Articles | Volume 14, issue 4
https://doi.org/10.5194/os-14-871-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-14-871-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Overflow of cold water across the Iceland–Faroe Ridge through the Western Valley
Bogi Hansen
CORRESPONDING AUTHOR
Faroe Marine Research Institute, P.O. Box 3051, 110 Tórshavn, Faroe Islands
Karin Margretha Húsgarð Larsen
Faroe Marine Research Institute, P.O. Box 3051, 110 Tórshavn, Faroe Islands
Steffen Malskær Olsen
Danish Meteorological Institute, Lyngbyvej 100, 2100 Copenhagen, Denmark
Detlef Quadfasel
University of Hamburg, Bundesstrasse 53, 20146 Hamburg, Germany
Kerstin Jochumsen
University of Hamburg, Bundesstrasse 53, 20146 Hamburg, Germany
Svein Østerhus
Uni Research Climate, Nygårdsgata 112, 5008 Bergen, Norway
Related authors
Bogi Hansen, Karin M. H. Larsen, Hjálmar Hátún, Steffen M. Olsen, Andrea M. U. Gierisch, Svein Østerhus, and Sólveig R. Ólafsdóttir
Ocean Sci., 19, 1225–1252, https://doi.org/10.5194/os-19-1225-2023, https://doi.org/10.5194/os-19-1225-2023, 2023
Short summary
Short summary
Based on in situ observations combined with sea level anomaly (SLA) data from satellite altimetry, volume as well as heat (relative to 0 °C) transport of the Iceland–Faroe warm-water inflow towards the Arctic (IF inflow) increased from 1993 to 2021. The reprocessed SLA data released in December 2021 represent observed variations accurately. The IF inflow crosses the Iceland–Faroe Ridge in two branches, with retroflection in between. The associated coupling to overflow reduces predictability.
Sissal Vágsheyg Erenbjerg, Jon Albretsen, Knud Simonsen, Erna Lava Olsen, Eigil Kaas, and Bogi Hansen
Ocean Sci., 17, 1639–1655, https://doi.org/10.5194/os-17-1639-2021, https://doi.org/10.5194/os-17-1639-2021, 2021
Short summary
Short summary
Here, we describe a strait that has narrow and shallow sills in both ends and is close to an amphidromic region. This generates tidally driven flows into and out of the strait, but with very different exchange rates across the entrances in both ends so that it behaves like a mixture between a strait and a fjord. Using a numerical model, we find a fortnightly signal in the net transport through the strait, generated by long-period tides. Our findings are verified by observations.
Bogi Hansen, Karin Margretha Húsgarð Larsen, Hjálmar Hátún, Steingrímur Jónsson, Sólveig Rósa Ólafsdóttir, Andreas Macrander, William Johns, N. Penny Holliday, and Steffen Malskær Olsen
Ocean Sci. Discuss., https://doi.org/10.5194/os-2021-14, https://doi.org/10.5194/os-2021-14, 2021
Preprint withdrawn
Short summary
Short summary
Compared to other freshwater sources, runoff from Iceland is small and usually flows into the Nordic Seas. Under certain wind conditions, it can, however, flow into the Iceland Basin and this occurred after 2014, when this region had already freshened from other causes. This explains why the surface freshening in this area became so extreme. The local and shallow character of this runoff allows it to have a disproportionate effect on vertical mixing, winter convection, and biological production.
Svein Østerhus, Rebecca Woodgate, Héðinn Valdimarsson, Bill Turrell, Laura de Steur, Detlef Quadfasel, Steffen M. Olsen, Martin Moritz, Craig M. Lee, Karin Margretha H. Larsen, Steingrímur Jónsson, Clare Johnson, Kerstin Jochumsen, Bogi Hansen, Beth Curry, Stuart Cunningham, and Barbara Berx
Ocean Sci., 15, 379–399, https://doi.org/10.5194/os-15-379-2019, https://doi.org/10.5194/os-15-379-2019, 2019
Short summary
Short summary
Two decades of observations of the Arctic Mediterranean (AM) exchanges show that the exchanges have been stable in terms of volume transport during a period when many other components of the global climate system have changed. The total AM import is found to be 9.1 Sv and has a seasonal variation in amplitude close to 1 Sv, and maximum import in October. Roughly one-third of the imported water leaves the AM as surface outflow.
