Response of Southern Ocean convection and abbyssal overturning to surface buoyancy perturbations.
This study explores how buoyancy-driven modulations in the abyssal overturning circulation affect Southern Ocean temperature and salinity in an eddy-permitting ocean model. Consistent with previous studies, the modeled surface ocean south of 50°S cools and freshens in response to enhanced surface fr...
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ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/104033 2024-01-14T10:10:50+01:00 Response of Southern Ocean convection and abbyssal overturning to surface buoyancy perturbations. Morrison, Adele England, Matthew Hogg, Andrew http://hdl.handle.net/1885/104033 https://doi.org/10.1175/JCLI-D-14-00110.1 https://openresearch-repository.anu.edu.au/bitstream/1885/104033/5/01_Morrison_Response_of_Southern_Ocean_2015.pdf.jpg unknown American Meteorological Society 0894-8755 http://hdl.handle.net/1885/104033 doi:10.1175/JCLI-D-14-00110.1 https://openresearch-repository.anu.edu.au/bitstream/1885/104033/5/01_Morrison_Response_of_Southern_Ocean_2015.pdf.jpg Author/s retain copyright Journal of Climate Journal article ftanucanberra https://doi.org/10.1175/JCLI-D-14-00110.1 2023-12-15T09:33:11Z This study explores how buoyancy-driven modulations in the abyssal overturning circulation affect Southern Ocean temperature and salinity in an eddy-permitting ocean model. Consistent with previous studies, the modeled surface ocean south of 50°S cools and freshens in response to enhanced surface freshwater fluxes. Paradoxically, upper-ocean cooling also occurs for small increases in the surface relaxation temperature. In both cases, the surface cooling and freshening trends are linked to reduced convection and a slowing of the abyssal overturning circulation, with associated changes in oceanic transport of heat and salt. For small perturbations, convective shutdown does not begin immediately, but instead develops via a slow feedback between the weakened overturning circulation and buoyancy anomalies. Two distinct phases of surface cooling are found: an initial smaller trend associated with the advective (overturning) adjustment of up to ~60 yr, followed by more rapid surface cooling during the convective shutdown period. The duration of the first advective phase decreases for larger forcing perturbations. As may be expected during the convective shutdown phase, the deep ocean warms and salinifies for both types of buoyancy perturbation. However, during the advective phase, the deep ocean freshens in response to freshwater perturbations but salinifies in the surface warming perturbations. The magnitudes of the modeled surface and abyssal trends during the advective phase are comparable to the recent observed multidecadal Southern Ocean temperature and salinity changes. Article in Journal/Newspaper Southern Ocean Australian National University: ANU Digital Collections Southern Ocean Journal of Climate 28 10 4263 4278 |
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Australian National University: ANU Digital Collections |
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description |
This study explores how buoyancy-driven modulations in the abyssal overturning circulation affect Southern Ocean temperature and salinity in an eddy-permitting ocean model. Consistent with previous studies, the modeled surface ocean south of 50°S cools and freshens in response to enhanced surface freshwater fluxes. Paradoxically, upper-ocean cooling also occurs for small increases in the surface relaxation temperature. In both cases, the surface cooling and freshening trends are linked to reduced convection and a slowing of the abyssal overturning circulation, with associated changes in oceanic transport of heat and salt. For small perturbations, convective shutdown does not begin immediately, but instead develops via a slow feedback between the weakened overturning circulation and buoyancy anomalies. Two distinct phases of surface cooling are found: an initial smaller trend associated with the advective (overturning) adjustment of up to ~60 yr, followed by more rapid surface cooling during the convective shutdown period. The duration of the first advective phase decreases for larger forcing perturbations. As may be expected during the convective shutdown phase, the deep ocean warms and salinifies for both types of buoyancy perturbation. However, during the advective phase, the deep ocean freshens in response to freshwater perturbations but salinifies in the surface warming perturbations. The magnitudes of the modeled surface and abyssal trends during the advective phase are comparable to the recent observed multidecadal Southern Ocean temperature and salinity changes. |
format |
Article in Journal/Newspaper |
author |
Morrison, Adele England, Matthew Hogg, Andrew |
spellingShingle |
Morrison, Adele England, Matthew Hogg, Andrew Response of Southern Ocean convection and abbyssal overturning to surface buoyancy perturbations. |
author_facet |
Morrison, Adele England, Matthew Hogg, Andrew |
author_sort |
Morrison, Adele |
title |
Response of Southern Ocean convection and abbyssal overturning to surface buoyancy perturbations. |
title_short |
Response of Southern Ocean convection and abbyssal overturning to surface buoyancy perturbations. |
title_full |
Response of Southern Ocean convection and abbyssal overturning to surface buoyancy perturbations. |
title_fullStr |
Response of Southern Ocean convection and abbyssal overturning to surface buoyancy perturbations. |
title_full_unstemmed |
Response of Southern Ocean convection and abbyssal overturning to surface buoyancy perturbations. |
title_sort |
response of southern ocean convection and abbyssal overturning to surface buoyancy perturbations. |
publisher |
American Meteorological Society |
url |
http://hdl.handle.net/1885/104033 https://doi.org/10.1175/JCLI-D-14-00110.1 https://openresearch-repository.anu.edu.au/bitstream/1885/104033/5/01_Morrison_Response_of_Southern_Ocean_2015.pdf.jpg |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Journal of Climate |
op_relation |
0894-8755 http://hdl.handle.net/1885/104033 doi:10.1175/JCLI-D-14-00110.1 https://openresearch-repository.anu.edu.au/bitstream/1885/104033/5/01_Morrison_Response_of_Southern_Ocean_2015.pdf.jpg |
op_rights |
Author/s retain copyright |
op_doi |
https://doi.org/10.1175/JCLI-D-14-00110.1 |
container_title |
Journal of Climate |
container_volume |
28 |
container_issue |
10 |
container_start_page |
4263 |
op_container_end_page |
4278 |
_version_ |
1788065675641618432 |