Effects of mesoscale eddies on global ocean distributions of CFC-11, CO 2 , and Δ 14 C
Global-scale tracer simulations are typically made at coarse resolution without explicitly modelling eddies. Here we ask what role do eddies play in ocean uptake, storage, and meridional transport of transient tracers. We made global anthropogenic transient-tracer simulations in coarse-resolution (2...
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ftdoajarticles:oai:doaj.org/article:e079f7eff28a49098211ec93e39b28e7 2023-05-15T13:46:43+02:00 Effects of mesoscale eddies on global ocean distributions of CFC-11, CO 2 , and Δ 14 C P. Delecluse J.-C. Dutay J. C. Orr Z. Lachkar 2007-10-01T00:00:00Z https://doaj.org/article/e079f7eff28a49098211ec93e39b28e7 EN eng Copernicus Publications http://www.ocean-sci.net/3/461/2007/os-3-461-2007.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 https://doaj.org/article/e079f7eff28a49098211ec93e39b28e7 Ocean Science, Vol 3, Iss 4, Pp 461-482 (2007) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2007 ftdoajarticles 2022-12-31T11:53:00Z Global-scale tracer simulations are typically made at coarse resolution without explicitly modelling eddies. Here we ask what role do eddies play in ocean uptake, storage, and meridional transport of transient tracers. We made global anthropogenic transient-tracer simulations in coarse-resolution (2°cosϕ×2°, ORCA2) and eddy-permitting (½°cosϕ×½°, ORCA05) versions of the ocean general circulation model OPA9. Our focus is on surface-to-intermediate waters of the southern extratropics where air-sea tracer fluxes, tracer storage, and meridional tracer transport are largest. Eddies have little effect on global and regional bomb Δ 14 C uptake and storage. Yet for anthropogenic CO 2 and CFC-11, refining the horizontal resolution reduced southern extratropical uptake by 25% and 28%, respectively. There is a similar decrease in corresponding inventories, which yields better agreement with observations. With higher resolution, eddies strengthen upper ocean vertical stratification and reduce excessive ventilation of intermediate waters by 20% between 60° S and 40° S. By weakening the residual circulation, i.e., the sum of Eulerian mean flow and the opposed eddy-induced flow, eddies reduce the supply of tracer-impoverished deep waters to the surface near the Antarctic divergence, thus reducing the air-sea tracer flux. Thus in the eddy permitting model, surface waters in that region have more time to equilibrate with the atmosphere before they are transported northward and subducted. As a result, the eddy permitting model's inventories of CFC-11 and anthropogenic CO 2 are lower in that region because mixed-layer concentrations of both tracers equilibrate with the atmosphere on relatively short time scales (15 days and 6 months, respectively); conversely, bomb Δ 14 C's air-sea equilibration time of 6 years is so slow that, even in the eddy permitting model, there is little time for surface concentrations to equilibrate with the atmosphere, i.e., before surface waters are subducted. Article in Journal/Newspaper Antarc* Antarctic Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
spellingShingle |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 P. Delecluse J.-C. Dutay J. C. Orr Z. Lachkar Effects of mesoscale eddies on global ocean distributions of CFC-11, CO 2 , and Δ 14 C |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
description |
Global-scale tracer simulations are typically made at coarse resolution without explicitly modelling eddies. Here we ask what role do eddies play in ocean uptake, storage, and meridional transport of transient tracers. We made global anthropogenic transient-tracer simulations in coarse-resolution (2°cosϕ×2°, ORCA2) and eddy-permitting (½°cosϕ×½°, ORCA05) versions of the ocean general circulation model OPA9. Our focus is on surface-to-intermediate waters of the southern extratropics where air-sea tracer fluxes, tracer storage, and meridional tracer transport are largest. Eddies have little effect on global and regional bomb Δ 14 C uptake and storage. Yet for anthropogenic CO 2 and CFC-11, refining the horizontal resolution reduced southern extratropical uptake by 25% and 28%, respectively. There is a similar decrease in corresponding inventories, which yields better agreement with observations. With higher resolution, eddies strengthen upper ocean vertical stratification and reduce excessive ventilation of intermediate waters by 20% between 60° S and 40° S. By weakening the residual circulation, i.e., the sum of Eulerian mean flow and the opposed eddy-induced flow, eddies reduce the supply of tracer-impoverished deep waters to the surface near the Antarctic divergence, thus reducing the air-sea tracer flux. Thus in the eddy permitting model, surface waters in that region have more time to equilibrate with the atmosphere before they are transported northward and subducted. As a result, the eddy permitting model's inventories of CFC-11 and anthropogenic CO 2 are lower in that region because mixed-layer concentrations of both tracers equilibrate with the atmosphere on relatively short time scales (15 days and 6 months, respectively); conversely, bomb Δ 14 C's air-sea equilibration time of 6 years is so slow that, even in the eddy permitting model, there is little time for surface concentrations to equilibrate with the atmosphere, i.e., before surface waters are subducted. |
format |
Article in Journal/Newspaper |
author |
P. Delecluse J.-C. Dutay J. C. Orr Z. Lachkar |
author_facet |
P. Delecluse J.-C. Dutay J. C. Orr Z. Lachkar |
author_sort |
P. Delecluse |
title |
Effects of mesoscale eddies on global ocean distributions of CFC-11, CO 2 , and Δ 14 C |
title_short |
Effects of mesoscale eddies on global ocean distributions of CFC-11, CO 2 , and Δ 14 C |
title_full |
Effects of mesoscale eddies on global ocean distributions of CFC-11, CO 2 , and Δ 14 C |
title_fullStr |
Effects of mesoscale eddies on global ocean distributions of CFC-11, CO 2 , and Δ 14 C |
title_full_unstemmed |
Effects of mesoscale eddies on global ocean distributions of CFC-11, CO 2 , and Δ 14 C |
title_sort |
effects of mesoscale eddies on global ocean distributions of cfc-11, co 2 , and δ 14 c |
publisher |
Copernicus Publications |
publishDate |
2007 |
url |
https://doaj.org/article/e079f7eff28a49098211ec93e39b28e7 |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
Ocean Science, Vol 3, Iss 4, Pp 461-482 (2007) |
op_relation |
http://www.ocean-sci.net/3/461/2007/os-3-461-2007.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 https://doaj.org/article/e079f7eff28a49098211ec93e39b28e7 |
_version_ |
1766245147038711808 |