet. These include 1) the zonally symmetric adjustments associated with the mean meridional circulation and the direct influence of the stratospheric anomalies on 2) the tropospheric synoptic-scale or 3) the tropospheric planetary-scale eddies. Although the anomalous tropospheric winds are primarily maintained against surface friction by the synoptic-scale eddies, this response can be entirely attributed to the eddy feedback term. The response of the planetary-scale eddies, in contrast, can be directly attributed to the stratosphere. The zonally symmetric tropospheric circulation associated with downward control is found to play little role in driving the tropospheric response.</jats:p> jats:pThe prospects of applying this methodology to reanalysis data are also considered, but statistical limitations and the relatively weak projection of the vertically integrated composite wind anomalies onto the leading EOF preclude any conclusions from being drawn.</jats:p>

Description

This is the final version of the article. It first appeared from American Meteorological Society via https://doi.org/10.1175/JAS-D-16-0056.1

Keywords

37 Earth Sciences, 3708 Oceanography, 3701 Atmospheric Sciences, 13 Climate Action

Journal Title

Journal of the Atmospheric Sciences

Conference Name

Journal ISSN

0022-4928
1520-0469

Volume Title

73

Publisher

American Meteorological Society
Sponsorship
PH acknowledges funding support from the European Research Council through the ACCI project (grant number 267760) lead by John Pyle and from an NSERC post-doctoral fellowship. IRS acknowledges support from National Science Foundation funding to the National Center for Atmospheric Research and NSF award AGS-1317469.