Damping of coastal trapped waves due to bottom friction in a baroclinic ocean

Abstract

The damping of coastal trapped waves due to bottom friction is investigated using a two-layer model in which both stratification and bottom topography are included. In this study, bottom friction is assumed to be much smaller than the combined effects of stratification and topography. Therefore, the lowest order solution represents a free hybrid wave as described by Allen and Romea (1980, Journal of Fluid Mechanics, 98, 555–585), while the next order solution represents wave damping. Results are summarized as follows: (1) the damping rate of the continental shelf wave family is larger than that of the internal Kelvin wave family, consistent with their vertical structure; (2) in the neighbourhood of a “kissing” condition, the damping rates of the two adjacent modes intersect each other and are associated with a change in the properties of the wave from one family to another. Evidence for differential dissipation between continental shelf waves and internal Kelvin waves in the ocean is also discussed.