Contrasting interannual and multidecadal NAO variability

Woollings, T.; Franzke, C.; Hodson, D. L. R.; Dong, B.; Barnes, E. A.; Raible, C. C.; Pinto, J. G. (2015). Contrasting interannual and multidecadal NAO variability. Climate dynamics, 45(1-2), pp. 539-556. Springer 10.1007/s00382-014-2237-y

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Decadal and longer timescale variability in the winter North Atlantic Oscillation (NAO) has considerable impact on regional climate, yet it remains unclear what fraction of this variability is potentially predictable. This study takes a new approach to this question by demonstrating clear physical differences between NAO variability on interannual-decadal (<30 year) and multidecadal (>30 year) timescales. It is shown that on the shorter timescale the NAO is dominated by variations in the latitude of the North Atlantic jet and storm track, whereas on the longer timescale it represents changes in their strength instead. NAO variability on the two timescales is associated with different dynamical behaviour in terms of eddy-mean flow interaction, Rossby wave breaking and blocking. The two timescales also exhibit different regional impacts on temperature and precipitation and different relationships to sea surface temperatures. These results are derived from linear regression analysis of the Twentieth Century and NCEP-NCAR reanalyses and of a high-resolution HiGEM General Circulation Model control simulation, with additional analysis of a long sea level pressure reconstruction. Evidence is presented for an influence of the ocean circulation on the longer timescale variability of the NAO, which is particularly clear in the model data. As well as providing new evidence of potential predictability, these findings are shown to have implications for the reconstruction and interpretation of long climate records.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Physics Institute > Climate and Environmental Physics

UniBE Contributor:

Raible, Christoph

Subjects:

500 Science > 530 Physics
500 Science > 550 Earth sciences & geology

ISSN:

0930-7575

Publisher:

Springer

Language:

English

Submitter:

Doris Rätz

Date Deposited:

09 Jan 2015 08:33

Last Modified:

10 Sep 2015 10:24

Publisher DOI:

10.1007/s00382-014-2237-y

Additional Information:

Corrections: Contrasting interannual and multidecadal NAO variability (vol 45, pg 539, 2015) By: Woollings, T.; Franzke, C.; Hodson, D. L. R.; et al. CLIMATE DYNAMICS Volume: 45 Issue: 1-2 Pages: 557-557 DOI: 10.1007/s00382-014-2298-y

BORIS DOI:

10.7892/boris.61485

URI:

https://boris.unibe.ch/id/eprint/61485

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