A preliminary simulation of the Terra Nova Bay polynya has been performed with a coupled atmosphere--polynya model. The atmospheric model is a hydrostatic primitive equations model that has been validated previously by a simulation of the strong katabatic winds observed in that area. The polynya model includes a representation of the free drift of frazil ice and simple sea-ice dynamics and thermodynamics. Two and three-dimensional experiments have been performed under polar night conditions. Two-dimensional experiments show that an open (warm) water area influences significantly the atmospheric circulation in the antarctic coastal zone: an additional ice-breeze effect is simulated and is responsible for the strengthening of the katabatic winds near the coast. Because of the important temperature difference between the continental air and the ice-free ocean (up to 40 ¿C), strong surface heat fluxes are simulated over the polynya. Finally, a three-dimensional experiment has been performed. The integration domain includes Terra Nova Bay. The polynya observed in that region is well simulated. It is found that heat losses from the polynya surface are stronger than previously thought but are probably constrained by the idealized representation of frazil ice, which is assumed to be uniform in each grid box. This stresses the need for having a better knowledge of frazil ice evolution in large polynyas.¿ 1997 American Geophysical Union