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Contact info

email: l.frankcombe [a] unsw.edu.au

Climate Change Research Centre (CCRC)
University of New South Wales
Sydney NSW 2052
Australia

tel: +61 (0)2 9385 8966

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 [3]. Variability from the North Atlantic can propagate into the Arctic through the Nordic seas and vice-versa [4].

Arctic mode

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 [5]).

Highly idealised models of the Arctic basin show that internal modes of variability exist there [5]. 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.

References

[1] Polyakov et al. (2003), J. Clim., vol. 16, pages 2078-2085.
[2] Polyakov et al. (2004), J. Clim., vol. 17, pages 4485-4497.
[3] Frankcombe et al. (2010), J. Clim., vol. 23, pages 3626-3638.
[4] Frankcombe and Dijkstra (2011), Geophys. Res. Lett., vol. 38, L16603.
[5] Frankcombe and Dijkstra (2010), J. Phys. Oceanog., vol. 40, pages 2496-2510.