Response of southern ocean convection and abyssal 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 508S cools and freshens in response to enhanced surface fr...
Published in: | Journal of Climate |
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American Meteorological Society
2015
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ftunswworks:oai:unsworks.library.unsw.edu.au:1959.4/unsworks_42093 2024-05-12T08:11:27+00:00 Response of southern ocean convection and abyssal overturning to surface buoyancy perturbations Morrison, AK England, MH Hogg, AMC 2015-05-01 http://hdl.handle.net/1959.4/unsworks_42093 https://doi.org/10.1175/JCLI-D-14-00110.1 unknown American Meteorological Society http://purl.org/au-research/grants/arc/FL100100214 http://hdl.handle.net/1959.4/unsworks_42093 https://doi.org/10.1175/JCLI-D-14-00110.1 metadata only access http://purl.org/coar/access_right/c_14cb CC-BY-NC-ND https://creativecommons.org/licenses/by-nc-nd/4.0/ urn:ISSN:0894-8755 urn:ISSN:1520-0442 Journal of Climate, 28, 10, 4263-4278 14 Life Below Water anzsrc-for: 0401 Atmospheric Sciences anzsrc-for: 0405 Oceanography anzsrc-for: 0909 Geomatic Engineering journal article http://purl.org/coar/resource_type/c_6501 2015 ftunswworks https://doi.org/10.1175/JCLI-D-14-00110.1 2024-04-17T15:18:05Z 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 508S 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 UNSW Sydney (The University of New South Wales): UNSWorks Southern Ocean Journal of Climate 28 10 4263 4278 |
institution |
Open Polar |
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UNSW Sydney (The University of New South Wales): UNSWorks |
op_collection_id |
ftunswworks |
language |
unknown |
topic |
14 Life Below Water anzsrc-for: 0401 Atmospheric Sciences anzsrc-for: 0405 Oceanography anzsrc-for: 0909 Geomatic Engineering |
spellingShingle |
14 Life Below Water anzsrc-for: 0401 Atmospheric Sciences anzsrc-for: 0405 Oceanography anzsrc-for: 0909 Geomatic Engineering Morrison, AK England, MH Hogg, AMC Response of southern ocean convection and abyssal overturning to surface buoyancy perturbations |
topic_facet |
14 Life Below Water anzsrc-for: 0401 Atmospheric Sciences anzsrc-for: 0405 Oceanography anzsrc-for: 0909 Geomatic Engineering |
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 508S 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, AK England, MH Hogg, AMC |
author_facet |
Morrison, AK England, MH Hogg, AMC |
author_sort |
Morrison, AK |
title |
Response of southern ocean convection and abyssal overturning to surface buoyancy perturbations |
title_short |
Response of southern ocean convection and abyssal overturning to surface buoyancy perturbations |
title_full |
Response of southern ocean convection and abyssal overturning to surface buoyancy perturbations |
title_fullStr |
Response of southern ocean convection and abyssal overturning to surface buoyancy perturbations |
title_full_unstemmed |
Response of southern ocean convection and abyssal overturning to surface buoyancy perturbations |
title_sort |
response of southern ocean convection and abyssal overturning to surface buoyancy perturbations |
publisher |
American Meteorological Society |
publishDate |
2015 |
url |
http://hdl.handle.net/1959.4/unsworks_42093 https://doi.org/10.1175/JCLI-D-14-00110.1 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
urn:ISSN:0894-8755 urn:ISSN:1520-0442 Journal of Climate, 28, 10, 4263-4278 |
op_relation |
http://purl.org/au-research/grants/arc/FL100100214 http://hdl.handle.net/1959.4/unsworks_42093 https://doi.org/10.1175/JCLI-D-14-00110.1 |
op_rights |
metadata only access http://purl.org/coar/access_right/c_14cb CC-BY-NC-ND https://creativecommons.org/licenses/by-nc-nd/4.0/ |
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 |
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1798855168201064448 |