Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North Atlantic
<p>Wintertime convection in the North Atlantic Ocean is a key component of the global climate as it produces dense waters at high latitudes that flow equatorward as part of the Atlantic Meridional Overturning Circulation (AMOC). Recent work has highlighted the dominant role of the Irminger and...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2021-10-01
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| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/17/1353/2021/os-17-1353-2021.pdf |
| _version_ | 1818690237510975488 |
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| author | T. Petit M. S. Lozier S. A. Josey S. A. Cunningham |
| author_facet | T. Petit M. S. Lozier S. A. Josey S. A. Cunningham |
| author_sort | T. Petit |
| collection | DOAJ |
| description | <p>Wintertime convection in the North Atlantic Ocean is a key component of the global climate as it produces dense waters at high latitudes that flow
equatorward as part of the Atlantic Meridional Overturning Circulation (AMOC). Recent work has highlighted the dominant role of the Irminger and
Iceland basins in the production of North Atlantic Deep Water. Dense water formation in these basins is mainly explained by buoyancy forcing that
transforms surface waters to the deep waters of the AMOC lower limb. Air–sea fluxes and the ocean surface density field are both key determinants of the buoyancy-driven transformation. We analyze these contributions to the transformation in order to better understand the connection between atmospheric forcing and the densification of surface water. More precisely, we study the impact of air–sea fluxes and the ocean surface density field on the transformation of subpolar mode water (SPMW) in the Iceland Basin, a water mass that “pre-conditions” dense water formation downstream. Analyses using 40 years of observations (1980–2019) reveal that the variance in SPMW transformation is mainly influenced by the
variance in density at the ocean surface. This surface density is set by a combination of advection, wind-driven upwelling and surface fluxes. Our
study shows that the latter explains <span class="inline-formula">∼</span> 30 % of the variance in outcrop area as expressed by the surface area between the outcropped SPMW
isopycnals. The key role of the surface density in SPMW transformation partly explains the unusually large SPMW transformation in winter 2014–2015 over the Iceland Basin.</p> |
| first_indexed | 2024-12-17T12:22:48Z |
| format | Article |
| id | doaj.art-c912679a9fc24067913b4b9d25d75958 |
| institution | Directory Open Access Journal |
| issn | 1812-0784 1812-0792 |
| language | English |
| last_indexed | 2024-12-17T12:22:48Z |
| publishDate | 2021-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Ocean Science |
| spelling | doaj.art-c912679a9fc24067913b4b9d25d759582022-12-21T21:48:54ZengCopernicus PublicationsOcean Science1812-07841812-07922021-10-01171353136510.5194/os-17-1353-2021Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North AtlanticT. Petit0M. S. Lozier1S. A. Josey2S. A. Cunningham3School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USASchool of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USANational Oceanography Centre, Southampton, UKScottish Association for Marine Science, Oban, UK<p>Wintertime convection in the North Atlantic Ocean is a key component of the global climate as it produces dense waters at high latitudes that flow equatorward as part of the Atlantic Meridional Overturning Circulation (AMOC). Recent work has highlighted the dominant role of the Irminger and Iceland basins in the production of North Atlantic Deep Water. Dense water formation in these basins is mainly explained by buoyancy forcing that transforms surface waters to the deep waters of the AMOC lower limb. Air–sea fluxes and the ocean surface density field are both key determinants of the buoyancy-driven transformation. We analyze these contributions to the transformation in order to better understand the connection between atmospheric forcing and the densification of surface water. More precisely, we study the impact of air–sea fluxes and the ocean surface density field on the transformation of subpolar mode water (SPMW) in the Iceland Basin, a water mass that “pre-conditions” dense water formation downstream. Analyses using 40 years of observations (1980–2019) reveal that the variance in SPMW transformation is mainly influenced by the variance in density at the ocean surface. This surface density is set by a combination of advection, wind-driven upwelling and surface fluxes. Our study shows that the latter explains <span class="inline-formula">∼</span> 30 % of the variance in outcrop area as expressed by the surface area between the outcropped SPMW isopycnals. The key role of the surface density in SPMW transformation partly explains the unusually large SPMW transformation in winter 2014–2015 over the Iceland Basin.</p>https://os.copernicus.org/articles/17/1353/2021/os-17-1353-2021.pdf |
| spellingShingle | T. Petit M. S. Lozier S. A. Josey S. A. Cunningham Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North Atlantic Ocean Science |
| title | Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North Atlantic |
| title_full | Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North Atlantic |
| title_fullStr | Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North Atlantic |
| title_full_unstemmed | Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North Atlantic |
| title_short | Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North Atlantic |
| title_sort | role of air sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the north atlantic |
| url | https://os.copernicus.org/articles/17/1353/2021/os-17-1353-2021.pdf |
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