As an alternative to the frequently used mixed boundary conditions in ocean GCM’s, we presenta dynamic atmospheric model (ECBILT) that is simple and yet describes the relevant dynamicand thermodynamic feedback processes to the ocean. This provides the possibility of studyingatmosphere/ocean dynamics on very long time-scales of the order of a thousand years. Themodel is two orders of magnitude faster than AGCMs. We have been running ECBILT withprescribed SSTs for a period of 500 years with seasonal cycle included both in the solar forcingand in the climatological SSTs. The mean state and the variability properties of ECBILT arereasonably realistic. The simulation of the surface fluxes is quite realistic and justifies couplingECBILT to an ocean GCM. We have done two SST anomaly experiments, one with a tropicalSST anomaly as observed during January 1983 and one with an SST anomaly in the northernextra-tropical Atlantic ocean. For the tropical SST anomaly experiment the amount of anomalousprecipitation agrees well with what has been found with atmospheric GCM’s, but theresulting extra-tropical teleconnection pattern is very weak. The atmospheric response patternto extra-tropical SST anomalies agrees well with similar SST anomaly experiments performedwith atmospheric GCM’s. We have tested the performance of ECBILT in coupled mode bycoupling it to a simple ocean GCM and thermodynamic sea-ice model and integrating thecoupled system for a period of thousand years after a spin up of 6000 years. The simulation ofthe mean water mass distribution and the mean circulation of the ocean resembles the observedocean circulation. It has a warm and fresh bias and the circulation and associated transportsare too diffuse and too weak. The ocean’s variability is realistic, considering the simplicity ofthe ocean model, although a bit too weak. We have explored the covariability between theatmosphere and ocean over the Northern Atlantic ocean by performing a singular value decompositionof SST anomalies and 800 hPa geopotential height anomalies. The 2nd mode showsa peak in both spectra at a timescale of about 18 years. The time scale of this mode is set bythe ocean but the physical mechanisms that are operating are not yet unambiguously identified.The simulation of this coupled extra tropical decadal mode of variability, which also shows upin the observations and in much more complex coupled models provides strong evidence forthe potential usefullness of ECBILT when studying atmosphere/ocean interaction and the associatedocean variability on time scales ranging from decades to many thousands of years. DOI: 10.1034/j.1600-0870.1998.t01-1-00007.x