Strait of Georgia: Swaters, Mixed bottom-friction, Gordon E., 2006: The Meridional Flow-2009

Gordon E. Swaters, Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada. Email: gordon.swaters@ualberta.ca

 

Swaters, Gordon E., 2006: The Meridional Flow of Source-Driven Abyssal Currents in a Stratified Basin with Topography. Part II: Numerical Simulation. J. Phys. Oceanogr., 36, 356–375.

doi: http://dx.doi.org/10.1175/JPO2868.1

The Meridional Flow of Source-Driven Abyssal Currents in a Stratified Basin with Topography. Part II: Numerical Simulation

Gordon E. Swaters

Applied Mathematics Institute, Department of Mathematical and Statistical Sciences, and Institute for Geophysical Research, University of Alberta, Edmonton, Alberta, Canada

A numerical simulation is described for source-driven abyssal currents in a 3660 km × 3660 km stratified Northern Hemisphere basin with zonally varying topography. The model is the two-layer quasigeostrophic equations, describing the overlying ocean, coupled to the finite-amplitude planetary geostrophic equations, describing the abyssal layer, on a midlatitude β plane. The source region is a fixed 75 km × 150 km area located in the northwestern sector of the basin with a steady downward volume transport of about 5.6 Sv (Sv ≡ 106 m3 s−1) corresponding to an average downwelling velocity of about 0.05 cm s−1. The other parameter values are characteristic of the North Atlantic Ocean. It takes about 3.2 yr for the abyssal water mass to reach the southern boundary and about 25 yr for a statistical state to develop. Time-averaged and instantaneous fields at a late time are described. The time-averaged fields show an equator-ward-flowing abyssal current with distinct up- and downslope groundings with decreasing height in the equator-ward direction. The average equator-ward abyssal transport is about 8 Sv, and the average abyssal current thickness is about 500 m and is about 400 km wide. The circulation in the upper layers is mostly cyclonic and is western intensified, with current speeds about 0.6 cm s−1. The upper layer cyclonic circulation intensifies in the source region with speeds about 4 cm s−1, and there is an anticyclonic circulation region immediately adjacent to the western boundary giving rise to a weak barotropic poleward current in the upper layers with a speed of about 0.6 cm s−1. The instantaneous fields are highly variable. Even though the source is steady, there is a pronounced spectral peak at the period of about 54 days. The frequency associated with the spectral peak is an increasing function of the …Abstract

Keywords: barotropic flow

Received: June 1, 2005; Accepted: October 20, 2005

Corresponding author address: Gordon E. Swaters, Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada. Email: gordon.swaters@ualberta.ca

Cited by

GORDON E. SWATERS. (2009) Mixed bottom-friction–Kelvin–Helmholtz destabilization of source-driven abyssal overflows in the ocean. Journal of Fluid Mechanics 626, 33
Online publication date: 1-May-2009.
CrossRef

Gordon E. Swaters. (2009) Ekman destabilization of inertially stable baroclinic abyssal flow on a sloping bottom. Physics of Fluids 21:8, 086601
Online publication date: 1-Jan-2009.
CrossRef

Gordon E. Swaters. (2006) The Meridional Flow of Source-Driven Abyssal Currents in a Stratified Basin with Topography. Part I: Model Development and Dynamical Properties. Journal of Physical Oceanography 36:3, 335-355
Online publication date: 1-Mar-2006.
Abstract . Full Text . PDF (514 KB)

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