Bogi Hansen, Turið Poulsen, Karin Margretha Húsgarð Larsen, Hjálmar Hátún, Svein Østerhus, Elin Darelius, Barbara Berx, Detlef Quadfasel, and Kerstin Jochumsen
Ocean Sci., 13, 873–888, https://doi.org/10.5194/os-13-873-2017, https://doi.org/10.5194/os-13-873-2017, 2017
Short summary
Short summary
On its way towards the Arctic, an important branch of warm Atlantic water passes through the Faroese Channels, but, in spite of more than a century of investigations, the detailed flow pattern through this channel system has not been resolved. This has strong implications for estimates of oceanic heat transport towards the Arctic. Here, we combine observations from various sources, which together paint a coherent picture of the Atlantic water flow and heat transport through this channel system.
Bogi Hansen, Karin Margretha Húsgarð Larsen, Hjálmar Hátún, and Svein Østerhus
Ocean Sci., 12, 1205–1220, https://doi.org/10.5194/os-12-1205-2016, https://doi.org/10.5194/os-12-1205-2016, 2016
Short summary
Short summary
The Faroe Bank Channel is one of the main passages for the flow of cold dense water from the Arctic into the depths of the world ocean where it feeds the deep branch of the AMOC. Based on in situ measurements, we show that the volume transport of this flow has been stable from 1995 to 2015. The water has warmed, but salinity increase has maintained its high density. Thus, this branch of the AMOC did not weaken during the last 2 decades, but increased its heat transport into the deep ocean.
S. M. Olsen, B. Hansen, S. Østerhus, D. Quadfasel, and H. Valdimarsson
Ocean Sci., 12, 545–560, https://doi.org/10.5194/os-12-545-2016, https://doi.org/10.5194/os-12-545-2016, 2016
Short summary
Short summary
About half of the warm Atlantic water that enters the Norwegian Sea flows between Iceland and the Faroes. Here it crosses the Iceland-Faroe Ridge and dynamically interacts with the cold, dense and deep return flow across the ridge. This flow is not resolved in climate models and the lack of interaction prevents realistic heat anomaly propagation towards the Arctic.
B. Hansen, K. M. H. Larsen, H. Hátún, R. Kristiansen, E. Mortensen, and S. Østerhus
Ocean Sci., 11, 743–757, https://doi.org/10.5194/os-11-743-2015, https://doi.org/10.5194/os-11-743-2015, 2015
Short summary
Short summary
The Faroe Current is the main ocean current transporting warm Atlantic water into the Arctic region and an important transporter of heat towards the Arctic. This study documents observed transport variations over two decades, from 1993 to 2013. It shows that the volume transport of Atlantic water in this current increased by 9% over the period, whereas the heat transport increased by 18%. This increase will have contributed to the observed warming and sea ice decline in the Arctic.
B. Berx, B. Hansen, S. Østerhus, K. M. Larsen, T. Sherwin, and K. Jochumsen
Ocean Sci., 9, 639–654, https://doi.org/10.5194/os-9-639-2013, https://doi.org/10.5194/os-9-639-2013, 2013
Michael Mayer, Takamasa Tsubouchi, Susanna Winkelbauer, Karin Margretha H. Larsen, Barbara Berx, Andreas Macrander, Doroteaciro Iovino, Steingrímur Jónsson, and Richard Renshaw
State Planet, 1-osr7, 14, https://doi.org/10.5194/sp-1-osr7-14-2023, https://doi.org/10.5194/sp-1-osr7-14-2023, 2023
Short summary
Short summary
This paper compares oceanic fluxes across the Greenland–Scotland Ridge (GSR) from ocean reanalyses to largely independent observational data. Reanalyses tend to underestimate the inflow of warm waters of subtropical Atlantic origin and hence oceanic heat transport across the GSR. Investigation of a strong negative heat transport anomaly around 2018 highlights the interplay of variability on different timescales and the need for long-term monitoring of the GSR to detect forced climate signals.
