NAO predictability from external forcing in the late 20th century

Jeremy M. Klavans, Mark A. Cane, Amy C. Clement, Lisa N. Murphy

Research output: Contribution to journalArticlepeer-review


The North Atlantic Oscillation (NAO) is predictable in climate models at near-decadal timescales. Predictive skill derives from ocean initialization, which can capture variability internal to the climate system, and from external radiative forcing. Herein, we show that predictive skill for the NAO in a very large uninitialized multi-model ensemble is commensurate with previously reported skill from a state-of-the-art initialized prediction system. The uninitialized ensemble and initialized prediction system produce similar levels of skill for northern European precipitation and North Atlantic SSTs. Identifying these predictable components becomes possible in a very large ensemble, confirming the erroneously low signal-to-noise ratio previously identified in both initialized and uninitialized climate models. Though the results here imply that external radiative forcing is a major source of predictive skill for the NAO, they also indicate that ocean initialization may be important for particular NAO events (the mid-1990s strong positive NAO), and, as previously suggested, in certain ocean regions such as the subpolar North Atlantic ocean. Overall, we suggest that improving climate models’ response to external radiative forcing may help resolve the known signal-to-noise error in climate models.

Original languageEnglish (US)
Article number22
Journalnpj Climate and Atmospheric Science
Issue number1
StatePublished - Dec 2021
Externally publishedYes

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Atmospheric Science


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