Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer
The seasonal warming of Antarctic Winter Water (WW) is a key process that occurs along the path of deep water transformation to intermediate waters. These intermediate waters then enter the upper branch of the circumpolar overturning circulation. Despite its importance, the driving mechanisms that m...
Published in: | Journal of Physical Oceanography |
---|---|
Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2023
|
Subjects: | |
Online Access: | http://hdl.handle.net/10204/13154 https://doi.org/10.1175/JPO-D-22-0259.1 |
id |
ftcsir:oai:researchspace.csir.co.za:10204/13154 |
---|---|
record_format |
openpolar |
spelling |
ftcsir:oai:researchspace.csir.co.za:10204/13154 2023-11-12T04:04:18+01:00 Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer Giddy, IS Fer, I Swart, S Nicholson, Sarah-Anne 2023-05 Fulltext application/pdf http://hdl.handle.net/10204/13154 https://doi.org/10.1175/JPO-D-22-0259.1 en eng https://journals.ametsoc.org/view/journals/phoc/aop/JPO-D-22-0259.1/JPO-D-22-0259.1.xml Giddy, I., Fer, I., Swart, S. & Nicholson, S. 2023. Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer. Journal of Physical Oceanography, 53(8). http://hdl.handle.net/10204/13154 0022-3670 1520-0485 https://doi.org/10.1175/JPO-D-22-0259.1 http://hdl.handle.net/10204/13154 Giddy, I., Fer, I., Swart, S., & Nicholson, S. (2023). Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer. Journal of Physical Oceanography, 53(8) , http://hdl.handle.net/10204/13154 Giddy, IS, I Fer, S Swart, and Sarah-Anne Nicholson "Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer." Journal of Physical Oceanography, 53(8) (2023) http://hdl.handle.net/10204/13154 Giddy I, Fer I, Swart S, Nicholson S. Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer. Journal of Physical Oceanography, 53(8). 2023; http://hdl.handle.net/10204/13154. 26848 Journal of Physical Oceanography, 53(8) Antarctic Winter Water Climate change Global warming Warming of Antarctic Winter Water Article 2023 ftcsir https://doi.org/10.1175/JPO-D-22-0259.1 2023-10-17T23:48:46Z The seasonal warming of Antarctic Winter Water (WW) is a key process that occurs along the path of deep water transformation to intermediate waters. These intermediate waters then enter the upper branch of the circumpolar overturning circulation. Despite its importance, the driving mechanisms that mediate the warming of Antarctic WW remain unknown, and their quantitative evaluation is lacking. Using 38 days of glider measurements of microstructure shear, we characterize the rate of turbulent dissipation and its drivers over a summer season in the northern Weddell Sea. Observed dissipation rates in the surface layer are mainly forced by winds, and explained by the stress scaling (r2=0.84). However, mixing to the base of the mixed layer during strong wind events is suppressed by vertical stratification from sea ice melt. Between the WW layer and the warm and saline circumpolar deep water, a subsurface layer of enhanced dissipation is maintained by double-diffusive convection (DDC). We develop a WW layer temperature budget and show that a warming trend (0.2°C over 28 days) is driven by a convergence of heat flux through mechanically-driven mixing at the base of the mixed layer and DDC at the base of the WW layer. Notably, excluding the contribution from DDC results in an underestimation of WW warming by 23%, highlighting the importance of adequately representing DDC in ocean models. These results further suggest that an increase in storm intensity and frequency during summer could increase the rate of warming of WW with implications for rates of upper ocean water mass transformation. 1941-1958 Copyright: 2023 American Meteorological Society. This published article is licensed under the terms of a Creative Commons Attribution 4.0 International (CC BY 4.0) License Smart Places Ocean Systems and Climate Article in Journal/Newspaper Antarc* Antarctic Sea ice Weddell Sea Council for Scientific and Industrial Research (South Africa): CSIR Research Space Antarctic Weddell Sea Weddell Journal of Physical Oceanography 53 8 1941 1958 |
institution |
Open Polar |
collection |
Council for Scientific and Industrial Research (South Africa): CSIR Research Space |
op_collection_id |
ftcsir |
language |
English |
topic |
Antarctic Winter Water Climate change Global warming Warming of Antarctic Winter Water |
