Processes and flow over the Iceland-Faroe Ridge (D2.3)

Summary Combining the results from the ester Valley Overflow field experiment with data from other in situ current measurements, from satellite tracked drifters, and from satellite altimetry, we find a consistent picture of the passage of Atlantic water across the Iceland-Faroe Ridge, which can be d...

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Main Authors: Olsen, Steffen, Gierisch, Andrea, Larsen, Karin, Hansen, Bogi
Format: Text
Language:English
Published: Zenodo 2019
Subjects:
Online Access:https://dx.doi.org/10.5281/zenodo.3631075
https://zenodo.org/record/3631075
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spelling ftdatacite:10.5281/zenodo.3631075 2023-05-15T16:11:18+02:00 Processes and flow over the Iceland-Faroe Ridge (D2.3) Olsen, Steffen Gierisch, Andrea Larsen, Karin Hansen, Bogi 2019 https://dx.doi.org/10.5281/zenodo.3631075 https://zenodo.org/record/3631075 en eng Zenodo https://zenodo.org/communities/blue-actionh2020 https://dx.doi.org/10.5281/zenodo.3631076 https://zenodo.org/communities/blue-actionh2020 Open Access Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode cc-by-4.0 info:eu-repo/semantics/openAccess CC-BY Text Project deliverable article-journal ScholarlyArticle 2019 ftdatacite https://doi.org/10.5281/zenodo.3631075 https://doi.org/10.5281/zenodo.3631076 2021-11-05T12:55:41Z Summary Combining the results from the ester Valley Overflow field experiment with data from other in situ current measurements, from satellite tracked drifters, and from satellite altimetry, we find a consistent picture of the passage of Atlantic water across the Iceland-Faroe Ridge, which can be described in terms of two branches. The Western branch passes through the Western Valley, where it is locked to the steep topography of the Icelandic slope, but part of it re-circulates back onto the ridge before entering the Norwegian Sea. It may have strong surface flow in a narrow current, but it is highly variable and its average volume transport is low. The Eastern branch passes the ridge as a broad flow with a core that shifts back and forth laterally (parallel to the ridge axis). In general, it exhibits weaker surface currents based on observations, but its volume transport is the dominant component and must be fairly stable to account for the stability of transport monitored at a section farther east. The available data on Mean Dynamic Topography seem to reflect realistic large-scale circulation features, but to smear out the spatial structure of surface currents and transports. The Sea Level Anomaly data from satellite altimetry appear to be well related to surface currents in this region, at least on time scales from weeks to longer. When calibrated with the results from the WOW field experiment, they allow long-term monitoring of volume transport of the Western branch. By applying a set of commentary modelling approaches, it is confirmed that the combined transport can be assessed and effectively monitored on a section north of the Faroes, disregarding that there is little model consensus on the strength of individual branches. Direct comparisons of model results and observations of the total transport show large discrepancies. Assessment of inherent model uncertainty for this and other inflow branches show that the Atlantic water flow across the Iceland-Faroe Ridge has a higher natural noise level and is less constrained by the applied forcing than could be expected. This new result puts emphasis on model ensemble approaches as the key to understand the climatic sensitivity of the system but also raises a concern about our capability to predict abrupt changes. Results suggests that adequately tuned ocean models of eddy permitting resolution are sufficient for simulating the main characteristics of the Iceland-Faroe Ridge inflow including horizontal structure, individual characteristics of the two branches as well as seasonality of the net transport. : The Blue-Action project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No 727852. Text Faroes Iceland Norwegian Sea DataCite Metadata Store (German National Library of Science and Technology) Norwegian Sea
institution Open Polar
collection DataCite Metadata Store (German National Library of Science and Technology)
op_collection_id ftdatacite
language English
description Summary Combining the results from the ester Valley Overflow field experiment with data from other in situ current measurements, from satellite tracked drifters, and from satellite altimetry, we find a consistent picture of the passage of Atlantic water across the Iceland-Faroe Ridge, which can be described in terms of two branches. The Western branch passes through the Western Valley, where it is locked to the steep topography of the Icelandic slope, but part of it re-circulates back onto the ridge before entering the Norwegian Sea. It may have strong surface flow in a narrow current, but it is highly variable and its average volume transport is low. The Eastern branch passes the ridge as a broad flow with a core that shifts back and forth laterally (parallel to the ridge axis). In general, it exhibits weaker surface currents based on observations, but its volume transport is the dominant component and must be fairly stable to account for the stability of transport monitored at a section farther east. The available data on Mean Dynamic Topography seem to reflect realistic large-scale circulation features, but to smear out the spatial structure of surface currents and transports. The Sea Level Anomaly data from satellite altimetry appear to be well related to surface currents in this region, at least on time scales from weeks to longer. When calibrated with the results from the WOW field experiment, they allow long-term monitoring of volume transport of the Western branch. By applying a set of commentary modelling approaches, it is confirmed that the combined transport can be assessed and effectively monitored on a section north of the Faroes, disregarding that there is little model consensus on the strength of individual branches. Direct comparisons of model results and observations of the total transport show large discrepancies. Assessment of inherent model uncertainty for this and other inflow branches show that the Atlantic water flow across the Iceland-Faroe Ridge has a higher natural noise level and is less constrained by the applied forcing than could be expected. This new result puts emphasis on model ensemble approaches as the key to understand the climatic sensitivity of the system but also raises a concern about our capability to predict abrupt changes. Results suggests that adequately tuned ocean models of eddy permitting resolution are sufficient for simulating the main characteristics of the Iceland-Faroe Ridge inflow including horizontal structure, individual characteristics of the two branches as well as seasonality of the net transport. : The Blue-Action project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No 727852.
format Text
author Olsen, Steffen
Gierisch, Andrea
Larsen, Karin
Hansen, Bogi
spellingShingle Olsen, Steffen
Gierisch, Andrea
Larsen, Karin
Hansen, Bogi
Processes and flow over the Iceland-Faroe Ridge (D2.3)
author_facet Olsen, Steffen
Gierisch, Andrea
Larsen, Karin
Hansen, Bogi
author_sort Olsen, Steffen
title Processes and flow over the Iceland-Faroe Ridge (D2.3)
title_short Processes and flow over the Iceland-Faroe Ridge (D2.3)
title_full Processes and flow over the Iceland-Faroe Ridge (D2.3)
title_fullStr Processes and flow over the Iceland-Faroe Ridge (D2.3)
title_full_unstemmed Processes and flow over the Iceland-Faroe Ridge (D2.3)
title_sort processes and flow over the iceland-faroe ridge (d2.3)
publisher Zenodo
publishDate 2019
url https://dx.doi.org/10.5281/zenodo.3631075
https://zenodo.org/record/3631075
geographic Norwegian Sea
geographic_facet Norwegian Sea
genre Faroes
Iceland
Norwegian Sea
genre_facet Faroes
Iceland
Norwegian Sea
op_relation https://zenodo.org/communities/blue-actionh2020
https://dx.doi.org/10.5281/zenodo.3631076
https://zenodo.org/communities/blue-actionh2020
op_rights Open Access
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
cc-by-4.0
info:eu-repo/semantics/openAccess
op_rightsnorm CC-BY
op_doi https://doi.org/10.5281/zenodo.3631075
https://doi.org/10.5281/zenodo.3631076
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