Seasonal oscillations in a mid-latitude ocean with barriers to deep flow
type: CreativeWork
description: A two-layer linear analytic model is used to study the response of the mid-latitude ocean to the seasonal variation of the windstress. The most important component of the response is a barotropic quasi-steady Sverdrup balance. A meridional ridge such as the Antilles Arc is modeled as an infinitely thin meridional barrier that blocks the lower layer but does not protrude into the upper layer. It is found that such a barrier has little effect on the upper layer flow across the barrier. This result is obtained provided the frequency of the motion is low enough so that free short Rossby waves are essentially nondivergent. In this case there is little coupling between the layers for energy propagating to the east away from the barrier. A study of the dynamics of flow over a sloping bottom is made and the results are used to determine the effect on seasonal oscillations of eastern boundary slopes and triangular ridges. It is found that the presence of a slope at the eastern boundary has little effect. A meridional ridge that does not reach the interface may cause substantial scattering of free Rossby waves, but unless the ridge is steep its effect on the quasi-steady Sverdrup balance is minimal. However, if the ridge height is a substantial fraction of the lower layer depth and the width is comparable to the scale of free short Rossby waves, the ridge will tend to block flow in the lower layer, acting like the infinitely thin barrier. The theory suggests that the Antilles Arc should have the effect of a thin barrier, while the Mid-Atlantic Ridge should have little effect on the response of the ocean to seasonal wind variations.
abstract: A two-layer linear analytic model is used to study the response of the mid-latitude ocean to the seasonal variation of the windstress. The most important component of the response is a barotropic quasi-steady Sverdrup balance. A meridional ridge such as the Antilles Arc is modeled as an infinitely thin meridional barrier that blocks the lower layer but does not protrude into the upper layer. It is found that such a barrier has little effect on the upper layer flow across the barrier. This result is obtained provided the frequency of the motion is low enough so that free short Rossby waves are essentially nondivergent. In this case there is little coupling between the layers for energy propagating to the east away from the barrier. A study of the dynamics of flow over a sloping bottom is made and the results are used to determine the effect on seasonal oscillations of eastern boundary slopes and triangular ridges. It is found that the presence of a slope at the eastern boundary has little effect. A meridional ridge that does not reach the interface may cause substantial scattering of free Rossby waves, but unless the ridge is steep its effect on the quasi-steady Sverdrup balance is minimal. However, if the ridge height is a substantial fraction of the lower layer depth and the width is comparable to the scale of free short Rossby waves, the ridge will tend to block flow in the lower layer, acting like the infinitely thin barrier. The theory suggests that the Antilles Arc should have the effect of a thin barrier, while the Mid-Atlantic Ridge should have little effect on the response of the ocean to seasonal wind variations.
author: Firing, Eric
language: en_US
keywords: Ocean circulation, Ocean currents, Ocean-atmosphere interaction, Ocean waves
date published: 1978-08
date modified: 2026-07-27T22:05:19Z
provider: Woods Hole Oceanographic Institute
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Massachusetts Institute of Technology and Woods Hole Oceanographic Institution

PropertyValue
property ID: Handle
value: https://hdl.handle.net/1912/1543

PropertyValue
property ID: DOI
value: 10.1575/1912/1543