Summary: | A two-dimensional zonally averaged model has been developed for simulating the seasonal cycle of the climate of the Northern Hemisphere. The atmospheric component of the model is based on the two-level quasi-geostrophic potential vorticity system of equations. At the surface, the model has land-sea resolution and incorporates detailed snow and sea-ice mass budgets. The upper ocean is represented by an integral mixed-layer model that takes into account the meridional advection and turbulent diffusion of heat. Comparisons between the computed present-day climate and climatological data show that the model does reasonably well in simulating the seasonal cycle of the temperature field. In response to a projected CO/sub 2/ trend based on the scenario of Wuebbles et al. (1984), the modelled annual hemispheric mean surface temperature increases by 2 degrees C between 1983 and 2063. In the high latitudes, the response undergoes significant seasonal variations. Anglais
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