Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water
Water mass ventilation provides an important link between the atmosphere and the global ocean circulation. In this study, we present a newly developed, probabilistic tool for offline water mass tracking. In particular, NEMOTAM, the tangent-linear and adjoint counterpart to the NEMO ocean general cir...
Published in: | Geoscientific Model Development |
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ftnerc:oai:nora.nerc.ac.uk:527943 2023-05-15T15:08:21+02:00 Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water Stephenson, Dafydd Müller, Simon A. Sévellec, Florian 2020-04-22 text http://nora.nerc.ac.uk/id/eprint/527943/ https://nora.nerc.ac.uk/id/eprint/527943/1/gmd-13-2031-2020.pdf https://doi.org/10.5194/gmd-13-2031-2020 en eng https://nora.nerc.ac.uk/id/eprint/527943/1/gmd-13-2031-2020.pdf Stephenson, Dafydd; Müller, Simon A.; Sévellec, Florian. 2020 Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water. Geoscientific Model Development, 13 (4). 2031-2050. https://doi.org/10.5194/gmd-13-2031-2020 <https://doi.org/10.5194/gmd-13-2031-2020> cc_by_4 CC-BY Publication - Article PeerReviewed 2020 ftnerc https://doi.org/10.5194/gmd-13-2031-2020 2023-02-04T19:50:47Z Water mass ventilation provides an important link between the atmosphere and the global ocean circulation. In this study, we present a newly developed, probabilistic tool for offline water mass tracking. In particular, NEMOTAM, the tangent-linear and adjoint counterpart to the NEMO ocean general circulation model, is modified to allow passive-tracer transport. By terminating dynamic feedbacks in NEMOTAM, tagged water can be tracked forward and backward in time as a passive dye, producing a probability distribution of pathways and origins, respectively. To represent surface (re-)ventilation, we optionally decrease the tracer concentration in the surface layer and track this concentration removal to produce a ventilation record. Two test cases are detailed, examining the creation and fate of North Atlantic Subtropical Mode Water (NASMW) and North Atlantic Deep Water (NADW) in a 2∘ configuration of NEMO run with repeated annual forcing for up to 400 years. Model NASMW is shown to have an expected age of 4.5 years and is predominantly eradicated by internal processes. A bed of more persistent NASMW is detected below the mixed layer with an expected age of 8.7 years. It is shown that while model NADW has two distinct outcrops (in the Arctic and North Atlantic), its formation primarily takes place in the subpolar Labrador and Irminger seas. Its expected age is 112 years. Article in Journal/Newspaper Arctic NADW North Atlantic Deep Water North Atlantic Natural Environment Research Council: NERC Open Research Archive Arctic Geoscientific Model Development 13 4 2031 2050 |
institution |
Open Polar |
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Natural Environment Research Council: NERC Open Research Archive |
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ftnerc |
language |
English |
description |
Water mass ventilation provides an important link between the atmosphere and the global ocean circulation. In this study, we present a newly developed, probabilistic tool for offline water mass tracking. In particular, NEMOTAM, the tangent-linear and adjoint counterpart to the NEMO ocean general circulation model, is modified to allow passive-tracer transport. By terminating dynamic feedbacks in NEMOTAM, tagged water can be tracked forward and backward in time as a passive dye, producing a probability distribution of pathways and origins, respectively. To represent surface (re-)ventilation, we optionally decrease the tracer concentration in the surface layer and track this concentration removal to produce a ventilation record. Two test cases are detailed, examining the creation and fate of North Atlantic Subtropical Mode Water (NASMW) and North Atlantic Deep Water (NADW) in a 2∘ configuration of NEMO run with repeated annual forcing for up to 400 years. Model NASMW is shown to have an expected age of 4.5 years and is predominantly eradicated by internal processes. A bed of more persistent NASMW is detected below the mixed layer with an expected age of 8.7 years. It is shown that while model NADW has two distinct outcrops (in the Arctic and North Atlantic), its formation primarily takes place in the subpolar Labrador and Irminger seas. Its expected age is 112 years. |
format |
Article in Journal/Newspaper |
author |
Stephenson, Dafydd Müller, Simon A. Sévellec, Florian |
spellingShingle |
Stephenson, Dafydd Müller, Simon A. Sévellec, Florian Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water |
author_facet |
Stephenson, Dafydd Müller, Simon A. Sévellec, Florian |
author_sort |
Stephenson, Dafydd |
title |
Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water |
title_short |
Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water |
title_full |
Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water |
title_fullStr |
Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water |
title_full_unstemmed |
Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water |
title_sort |
tracking water masses using passive-tracer transport in nemo v3.4 with nemotam: application to north atlantic deep water and north atlantic subtropical mode water |
publishDate |
2020 |
url |
http://nora.nerc.ac.uk/id/eprint/527943/ https://nora.nerc.ac.uk/id/eprint/527943/1/gmd-13-2031-2020.pdf https://doi.org/10.5194/gmd-13-2031-2020 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic NADW North Atlantic Deep Water North Atlantic |
genre_facet |
Arctic NADW North Atlantic Deep Water North Atlantic |
op_relation |
https://nora.nerc.ac.uk/id/eprint/527943/1/gmd-13-2031-2020.pdf Stephenson, Dafydd; Müller, Simon A.; Sévellec, Florian. 2020 Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water. Geoscientific Model Development, 13 (4). 2031-2050. https://doi.org/10.5194/gmd-13-2031-2020 <https://doi.org/10.5194/gmd-13-2031-2020> |
op_rights |
cc_by_4 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/gmd-13-2031-2020 |
container_title |
Geoscientific Model Development |
container_volume |
13 |
container_issue |
4 |
container_start_page |
2031 |
op_container_end_page |
2050 |
_version_ |
1766339720941404160 |