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Title: The Impact of Parameterized Lateral Mixing on the Antarctic Circumpolar Current in a Coupled Climate Model

Abstract

This study examines the impact of changing the lateral diffusion coefficient A Redi on the transport of the Antarctic Circumpolar Current (ACC). The lateral diffusion coefficient A Redi is poorly constrained, with values ranging across an order of magnitude in climate models. The ACC is difficult to accurately simulate, and there is a large spread in eastward transport in the Southern Ocean (SO) in these models. This paper examines how much of that spread can be attributed to different eddy parameterization coefficients. A coarse-resolution, fully coupled model suite was run with A Redi = 400, 800, 1200, and 2400 m 2 s −1 . Additionally, two simulations were run with two-dimensional representations of the mixing coefficient based on satellite altimetry. Relative to the 400 m 2 s −1 case, the 2400 m 2 s −1 case exhibits 1) an 11% decrease in average wind stress from 50° to 65°S, 2) a 20% decrease in zonally averaged eastward transport in the SO, and 3) a 14% weaker transport through the Drake Passage. The decrease in transport is well explained by changes in the thermal current shear, largely due to increases in ocean density occurring on the northern side of the ACC.more » In intermediate waters these increases are associated with changes in the formation of intermediate waters in the North Pacific. We hypothesize that the deep increases are associated with changes in the wind stress curl allowing Antarctic Bottom Water to escape and flow northward.« less

Authors:
ORCiD logo [1];  [2];  [2]
  1. School of Oceanography, University of Washington, Seattle, Washington
  2. Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, Maryland
Publication Date:
Research Org.:
Johns Hopkins Univ., Baltimore, MD (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1607828
Alternate Identifier(s):
OSTI ID: 1803713
Grant/Contract Number:  
SC0019344
Resource Type:
Journal Article: Published Article
Journal Name:
Journal of Physical Oceanography
Additional Journal Information:
Journal Name: Journal of Physical Oceanography Journal Volume: 50 Journal Issue: 4; Journal ID: ISSN 0022-3670
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Oceanography; Eddies; Isopycnal mixing; Mesoscale processes; Climate models; Parameterization; Subgrid-scale processes

Citation Formats

Ragen, Sarah, Pradal, Marie-Aude, and Gnanadesikan, Anand. The Impact of Parameterized Lateral Mixing on the Antarctic Circumpolar Current in a Coupled Climate Model. United States: N. p., 2020. Web. doi:10.1175/JPO-D-19-0249.1.
Ragen, Sarah, Pradal, Marie-Aude, & Gnanadesikan, Anand. The Impact of Parameterized Lateral Mixing on the Antarctic Circumpolar Current in a Coupled Climate Model. United States. https://doi.org/10.1175/JPO-D-19-0249.1
Ragen, Sarah, Pradal, Marie-Aude, and Gnanadesikan, Anand. 2020. "The Impact of Parameterized Lateral Mixing on the Antarctic Circumpolar Current in a Coupled Climate Model". United States. https://doi.org/10.1175/JPO-D-19-0249.1.
@article{osti_1607828,
title = {The Impact of Parameterized Lateral Mixing on the Antarctic Circumpolar Current in a Coupled Climate Model},
author = {Ragen, Sarah and Pradal, Marie-Aude and Gnanadesikan, Anand},
abstractNote = {This study examines the impact of changing the lateral diffusion coefficient A Redi on the transport of the Antarctic Circumpolar Current (ACC). The lateral diffusion coefficient A Redi is poorly constrained, with values ranging across an order of magnitude in climate models. The ACC is difficult to accurately simulate, and there is a large spread in eastward transport in the Southern Ocean (SO) in these models. This paper examines how much of that spread can be attributed to different eddy parameterization coefficients. A coarse-resolution, fully coupled model suite was run with A Redi = 400, 800, 1200, and 2400 m 2 s −1 . Additionally, two simulations were run with two-dimensional representations of the mixing coefficient based on satellite altimetry. Relative to the 400 m 2 s −1 case, the 2400 m 2 s −1 case exhibits 1) an 11% decrease in average wind stress from 50° to 65°S, 2) a 20% decrease in zonally averaged eastward transport in the SO, and 3) a 14% weaker transport through the Drake Passage. The decrease in transport is well explained by changes in the thermal current shear, largely due to increases in ocean density occurring on the northern side of the ACC. In intermediate waters these increases are associated with changes in the formation of intermediate waters in the North Pacific. We hypothesize that the deep increases are associated with changes in the wind stress curl allowing Antarctic Bottom Water to escape and flow northward.},
doi = {10.1175/JPO-D-19-0249.1},
url = {https://www.osti.gov/biblio/1607828}, journal = {Journal of Physical Oceanography},
issn = {0022-3670},
number = 4,
volume = 50,
place = {United States},
year = {Wed Apr 01 00:00:00 EDT 2020},
month = {Wed Apr 01 00:00:00 EDT 2020}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at https://doi.org/10.1175/JPO-D-19-0249.1