Bogi Hansen, Karin M. H. Larsen, Hjálmar Hátún, Steffen M. Olsen, Andrea M. U. Gierisch, Svein Østerhus, and Sólveig R. Ólafsdóttir
Ocean Sci., 19, 1225–1252, https://doi.org/10.5194/os-19-1225-2023, https://doi.org/10.5194/os-19-1225-2023, 2023
Short summary
Short summary
Based on in situ observations combined with sea level anomaly (SLA) data from satellite altimetry, volume as well as heat (relative to 0 °C) transport of the Iceland–Faroe warm-water inflow towards the Arctic (IF inflow) increased from 1993 to 2021. The reprocessed SLA data released in December 2021 represent observed variations accurately. The IF inflow crosses the Iceland–Faroe Ridge in two branches, with retroflection in between. The associated coupling to overflow reduces predictability.
Sissal Vágsheyg Erenbjerg, Jon Albretsen, Knud Simonsen, Erna Lava Olsen, Eigil Kaas, and Bogi Hansen
Ocean Sci., 17, 1639–1655, https://doi.org/10.5194/os-17-1639-2021, https://doi.org/10.5194/os-17-1639-2021, 2021
Short summary
Short summary
Here, we describe a strait that has narrow and shallow sills in both ends and is close to an amphidromic region. This generates tidally driven flows into and out of the strait, but with very different exchange rates across the entrances in both ends so that it behaves like a mixture between a strait and a fjord. Using a numerical model, we find a fortnightly signal in the net transport through the strait, generated by long-period tides. Our findings are verified by observations.
Bogi Hansen, Karin Margretha Húsgarð Larsen, Hjálmar Hátún, Steingrímur Jónsson, Sólveig Rósa Ólafsdóttir, Andreas Macrander, William Johns, N. Penny Holliday, and Steffen Malskær Olsen
Ocean Sci. Discuss., https://doi.org/10.5194/os-2021-14, https://doi.org/10.5194/os-2021-14, 2021
Preprint withdrawn
Short summary
Short summary
Compared to other freshwater sources, runoff from Iceland is small and usually flows into the Nordic Seas. Under certain wind conditions, it can, however, flow into the Iceland Basin and this occurred after 2014, when this region had already freshened from other causes. This explains why the surface freshening in this area became so extreme. The local and shallow character of this runoff allows it to have a disproportionate effect on vertical mixing, winter convection, and biological production.
Svein Østerhus, Rebecca Woodgate, Héðinn Valdimarsson, Bill Turrell, Laura de Steur, Detlef Quadfasel, Steffen M. Olsen, Martin Moritz, Craig M. Lee, Karin Margretha H. Larsen, Steingrímur Jónsson, Clare Johnson, Kerstin Jochumsen, Bogi Hansen, Beth Curry, Stuart Cunningham, and Barbara Berx
Ocean Sci., 15, 379–399, https://doi.org/10.5194/os-15-379-2019, https://doi.org/10.5194/os-15-379-2019, 2019
Short summary
Short summary
Two decades of observations of the Arctic Mediterranean (AM) exchanges show that the exchanges have been stable in terms of volume transport during a period when many other components of the global climate system have changed. The total AM import is found to be 9.1 Sv and has a seasonal variation in amplitude close to 1 Sv, and maximum import in October. Roughly one-third of the imported water leaves the AM as surface outflow.
Bogi Hansen, Turið Poulsen, Karin Margretha Húsgarð Larsen, Hjálmar Hátún, Svein Østerhus, Elin Darelius, Barbara Berx, Detlef Quadfasel, and Kerstin Jochumsen
Ocean Sci., 13, 873–888, https://doi.org/10.5194/os-13-873-2017, https://doi.org/10.5194/os-13-873-2017, 2017
Short summary
Short summary
On its way towards the Arctic, an important branch of warm Atlantic water passes through the Faroese Channels, but, in spite of more than a century of investigations, the detailed flow pattern through this channel system has not been resolved. This has strong implications for estimates of oceanic heat transport towards the Arctic. Here, we combine observations from various sources, which together paint a coherent picture of the Atlantic water flow and heat transport through this channel system.
