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An impediment to progress in the theory of ocean circulation has been the mathematical difficulties of solving the A model is presented for studying ocean circulation problems taking into account the complicated outline and bottom topography equations of even very simplified ocean circulation models.of the World Ocean. To obtain an efficient scheme for the study of This is caused by the complicated geometry of ocean balow-frequency, large-scale current systems, surface gravity-inertial sins, and more importantly by the nonlinear nature of the waves are filtered out by the ''rigid-lid'' approximation. To resolve equations. The availability of large-scale computers in respecial features of the ocean circulation, such as the Equatorial cent years has now made it possible to carry out ''numerical Undercurrent, the numerical model allows for a variable spacing in either the zonal or meridional direction. The model is designed to experiments'' using a direct computational approach in be as consistent as possible with the continuous equations with obtaining solutions to problems too complex to handle by respect to energy. It is demonstrated that no fictitious energy gener-any analytical method. The first ocean circulation research ation or decay is associated with the nonlinear terms in the finite carried out along these lines was done in a series of studies difference form of the momentum equations. The energy generation by buoyancy forces for the numerical model is also designed in by Sarkisyan [18, 19] in the Soviet Union.such a way that no energy ''leak'' occurs in the transformation fromThe present paper describes in detail a computational potential to kinetic energy. ᮊ 1969 Academic Press procedure to be used in ocean circulation studies. While it has certain features in common to that used in two earlier studies of a baroclinic ocean [3,4], the present method

A numerical model of the world ocean is developed to investigate the role of the ocean in the earth's heat balance. Climatological wind stress, temperature, and salinity are imposed as upper boundary conditions. An equilibrium solution is obtained based on an extended numerical integration over the equivalent of 1000 years. Seasonal variations are included. A series of numerical integrations over shorter periods indicate that quantitative aspects, such as the scale depth of the thermocline, are very sensitive to the closure parameterization representing the effect of unresolved scales of motion. The mean depth of the thermocline is found to be in proportion to the global available potential energy. Larger wind driving increases the scale depth of the thermocline, while larger lateral friction or diffusion leads to a shallower thermocline. The model predicts three major meridional cells in the upper thermocline in each hemisphere, corresponding to the three meridional cells of the atmosphere. The tropical and mid‐latitude cells are largely wind driven. Thermohaline effects are dominant in the polar meridional cells. Seasonal changes in winds have a profound effect on the meridional circulation in the tropics and cause a flux of surface water from the summer to the winter hemisphere. It is suggested that this mechanism is an important factor in moderating climate by transferring excess heat from the summer hemisphere into the winter hemisphere.

The climatic effects of very large changes of CO 2 concentration in the atmosphere are explored using a general circulation model of the coupled ocean-atmosphere system. As a simplification the model has an annual mean insolation and a highly idealized geography.

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Atmospheric weather systems become unpredictable beyond a few weeks, but climate variations can be predictable over much longer periods because of the coupling of the ocean and atmosphere. With the use of a global coupled ocean-atmosphere model, it is shown that the North Atlantic may have climatic predictability on the order of a decade or longer. These results suggest that variations of the dominant multidecadal sea surface temperature patterns in the North Atlantic, which have been associated with changes in climate over Eurasia, can be predicted if an adequate and sustainable system for monitoring the Atlantic Ocean exists.

This paper presents the results of five numerical simulations of the radiocarbon distribution in the ocean using the Geophysical Fluid Dynamics Laboratory primitive equation world ocean general circulation model. The model has a 4.5° latitude by 3.75° longitude grid, 12 vertical levels, and realistic continental boundaries and bottom topography. The model is forced at the surface by observed, annually averaged temperatures, salinities, and wind stresses. There are no chemical transformations or transport of 14C by biological processes in the model. Each simulation in this paper has been run out the equivalent of several thousand years to simulate the natural, steady state distribution of 14C in the ocean. In a companion paper the final state of these simulations is used as the starting point for simulations of the ocean's transient uptake of bomb‐produced 14C. The model reproduces the mid‐depth 14C minimum observed in the North Pacific and the strong front near 45°S between old, deep Pacific waters and younger circumpolar waters. In the Atlantic, the model's deep 14C distribution is much too strongly layered with relatively old water from the Antarctic penetrating into the northern reaches of the North Atlantic basin. Two thirds of the decay of 14C between 35°S and 35°N is balanced by local 14C input from the atmosphere and downward transport by vertical mixing (both diffusion and advective stirring). Only one third is balanced by transport of 14C from high latitudes. A moderately small mixing coefficient of 0.3 cm2 s−1 adequately parameterizes vertical diffusion in the upper kilometer. Spatial variation in gas exchange rates is found to have a negligible effect on deepwater radiocarbon values. Ventilation of the circumpolar region is organized in the model as a deep overturning cell which penetrates as much as 3500 m below the surface. While allowing the circumpolar deep water to be relatively well ventilated, the overturning cell restricts the ventilation of the deep Pacific and Indian basins to the north. This study utilizes three different realizations of the ocean circulation. One is generated by a purely prognostic model, in which only surface temperatures and salinities are restored to observed values. Two are generated by a semidiagnostic model, in which interior temperatures and salinities are restored toward observed values with a 1/50 year−1 time constant. The prognostic version is found to produce a clearly superior deep circulation in spite of producing interior temperatures and salinities which deviate very noticeably from observed values. The weak restoring terms in the diagnostic model suppress convection and other vertical motions, causing major disruptions in the diagnostic model's deep sea ventilation.

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