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The role of coupled feedbacks in the decadal variability of the SH eddy-driven jet
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  • Dongxia Yang,
  • Julie M. Arblaster,
  • Gerald A. Meehl,
  • Matthew H. England
Dongxia Yang
Monash University

Corresponding Author:dongxia.yang@monash.edu

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Julie M. Arblaster
Monash University
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Gerald A. Meehl
National Center for Atmospheric Research (UCAR)
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Matthew H. England
University of New South Wales
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Recent work has suggested that tropical Pacific decadal variability and external forcings have had a comparable influence on the observed changes in the Southern Hemisphere (SH) summertime eddy-driven jet over the satellite era. Here we contrast the zonally asymmetric response of the SH eddy-driven jet to tropical Pacific decadal variability using ensembles of the Community Earth System Model version 1 (CESM1) in a pacemaker framework, where sea surface temperatures (SSTA) in the tropical Pacific are nudged to observations. In both coupled and uncoupled experiments, the observed South Pacific jet intensification is found in all seasons, indicating the tropical Pacific SST cooling anomaly impacts the South Pacific jet mainly via direct atmospheric processes. By contrast, only the coupled pacemaker reproduces the South Atlantic-Indian jet poleward shift in the summertime, suggesting that the air-sea coupling is essential in driving the teleconnections between tropical Pacific SSTA and South Atlantic-Indian jet variations.