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Works referenced in this record:

Global surface eddy diffusivities derived from satellite altimetry: GLOBAL SURFACE MIXING RATES
journal, February 2013


Ice-Sheet and Sea-Level Changes
journal, October 2005


Oceanic Forcing of Ice-Sheet Retreat: West Antarctica and More
journal, May 2015


Variations in Ocean Deoxygenation Across Earth System Models: Isolating the Role of Parameterized Lateral Mixing
journal, June 2019


The Norwegian Earth System Model, NorESM1-M – Part 1: Description and basic evaluation of the physical climate
journal, January 2013


Transport and variability of the Antarctic Circumpolar Current in Drake Passage
journal, January 2003


Effects of vertical variations of thickness diffusivity in an ocean general circulation model
journal, January 2007


The ERA-Interim reanalysis: configuration and performance of the data assimilation system
journal, April 2011


Mean Antarctic Circumpolar Current transport measured in Drake Passage: MEAN ACC TRANSPORT
journal, November 2016


GFDL’s ESM2 Global Coupled Climate–Carbon Earth System Models. Part I: Physical Formulation and Baseline Simulation Characteristics
journal, October 2012


The effects of the eddy-induced advection coefficient in a coarse-resolution coupled climate model
journal, January 2011


Interhemispheric influence of surface buoyancy conditions on a circumpolar current
journal, January 2007


Climate Variability and Radiocarbon in the CM2Mc Earth System Model
journal, August 2011


Isopycnal Mixing in Ocean Circulation Models
journal, January 1990


What sets the mean transport through Drake Passage?
journal, February 2001


On the Relationship of the Circumpolar Current to Southern Hemisphere Winds in Coarse-Resolution Ocean Models
journal, August 2000


GFDL's CM2 Global Coupled Climate Models. Part II: The Baseline Ocean Simulation
journal, March 2006


Critical role for mesoscale eddy diffusion in supplying oxygen to hypoxic ocean waters
journal, October 2013


Exploring the isopycnal mixing and helium–heat paradoxes in a suite of Earth system models
journal, January 2015


Isopycnal mixing by mesoscale eddies significantly impacts oceanic anthropogenic carbon uptake
journal, June 2015


The Gent–McWilliams Skew Flux
journal, May 1998


An Exploration of the Role of Transient Eddies in Determining the Transport of a Zonally Reentrant Current
journal, November 2001


Nonlinear vorticity balance of the Antarctic Circumpolar Current
journal, January 2005


Anthropogenic carbon dioxide transport in the Southern Ocean driven by Ekman flow
journal, January 2010


On the size of the Antarctic Circumpolar Current
journal, January 1989


The transient response of the Southern Ocean pycnocline to changing atmospheric winds: TRANSIENT RESPONSE OF THE SOUTHERN OCEAN
journal, August 2011


Testing theories of the vertical stratification of the ACC against observations
journal, November 2002


Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean
journal, April 2015


Mixing of a tracer in the pycnocline
journal, September 1998


Lagrangian statistics in the central North Pacific
journal, May 2001


The Southern Ocean in the Coupled Model Intercomparison Project phase 5
journal, July 2014


Representation of the Antarctic Circumpolar Current in the CMIP5 climate models and future changes under warming scenarios: ACC REPRESENTATION IN CMIP5
journal, December 2012


Circumpolar response of Southern Ocean eddy activity to a change in the Southern Annular Mode
journal, January 2006


Eddy Saturation of Equilibrated Circumpolar Currents
journal, March 2013


Note on the Dynamics of the Antarctic Circumpolar Current
journal, January 1951


A Microscale View of Mixing and Overturning across the Antarctic Circumpolar Current
journal, January 2016


How does the Redi parameter for mesoscale mixing impact global climate in an Earth System Model?
journal, July 2014


Antarctic ice-sheet loss driven by basal melting of ice shelves
journal, April 2012


Intercomparison of the Southern Ocean Circulations in IPCC Coupled Model Control Simulations
journal, September 2006


Transient Response of the Southern Ocean to Changing Ozone: Regional Responses and Physical Mechanisms
journal, April 2017


On the Dynamics of Wind-Driven Circumpolar Currents
journal, November 2001


On the Obscurantist Physics of “Form Drag” in Theorizing about the Circumpolar Current
journal, October 1996


Volume Transport of the Antarctic Circumpolar Current from Bottom Pressure Measurements
journal, June 1985