On the propagation of stable baroclinic Rossby waves through a mean shear flow

Abstract

Propagation of mid-latitude baroclinic Rossby waves through an ocean with a weak (1 to 2 cm s −1) mean flow is considered. It is shown that north-south propagation of waves is strongly affected and can be suppressed; in particular, total reflection can occur from eastward flow of less than 1 cm s −1. A range of simple problems is considered to demonstrate the variety of possible effects of mean flow. Barotropic and baroclinic mean flows are both discussed, as are initial value and temporal normal mode problems. East-west mean flow is shown to be much more efficient at preventing wave propagation normal to itself than any other orientation. Some problems connected with the observation of Rossby waves in the ocean are discussed; in particular, only waves with wavelengths of many internal deformation radii are likely to be identifiable.