On the Teleconnectivity of the "Arctic Oscillation"

The term "Arctic Oscillation" (AO) has recently been introduced to describe the leading structure of SLP variability over the Northern Hemisphere. A key feature of the AO is its zonally symmetric appearance, with a primary center of action over the Arctic and opposing anomalies in midlatitudes. Does the AO's annular appearance result from significant temporal correlations between SLP anomalies at distant longitudes? The results presented indicate that the temporal coherence between the Arctic and midlatitudes is strongest over the Atlantic sector, with weak correlations between the Atlantic and Pacific midlatitudes, both on intraseasonal and interannual time scales during the past 50 yrs. Hence, the "annular" character of the AO is more a reflection of the dominance of its Arctic center of action than any coordinated behavior of the Atlantic and Pacific centers of action in the SLP field. The AO is nearly indistinguishable from the leading structure of variability in the Atlantic sector (e.g., the North Atlantic Oscillation): their temporal correlation is 0.95 for monthly data.