Pathways and variability of the circulation in the subpolar eastern North Atlantic studied with inverted echo sounders and model data
The North Atlantic Current (NAC) as part of the Atlantic Meridional Overturning Circulation (AMOC) is the major pathway for warm and saline water from the subtropics into the subpolar North Atlantic. Due to buoyancy loss along its flow path and subsequent deep water formation, it connects the upper...
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Universität Bremen
2021
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ftsubbremen:oai:media.suub.uni-bremen.de:Publications/elib/5223 2023-05-15T17:24:24+02:00 Pathways and variability of the circulation in the subpolar eastern North Atlantic studied with inverted echo sounders and model data Nowitzki, Hannah Rhein, Monika Spreen, Gunnar 2021-07-29 application/pdf https://media.suub.uni-bremen.de/handle/elib/5223 https://doi.org/10.26092/elib/1020 https://nbn-resolving.org/urn:nbn:de:gbv:46-elib52237 eng eng Universität Bremen Fachbereich 01: Physik/Elektrotechnik (FB 01) https://media.suub.uni-bremen.de/handle/elib/5223 http://dx.doi.org/10.26092/elib/1020 doi:10.26092/elib/1020 urn:nbn:de:gbv:46-elib52237 info:eu-repo/semantics/openAccess Attribution-NonCommercial-NoDerivs 3.0 Germany http://creativecommons.org/licenses/by-nc-nd/3.0/de/ CC-BY-NC-ND North Atlantic Current inverted echo sounder ANHA12 NEMO model volume transport NOAC array North Atlantic Subpolar Gyre 500 500 Science ddc:500 Dissertation doctoralThesis 2021 ftsubbremen https://doi.org/10.26092/elib/1020 2022-11-09T07:10:20Z The North Atlantic Current (NAC) as part of the Atlantic Meridional Overturning Circulation (AMOC) is the major pathway for warm and saline water from the subtropics into the subpolar North Atlantic. Due to buoyancy loss along its flow path and subsequent deep water formation, it connects the upper warm limb of the AMOC with the deeper cold limb. Associated volume fluxes and their variability are thus of great interest, especially in the context of climate change. The main branch of the NAC and related transports are widely studied. The NAC crosses 47°/48°N in the western North Atlantic and further north the Mid-Atlantic Ridge (MAR) before entering the eastern subpolar basin where it partly feeds the Subpolar Gyre or flows into the Nordic Seas. To quantify the meridional exchange of water between the subtropical and subpolar regime in the interior eastern North Atlantic where studies are scarce, in this work, long-term (1993 to 2017) transport time series were calculated by combining data from inverted echo sounders taken in 2016 and 2017 with satellite altimetry. The results obtained from observational data are complemented with transport time series calculated from high resolution model output of the ANHA12 configuration of the NEMO model and with the analysis of particle trajectories calculated from the Lagrangian model ARIANE. The observational data reveal an additional more direct pathway from the south across 47°/48°N into the subpolar eastern North Atlantic with a mean northward transport of +9.1 Sv ± 0.8 Sv contributing about 22% to the total inflow of +41.4 Sv into the eastern basin. The meridional transport of this pathway is significantly anticorrelated to the transport across the MAR (R = −0.7), damping the interannual variability of the total inflow into the subpolar eastern North Atlantic. Moreover, for the meridional transport in the interior eastern basin, a positive trend of +2.0 Sv ± 1.5 Sv per decade is found, partly balancing the negative decadal trend of −6.0 Sv ± 5.7 Sv observed for the ... Doctoral or Postdoctoral Thesis Nordic Seas north atlantic current North Atlantic Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen) Mid-Atlantic Ridge |
institution |
Open Polar |
collection |
Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen) |
op_collection_id |
ftsubbremen |
language |
English |
topic |
North Atlantic Current inverted echo sounder ANHA12 NEMO model volume transport NOAC array North Atlantic Subpolar Gyre 500 500 Science ddc:500 |
spellingShingle |
