Interplay of oxygen and hydrography in the eastern tropical North Atlantic on decadal to multi-decadal time scales
Ocean observations in the oxygen minimum zone (OMZ) of the eastern tropical North Atlantic (ETNA) are analyzed to study decadal oxygen variability. Corresponding changes in hydrography are discussed and associated with changes in the circulation and ventilation. The data set consists of repeat shipb...
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ftoceanrep:oai:oceanrep.geomar.de:35453 2023-05-15T17:31:43+02:00 Interplay of oxygen and hydrography in the eastern tropical North Atlantic on decadal to multi-decadal time scales Hahn, Johannes Brandt, Peter Schmidtko, Sunke Krahmann, Gerd 2016-04-20 slideshow https://oceanrep.geomar.de/id/eprint/35453/ https://oceanrep.geomar.de/id/eprint/35453/1/Hahn_et_al_EGU2016_6662_OS3_1_BG3_8.pptx en eng https://oceanrep.geomar.de/id/eprint/35453/1/Hahn_et_al_EGU2016_6662_OS3_1_BG3_8.pptx Hahn, J. , Brandt, P. , Schmidtko, S. and Krahmann, G. (2016) Interplay of oxygen and hydrography in the eastern tropical North Atlantic on decadal to multi-decadal time scales. [Talk] In: EGU General Assembly 2016. , 17.-22.04.2016, Vienna, Austria . info:eu-repo/semantics/closedAccess Conference or Workshop Item NonPeerReviewed 2016 ftoceanrep 2023-04-07T15:30:09Z Ocean observations in the oxygen minimum zone (OMZ) of the eastern tropical North Atlantic (ETNA) are analyzed to study decadal oxygen variability. Corresponding changes in hydrography are discussed and associated with changes in the circulation and ventilation. The data set consists of repeat shipboard hydrographic, oxygen and velocity observations along 23°W as well as of three multi-year long moored observations both acquired during the last decade. It is examined in comparison to historic hydrographic data on a decadal to multi-decadal time scale perspective. During the last decade, a strong deoxygenation was observed at depth of the deep oxycline representing a shallowing of the ETNA OMZ, while oxygen increased below in the OMZ core. Both trends are superimposed with a moderate multi-decadal oxygen decrease over the whole depth range. Water mass analysis indicates that this dipole pattern in the decadal oxygen variability is associated with a shift in the ventilation pathways having their origin either in the northern or southern hemisphere. The decadal and multi-decadal oxygen trend is implemented in the oxygen budget for the ETNA OMZ, which is based on recent estimates of oxygen consumption as well as lateral and diapycnal diffusive oxygen supply. The change in the residual of this oxygen budget derived from multi-decadal and decadal oxygen trend patterns indicates a shallower wind-driven near-surface circulation during the last decade compared to the period before. In contrast, the latitudinally alternating zonal jets that were suggested to generally weaken since the 70ies might have intensified during the last decade providing the enhanced oxygen supply at the core depth of the OMZ. Conference Object North Atlantic OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
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Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
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ftoceanrep |
language |
English |
description |
Ocean observations in the oxygen minimum zone (OMZ) of the eastern tropical North Atlantic (ETNA) are analyzed to study decadal oxygen variability. Corresponding changes in hydrography are discussed and associated with changes in the circulation and ventilation. The data set consists of repeat shipboard hydrographic, oxygen and velocity observations along 23°W as well as of three multi-year long moored observations both acquired during the last decade. It is examined in comparison to historic hydrographic data on a decadal to multi-decadal time scale perspective. During the last decade, a strong deoxygenation was observed at depth of the deep oxycline representing a shallowing of the ETNA OMZ, while oxygen increased below in the OMZ core. Both trends are superimposed with a moderate multi-decadal oxygen decrease over the whole depth range. Water mass analysis indicates that this dipole pattern in the decadal oxygen variability is associated with a shift in the ventilation pathways having their origin either in the northern or southern hemisphere. The decadal and multi-decadal oxygen trend is implemented in the oxygen budget for the ETNA OMZ, which is based on recent estimates of oxygen consumption as well as lateral and diapycnal diffusive oxygen supply. The change in the residual of this oxygen budget derived from multi-decadal and decadal oxygen trend patterns indicates a shallower wind-driven near-surface circulation during the last decade compared to the period before. In contrast, the latitudinally alternating zonal jets that were suggested to generally weaken since the 70ies might have intensified during the last decade providing the enhanced oxygen supply at the core depth of the OMZ. |
format |
Conference Object |
author |
Hahn, Johannes Brandt, Peter Schmidtko, Sunke Krahmann, Gerd |
spellingShingle |
Hahn, Johannes Brandt, Peter Schmidtko, Sunke Krahmann, Gerd Interplay of oxygen and hydrography in the eastern tropical North Atlantic on decadal to multi-decadal time scales |
author_facet |
Hahn, Johannes Brandt, Peter Schmidtko, Sunke Krahmann, Gerd |
author_sort |
Hahn, Johannes |
title |
Interplay of oxygen and hydrography in the eastern tropical North Atlantic on decadal to multi-decadal time scales |
title_short |
Interplay of oxygen and hydrography in the eastern tropical North Atlantic on decadal to multi-decadal time scales |
title_full |
Interplay of oxygen and hydrography in the eastern tropical North Atlantic on decadal to multi-decadal time scales |
title_fullStr |
Interplay of oxygen and hydrography in the eastern tropical North Atlantic on decadal to multi-decadal time scales |
title_full_unstemmed |
Interplay of oxygen and hydrography in the eastern tropical North Atlantic on decadal to multi-decadal time scales |
title_sort |
interplay of oxygen and hydrography in the eastern tropical north atlantic on decadal to multi-decadal time scales |
publishDate |
2016 |
url |
https://oceanrep.geomar.de/id/eprint/35453/ https://oceanrep.geomar.de/id/eprint/35453/1/Hahn_et_al_EGU2016_6662_OS3_1_BG3_8.pptx |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://oceanrep.geomar.de/id/eprint/35453/1/Hahn_et_al_EGU2016_6662_OS3_1_BG3_8.pptx Hahn, J. , Brandt, P. , Schmidtko, S. and Krahmann, G. (2016) Interplay of oxygen and hydrography in the eastern tropical North Atlantic on decadal to multi-decadal time scales. [Talk] In: EGU General Assembly 2016. , 17.-22.04.2016, Vienna, Austria . |
op_rights |
info:eu-repo/semantics/closedAccess |
_version_ |
1766129412129947648 |