The Role of Ice–Ocean Interactions in the Variability of the North Atlantic Thermohaline Circulation

The simulated influence of Arctic sea ice on the variability of the North Atlantic climate is discussed in the context of a global coupled ice-ocean-atmosphere model. This coupled system incorporates a general circulation ocean model, an atmospheric energy moisture balance model, and a dynamic-thermodynamic sea ice model. Under steady seasonal forcing, an equilibrium solution is obtained with very little variability. To induce variability in the model, daily varying stochastic anomalies are applied to the wind forcing of the Northern Hemisphere sea ice cover. These stochastic anomalies have observed spatial patterns but are random in time. Model simulations are run for 1000 yr from an equilibrium state and the variability in the system is analyzed. The sensitivity of the system to the ice-ocean coupling of both heat and freshwater is also examined.