Does the North Atlantic Oscillation show unusual persistence on intraseasonal timescales?

Keeley, S. P. E., Sutton, R. T. ORCID: https://orcid.org/0000-0001-8345-8583 and Shaffrey, L. C. ORCID: https://orcid.org/0000-0003-2696-752X (2009) Does the North Atlantic Oscillation show unusual persistence on intraseasonal timescales? Geophysical Research Letters, 36. L22706. ISSN 0094-8276 doi: 10.1029/2009GL040367

Abstract/Summary

Previous studies have argued that the autocorrelation of the winter North Atlantic Oscillation (NAO) index provides evidence of unusually persistent intraseasonal dynamics. We demonstrate that the autocorrelation on intraseasonal time-scales of 10–30 days is sensitive to the presence of interannual variability, part of which arises from the sampling of intraseasonal variability and the remainder of which we consider to be “externally forced”. Modelling the intraseasonal variability of the NAO as a red noise process we estimate, for winter, ~70% of the interannual variability is externally forced, whereas for summer sampling accounts for almost all of the interannual variability. Correcting for the externally forced interannual variability has a major impact on the autocorrelation function for winter. When externally forced interannual variability is taken into account the intrinsic persistence of the NAO is very similar in summer and winter (~5 days). This finding has implications for understanding the dynamics of the NAO.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/1765
Item Type	Article
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology Interdisciplinary Research Centres (IDRCs) > Walker Institute Science > School of Mathematical, Physical and Computational Sciences > NCAS
Uncontrolled Keywords	persistence, North Atlantic Oscillation
Publisher	American Geophysical Union
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