DISTRIBUTION UNLIMITED.

A r.ia thematic a 1 model of a zonally uniform ocean is constructed in order to investigate the steady circulation and the nonhomogeneous distribution of density maintained by elementary thermodynamic processes. The thermodynamic processes are considered implicitly by introducing an equation to represent the transfer of mass by convection and diffusion. The thermo-dynamic processes which affect the density in the surface layers of the ocean are replaced by a distribution of equivalent mass flux across the surface. A simplified system of equations is derived from the general system of hydrodynamic equations representing the model by neglecting small terms in the equations. The simplified 3ystem of equations is nonlinear and of the boundary-layer type. An approximate analysis is carried out using simplified boundary-layer methods and the following types of flow with their associated density fields are studied in detail: (A) the flow set up in a • omogeneous ocean by surface wind stress, (B) the flow and the density field set up by a given mass flux across the ocean surface in the absence of wind stress, (C) the flow and the density field set up by a given mass flux across the ocean surface in the presence of wind stress. For purposes of comparison, the same distributions of wind stress and surface mass flux are used in studying the three different types of flow. The different types of flow are illustrated by diagrams showing the streamlines of the meridional circulation and the distribution of isopycnals in a meridional section. The vertical distributions of the zonal velocity component for the different types of flow are also compared. Prom the analysis of this model, it is concluded that thermodynamic processes affecting the density of sea water cannot be neglected in the study of zonally uniform currents in the ocean. Thus, it does not appear to be possible to account for the observed features of an ocean current, such as the Antarctic Circumpolar Current, in terms of surface wind scress alone.- ii