Decadal-to-interdecadal fluctuations of Arctic sea-ice cover and the atmospheric circulation during 1954-1994

The relationship between the Arctic and subarctic sea-ice concentration (SI C) anomalies, particularly those associated with the decadal-scale Greenlan d and Labrador Seas' "Ice and Salinity Anomalies (ISAs)", and the overring atmospheric circulation fluctuations is investigated using the singular val ue decomposition (SVD) and composite map analysis methods. The delta analyz ed are monthly SIC and sea level pressure (SLP) anomalies, which col er the northern hemisphere poleward of 45 degrees N and extend over the 41-year p eriod 1954-1994. The SVD1 (first) mode of the coupled variability which accounts for 57% of the square covariance, is for the most part an atmosphere-to-ice-forcing,no de characterized by the decadal timescale. The aforementioned ISA anomalies are clearly captured by this mode whose SIC anomalies are dominated by a s trong dipole across Greenland. However as part of the same mode, there is a lso a weaker SIC dipole in the northern North Pacific which has opposite-si gned anomalies in the Sea of Okhotsk and the Bering Sea. Tt is also shown t hat there exists a significant negative correlation between the decadal SIC variability in the Greenland-Barents Seas region associated with this mode and the North Atlantic Oscillation, rr;hose spectrum also exhibits a quasi -decadal signal. The SVD2 mode accounts for 12% of the square covariance and shows no eviden ce of a dominant forcing field of either SIC or SLP. This SVD merle exhibit s very low frequency (interdecadal) variability, and its co-variability is mainly concentrated in the northern North Pacific. It appears to be a high- latitude extension of the recently investigated interdecadal North Pacific Oscillation. The spatial structure of the second mode complements the case of the first SVD mode whose co-variability mainly occurs in the northern No rth Atlantic.