Gary Shaffer, Esteban Fernández Villanueva, Roberto Rondanelli, Jens Olaf Pepke Pedersen, Steffen Malskær Olsen, and Matthew Huber
Geosci. Model Dev., 10, 4081–4103, https://doi.org/10.5194/gmd-10-4081-2017, https://doi.org/10.5194/gmd-10-4081-2017, 2017
Short summary
Short summary
We include methane cycling in the simplified but well-tested Danish Center for Earth System Science model. We now can deal with very large methane inputs to the Earth system that can lead to more methane in the atmosphere, extreme warming and ocean dead zones. We can now study ancient global warming events, probably forced by methane inputs. Some such events were accompanied by mass extinctions. We wish to understand such events, both for learning about the past and for looking into the future.
Amelie Driemel, Eberhard Fahrbach, Gerd Rohardt, Agnieszka Beszczynska-Möller, Antje Boetius, Gereon Budéus, Boris Cisewski, Ralph Engbrodt, Steffen Gauger, Walter Geibert, Patrizia Geprägs, Dieter Gerdes, Rainer Gersonde, Arnold L. Gordon, Hannes Grobe, Hartmut H. Hellmer, Enrique Isla, Stanley S. Jacobs, Markus Janout, Wilfried Jokat, Michael Klages, Gerhard Kuhn, Jens Meincke, Sven Ober, Svein Østerhus, Ray G. Peterson, Benjamin Rabe, Bert Rudels, Ursula Schauer, Michael Schröder, Stefanie Schumacher, Rainer Sieger, Jüri Sildam, Thomas Soltwedel, Elena Stangeew, Manfred Stein, Volker H Strass, Jörn Thiede, Sandra Tippenhauer, Cornelis Veth, Wilken-Jon von Appen, Marie-France Weirig, Andreas Wisotzki, Dieter A. Wolf-Gladrow, and Torsten Kanzow
Earth Syst. Sci. Data, 9, 211–220, https://doi.org/10.5194/essd-9-211-2017, https://doi.org/10.5194/essd-9-211-2017, 2017
Short summary
Short summary
Our oceans are always in motion – huge water masses are circulated by winds and by global seawater density gradients resulting from different water temperatures and salinities. Measuring temperature and salinity of the world's oceans is crucial e.g. to understand our climate. Since 1983, the research icebreaker Polarstern has been the basis of numerous water profile measurements in the Arctic and the Antarctic. We report on a unique collection of 33 years of polar salinity and temperature data.
Bogi Hansen, Karin Margretha Húsgarð Larsen, Hjálmar Hátún, and Svein Østerhus
Ocean Sci., 12, 1205–1220, https://doi.org/10.5194/os-12-1205-2016, https://doi.org/10.5194/os-12-1205-2016, 2016
Short summary
Short summary
The Faroe Bank Channel is one of the main passages for the flow of cold dense water from the Arctic into the depths of the world ocean where it feeds the deep branch of the AMOC. Based on in situ measurements, we show that the volume transport of this flow has been stable from 1995 to 2015. The water has warmed, but salinity increase has maintained its high density. Thus, this branch of the AMOC did not weaken during the last 2 decades, but increased its heat transport into the deep ocean.
S. M. Olsen, B. Hansen, S. Østerhus, D. Quadfasel, and H. Valdimarsson
Ocean Sci., 12, 545–560, https://doi.org/10.5194/os-12-545-2016, https://doi.org/10.5194/os-12-545-2016, 2016
Short summary
Short summary
About half of the warm Atlantic water that enters the Norwegian Sea flows between Iceland and the Faroes. Here it crosses the Iceland-Faroe Ridge and dynamically interacts with the cold, dense and deep return flow across the ridge. This flow is not resolved in climate models and the lack of interaction prevents realistic heat anomaly propagation towards the Arctic.
