A new approximation for the dynamics of topographic Rossby waves

Abstract

A new theory of non-harmonic topographic Rossby waves over a slowly varying bottom depth of arbitrary, 1-D, profile is developed based on the linearised shallow water equations on the f-plane. The theory yields explicit approximate expressions for the phase speed and non-harmonic cross-slope structure of waves. Analytical expressions are derived in both Cartesian and Polar coordinates by letting the frequency vary in the cross-shelf direction and are verified by comparing them with the numerical results obtained by running an ocean general circulation model (the MITgcm). The proposed approximation may be suitable for studying open ocean and coastal shelf wave dynamics.

Keywords

• topographic waves
• perturbation method
• lake dynamics
• linearised shallow water equations
• polar coordinates