The link between the North Atlantic oscillation and Arctic sea ice export through Fram Strait

Abstract

Recently, Hilmer and Jung have shown that the wintertime link between the North Atlantic oscillation (NAO) and the sea ice export through Fram Strait changed from zero correlation (1958-77) to about 0.7 (1978-97) during the last four decades. In the current study, the authors focus on the question of how the two phenomena are linked in a long-term context during wintertime (December-March). This is done on a statistical basis using data from a century-scale control integration of the coupled general circulation model ECHAM4-OPYC3 along with historical sea level pressure data for the period 1908-97. From the results of this study there is less indication that a significant link on interannual and decadal timescales between the NAO and the sea ice export through Fram Strait is a characteristic property of the climate system- at least under present-day climate conditions. This missing link can be explained by a vanishing net impact of the NAO on sea ice thickness as well as sea ice drift near Fram Strait and thus the sea ice volume export through Fram Strait. It is argued that the spatial pattern of interannual NAO variability as observed during the last two decades of the twentieth century is unusual and so is the high correlation between the NAO and Arctic sea ice export for the period 1978-97.