E. Darelius, I. Fer, T. Rasmussen, C. Guo, and K. M. H. Larsen
Ocean Sci., 11, 855–871, https://doi.org/10.5194/os-11-855-2015, https://doi.org/10.5194/os-11-855-2015, 2015
Short summary
Short summary
Quasi-regular eddies are known to be generated in the outflow of dense water through the Faroe Bank Channel. One year long mooring records from the plume region show that (1) the energy associated with the eddies varies by a factor of 10 throughout the year and (2) the frequency of the eddies shifts between 3 and 6 days and is related to the strength of the outflow. Similar variability is shown by a high-resolution regional model and the observations agree with theory on baroclinic instability.
B. Hansen, K. M. H. Larsen, H. Hátún, R. Kristiansen, E. Mortensen, and S. Østerhus
Ocean Sci., 11, 743–757, https://doi.org/10.5194/os-11-743-2015, https://doi.org/10.5194/os-11-743-2015, 2015
Short summary
Short summary
The Faroe Current is the main ocean current transporting warm Atlantic water into the Arctic region and an important transporter of heat towards the Arctic. This study documents observed transport variations over two decades, from 1993 to 2013. It shows that the volume transport of Atlantic water in this current increased by 9% over the period, whereas the heat transport increased by 18%. This increase will have contributed to the observed warming and sea ice decline in the Arctic.
B. Berx, B. Hansen, S. Østerhus, K. M. Larsen, T. Sherwin, and K. Jochumsen
Ocean Sci., 9, 639–654, https://doi.org/10.5194/os-9-639-2013, https://doi.org/10.5194/os-9-639-2013, 2013
M. Eby, A. J. Weaver, K. Alexander, K. Zickfeld, A. Abe-Ouchi, A. A. Cimatoribus, E. Crespin, S. S. Drijfhout, N. R. Edwards, A. V. Eliseev, G. Feulner, T. Fichefet, C. E. Forest, H. Goosse, P. B. Holden, F. Joos, M. Kawamiya, D. Kicklighter, H. Kienert, K. Matsumoto, I. I. Mokhov, E. Monier, S. M. Olsen, J. O. P. Pedersen, M. Perrette, G. Philippon-Berthier, A. Ridgwell, A. Schlosser, T. Schneider von Deimling, G. Shaffer, R. S. Smith, R. Spahni, A. P. Sokolov, M. Steinacher, K. Tachiiri, K. Tokos, M. Yoshimori, N. Zeng, and F. Zhao
Clim. Past, 9, 1111–1140, https://doi.org/10.5194/cp-9-1111-2013, https://doi.org/10.5194/cp-9-1111-2013, 2013
Related subject area
Approach: In situ Observations | Depth range: All Depths | Geographical range: Nordic Seas | Phenomena: Current Field
Norwegian Atlantic Slope Current along the Lofoten Escarpment
Does the East Greenland Current exist in the northern Fram Strait?
Volume transport and mixing of the Faroe Bank Channel overflow from one year of moored measurements
On the modulation of the periodicity of the Faroe Bank Channel overflow instabilities
Transport of volume, heat, and salt towards the Arctic in the Faroe Current 1993–2013
Combining in situ measurements and altimetry to estimate volume, heat and salt transport variability through the Faroe–Shetland Channel
A quantitative description of the Norwegian Atlantic Current by combining altimetry and hydrography
Ilker Fer, Anthony Bosse, and Johannes Dugstad
Ocean Sci., 16, 685–701, https://doi.org/10.5194/os-16-685-2020, https://doi.org/10.5194/os-16-685-2020, 2020
Short summary
Short summary
We analyzed 14-month-long observations from moored instruments to describe the average features and the variability of the Norwegian Atlantic Slope Current at the Lofoten Escarpment (13°E, 69°N). The slope current varies strongly with depth and in time. Pulses of strong current occur, lasting for 1 to 2 weeks, and extend as deep as 600 m. The average volume transport is 2 x 106 m3 s-1.