North Atlantic Current inverted echo sounder ANHA12 NEMO model volume transport NOAC array North Atlantic Subpolar Gyre 500 500 Science ddc:500 Nowitzki, Hannah Pathways and variability of the circulation in the subpolar eastern North Atlantic studied with inverted echo sounders and model data |
topic_facet |
North Atlantic Current inverted echo sounder ANHA12 NEMO model volume transport NOAC array North Atlantic Subpolar Gyre 500 500 Science ddc:500 |
description |
The North Atlantic Current (NAC) as part of the Atlantic Meridional Overturning Circulation (AMOC) is the major pathway for warm and saline water from the subtropics into the subpolar North Atlantic. Due to buoyancy loss along its flow path and subsequent deep water formation, it connects the upper warm limb of the AMOC with the deeper cold limb. Associated volume fluxes and their variability are thus of great interest, especially in the context of climate change. The main branch of the NAC and related transports are widely studied. The NAC crosses 47°/48°N in the western North Atlantic and further north the Mid-Atlantic Ridge (MAR) before entering the eastern subpolar basin where it partly feeds the Subpolar Gyre or flows into the Nordic Seas. To quantify the meridional exchange of water between the subtropical and subpolar regime in the interior eastern North Atlantic where studies are scarce, in this work, long-term (1993 to 2017) transport time series were calculated by combining data from inverted echo sounders taken in 2016 and 2017 with satellite altimetry. The results obtained from observational data are complemented with transport time series calculated from high resolution model output of the ANHA12 configuration of the NEMO model and with the analysis of particle trajectories calculated from the Lagrangian model ARIANE. The observational data reveal an additional more direct pathway from the south across 47°/48°N into the subpolar eastern North Atlantic with a mean northward transport of +9.1 Sv ± 0.8 Sv contributing about 22% to the total inflow of +41.4 Sv into the eastern basin. The meridional transport of this pathway is significantly anticorrelated to the transport across the MAR (R = −0.7), damping the interannual variability of the total inflow into the subpolar eastern North Atlantic. Moreover, for the meridional transport in the interior eastern basin, a positive trend of +2.0 Sv ± 1.5 Sv per decade is found, partly balancing the negative decadal trend of −6.0 Sv ± 5.7 Sv observed for the ... |
author2 |
Rhein, Monika Spreen, Gunnar |
format |
Doctoral or Postdoctoral Thesis |
author |
Nowitzki, Hannah |
author_facet |
Nowitzki, Hannah |
author_sort |
Nowitzki, Hannah |
title |
Pathways and variability of the circulation in the subpolar eastern North Atlantic studied with inverted echo sounders and model data |
title_short |
Pathways and variability of the circulation in the subpolar eastern North Atlantic studied with inverted echo sounders and model data |
title_full |
Pathways and variability of the circulation in the subpolar eastern North Atlantic studied with inverted echo sounders and model data |
title_fullStr |
Pathways and variability of the circulation in the subpolar eastern North Atlantic studied with inverted echo sounders and model data |
title_full_unstemmed |
Pathways and variability of the circulation in the subpolar eastern North Atlantic studied with inverted echo sounders and model data |
title_sort |
pathways and variability of the circulation in the subpolar eastern north atlantic studied with inverted echo sounders and model data |
publisher |
Universität Bremen |
publishDate |
2021 |
url |
https://media.suub.uni-bremen.de/handle/elib/5223 https://doi.org/10.26092/elib/1020 https://nbn-resolving.org/urn:nbn:de:gbv:46-elib52237 |
geographic |
Mid-Atlantic Ridge |
geographic_facet |
Mid-Atlantic Ridge |
genre |
Nordic Seas north atlantic current North Atlantic |
genre_facet |
Nordic Seas north atlantic current North Atlantic |
op_relation |
https://media.suub.uni-bremen.de/handle/elib/5223 http://dx.doi.org/10.26092/elib/1020 doi:10.26092/elib/1020 urn:nbn:de:gbv:46-elib52237 |
op_rights |
info:eu-repo/semantics/openAccess Attribution-NonCommercial-NoDerivs 3.0 Germany http://creativecommons.org/licenses/by-nc-nd/3.0/de/ |
op_rightsnorm |
CC-BY-NC-ND |
op_doi |
https://doi.org/10.26092/elib/1020 |
_version_ |
1766115397245861888 |