Is the observed NAO variability during the instrumental record unusual?

Observed multidecadal variability (30 yr running means, trends, and moving standard deviations) of the North Atlantic Oscillation (NAO) during the instrumental record is compared to that simulated by two different coupled general circulation models in extended-range control experiments. Simulated NA...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Semenov, Vladimir, Latif, Mojib, Jungclaus, J., Park, Wonsun
Format: Article in Journal/Newspaper
Language:English
Published: AGU (American Geophysical Union) 2008
Subjects:
Online Access:https://oceanrep.geomar.de/id/eprint/8413/
https://oceanrep.geomar.de/id/eprint/8413/1/180_Semenov_2008_IsTheObservedNaoVariability_Artzeit_pubid9856.pdf
https://doi.org/10.1029/2008GL033273
Description
Summary:Observed multidecadal variability (30 yr running means, trends, and moving standard deviations) of the North Atlantic Oscillation (NAO) during the instrumental record is compared to that simulated by two different coupled general circulation models in extended-range control experiments. Simulated NAO exhibits strong low frequency fluctuations, even on multi-centennial time scale. Observed multi-decadal NAO variations agree well with the model variability. Trend probability distribution functions, observed and simulated, were not found to be different with statistical significance. Thus, multi-decadal NAO changes similar to those observed during the instrumental record, including the recent increase in 1965–1995, may be internally generated within the coupled atmosphere-ocean system without considering external forcing.