Maren Elisabeth Richter, Wilken-Jon von Appen, and Claudia Wekerle
Ocean Sci., 14, 1147–1165, https://doi.org/10.5194/os-14-1147-2018, https://doi.org/10.5194/os-14-1147-2018, 2018
Short summary
Short summary
In the Fram Strait, Arctic Ocean outflow is joined by Atlantic Water (AW) that has not flowed through the Arctic Ocean. The confluence creates a density gradient which steepens and draws closer to the east Greenland shelf break from N to S. This brings the warm AW closer to the shelf break. South of 79° N, AW has reached the shelf break and the East Greenland Current has formed. When AW reaches the Greenland shelf it may propagate through troughs to glacier termini and contribute to glacier melt.
Jenny E. Ullgren, Elin Darelius, and Ilker Fer
Ocean Sci., 12, 451–470, https://doi.org/10.5194/os-12-451-2016, https://doi.org/10.5194/os-12-451-2016, 2016
Short summary
Short summary
One-year long moored measurements of currents and hydrographic properties in the overflow region of the Faroe Bank Channel have provided a more accurate observational-based estimate of the volume transport, entrainment, and eddy diffusivities associated with the overflow plume. The data set resolves the temporal variability and covers the entire lateral and vertical extent of the plume.
E. Darelius, I. Fer, T. Rasmussen, C. Guo, and K. M. H. Larsen
Ocean Sci., 11, 855–871, https://doi.org/10.5194/os-11-855-2015, https://doi.org/10.5194/os-11-855-2015, 2015
Short summary
Short summary
Quasi-regular eddies are known to be generated in the outflow of dense water through the Faroe Bank Channel. One year long mooring records from the plume region show that (1) the energy associated with the eddies varies by a factor of 10 throughout the year and (2) the frequency of the eddies shifts between 3 and 6 days and is related to the strength of the outflow. Similar variability is shown by a high-resolution regional model and the observations agree with theory on baroclinic instability.
B. Hansen, K. M. H. Larsen, H. Hátún, R. Kristiansen, E. Mortensen, and S. Østerhus
Ocean Sci., 11, 743–757, https://doi.org/10.5194/os-11-743-2015, https://doi.org/10.5194/os-11-743-2015, 2015
Short summary
Short summary
The Faroe Current is the main ocean current transporting warm Atlantic water into the Arctic region and an important transporter of heat towards the Arctic. This study documents observed transport variations over two decades, from 1993 to 2013. It shows that the volume transport of Atlantic water in this current increased by 9% over the period, whereas the heat transport increased by 18%. This increase will have contributed to the observed warming and sea ice decline in the Arctic.
B. Berx, B. Hansen, S. Østerhus, K. M. Larsen, T. Sherwin, and K. Jochumsen
Ocean Sci., 9, 639–654, https://doi.org/10.5194/os-9-639-2013, https://doi.org/10.5194/os-9-639-2013, 2013
K. A. Mork and Ø. Skagseth
Ocean Sci., 6, 901–911, https://doi.org/10.5194/os-6-901-2010, https://doi.org/10.5194/os-6-901-2010, 2010
Cited articles
Beaird, N. L., Rhines, P. B., and Eriksen, C. C.: Overflow waters at the
Iceland-Faroe Ridge observed in multiyear Seaglider surveys, J. Phys. Oceanogr.,
43, 2334–2351, https://doi.org/10.1175/JPO-D-13-029.1, 2013.
Beaird, N. L., Rhines, P. B., and Eriksen, C. C.: Observations of seasonal
subduction at the Iceland-Faroe Front, J. Geophys. Res.-Oceans, 121, 4026–4040,
https://doi.org/10.1002/2015JC011501, 2016.
Dickson, R. R. and Brown, J.: The production of North Atlantic deep water,
sources, rates, and pathways, J. Geophys. Res., 99, 12319–12341, https://doi.org/10.1029/94JC00530, 1994.
ENVOFAR: ADCP data from the field experiment, Environmental data on terrestrial
and marine ecosystems in the Faroe Islands, available at: ftp://www.envofar.fo/Currents/ADCP_Data/, last access: 15 August 2018.
