Abstract
A global climatic model, allowing for seasonal coupling and interaction between continents and oceans, is developed, utilizing an idealized land-water distribution similar to that observed. The basic equation used is the thermodynamic energy equation averaged over time and space. It is written and solved for the mean surface temperature separately for continents and oceans. A time step of one month is used. The vertical variations of temperature, specific humidity, and the zonal and meridional components of the wind velocity are parameterized. The surface velocity components are obtained from modified forms of the first two equations of motion. The model includes variable snow and ice cover, meridional transport of heat and water vapor by mean and eddy atmospheric circulations, storage and transport of heat by the oceans, the effect of aerosols on atmospheric turbidity, and the contribution of H2O, CO2, O3, and clouds to the infrared balance. Cloud cover, the surface relative humidity, and the surface albedo of snow- and ice-free areas are specified.
Using present values for the input parameters, the model reproduces quite well several of the major thermal and dynamic characteristics of the earth-atmosphere system. It is very sensitive to variations of the optical thickness of the atmosphere and of the solar constant. Slight changes in these variables greatly modify the surface temperature field, especially at high latitudes of the Northern Hemisphere. There is some indication of the existence of at least two possible steady-state climates with the same set of input parameters.
