The response of an equatorial ocean to simple wind stress patterns: I. Model formulation and analytic results

A simple model is developed to study the wind-driven equatorial ocean circulation. It is a time dependent, primitive equation, beta plane model that is two-dimensional in the horizontal. The vertical structure consists of two layers above the thermocline with the same constant density. The ocean below the thermocline is taken to be of a higher constant density and to be approximately at rest. The surface layer is of constant depth and is acted upon directly by the wind...

The response of an equatorial ocean to simple wind stress patterns: II. Numerical results

The model developed by Cane (1978) is used to study the wind-driven circulation in an equatorial ocean.· Simple wind stress patterns are imposed and the model evolution and eventual steady state are calculated· numerically. Both linear and fully nonlinear responses are discussed; dynamical arguments are presented to account for the principal features...

On topographic pressure drag in a zonal channel

The effect of bottom topography H on the barotropic transport in a periodic zonal channel is studied. An asymptotic approximation is found for the zonal transport on an f-plane and a β-plane when all f/H isolines are blocked by the zonal walls. It is shown that to leading order, the zonal channel transport is independent of friction. In this it is similar to the Sverdrup transport in a basin. To leading order, the transport is proportional to the bottom topographic wavelength, and inversely proportional to the height of the topography and to R, the range of values of f/H that exists on both sides of the channel. For sufficiently high topography the transport varies inversely with the topographic height squared. The analytic results are verified by numerical experiments

The response of a linear baroclinic equatorial ocean to periodic forcing

This paper examines the response of the linear inviscid shallow water equations on a meridionally infinite but zonally bounded equatorial β-plane to periodic zonal forcings at a low frequency ω…

Forced baroclinic ocean motions. I. The linear equatorial unbounded case

A method is developed for calculating the response of an unbounded inviscid ocean to wind stress and thermal forcings. Although emphasis is on equatorial baroclinic motions, the mathematical technique is first illustrated in detail for the motions described by the similar but simpler barotropic vorticity equation. This serves to clarify the significance of the asymptotic approximations made for the baroclinic planetary modes...

Forced baroclinic ocean motions, III: The linear equatorial basin case

Previous work on the linear spin-up of an equatorial ocean is extended to include the specific effects of the north-south extent of the basin, thus allowing a detailed comparison of analytic spin-up theory with numerical calculations…

Forced baroclinic ocean motions: II. The linear equatorial bounded case

This paper extends the results of Cane and Sarachik (1976) to an ocean bounded by two meridians. A complete solution is obtained for the asymptotic linear inviscid response to wind stress and thermal forcings independent of longitude, switched on at t=0 and steady thereafter. The mathematics is greatly simplified by building on the results of the earlier paper. The form of the solution is relatively simple..

On the dynamics of equatorial currents, with application to the Indian Ocean

The dynamics of equatorial currents are considered in the light of the wind and current measurement at Gan (0.5°S, 73°E) reported by Knox (Deep-Sea Research, 23, 211–221, 1976). For westerly and meridional winds the response of equatorial currents is predominantly local and rapid. It follows that the current reversals observed at Gan are most likely due to changes in the local winds and not to a reflection from the eastern boundary, as was previously suggested. The winds at Gan are predominantly westerly, resulting in downwelling at the equator. The eastward momentum put in by the wind at the surface is advected downward giving subsurface eastward flow. With persistent easterlies (as in the Atlantic and Pacific) there is an undercurrent driven by the eastward pressure gradient force, both because of the direct, down gradient flow and because of the vorticity transported by the associated meridional circulation. It is suggested that the undercurrent that has been observed in the Indian Ocean in the early spring is similarly driven by an eastward pressure force. This pressure gradient is a non-local transient feature generated by the zonal readjustment of mass induced by the relaxation of the winds at the fall monsoon transition. This idea is consistent with the presence of the undercurrent in 1973 and its absence in 1974