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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)

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)

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)

The role of wind in determining the timing of the spring bloom in the Strait of Georgia.( September 1, 2009 | Collins, A. Kathleen; Allen, Susan E.; Pawlowicz, Rich | Copyright.

The role of wind in determining the timing of the spring bloom in the Strait of Georgia.( September 1, 2009 | Collins, A. Kathleen; Allen, Susan E.; Pawlowicz, Rich | Copyright.

Strait of Georgia (SoG) semi enclosed, maximum depth 400 meters Wind controls ocean current Spr bloom Fraser low

The role of wind in determining the timing of the spring bloom in the Strait of Georgia.(Report)

                       

Canadian Journal of Fisheries and Aquatic Sciences

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September 1, 2009 | Collins, A. Kathleen; Allen, Susan E.; Pawlowicz, Rich | Copyright. http://www.highbeam.com/doc/1G1-209043866.html

 

COPYRIGHT 2008 NRC Research Press. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights or concerns about this content should be directed to Customer Service.

 

 

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<a href=”http://www.highbeam.com/doc/1G1-209043866.html&#8221; title=”The role of wind in determining the timing of the spring bloom in the Strait of Georgia.(Report) | HighBeam Research”>The role of wind in determining the timing of the spring bloom in the Strait of Georgia.(Report)</a>

Introduction

The Strait of Georgia (SoG) is a semi-enclosed, deep sea (maximum depth 400 m) located off the coast of mainland British Columbia, Canada (Fig. 1). In the southern SoG, the near-surface physical oceanography is dominated by the Fraser River plume and the estuarine flow it produces (Pawlowicz et al. 2007). The SoG is too large to be considered a classic estuary, but its dynamics are similar to those of smaller fjord estuaries. It is productive (yearly average productivity 1.6 g C x [m.sup.-2] x [day.sup.-1]) and, being a temperate sea, has a classic diatom-dominated spring bloom and a weaker fall bloom (R. Pawlowicz, A.R. Sastri, S.E. Allen, D. Cassis, O. Riche, M. Halverson, R. El-Sabaawi, and J.F. Dower, unpublished data). The timing of the spring bloom has been observed to vary interannually by as much as 6 weeks, with blooms as early as February and as late as mid-April (R. Pawlowicz, A.R. Sastri, S.E. Allen, D. Cassis, O. Riche, M. Halverson, R. El-Sabaawi, and J.F. Dower, unpublished data). …

In this paper, we will investigate the role of the principal physical forcings on the SoG, which vary interannually (wind, freshwater flux, and cloud fraction). We wish to determine which of these physical forcings, within the observed variation of the forcing, most strongly influence the timing of the spring bloom.

To directly observe mixing-layer depth, one can use various instantaneous turbulence measurements, but it is much harder to maintain measurements over an extended period, and unlike mixed depth, which is due to the integrative effects of mixing, mixing-layer depth varies rapidly. Here, the depth of the mixing layer will be calculated using a turbulence closure model designed for the surface ocean (Large et al. 1994). Recent one-dimensional (1D) models have considered the timing of the spring bloom in Prince William Sound (Eslinger et al. 2001) and the Bering Sea (Jin et al. 2006). In both cases, the phytoplankton is light-limited and the initiation of the bloom is due to reduced mixing and increased stratification. In the Bering Sea, ice is usually a controlling factor, but in ice-free years, Jin et al. (2006) showed that wind mixing and thermal stratification controlled the mixing-layer depth and thus the timing of the bloom. They were limited in their investigation of interannual variations as they had only one year of ice-free data. Using three years of data in Prince William Sound, Eslinger et al. (2001) showed that, again, wind mixing controlled the mixing-layer depth and the timing of the spring bloom. In both these regions, thermal stratification dominates over salinity stratification; whereas in the SoG, salinity stratification dominates due to the large freshwater fluxes. For the SoG, it has therefore been postulated that the beginning of the large freshwater flux due to snowmelt (the freshet) is necessary for the mixing layer to shallow and the bloom to begin (Yin et al. 1997b).

3D Oceanic Model Assimilating Geostrophic Currents

<a href="A Simplified 3D Oceanic Model Assimilating Geostrophic Currents: Application to the POMME Experiment” title=”3D Oceanic Model Assimilating Geostrophic Currents “>3D Oceanic Model Assimilating Geostrophic Currents

3D Oceanic Model Assimilating Geostrophic Currents

Journal of Physical Oceanography

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May 1, 2005 | Giordani, Hervé; Caniaux, Guy; Prieur, Louis | Copyrighthttp://www.highbeam.com/doc/1P3-858085241.html

 

 

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<a href=”http://www.highbeam.com/doc/1P3-858085241.html&#8221; title=”A Simplified 3D Oceanic Model Assimilating Geostrophic Currents: Application to the POMME Experiment | HighBeam Research”>A Simplified 3D Oceanic Model Assimilating Geostrophic Currents: Application to the POMME Experiment</a>

ABSTRACT

A simplified oceanic model is developed to easily perform cheap and realistic mesoscale simulations on an annual scale. This simplified three-dimensional oceanic model is obtained by degenerating the primitive equations system by prescribing continuously analysis-derived geostrophic currents U^sub g^ into the momentum equation in substitution of the horizontal pressure gradient. Simplification is provided by a time sequence of U^sub g^ called guide, which is used as a low-resolution and low-frequency interpolator. This model is thus necessarily coupled to systems providing geostrophic currents-that is, ocean circulation models, analyzed/ reanalyzed fields, or …