National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 2001

On the temporal character and regionality of the Arctic Oscillation

Overland, J.E., and J.M. Adams

Geophys. Res. Lett., 28(14), 2811–2814, doi: 10.1029/2000GL011739 (2001)

Decadal differences between the 1990s and 1980s in winter (JFM) sea-level pressure and 300 mb zonal winds have an Arctic-centered character with nearly equal contributions from the Atlantic and Pacific sectors. In contrast, the differences between positive and negative Arctic Oscillation (AO) composites defined from monthly values of Principal Components from the same period have similar magnitudes in the Pacific and Arctic, but have an additional large North Atlantic Oscillation (NAO) signature in the Atlantic sector. Thus Arctic changes on decadal scales are more symmetric with the pole than suggested by the standard AO index definition. Change point analysis of the AO shows that a shift in value near 1989 is an alternate hypothesis to a linear trend. Analysis of zonal and meridional winds by longitudinal sectors shows the importance of the standing wave pattern in interpreting the AO, which supplements the view of the AO as a simple zonal average (annular) mode.

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