Rossby Wave Scattering By Topography In A Continuously Stratified Ocean
Abstract
Rossby waves, or planetary waves, play a crucial rôle in global oceanic circulation. These waves propagate in regions of non-uniform ambient potential vorticity (PV) by conserving the PV of the flow. Bottom topography and the variation of the Coriolis parameter with latitude both give rise to a non-uniform ambient PV field. Baroclinic Rossby waves typically propagate at low speeds and have periods of the order of six months or longer. We are interested in the interactions of these wave with the topography of the ocean floor, in particular ocean ridges. We model the ocean by a continuously stratified Boussinesq fluid on a mid-latitude (β)-plane, with background density linear with depth and assume the flow is quasi-geostrophic. The pressure field, (p), satisfies the Rossby wave equation: begin{displaymath} frac{partial}{partial{t}} left\{ nabla^2_H p + frac{partial}{partial z} [ frac {f_0^2} {N_0^2(z)} frac{partial{p}}{partial{z}} ] right\} + βfrac{partial{p}}{partial{X}} = 0, where (N_0(z)) is the buoyancy frequency and the (X) and (Y) axes are aligned with east and north, respectively. In our previous work, we have considered only the special case of a ridge of infinitesimal width in an ocean of constant density gradient. This work has now been extended to cover ridges of finite width and oceans with arbitrary exponential stratification. Comparisons are made with the predictions of layered models and our previous result are recovered in the appropriate limits.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....11587O