A time-dependent model for coupled atmospheric and oceanic boundary layers is described. The model is one-dimensional; hence horizontal gradients of the dependent variables are specified rather than computed. Turbulent viscous and diffusive processes are incorporated by means of the eddy coefficient concept. Using a formulation which is in accord with both surface and Ekman layer observations, the vertical dependence of the eddy coefficient is specified a priori.Experiments with the model were performed with input conditions representative of the climatology of the Gulf of St. Lawrence in autumn and winter. Fairly reasonable profiles of wind, current, stress, temperature, humidity and salinity were obtained. The water surface temperature and the surface fluxes were also reasonably behaved functions of time. The exact date of freeze-up, however, was rather sensitive to the amount of oceanic cold advection determined from the specified oceanic temperature gradients and the calculated ocean current.