Structure and Evolution of the Abyssal Jet in the Vema Channel of the South Atlantic
The Vema Channel represents the only major conduit through which the deepest and coldest (<0.2 °C potential temperature) Antarctic Bottom Water (AABW) flows from the Argentine into the Brazil Basin. From 2003 to 2007 two current meter moorings were present on each side of the Vema Sill, close to...
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ftoceanrep:oai:oceanrep.geomar.de:13784 2023-05-15T13:43:38+02:00 Structure and Evolution of the Abyssal Jet in the Vema Channel of the South Atlantic Zenk, Walter Visbeck, Martin 2013 text https://oceanrep.geomar.de/id/eprint/13784/ https://oceanrep.geomar.de/id/eprint/13784/1/1-s2.0-S0967064512001191-main.pdf https://doi.org/10.1016/j.dsr2.2012.07.033 en eng Elsevier https://oceanrep.geomar.de/id/eprint/13784/1/1-s2.0-S0967064512001191-main.pdf Zenk, W. and Visbeck, M. (2013) Structure and Evolution of the Abyssal Jet in the Vema Channel of the South Atlantic. Deep Sea Research Part II: Topical Studies in Oceanography, 85 . pp. 244-260. DOI 10.1016/j.dsr2.2012.07.033 <https://doi.org/10.1016/j.dsr2.2012.07.033>. doi:10.1016/j.dsr2.2012.07.033 info:eu-repo/semantics/restrictedAccess Article PeerReviewed 2013 ftoceanrep https://doi.org/10.1016/j.dsr2.2012.07.033 2023-04-07T15:02:58Z The Vema Channel represents the only major conduit through which the deepest and coldest (<0.2 °C potential temperature) Antarctic Bottom Water (AABW) flows from the Argentine into the Brazil Basin. From 2003 to 2007 two current meter moorings were present on each side of the Vema Sill, close to the narrowest spot of the Vema Channel. The data from the moorings are compared with earlier current and temperature observations. On average the maximum current core lies ∼100 m above the bottom of the sill with a mean northward speed of 0.3 m s−1. Farther up in the water column where Lower Circumpolar Deep Water and North Atlantic Deep Water prevail, one finds a level of sluggish currents with a southward tendency in the sub-centimeter-per-second range. The lower boundary of a layer of ‘no’ motion was observed at ∼3700 m depth where the mean potential temperature amounts to 1.5 °C. The evolution of the abyssal warming phenomenon over the last decades with notable fluctuations at the choke point between the Argentine and the Brazil Basin differs from the more stable attitude of deep horizontal currents. Starting with CTD observations in 1972 we find a steady increase of temperatures of the coldest AABW in the Vema Channel. This general trend of rising abyssal potential temperatures of almost 2 mKelvin per year is based on mostly annual CTD observations. The overall warming trend is fully compatible with our three-year moored temperature series in agreement with earlier records with high temporal resolution. Distinct frequently fluctuating horizontal current shear between the western and eastern sides of the Vema Sill may be explained by two different catchment areas for AABW at the mouth of the Vema Channel. One pathway originates at the American continental rise and advects bottom water in form of the deep western boundary current. A second pathway is supplied by an eastern boundary current along the Mid Atlantic Ridge in the Argentine Basin. Both source waters merge at the channel entrance, mix, and their ... Article in Journal/Newspaper Antarc* Antarctic North Atlantic Deep Water North Atlantic OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Antarctic Argentine Mid-Atlantic Ridge Deep Sea Research Part II: Topical Studies in Oceanography 85 244 260 |
institution |
Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
The Vema Channel represents the only major conduit through which the deepest and coldest (<0.2 °C potential temperature) Antarctic Bottom Water (AABW) flows from the Argentine into the Brazil Basin. From 2003 to 2007 two current meter moorings were present on each side of the Vema Sill, close to the narrowest spot of the Vema Channel. The data from the moorings are compared with earlier current and temperature observations. On average the maximum current core lies ∼100 m above the bottom of the sill with a mean northward speed of 0.3 m s−1. Farther up in the water column where Lower Circumpolar Deep Water and North Atlantic Deep Water prevail, one finds a level of sluggish currents with a southward tendency in the sub-centimeter-per-second range. The lower boundary of a layer of ‘no’ motion was observed at ∼3700 m depth where the mean potential temperature amounts to 1.5 °C. The evolution of the abyssal warming phenomenon over the last decades with notable fluctuations at the choke point between the Argentine and the Brazil Basin differs from the more stable attitude of deep horizontal currents. Starting with CTD observations in 1972 we find a steady increase of temperatures of the coldest AABW in the Vema Channel. This general trend of rising abyssal potential temperatures of almost 2 mKelvin per year is based on mostly annual CTD observations. The overall warming trend is fully compatible with our three-year moored temperature series in agreement with earlier records with high temporal resolution. Distinct frequently fluctuating horizontal current shear between the western and eastern sides of the Vema Sill may be explained by two different catchment areas for AABW at the mouth of the Vema Channel. One pathway originates at the American continental rise and advects bottom water in form of the deep western boundary current. A second pathway is supplied by an eastern boundary current along the Mid Atlantic Ridge in the Argentine Basin. Both source waters merge at the channel entrance, mix, and their ... |
format |
Article in Journal/Newspaper |
author |
Zenk, Walter Visbeck, Martin |
spellingShingle |
Zenk, Walter Visbeck, Martin Structure and Evolution of the Abyssal Jet in the Vema Channel of the South Atlantic |
author_facet |
Zenk, Walter Visbeck, Martin |
author_sort |
Zenk, Walter |
title |
Structure and Evolution of the Abyssal Jet in the Vema Channel of the South Atlantic |
title_short |
Structure and Evolution of the Abyssal Jet in the Vema Channel of the South Atlantic |
title_full |
Structure and Evolution of the Abyssal Jet in the Vema Channel of the South Atlantic |
title_fullStr |
Structure and Evolution of the Abyssal Jet in the Vema Channel of the South Atlantic |
title_full_unstemmed |
Structure and Evolution of the Abyssal Jet in the Vema Channel of the South Atlantic |
title_sort |
structure and evolution of the abyssal jet in the vema channel of the south atlantic |
publisher |
Elsevier |
publishDate |
2013 |
url |
https://oceanrep.geomar.de/id/eprint/13784/ https://oceanrep.geomar.de/id/eprint/13784/1/1-s2.0-S0967064512001191-main.pdf https://doi.org/10.1016/j.dsr2.2012.07.033 |
geographic |
Antarctic Argentine Mid-Atlantic Ridge |
geographic_facet |
Antarctic Argentine Mid-Atlantic Ridge |
genre |
Antarc* Antarctic North Atlantic Deep Water North Atlantic |
genre_facet |
Antarc* Antarctic North Atlantic Deep Water North Atlantic |
op_relation |
https://oceanrep.geomar.de/id/eprint/13784/1/1-s2.0-S0967064512001191-main.pdf Zenk, W. and Visbeck, M. (2013) Structure and Evolution of the Abyssal Jet in the Vema Channel of the South Atlantic. Deep Sea Research Part II: Topical Studies in Oceanography, 85 . pp. 244-260. DOI 10.1016/j.dsr2.2012.07.033 <https://doi.org/10.1016/j.dsr2.2012.07.033>. doi:10.1016/j.dsr2.2012.07.033 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/j.dsr2.2012.07.033 |
container_title |
Deep Sea Research Part II: Topical Studies in Oceanography |
container_volume |
85 |
container_start_page |
244 |
op_container_end_page |
260 |
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1766191408626008064 |