Some Examples of Stationary Planetary Flow Patterns in Bounded Basins

Abstract

A simple regime of fluid flow is defined. This regime can occur in a homogeneous layer of fluid (i) of uniform depth on a rotating sphere and bounded by meridional barriers (ii) of uniform depth on a betaplane and bounded by barriers running north-south (iii) of radially non-uniform depth on a rotating plane and bounded by radial barriers. The essential elements defining the regime are: (a) the flow in the whole layer is steady and geostrophic except and only (b) at the western boundary where a narrow, intense western boundary current is permitted to depart markedly from geostrophy, and (c) the system, which would otherwise be at rest, is driven by a distribution of sources and sinks of fluid (this includes driving agents such as the wind, which can be expressed in terms of source and sink distributions). Predictions concerning patterns of flow have been deduced from the defined regime and verified experimentally on a rotating model of type (iii). Certain results obtained were by no means intuitively obvious from a priori considerations.