Energy Transmission by Barotropic Rossby Waves across Large-Scale Topography

Abstract

An analytical study investigates the energy transmission by free, barotropic, linear Rossby waves across a large scale bottom topography when topographic and beta-effects have the same order of magnitude. In open ocean regions which are not characterized by a flat bottom, the change in topography is assumed to occur in only one direction and is described by exponential depth profiles. The solution expressed as a plane-wave streamfunction has a nondivergent energy flux vector. An energy transmission coefficient, which represents the fraction of energy that an incident wave can carry across the topography, is defined as the ratio of the upslope component of the energy flux vector in the transmission region to the one in the incident region. The evaluation of the energy transmission coefficient for a ridge similar to the Mid-Atlantic Ridge shows that the low-frequency waves (of period larger than one week) are strongly reflected and that the ridge acts like a barrier which separates the ocean in two basins with independent low-frequency characteristics.