Amplified Decadal Variability of Extratropical Surface Temperatures by Stratosphere-Troposphere Coupling

Amy H. Butler*, Alexey Yu Karpechko, Chaim I. Garfinkel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The dominant pattern of Northern Hemisphere extratropical climate variability is the Northern Annular Mode (NAM), which in wintertime represents the coupling of the stratospheric and tropospheric circulations. The internal variability associated with the NAM has been shown to give rise to substantial uncertainty in climate projections of regional surface air temperatures (SATs), but it's unclear how much of this variability arises from stratosphere-troposphere coupling processes. Here, using three large-ensemble coupled climate model simulations from 1850 to 2100 with varying fidelity of stratosphere-troposphere coupling processes, we demonstrate that regional SAT variability across timescales is amplified when the tropospheric NAM is coupled to the stratospheric NAM. Moreover, models that lack adequate simulation of stratosphere-troposphere coupling processes may not capture the magnitude of uncertainty in near-term SAT projections associated with this coupling.

Original languageAmerican English
Article numbere2023GL104607
JournalGeophysical Research Letters
Issue number16
StatePublished - 28 Aug 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.


  • climate variability
  • decadal variability
  • large ensembles
  • stratosphere
  • stratosphere-troposphere coupling


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