On Mean Flow Instabilities within the Planetary Geostrophic Equations

Abstract

IFREMER, Cent. Brest, B.P. 337, 29273 Brest Cedex, France J (Journal-Article) M (Marine) This note draws attention to the natural instabilities of a mean zonal flow that arise with the planetary geostrophic equations increasingly used in theories of large-scale oceanic circulation. Baroclinic instability is not excised by the absence of the relative acceleration terms in the momentum equations. The growth rate is shown to increase linearly with wavenumber, yielding an ill-posed mathematical problem. A small amount of lateral friction cures the problem, however, as shown in a three-layer model, which possesses the minimal vertical structure to exhibit the instability Ocean Technology, Policy and Non Living Resources (Q2) 1808607 -------------------------------------------------------------------------------- Record 1548 of 1621 - ASFA 1988-1996