Coastal-Trapped and Frontal-Trapped Waves in a Continuously Stratified Western Boundary Current - A Contribution to the Gulf Stream Meanders Experiment

Coastal-Trapped and Frontal-Trapped Waves in a Continuously Stratified Western Boundary Current - A Contribution to the Gulf Stream Meanders Experiment
Author: Mark E. Luther
Publisher:
Total Pages: 85
Release: 1980
Genre:
ISBN:

The effects of a realistic western boundary current on the alongshore propagation of sub-initial waves trapped by a sloping bottom topography are studied using a numerical model incorporating realistic bottom topography and a current field which is in thermal wind balance with the density field. This models the Gulf Stream as it flows along the continental slope off North Carolina. The mean state velocity and density fields do not vary alongshore and are continuous in the horizontal as well as the vertical. The linearized, inviscid equations of motion for small amplitude disturbances yield a single governing equation for the perturbation pressure. This equation is solved using a marching method for elliptical problems. The dispersion relations are obtained by searching for the resonance response of the system to an arbitrary uniform forcing term. Four discrete stable modes of Rossby-like waves are identified, all propagating in the upstream direction. A mode-coupling resonance is found between the first two modes. For small wavenumber, the first mode is trapped within the frontal zone on the cyclonic side of the mean current with a smaller barotropic component over the shelf. This 'frontal trapping' is due to the quasi-geostrophic potential vorticity gradient in the mean current. For larger wavenumber, the first mode becomes primarily a barotropic shelf wave. The second mode is a purely barotropic shelf wave for small wavenumbers, but becomes a frontal-trapped wave at large wavenumbers. For the higher wave modes, most of the energy is trapped near the surface in the frontal zone. (Author).

On Coastal Trapped Waves at Low Latitudes in a Stratified Ocean

On Coastal Trapped Waves at Low Latitudes in a Stratified Ocean
Author: Richard Dennis Romea
Publisher:
Total Pages: 506
Release: 1982
Genre: Ocean waves
ISBN:

The response on the continental shelf of a baroclinic ocean to driving by an alongshore coastal wind stress and by barotropic and baroclinic wind forced interior motions is studied as a function of latitude. The relative excitation of continental shelf waves and internal Kelvin waves is studied. The response of a rotating stratified ocean with a vertical boundary, forced at the surface by an alongshore coastal wind stress, shows vertically propagating subinertial motions. Several examples which illustrate the basic properties of the response are presented. Changes in amplitude and frequency with depth are predicted. Components that decay with depth from the surface and components that represent coastal internal Kelvin waves with negative vertical group velocity and upward phase propagation are forced. The effect of bottom Ekman layer friction and slope topography on free internal Kelvin waves is examined, using both a steep and weak slope model. The steep slope represents the low latitude case while the weak slope represents the mid-latitude case. There are substantial differences between the results from the two models. Free waves are frictionally damped and offshore and vertical phase shifts are induced by friction, as well as an onshore flow. Topography induces changes to the wave frequency and alongshore phase speed. The modal amplitude is altered and an onshore flow is induced. Sea level and current velocity data from the equator to 17°S on the west coast of South America show that low frequency (0.1-0.2 cpd) fluctuations propagate poleward with phase speeds similar to those predicted for first mode baroclinic Kelvin waves. The sea level and currents are coherent and approximately 1800 out of phase. The waves do not appear to be the result of local atmospheric forcing. Empirical orthogonal functions show that the alongshore and vertical structure of alongshore velocity is consistent with first mode internal Kelvin waves.

Baroclinic Processes on Continental Shelves

Baroclinic Processes on Continental Shelves
Author: Christopher N. K. Mooers
Publisher: American Geophysical Union
Total Pages: 148
Release: 1986
Genre: Science
ISBN:

Published by the American Geophysical Union as part of the Coastal and Estuarine Sciences, Volume 3. The AGU Monograph Series on Coastal and Estuarine Regimes provides timely summaries and reviews of major process and regional studies, both observational and theoretical, and of theoretical and numerical models. It grew out of an IAPSO/SCOR/ECOR working group initiative several years ago intended to enhance scientific communications on this topic. The series' authors and editors are drawn from the international community. The ultimate goal is to stimulate bringing the theory, observations, and modeling of coastal and estuarine regimes together on the global scale.

Physical Oceanography of Continental Shelves

Physical Oceanography of Continental Shelves
Author: K.H. Brink
Publisher: Princeton University Press
Total Pages: 273
Release: 2023-09-12
Genre: Science
ISBN: 0691236461

An authoritative graduate textbook and professional reference on the physical dynamics of the coastal ocean This book provides an up-to-date, systematic treatment of the processes governing the velocity, pressure, temperature, and salinity of the coastal ocean. Written by a leading expert with decades of experience with theory, observations, and numerical models, it builds on the idea that knowledge of fundamental phenomena allows for an understanding of continental shelf waters globally. Featuring a wealth of ocean observations from a wide variety of locales, Physical Oceanography of Continental Shelves is an essential resource for both students and researchers on this critical region of the world’s oceans. Covers the physical dynamics and properties of the coastal ocean, synthesizing theory and global observations Topics include turbulent boundary layers, wind driving, coastal-trapped waves, the inner shelf, tides, buoyancy currents, instabilities, and connections with the deep open ocean Ideal for graduate students in physical oceanography Includes exercises to strengthen understanding and draws on the author’s experience teaching the subject A must for oceanographers and engineers seeking a comprehensive synthesis of continental shelf processes