The Reflection of Unstable Baroclinic Waves and the Production of Mean Coastal Currents

Abstract

The problem of the reflection of unstable baroclinic waves from straight boundaries inclined with respect to latitude circles is studied. The basic flow in which the incident unstable wave is embedded is a flow with only vertical shear flowing parallel to the boundary. The analysis is done for a two-layer model on the ? plane. For a wave packet centered on the most unstable wave, the reflection process produces two reflected modes, each trapped to the boundary. The trapping scale is of the order of the Rossby radius of deformation. This trapping occurs whenever the current is inclined with respect to a latitude circle, in which case all shears, no matter how small, will support unstable waves. It is argued that the trapped character of the reflected disturbance will produce a rectified current along the boundary with a net barotropic component.