Hansen, B. and Østerhus, S.: North Atlantic–Nordic Seas exchanges, Prog.
Oceanogr., 45, 109–208, 2000.
Hansen, B., Østerhus, S., Quadfasel, D., and Turrell, W.: Already the day
after tomorrow?, Science, 305, 953–954, 2004.
Hansen, B., Larsen, K. M. H., Hátún, H., Kristiansen, R., Mortensen, E.,
and Østerhus, S.: Transport of volume, heat, and salt towards the Arctic in
the Faroe Current 1993–2013, Ocean Sci., 11, 743–757, https://doi.org/10.5194/os-11-743-2015, 2015.
Hansen, B., Larsen, K. M. H., Hátún, H., and Østerhus, S.: A stable
Faroe Bank Channel overflow 1995–2015, Ocean Sci., 12, 1205–1220, https://doi.org/10.5194/os-12-1205-2016, 2016.
Hansen, B., Larsen, K. M. H., Kristiansen, R., Mortensen, E., Quadfasel, D.,
Jochumsen, K., and Østerhus, S.: Observations from the WOW field experiment
in the Western Valley 2016–2017 Data report, Havstovan nr. 17-03, Technical
report, http://www.hav.fo/PDF/Ritgerdir/2017/TecRep1703.pdf (last access: 8 August 2018), 2017a.
Hansen, B., Larsen, K. M. H., Quadfasel, D., and Jochumsen, K.: Historical
oceanographic observations in the Western Valley Data report, Havstovan nr. 17-02,
Technical report, http://www.hav.fo/PDF/Ritgerdir/2017/TecRep1702.pdf, (last access: 8 August 2018), 2017b.
Hermann, F.: The TS diagram analysis of the water masses over the Iceland–Faroe
Ridge and in the Faroe Bank Channel, Rapp. PV Reun. Cons. Int. Explor. Mer.,
157, 139–149, 1967.
Jakobsen, P. K., Ribergaard, M. H., Quadfasel, D., Schmith, T., and Hughes, C.
W.: Near-surface circulation in the northern North Atlantic as inferred from
Lagrangian drifters: variability from the mesoscale to interannual, J. Geophys.
Res.-Oceans, 108, 3251, https://doi.org/10.1029/2002JC001554, 2003.
Jochumsen, K., Moritz, M., Nunes, N., Quadfasel, D., Larsen, K. M. H., Hansen,
B., Valdimarsson, H., and Jonsson, S.: Revised transport estimates of the
Denmark Strait overflow, J. Geophys. Res.-Oceans, 122, 3434–3450, https://doi.org/10.1002/2017JC012803, 2017.
Knudsen, M.: Den Danske Ingolf-expedition, Bianco Lunos Kgl. Hof-Bogtrykkeri
(F. Dreyer), København, 1, 21–154, 1898.
Koszalka, I., LaCasce, J. H., Andersson, M., Orvik, K. A., and Mauritzen, C.:
Surface circulation in the Nordic Seas from clustered drifters, Deep-Sea
Res. Pt. I, 58, 468–485, https://doi.org/10.1016/j.dsr.2011.01.007, 2011.
Nilsen, J. E., Hátún, H., Mork, K., and Valdimarsson, H.: The NISE
Dataset, Faroese Fisheries Laboratory Technical Report 08-01, http://www.hav.fo/PDF/Ritgerdir/2008/TecRep0801.pdf
(last access: 8 August 2018), 2008.
Nøst, O. A. and Isachsen, P. E.: The large-scale time-mean ocean circulation
in the Nordic Seas and Arctic Ocean estimated from simplified dynamics, J. Mar.
Res., 61, 175–210, 2003.
Olsen, S. M., Hansen, B., Østerhus, S., Quadfasel, D., and Valdimarsson, H.:
Biased thermohaline exchanges with the arctic across the Iceland-Faroe Ridge in
ocean climate models, Ocean Sci., 12, 545–560, https://doi.org/10.5194/os-12-545-2016, 2016.
