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 (O2 ≤ 60 μmol kg−1) oxygen minimum zone (OMZ) at 400 to 500 m depth. The poorly known subsurface circulation in the OMZ region is derived from observations and...
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Copernicus Publications (EGU)
2016
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Online Access: | https://oceanrep.geomar.de/id/eprint/29863/ https://oceanrep.geomar.de/id/eprint/29863/1/os-12-153-2016.pdf https://oceanrep.geomar.de/id/eprint/29863/2/os-12-153-2016-supplement.zip https://doi.org/10.5194/os-12-153-2016 |
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ftoceanrep:oai:oceanrep.geomar.de:29863 2023-05-15T17:30:42+02:00 The flow field of the upper hypoxic Eastern Tropical North Atlantic oxygen minimum zone Stramma, Lothar Czeschel, Rena Tanhua, Toste Brandt, Peter Visbeck, Martin Giese, B. S. 2016-01-18 text archive https://oceanrep.geomar.de/id/eprint/29863/ https://oceanrep.geomar.de/id/eprint/29863/1/os-12-153-2016.pdf https://oceanrep.geomar.de/id/eprint/29863/2/os-12-153-2016-supplement.zip https://doi.org/10.5194/os-12-153-2016 en eng Copernicus Publications (EGU) https://oceanrep.geomar.de/id/eprint/29863/1/os-12-153-2016.pdf https://oceanrep.geomar.de/id/eprint/29863/2/os-12-153-2016-supplement.zip Stramma, L. , Czeschel, R., Tanhua, T. , Brandt, P. , Visbeck, M. and Giese, B. S. (2016) The flow field of the upper hypoxic Eastern Tropical North Atlantic oxygen minimum zone. Open Access Ocean Science, 12 (1). pp. 153-167. DOI 10.5194/os-12-153-2016 <https://doi.org/10.5194/os-12-153-2016>. doi:10.5194/os-12-153-2016 cc_by_3.0 info:eu-repo/semantics/openAccess Article PeerReviewed 2016 ftoceanrep https://doi.org/10.5194/os-12-153-2016 2023-04-07T15:21:05Z 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 (O2 ≤ 60 μmol kg−1) oxygen minimum zone (OMZ) at 400 to 500 m depth. The poorly known subsurface circulation in the OMZ region is derived from observations and data assimilation results. Measurements in the eastern tropical North Atlantic in November/December 2008, in November/December 2009 and October/November 2010 of velocity, oxygen and of a tracer (CF3SF5) that was released in April 2008 at ∼ 8° N, 23° W (at ∼ 330 m depth) show 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 park depth. South of 9° N, the zonal surface velocity estimate from float data alternate seasonally. At the 350 m park depth north of 9° N a cyclonic northwestward flow across the OMZ was observed. The northward shift into the upper OMZ and the 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 expands 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 other recent cruises up to the year 2014 confirm the continuous deoxygenation trend in the upper OMZ since the 1960's near the Guinea Dome. The three floats deployed with the tracer show spreading paths consistent with the overall observed tracer spreading. Mesoscale eddies may modify the oxygen distribution in the OMZs. 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. However, in general eddies are ... Article in Journal/Newspaper North Atlantic OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Dome The ENVELOPE(166.000,166.000,-85.367,-85.367) Ocean Science 12 1 153 167 |
institution |
Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
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 (O2 ≤ 60 μmol kg−1) oxygen minimum zone (OMZ) at 400 to 500 m depth. The poorly known subsurface circulation in the OMZ region is derived from observations and data assimilation results. Measurements in the eastern tropical North Atlantic in November/December 2008, in November/December 2009 and October/November 2010 of velocity, oxygen and of a tracer (CF3SF5) that was released in April 2008 at ∼ 8° N, 23° W (at ∼ 330 m depth) show 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 park depth. South of 9° N, the zonal surface velocity estimate from float data alternate seasonally. At the 350 m park depth north of 9° N a cyclonic northwestward flow across the OMZ was observed. The northward shift into the upper OMZ and the 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 expands 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 other recent cruises up to the year 2014 confirm the continuous deoxygenation trend in the upper OMZ since the 1960's near the Guinea Dome. The three floats deployed with the tracer show spreading paths consistent with the overall observed tracer spreading. Mesoscale eddies may modify the oxygen distribution in the OMZs. 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. However, in general eddies are ... |
format |
Article in Journal/Newspaper |
author |
Stramma, Lothar Czeschel, Rena Tanhua, Toste Brandt, Peter Visbeck, Martin Giese, B. S. |
spellingShingle |
Stramma, Lothar Czeschel, Rena Tanhua, Toste Brandt, Peter Visbeck, Martin Giese, B. S. The flow field of the upper hypoxic Eastern Tropical North Atlantic oxygen minimum zone |
author_facet |
Stramma, Lothar Czeschel, Rena Tanhua, Toste Brandt, Peter Visbeck, Martin Giese, B. S. |
author_sort |
Stramma, Lothar |
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 (EGU) |
publishDate |
2016 |
url |
https://oceanrep.geomar.de/id/eprint/29863/ https://oceanrep.geomar.de/id/eprint/29863/1/os-12-153-2016.pdf https://oceanrep.geomar.de/id/eprint/29863/2/os-12-153-2016-supplement.zip https://doi.org/10.5194/os-12-153-2016 |
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_relation |
https://oceanrep.geomar.de/id/eprint/29863/1/os-12-153-2016.pdf https://oceanrep.geomar.de/id/eprint/29863/2/os-12-153-2016-supplement.zip Stramma, L. , Czeschel, R., Tanhua, T. , Brandt, P. , Visbeck, M. and Giese, B. S. (2016) The flow field of the upper hypoxic Eastern Tropical North Atlantic oxygen minimum zone. Open Access Ocean Science, 12 (1). pp. 153-167. DOI 10.5194/os-12-153-2016 <https://doi.org/10.5194/os-12-153-2016>. doi:10.5194/os-12-153-2016 |
op_rights |
cc_by_3.0 info:eu-repo/semantics/openAccess |
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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1766127583418646528 |