The flow field of the upper hypoxic eastern tropical North Atlantic oxygen minimum zone
A subsurface low oxygen zone is located in the eastern tropical North Atlantic Ocean (ETNA) in the upper ocean with the core of the hypoxic (O 2 ≦60 µmol kg −1 ) oxygen minimum zone (OMZ) at 400 to 500 m depth. The subsurface circulation in the OMZ region is derived from observations and data assimi...
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ftdoajarticles:oai:doaj.org/article:8e3f1a5bc9474f77bab66a3de32d0658 2023-05-15T17:32:57+02:00 The flow field of the upper hypoxic eastern tropical North Atlantic oxygen minimum zone L. Stramma R. Czeschel T. Tanhua P. Brandt M. Visbeck B. S. Giese 2016-01-01T00:00:00Z https://doi.org/10.5194/os-12-153-2016 https://doaj.org/article/8e3f1a5bc9474f77bab66a3de32d0658 EN eng Copernicus Publications http://www.ocean-sci.net/12/153/2016/os-12-153-2016.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 doi:10.5194/os-12-153-2016 https://doaj.org/article/8e3f1a5bc9474f77bab66a3de32d0658 Ocean Science, Vol 12, Iss 1, Pp 153-167 (2016) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2016 ftdoajarticles https://doi.org/10.5194/os-12-153-2016 2022-12-31T01:50:49Z A subsurface low oxygen zone is located in the eastern tropical North Atlantic Ocean (ETNA) in the upper ocean with the core of the hypoxic (O 2 ≦60 µmol kg −1 ) oxygen minimum zone (OMZ) at 400 to 500 m depth. The subsurface circulation in the OMZ region is derived from observations and data assimilation results. Measurements in the ETNA of velocity, oxygen and of a tracer (CF 3 SF 5 ) that was released in April 2008 at ∼ 8° N, 23° W (at ∼ 330 m depth) in November–December 2008, in November–December 2009 and October–November 2010 show the circulation in the upper part of the OMZ with spreading to the east in the North Equatorial Countercurrent (NECC) region and northwestward around the Guinea Dome. Three floats equipped with oxygen sensors deployed at ∼ 8° N, 23° W with parking depths at 330, 350 and 400 m depths were used to estimate velocity along the float trajectory at the surface and at the parking depth. At the 350 m park depth north of 9° N a cyclonic northwestward flow across the OMZ was observed. The northward drift of a float into the upper OMZ and a stronger cyclonic flow around the Guinea Dome seem to be connected to a strong Atlantic Meridional Mode (AMM) event in 2009. A near-surface cyclonic circulation cell east of the Cape Verde Islands reaches down into the OMZ layer. The circulation of the upper OMZ mirrors the near-surface circulation. Oxygen measurements from the cruises used here, as well as from other recent cruises up to the year 2014, confirm the continuous deoxygenation trend in the upper OMZ since the 1960s near the Guinea Dome. The three floats deployed with the tracer show spreading paths consistent with the overall observed tracer spreading. Oxygen sensors on the floats remained well calibrated for more than 20 months, and so the oxygen profiles can be used to investigate mesoscale eddy signatures. Mesoscale eddies may modify the oxygen distribution in OMZs. However, in general eddies are less energetic in the ETNA south of the Cape Verde Islands compared to similar latitudes in ... Article in Journal/Newspaper North Atlantic Directory of Open Access Journals: DOAJ Articles Dome The ENVELOPE(166.000,166.000,-85.367,-85.367) Ocean Science 12 1 153 167 |
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 L. Stramma R. Czeschel T. Tanhua P. Brandt M. Visbeck B. S. Giese The flow field of the upper hypoxic eastern tropical North Atlantic oxygen minimum zone |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
description |
A subsurface low oxygen zone is located in the eastern tropical North Atlantic Ocean (ETNA) in the upper ocean with the core of the hypoxic (O 2 ≦60 µmol kg −1 ) oxygen minimum zone (OMZ) at 400 to 500 m depth. The subsurface circulation in the OMZ region is derived from observations and data assimilation results. Measurements in the ETNA of velocity, oxygen and of a tracer (CF 3 SF 5 ) that was released in April 2008 at ∼ 8° N, 23° W (at ∼ 330 m depth) in November–December 2008, in November–December 2009 and October–November 2010 show the circulation in the upper part of the OMZ with spreading to the east in the North Equatorial Countercurrent (NECC) region and northwestward around the Guinea Dome. Three floats equipped with oxygen sensors deployed at ∼ 8° N, 23° W with parking depths at 330, 350 and 400 m depths were used to estimate velocity along the float trajectory at the surface and at the parking depth. At the 350 m park depth north of 9° N a cyclonic northwestward flow across the OMZ was observed. The northward drift of a float into the upper OMZ and a stronger cyclonic flow around the Guinea Dome seem to be connected to a strong Atlantic Meridional Mode (AMM) event in 2009. A near-surface cyclonic circulation cell east of the Cape Verde Islands reaches down into the OMZ layer. The circulation of the upper OMZ mirrors the near-surface circulation. Oxygen measurements from the cruises used here, as well as from other recent cruises up to the year 2014, confirm the continuous deoxygenation trend in the upper OMZ since the 1960s near the Guinea Dome. The three floats deployed with the tracer show spreading paths consistent with the overall observed tracer spreading. Oxygen sensors on the floats remained well calibrated for more than 20 months, and so the oxygen profiles can be used to investigate mesoscale eddy signatures. Mesoscale eddies may modify the oxygen distribution in OMZs. However, in general eddies are less energetic in the ETNA south of the Cape Verde Islands compared to similar latitudes in ... |
format |
Article in Journal/Newspaper |
author |
L. Stramma R. Czeschel T. Tanhua P. Brandt M. Visbeck B. S. Giese |
author_facet |
L. Stramma R. Czeschel T. Tanhua P. Brandt M. Visbeck B. S. Giese |
author_sort |
L. Stramma |
title |
The flow field of the upper hypoxic eastern tropical North Atlantic oxygen minimum zone |
title_short |
The flow field of the upper hypoxic eastern tropical North Atlantic oxygen minimum zone |
title_full |
The flow field of the upper hypoxic eastern tropical North Atlantic oxygen minimum zone |
title_fullStr |
The flow field of the upper hypoxic eastern tropical North Atlantic oxygen minimum zone |
title_full_unstemmed |
The flow field of the upper hypoxic eastern tropical North Atlantic oxygen minimum zone |
title_sort |
flow field of the upper hypoxic eastern tropical north atlantic oxygen minimum zone |
publisher |
Copernicus Publications |
publishDate |
2016 |
url |
https://doi.org/10.5194/os-12-153-2016 https://doaj.org/article/8e3f1a5bc9474f77bab66a3de32d0658 |
long_lat |
ENVELOPE(166.000,166.000,-85.367,-85.367) |
geographic |
Dome The |
geographic_facet |
Dome The |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Ocean Science, Vol 12, Iss 1, Pp 153-167 (2016) |
op_relation |
http://www.ocean-sci.net/12/153/2016/os-12-153-2016.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 doi:10.5194/os-12-153-2016 https://doaj.org/article/8e3f1a5bc9474f77bab66a3de32d0658 |
op_doi |
https://doi.org/10.5194/os-12-153-2016 |
container_title |
Ocean Science |
container_volume |
12 |
container_issue |
1 |
container_start_page |
153 |
op_container_end_page |
167 |
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1766131280588570624 |