Seasonal Predictability of the Winter North Atlantic Oscillation From a Jet Stream Perspective

The winter North Atlantic Oscillation (NAO) has varied on interannual and decadal timescales over the last century, associated with variations in the speed and latitude of the eddy‐driven jet stream. This paper uses hindcasts from two operational seasonal forecast systems (the European Centre for Me...

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Bibliographic Details
Published in:Geophysical research letters 2019-08, Vol.46 (16), p.10159-10167
Main Authors: Parker, Tess, Woollings, Tim, Weisheimer, Antje, O'Reilly, Chris, Baker, Laura, Shaffrey, Len
Format: Article
Language:English
Subjects:
Annual variations
Atmospheric forcing
Atmospheric models
ECMWF IFS
Interannual variations
Jet stream
Jet streams (meteorology)
Latitude
Mathematical models
North Atlantic Oscillation
Ocean-atmosphere system
Rivers
seasonal forecasting
Temperature
Variability
Weather forecasting
Winter
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Summary:The winter North Atlantic Oscillation (NAO) has varied on interannual and decadal timescales over the last century, associated with variations in the speed and latitude of the eddy‐driven jet stream. This paper uses hindcasts from two operational seasonal forecast systems (the European Centre for Medium‐range Weather Forecasts's seasonal forecast system, and the U.K. Met Office global seasonal forecast system) and a century‐long atmosphere‐only experiment (using the European Centre for Medium‐range Weather Forecasts's Integrated Forecasting System model) to relate seasonal prediction skill in the NAO to these aspects of jet variability. This shows that the NAO skill realized so far arises from interannual variations in the jet, largely associated with its latitude rather than speed. There likely remains further potential for predictability on longer, decadal timescales. In the small sample of models analyzed here, improved representation of the structure of jet variability does not translate to enhanced seasonal forecast skill. Key Points Multilinear regressions of jet latitude and jet speed are used to investigate prediction skill for the winter NAO Data are sourced from ECMWF and UKMO operational seasonal forecast systems and a long seasonal hindcast experiment Prediction skill for the winter NAO is due to skill in predicting fast variations in jet latitude
ISSN:0094-8276
1944-8007
DOI:10.1029/2019GL084402