Southern Ocean warming delayed by circumpolar upwelling and equatorward transport
The Southern Ocean has shown little warming over recent decades, in stark contrast to the rapid warming observed in the Arctic. Along the northern flank of the Antarctic Circumpolar Current, however, the upper ocean has warmed substantially. Here we present analyses of oceanographic observations and...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | en_US |
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Nature Publishing Group
2017
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| Online Access: | http://hdl.handle.net/1721.1/106534 https://orcid.org/0000-0001-9230-3591 |
| _version_ | 1826213761656029184 |
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| author | Armour, Kyle C. Donohoe, Aaron Newsom, Emily R. Marshall, John C Scott, Jeremy |
| author2 | Massachusetts Institute of Technology. Center for Global Change Science |
| author_facet | Massachusetts Institute of Technology. Center for Global Change Science Armour, Kyle C. Donohoe, Aaron Newsom, Emily R. Marshall, John C Scott, Jeremy |
| author_sort | Armour, Kyle C. |
| collection | MIT |
| description | The Southern Ocean has shown little warming over recent decades, in stark contrast to the rapid warming observed in the Arctic. Along the northern flank of the Antarctic Circumpolar Current, however, the upper ocean has warmed substantially. Here we present analyses of oceanographic observations and general circulation model simulations showing that these patterns—of delayed warming south of the Antarctic Circumpolar Current and enhanced warming to the north—are fundamentally shaped by the Southern Ocean’s meridional overturning circulation: wind-driven upwelling of unmodified water from depth damps warming around Antarctica; greenhouse gas-induced surface heat uptake is largely balanced by anomalous northward heat transport associated with the equatorward flow of surface waters; and heat is preferentially stored where surface waters are subducted to the north. Further, these processes are primarily due to passive advection of the anomalous warming signal by climatological ocean currents; changes in ocean circulation are secondary. These findings suggest the Southern Ocean responds to greenhouse gas forcing on the centennial, or longer, timescale over which the deep ocean waters that are upwelled to the surface are warmed themselves. It is against this background of gradual warming that multidecadal Southern Ocean temperature trends must be understood. |
| first_indexed | 2024-09-23T15:54:24Z |
| format | Article |
| id | mit-1721.1/106534 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:54:24Z |
| publishDate | 2017 |
| publisher | Nature Publishing Group |
| record_format | dspace |
| spelling | mit-1721.1/1065342024-05-15T05:21:48Z Southern Ocean warming delayed by circumpolar upwelling and equatorward transport Armour, Kyle C. Donohoe, Aaron Newsom, Emily R. Marshall, John C Scott, Jeremy Massachusetts Institute of Technology. Center for Global Change Science Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Marshall, John C Scott, Jeffery R The Southern Ocean has shown little warming over recent decades, in stark contrast to the rapid warming observed in the Arctic. Along the northern flank of the Antarctic Circumpolar Current, however, the upper ocean has warmed substantially. Here we present analyses of oceanographic observations and general circulation model simulations showing that these patterns—of delayed warming south of the Antarctic Circumpolar Current and enhanced warming to the north—are fundamentally shaped by the Southern Ocean’s meridional overturning circulation: wind-driven upwelling of unmodified water from depth damps warming around Antarctica; greenhouse gas-induced surface heat uptake is largely balanced by anomalous northward heat transport associated with the equatorward flow of surface waters; and heat is preferentially stored where surface waters are subducted to the north. Further, these processes are primarily due to passive advection of the anomalous warming signal by climatological ocean currents; changes in ocean circulation are secondary. These findings suggest the Southern Ocean responds to greenhouse gas forcing on the centennial, or longer, timescale over which the deep ocean waters that are upwelled to the surface are warmed themselves. It is against this background of gradual warming that multidecadal Southern Ocean temperature trends must be understood. National Science Foundation (U.S.) (grant OCE-1259388) National Science Foundation (U.S.) (grant OCE-1338814) National Science Foundation (U.S.) (grant OCE-1523641) National Science Foundation (U.S.) (grant PLR-1341497) United States. National Aeronautics and Space Administration (award NNX11AL79G) 2017-01-19T19:07:49Z 2017-01-19T19:07:49Z 2016-05 2016-02 Article http://purl.org/eprint/type/JournalArticle 1752-0894 1752-0908 http://hdl.handle.net/1721.1/106534 Armour, Kyle C., John Marshall, Jeffery R. Scott, Aaron Donohoe, and Emily R. Newsom. “Southern Ocean Warming Delayed by Circumpolar Upwelling and Equatorward Transport.” Nature Geoscience, vol. 9, no. 7, 2016, pp. 549–554. https://orcid.org/0000-0001-9230-3591 en_US http://dx.doi.org/10.1038/ngeo2731 Nature Geoscience Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf Nature Publishing Group MIT Web Domain |
| spellingShingle | Armour, Kyle C. Donohoe, Aaron Newsom, Emily R. Marshall, John C Scott, Jeremy Southern Ocean warming delayed by circumpolar upwelling and equatorward transport |
| title | Southern Ocean warming delayed by circumpolar upwelling and equatorward transport |
| title_full | Southern Ocean warming delayed by circumpolar upwelling and equatorward transport |
| title_fullStr | Southern Ocean warming delayed by circumpolar upwelling and equatorward transport |
| title_full_unstemmed | Southern Ocean warming delayed by circumpolar upwelling and equatorward transport |
| title_short | Southern Ocean warming delayed by circumpolar upwelling and equatorward transport |
| title_sort | southern ocean warming delayed by circumpolar upwelling and equatorward transport |
| url | http://hdl.handle.net/1721.1/106534 https://orcid.org/0000-0001-9230-3591 |
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