spellingShingle |
Antarctic Winter Water Climate change Global warming Warming of Antarctic Winter Water Giddy, IS Fer, I Swart, S Nicholson, Sarah-Anne Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer |
topic_facet |
Antarctic Winter Water Climate change Global warming Warming of Antarctic Winter Water |
description |
The seasonal warming of Antarctic Winter Water (WW) is a key process that occurs along the path of deep water transformation to intermediate waters. These intermediate waters then enter the upper branch of the circumpolar overturning circulation. Despite its importance, the driving mechanisms that mediate the warming of Antarctic WW remain unknown, and their quantitative evaluation is lacking. Using 38 days of glider measurements of microstructure shear, we characterize the rate of turbulent dissipation and its drivers over a summer season in the northern Weddell Sea. Observed dissipation rates in the surface layer are mainly forced by winds, and explained by the stress scaling (r2=0.84). However, mixing to the base of the mixed layer during strong wind events is suppressed by vertical stratification from sea ice melt. Between the WW layer and the warm and saline circumpolar deep water, a subsurface layer of enhanced dissipation is maintained by double-diffusive convection (DDC). We develop a WW layer temperature budget and show that a warming trend (0.2°C over 28 days) is driven by a convergence of heat flux through mechanically-driven mixing at the base of the mixed layer and DDC at the base of the WW layer. Notably, excluding the contribution from DDC results in an underestimation of WW warming by 23%, highlighting the importance of adequately representing DDC in ocean models. These results further suggest that an increase in storm intensity and frequency during summer could increase the rate of warming of WW with implications for rates of upper ocean water mass transformation. 1941-1958 Copyright: 2023 American Meteorological Society. This published article is licensed under the terms of a Creative Commons Attribution 4.0 International (CC BY 4.0) License Smart Places Ocean Systems and Climate |
format |
Article in Journal/Newspaper |
author |
Giddy, IS Fer, I Swart, S Nicholson, Sarah-Anne |
author_facet |
Giddy, IS Fer, I Swart, S Nicholson, Sarah-Anne |
author_sort |
Giddy, IS |
title |
Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer |
title_short |
Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer |
title_full |
Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer |
title_fullStr |
Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer |
title_full_unstemmed |
Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer |
title_sort |
vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of antarctic winter water in summer |
publishDate |
2023 |
url |
http://hdl.handle.net/10204/13154 https://doi.org/10.1175/JPO-D-22-0259.1 |
geographic |
Antarctic Weddell Sea Weddell |
geographic_facet |
Antarctic Weddell Sea Weddell |
genre |
Antarc* Antarctic Sea ice Weddell Sea |
genre_facet |
Antarc* Antarctic Sea ice Weddell Sea |
op_source |
Journal of Physical Oceanography, 53(8) |
op_relation |
https://journals.ametsoc.org/view/journals/phoc/aop/JPO-D-22-0259.1/JPO-D-22-0259.1.xml Giddy, I., Fer, I., Swart, S. & Nicholson, S. 2023. Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer. Journal of Physical Oceanography, 53(8). http://hdl.handle.net/10204/13154 0022-3670 1520-0485 https://doi.org/10.1175/JPO-D-22-0259.1 http://hdl.handle.net/10204/13154 Giddy, I., Fer, I., Swart, S., & Nicholson, S. (2023). Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer. Journal of Physical Oceanography, 53(8) , http://hdl.handle.net/10204/13154 Giddy, IS, I Fer, S Swart, and Sarah-Anne Nicholson "Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer." Journal of Physical Oceanography, 53(8) (2023) http://hdl.handle.net/10204/13154 Giddy I, Fer I, Swart S, Nicholson S. Vertical convergence of turbulent and double-diffusive heat flux drives warming and erosion of Antarctic Winter Water in summer. Journal of Physical Oceanography, 53(8). 2023; http://hdl.handle.net/10204/13154. 26848 |
op_doi |
https://doi.org/10.1175/JPO-D-22-0259.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
53 |
container_issue |
8 |
container_start_page |
1941 |
op_container_end_page |
1958 |
_version_ |
1782341548758794240 |