Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO[subscript 2]
The effect of idealized wind-driven circulation changes in the Southern Ocean on atmospheric CO[subscript 2] and the ocean carbon inventory is investigated using a suite of coarse-resolution, global coupled ocean circulation and biogeochemistry experiments with parameterized eddy activity and only m...
| Main Authors: | , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
Springer-Verlag
2015
|
| Online Access: | http://hdl.handle.net/1721.1/97886 https://orcid.org/0000-0002-3102-0341 |
| _version_ | 1811068488276508672 |
|---|---|
| author | Lauderdale, Jonathan Garabato, Alberto C. Naveira Oliver, Kevin I. C. Williams, Richard G. Follows, Michael J |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Lauderdale, Jonathan Garabato, Alberto C. Naveira Oliver, Kevin I. C. Williams, Richard G. Follows, Michael J |
| author_sort | Lauderdale, Jonathan |
| collection | MIT |
| description | The effect of idealized wind-driven circulation changes in the Southern Ocean on atmospheric CO[subscript 2] and the ocean carbon inventory is investigated using a suite of coarse-resolution, global coupled ocean circulation and biogeochemistry experiments with parameterized eddy activity and only modest changes in surface buoyancy forcing, each experiment integrated for 5,000 years. A positive correlation is obtained between the meridional overturning or residual circulation in the Southern Ocean and atmospheric CO[subscript 2]: stronger or northward-shifted westerly winds in the Southern Hemisphere result in increased residual circulation, greater upwelling of carbon-rich deep waters and oceanic outgassing, which increases atmospheric pCO[subscript 2] by ~20 μatm; weaker or southward-shifted winds lead to the opposing result. The ocean carbon inventory in our model varies through contrasting changes in the saturated, disequilibrium and biogenic (soft-tissue and carbonate) reservoirs, each varying by O(10–100) PgC, all of which contribute to the net anomaly in atmospheric CO[subscript 2]. Increased residual overturning deepens the global pycnocline, warming the upper ocean and decreasing the saturated carbon reservoir. Increased upwelling of carbon- and nutrient-rich deep waters and inefficient biological activity results in subduction of unutilized nutrients into the ocean interior, decreasing the biogenic carbon reservoir of intermediate and mode waters ventilating the Northern Hemisphere, and making the disequilibrium carbon reservoir more positive in the mode waters due to the reduced residence time at the surface. Wind-induced changes in the model carbon inventory are dominated by the response of the global pycnocline, although there is an additional abyssal response when the peak westerly winds change their latitude, altering their proximity to Drake Passage and changing the depth extent of the southward return flow of the overturning: a northward shift of the westerly winds isolates dense isopycnals, allowing biogenic carbon to accumulate in the deep ocean of the Southern Hemisphere, while a southward shift shoals dense isopycnals that outcrop in the Southern Ocean and reduces the biogenic carbon store in the deep ocean. |
| first_indexed | 2024-09-23T07:56:43Z |
| format | Article |
| id | mit-1721.1/97886 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T07:56:43Z |
| publishDate | 2015 |
| publisher | Springer-Verlag |
| record_format | dspace |
| spelling | mit-1721.1/978862024-05-15T08:57:46Z Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO[subscript 2] Lauderdale, Jonathan Garabato, Alberto C. Naveira Oliver, Kevin I. C. Williams, Richard G. Follows, Michael J Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Follows, Michael J. The effect of idealized wind-driven circulation changes in the Southern Ocean on atmospheric CO[subscript 2] and the ocean carbon inventory is investigated using a suite of coarse-resolution, global coupled ocean circulation and biogeochemistry experiments with parameterized eddy activity and only modest changes in surface buoyancy forcing, each experiment integrated for 5,000 years. A positive correlation is obtained between the meridional overturning or residual circulation in the Southern Ocean and atmospheric CO[subscript 2]: stronger or northward-shifted westerly winds in the Southern Hemisphere result in increased residual circulation, greater upwelling of carbon-rich deep waters and oceanic outgassing, which increases atmospheric pCO[subscript 2] by ~20 μatm; weaker or southward-shifted winds lead to the opposing result. The ocean carbon inventory in our model varies through contrasting changes in the saturated, disequilibrium and biogenic (soft-tissue and carbonate) reservoirs, each varying by O(10–100) PgC, all of which contribute to the net anomaly in atmospheric CO[subscript 2]. Increased residual overturning deepens the global pycnocline, warming the upper ocean and decreasing the saturated carbon reservoir. Increased upwelling of carbon- and nutrient-rich deep waters and inefficient biological activity results in subduction of unutilized nutrients into the ocean interior, decreasing the biogenic carbon reservoir of intermediate and mode waters ventilating the Northern Hemisphere, and making the disequilibrium carbon reservoir more positive in the mode waters due to the reduced residence time at the surface. Wind-induced changes in the model carbon inventory are dominated by the response of the global pycnocline, although there is an additional abyssal response when the peak westerly winds change their latitude, altering their proximity to Drake Passage and changing the depth extent of the southward return flow of the overturning: a northward shift of the westerly winds isolates dense isopycnals, allowing biogenic carbon to accumulate in the deep ocean of the Southern Hemisphere, while a southward shift shoals dense isopycnals that outcrop in the Southern Ocean and reduces the biogenic carbon store in the deep ocean. 2015-07-22T18:16:30Z 2015-07-22T18:16:30Z 2013-01 2012-07 Article http://purl.org/eprint/type/JournalArticle 0930-7575 1432-0894 http://hdl.handle.net/1721.1/97886 Lauderdale, Jonathan M., Alberto C. Naveira Garabato, Kevin I. C. Oliver, Michael J. Follows, and Richard G. Williams. “Wind-Driven Changes in Southern Ocean Residual Circulation, Ocean Carbon Reservoirs and Atmospheric CO[subscript 2].” Climate Dynamics 41, no. 7–8 (January 12, 2013): 2145–2164. https://orcid.org/0000-0002-3102-0341 en_US http://dx.doi.org/10.1007/s00382-012-1650-3 Climate Dynamics Creative Commons Attribution http://creativecommons.org/ application/pdf Springer-Verlag Springer |
| spellingShingle | Lauderdale, Jonathan Garabato, Alberto C. Naveira Oliver, Kevin I. C. Williams, Richard G. Follows, Michael J Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO[subscript 2] |
| title | Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO[subscript 2] |
| title_full | Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO[subscript 2] |
| title_fullStr | Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO[subscript 2] |
| title_full_unstemmed | Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO[subscript 2] |
| title_short | Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO[subscript 2] |
| title_sort | wind driven changes in southern ocean residual circulation ocean carbon reservoirs and atmospheric co subscript 2 |
| url | http://hdl.handle.net/1721.1/97886 https://orcid.org/0000-0002-3102-0341 |
| work_keys_str_mv | AT lauderdalejonathan winddrivenchangesinsouthernoceanresidualcirculationoceancarbonreservoirsandatmosphericcosubscript2 AT garabatoalbertocnaveira winddrivenchangesinsouthernoceanresidualcirculationoceancarbonreservoirsandatmosphericcosubscript2 AT oliverkevinic winddrivenchangesinsouthernoceanresidualcirculationoceancarbonreservoirsandatmosphericcosubscript2 AT williamsrichardg winddrivenchangesinsouthernoceanresidualcirculationoceancarbonreservoirsandatmosphericcosubscript2 AT followsmichaelj winddrivenchangesinsouthernoceanresidualcirculationoceancarbonreservoirsandatmosphericcosubscript2 |