Decadal Variability of the Midlatitude Climate System Driven by the Ocean Circulation

Andrew McC. Hogg, William K. Dewar, Peter D. Killworth and Jeffrey R. Blundell

Abstract

A midlatitude coupled ocean-atmosphere model is used to investigate interactions between the atmosphere and the wind-driven ocean circulation. This model uses idealised geometry, yet rich and complicated dynamic flow regimes arise in the ocean due to the explicit simulation of geostrophic turbulence. An interdecadal mode of intrinsic ocean variability is found, and this mode both projects onto existing atmospheric modes of variability, and induces a weak positive feedback in the system. It is also shown that ocean circulation controls the timescale of the SST response to Ekman pumping, and that coupled feedback mechanisms thus modify variability of the atmospheric circulation.