The Effects of Friction and β on Finite-Amplitude Baroclinic Waves

Abstract

A linear and finite-amplitude analysis of the baroclinic instability of a zonal current is presented. Both the β effect and viscosity are included. A small but finite amount of dissipation destabilizes the system, lowering the curve of marginal stability by an O(1) amount. In the limit of vanishing viscosity, steady unstable waves of finite amplitude are discovered for shears which are subcritical with respect to the inviscid criterion.