Understanding the Intermittency of the Wintertime North Atlantic Oscillation and East Atlantic Pattern Seasonal Forecast Skill in the Copernicus C3S Multi‐Model Ensemble

Abstract The wintertime North Atlantic Oscillation (NAO) and East Atlantic Pattern (EA) are the two leading modes of North Atlantic pressure variability and have a substantial impact on winter weather in Europe. The year‐to‐year contributions to multi‐model seasonal forecast skill in the Copernicus...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: L. H. Baker, L. C. Shaffrey, S. J. Johnson, A. Weisheimer
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2024
Subjects:
seasonal forecasting
North Atlantic
East Atlantic Pattern
predictability
forecast skill
Geophysics. Cosmic physics
QC801-809
North Atlantic oscillation
Online Access:https://doi.org/10.1029/2024GL108472
https://doaj.org/article/8d9854a14094462c95a998560fd5292a
Description
Summary:Abstract The wintertime North Atlantic Oscillation (NAO) and East Atlantic Pattern (EA) are the two leading modes of North Atlantic pressure variability and have a substantial impact on winter weather in Europe. The year‐to‐year contributions to multi‐model seasonal forecast skill in the Copernicus C3S ensemble of seven prediction systems are assessed for the wintertime NAO and EA, and well‐forecast and poorly‐forecast years are identified. Years with high NAO predictability are associated with substantial tropical forcing, generally from the El Niño Southern Oscillation (ENSO), while poor forecasts of the NAO occur when ENSO forcing is weak. Well‐forecast EA winters also generally occurred when there was substantial tropical forcing, although the relationship was less robust than for the NAO. These results support previous findings of the impacts of tropical forcing on the North Atlantic and show this is important from a multi‐model seasonal forecasting perspective.

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