Characteristics and causes of Deep Western Boundary Current transport variability at 34.5° S during 2009–2014
The Deep Western Boundary Current (DWBC) at 34.5° S in the South Atlantic carries a significant fraction of the cold deep limb of the Meridional Overturning Circulation (MOC), and therefore its variability affects the meridional heat transport and consequently the regional and global climate. Nearly...
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ftdoajarticles:oai:doaj.org/article:d825a77e771a4bb3bd36e35b976e67b5 2023-05-15T17:25:28+02:00 Characteristics and causes of Deep Western Boundary Current transport variability at 34.5° S during 2009–2014 C. S. Meinen S. L. Garzoli R. C. Perez E. Campos A. R. Piola M. P. Chidichimo S. Dong O. T. Sato 2017-03-01T00:00:00Z https://doi.org/10.5194/os-13-175-2017 https://doaj.org/article/d825a77e771a4bb3bd36e35b976e67b5 EN eng Copernicus Publications http://www.ocean-sci.net/13/175/2017/os-13-175-2017.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 doi:10.5194/os-13-175-2017 https://doaj.org/article/d825a77e771a4bb3bd36e35b976e67b5 Ocean Science, Vol 13, Iss 1, Pp 175-194 (2017) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2017 ftdoajarticles https://doi.org/10.5194/os-13-175-2017 2022-12-31T11:41:34Z The Deep Western Boundary Current (DWBC) at 34.5° S in the South Atlantic carries a significant fraction of the cold deep limb of the Meridional Overturning Circulation (MOC), and therefore its variability affects the meridional heat transport and consequently the regional and global climate. Nearly 6 years of observations from a line of pressure-equipped inverted echo sounders (PIESs) have yielded an unprecedented data set for studying the characteristics of the time-varying DWBC volume transport at 34.5° S. Furthermore, the horizontal resolution of the observing array was greatly improved in December 2012 with the addition of two current-and-pressure-equipped inverted echo sounders (CPIESs) at the midpoints of the two westernmost pairs of PIES moorings. Regular hydrographic sections along the PIES/CPIES line confirm the presence of recently ventilated North Atlantic Deep Water carried by the DWBC. The time-mean absolute geostrophic transport integrated within the DWBC layer, defined between 800–4800 dbar and within longitude bounds of 51.5 to 44.5° W, is −15 Sv (1 Sv = 10 6 m 3 s −1 negative indicates southward flow). The observed peak-to-peak range in volume transport using these integration limits is from −89 to +50 Sv, and the temporal standard deviation is 23 Sv. Testing different vertical integration limits based on time-mean water-mass property levels yields small changes to these values, but no significant alteration to the character of the transport time series. The time-mean southward DWBC flow at this latitude is confined west of 49.5° W, with recirculations dominating the flow further offshore. As with other latitudes where the DWBC has been observed for multiple years, the time variability greatly exceeds the time mean, suggesting the presence of strong coherent vortices and/or Rossby Wave-like signals propagating to the boundary from the interior. Article in Journal/Newspaper North Atlantic Deep Water North Atlantic Directory of Open Access Journals: DOAJ Articles Peak Range ENVELOPE(-126.753,-126.753,57.500,57.500) Ocean Science 13 1 175 194 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
spellingShingle |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 C. S. Meinen S. L. Garzoli R. C. Perez E. Campos A. R. Piola M. P. Chidichimo S. Dong O. T. Sato Characteristics and causes of Deep Western Boundary Current transport variability at 34.5° S during 2009–2014 |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
description |
The Deep Western Boundary Current (DWBC) at 34.5° S in the South Atlantic carries a significant fraction of the cold deep limb of the Meridional Overturning Circulation (MOC), and therefore its variability affects the meridional heat transport and consequently the regional and global climate. Nearly 6 years of observations from a line of pressure-equipped inverted echo sounders (PIESs) have yielded an unprecedented data set for studying the characteristics of the time-varying DWBC volume transport at 34.5° S. Furthermore, the horizontal resolution of the observing array was greatly improved in December 2012 with the addition of two current-and-pressure-equipped inverted echo sounders (CPIESs) at the midpoints of the two westernmost pairs of PIES moorings. Regular hydrographic sections along the PIES/CPIES line confirm the presence of recently ventilated North Atlantic Deep Water carried by the DWBC. The time-mean absolute geostrophic transport integrated within the DWBC layer, defined between 800–4800 dbar and within longitude bounds of 51.5 to 44.5° W, is −15 Sv (1 Sv = 10 6 m 3 s −1 negative indicates southward flow). The observed peak-to-peak range in volume transport using these integration limits is from −89 to +50 Sv, and the temporal standard deviation is 23 Sv. Testing different vertical integration limits based on time-mean water-mass property levels yields small changes to these values, but no significant alteration to the character of the transport time series. The time-mean southward DWBC flow at this latitude is confined west of 49.5° W, with recirculations dominating the flow further offshore. As with other latitudes where the DWBC has been observed for multiple years, the time variability greatly exceeds the time mean, suggesting the presence of strong coherent vortices and/or Rossby Wave-like signals propagating to the boundary from the interior. |
format |
Article in Journal/Newspaper |
author |
C. S. Meinen S. L. Garzoli R. C. Perez E. Campos A. R. Piola M. P. Chidichimo S. Dong O. T. Sato |
author_facet |
C. S. Meinen S. L. Garzoli R. C. Perez E. Campos A. R. Piola M. P. Chidichimo S. Dong O. T. Sato |
author_sort |
C. S. Meinen |
title |
Characteristics and causes of Deep Western Boundary Current transport variability at 34.5° S during 2009–2014 |
title_short |
Characteristics and causes of Deep Western Boundary Current transport variability at 34.5° S during 2009–2014 |
title_full |
Characteristics and causes of Deep Western Boundary Current transport variability at 34.5° S during 2009–2014 |
title_fullStr |
Characteristics and causes of Deep Western Boundary Current transport variability at 34.5° S during 2009–2014 |
title_full_unstemmed |
Characteristics and causes of Deep Western Boundary Current transport variability at 34.5° S during 2009–2014 |
title_sort |
characteristics and causes of deep western boundary current transport variability at 34.5° s during 2009–2014 |
publisher |
Copernicus Publications |
publishDate |
2017 |
url |
https://doi.org/10.5194/os-13-175-2017 https://doaj.org/article/d825a77e771a4bb3bd36e35b976e67b5 |
long_lat |
ENVELOPE(-126.753,-126.753,57.500,57.500) |
geographic |
Peak Range |
geographic_facet |
Peak Range |
genre |
North Atlantic Deep Water North Atlantic |
genre_facet |
North Atlantic Deep Water North Atlantic |
op_source |
Ocean Science, Vol 13, Iss 1, Pp 175-194 (2017) |
op_relation |
http://www.ocean-sci.net/13/175/2017/os-13-175-2017.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 doi:10.5194/os-13-175-2017 https://doaj.org/article/d825a77e771a4bb3bd36e35b976e67b5 |
op_doi |
https://doi.org/10.5194/os-13-175-2017 |
container_title |
Ocean Science |
container_volume |
13 |
container_issue |
1 |
container_start_page |
175 |
op_container_end_page |
194 |
_version_ |
1766116908355026944 |