Modes in the Arctic
One possible source of variability in the North Atlantic is the Arctic. Low frequency variability has been observed in the Arctic [1,2] and found in GCMs . Variability from the North Atlantic can propagate into the Arctic through the Nordic seas and vice-versa .
Figure 1: An oscillatory mode is found in a simple model of the Arctic basin. Like the AMO mode it arises through a Hopf bifurcation (from ).
Highly idealised models of the Arctic basin show that internal modes of variability exist there . Figure 1 shows three time steps of an oscillation with a period of about 50 years which occurs in the idealised model. The oscillation is damped and would therefore need to be excited by some sort of external forcing, perhaps from the atmosphere or from variability in the North Atlantic inflow to the Arctic.
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