Østerhus, S., Sherwin, T., Quadfasel,D., and Hansen, B.: The overflow
transport east of Iceland, Chap. 18, in: Arctic-Subarctic Ocean Fluxes: Defining
the Role of the Northern Seas in Climate, edited by: Dickson, R. R., Meincke,
J., and Rhines, P., Springer Science C Business Media B.V., The Netherlands, 427–441, 2008.
Perkins, H., Sherwin, T. J., and Hopkins, T. S.: Amplification of tidal currents
by overflow on the Iceland-Faeroe Ridge, J. Phys. Oceanogr., 24, 721–735, 1994.
Perkins, H., Hopkins, T. S., Malmberg, S. A., Poulain, P. M., and Warn-Varnas,
A.: Oceanographic conditions east of Iceland, J. Geophys. Res.-Oceans,
103, 21531–21542, 1998.
Pyper, B. J. and Peterman, R. M.: Comparison of methods to account for
autocorrelation in correlation analyses of fish data, Can. J. Fish. Aquat. Sci.,
55, 2127–2140, https://doi.org/10.1139/f98-104, 1998.
Quadfasel, D.: Physical oceanography during POSEIDON cruise POS503, Institut für Meereskunde,
Universität Hamburg, PANGAEA, https://doi.org/10.1594/PANGAEA.890699, 2018.
Read, J. F. and Pollard, R. T.: Water masses in the region of the Iceland–Faeroes
Front, J. Phys. Oceanogr., 22, 1365–1378, 1992.
Rossby, T., Prater, M. D., and Søiland, H.: Pathways of inflow and dispersion
of warm waters in the Nordic seas, J. Geophys. Res.-Oceans, 114, C04011,
https://doi.org/10.1029/2008JC005073, 2009.
Sabine, C. L., Feely, R. A., Gruber, N., Key, R. M., Lee, K., Bullister, J. L.,
Wanninkhof, R., Wong, C. S., Wallace, D. W. R., Tilbrook, B., Millero, F. J.,
Peng, T.-H., Kozyr, A., Ono, T., and Rios, A. F.: The oceanic sink for
anthropogenic CO2, Science, 305, 367–371, 2004.
Saunders, P. M.: The dense northern overflows, Chap. 5.6, in: Ocean Circulation
and Climate, edited by: Siedler, G., Church, J., and Gould, J., Academic Press,
London, UK, 401–417, 2001.
Søiland, H., Prater, M. D., and Rossby, T.: Rigid topographic control of
currents in the Nordic Seas, Geophys. Res. Lett., 35, L18607, https://doi.org/10.1029/2008GL034846, 2008.
Voet, G.: On the Nordic Overturning Circulation, Dissertation zur Erlangung des
Doktorgrades der Naturwissenschaften im Fachbereich Geowissenschaften der
Universität Hamburg, Hamburg, 98 pp., 2010.
von Storch, H.: Misuses of Statistical Analysis in Climate Research, Chap. 2,
in: Analysis of Climate Variability, edited by: von Storch, H. and Navarra, A.,
Springer, Berlin, Heidelberg, 11–26, 1999.
Whitehead, J. A.: Topographic control of oceanic flows in deep passages and
straits, Rev. Geophys., 36, 423–440, 1998.
Wilkenskjeld, S. and Quadfasel, D.: Response of the Greenland-Scotland overflow
to changing deep water supply from the Arctic Mediterranean, Geophys. Res. Lett.,
32, L21607, https://doi.org/10.1029/2005GL024140, 2005.
Short summary
The Western Valley is one of the passages across the Iceland–Scotland Ridge through which a strong overflow of cold, dense water has been thought to feed the deep limb of the Atlantic Meridional Overturning Circulation (AMOC), but its strength has not been known. Based on a field experiment with instruments moored across the valley, we show that this overflow branch is much weaker than previously thought and that this is because it is suppressed by the warm countercurrent in the upper layers.
The Western Valley is one of the passages across the Iceland–Scotland Ridge through which a...