AbstractThe general circulation model whose formulation is described in Corbyet al.(1972) was integrated for 60 days from real data with January radiation and sea surface temperatures. The deficiencies of the model as a representation of the atmosphere were revealed by the extent and rate of the systematic changes as an equilibrium state was approached. For the first ten days, the model lost eddy kinetic energy, then gradually recovered and from about day 30 its tropospheric simulations both synoptically and in its time‐mean cross‐sections at various longitudes, had many realistic features; it failed, however, to maintain a substantial Siberian winter anticyclone. A major weakness, resulting from the use of a single level to represent the 0–200 mb layer, was the progressive deterioration of the model stratos