Articles | Volume 19, issue 4
https://doi.org/10.5194/os-19-1225-2023
© Author(s) 2023. 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-19-1225-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
16 Aug 2023
Research article |
| 16 Aug 2023
| 16 Aug 2023
The Iceland–Faroe warm-water flow towards the Arctic estimated from satellite altimetry and in situ observations
Bogi Hansen
CORRESPONDING AUTHOR
Environmental Department, Faroe Marine Research Institute, Tórshavn, Faroe Islands
Karin M. H. Larsen
Environmental Department, Faroe Marine Research Institute, Tórshavn, Faroe Islands
Hjálmar Hátún
Environmental Department, Faroe Marine Research Institute, Tórshavn, Faroe Islands
Steffen M. Olsen
Danish Meteorological Institute, Copenhagen, Denmark
Andrea M. U. Gierisch
Danish Meteorological Institute, Copenhagen, Denmark
Svein Østerhus
NORCE Norwegian Research Centre, Bjerknes Centre for Climate
Research, Bergen, Norway
Sólveig R. Ólafsdóttir
Environmental Division, Marine and Freshwater Research Institute, Hafnarfjörður,
Iceland
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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
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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Preprint withdrawn
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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
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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, Karin Margretha Húsgarð Larsen, Steffen Malskær Olsen, Detlef Quadfasel, Kerstin Jochumsen, and Svein Østerhus
Ocean Sci., 14, 871–885, https://doi.org/10.5194/os-14-871-2018, https://doi.org/10.5194/os-14-871-2018, 2018
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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.
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
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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.
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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
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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
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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.
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Moored observations confirm that strong westward ocean surface stress events ("storms'') can increase the speed of the Antarctic Slope Current and the circulation in the Filchner Trough region. Roughly one-third of the identified storm events cause an increased southward current speed on the shelf. This enhances the southward transport of heat already present on the shelf and the likelihood that this heat reaches the ice shelf front before it is lost to the atmosphere during winter.
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Filippa Fransner, Friederike Fröb, Jerry Tjiputra, Nadine Goris, Siv K. Lauvset, Ingunn Skjelvan, Emil Jeansson, Abdirahman Omar, Melissa Chierici, Elizabeth Jones, Agneta Fransson, Sólveig R. Ólafsdóttir, Truls Johannessen, and Are Olsen
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Ocean acidification, a direct consequence of the CO2 release by human activities, is a serious threat to marine ecosystems. In this study, we conduct a detailed investigation of the acidification of the Nordic Seas, from 1850 to 2100, by using a large set of samples taken during research cruises together with numerical model simulations. We estimate the effects of changes in different environmental factors on the rate of acidification and its potential effects on cold-water corals.
Yu Yan, Wei Gu, Andrea M. U. Gierisch, Yingjun Xu, and Petteri Uotila
Geosci. Model Dev., 15, 1269–1288, https://doi.org/10.5194/gmd-15-1269-2022, https://doi.org/10.5194/gmd-15-1269-2022, 2022
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In this study, we developed NEMO-Bohai, an ocean–ice model for the Bohai Sea, China. This study presented the scientific design and technical choices of the parameterizations for the NEMO-Bohai model. The model was calibrated and evaluated with in situ and satellite observations of ocean and sea ice. NEMO-Bohai is intended to be a valuable tool for long-term ocean and ice simulations and climate change studies.
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
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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.
Jon Olafsson, Solveig R. Olafsdottir, Taro Takahashi, Magnus Danielsen, and Thorarinn S. Arnarson
Biogeosciences, 18, 1689–1701, https://doi.org/10.5194/bg-18-1689-2021, https://doi.org/10.5194/bg-18-1689-2021, 2021
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The Atlantic north of 50° N is an intense ocean sink area for atmospheric CO2. Observations in the vicinity of Iceland reveal a previously unrecognized Arctic contribution to the North Atlantic CO2 sink. Sustained CO2 influx to waters flowing from the Arctic Ocean is linked to their excess alkalinity derived from sources in the changing Arctic. The results relate to the following question: will the North Atlantic continue to absorb CO2 in the future as it has in the past?
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
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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.
Coraline Leseurre, Claire Lo Monaco, Gilles Reverdin, Nicolas Metzl, Jonathan Fin, Solveig Olafsdottir, and Virginie Racapé
Biogeosciences, 17, 2553–2577, https://doi.org/10.5194/bg-17-2553-2020, https://doi.org/10.5194/bg-17-2553-2020, 2020
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In this study, we investigate the evolution of CO2 uptake and ocean acidification in the North Atlantic Subpolar surface water. Our results show an important reduction in the capacity of the ocean to absorb CO2 from the atmosphere (1993–2007), due to a rapid increase in the fCO2 and associated with a rapid decrease in pH. Conversely, data obtained during the last decade (2008–2017) show a stagnation of fCO2 (increasing the ocean sink for CO2) and pH.
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Ocean Sci., 15, 379–399, https://doi.org/10.5194/os-15-379-2019, https://doi.org/10.5194/os-15-379-2019, 2019
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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.
Adrienne J. Sutton, Richard A. Feely, Stacy Maenner-Jones, Sylvia Musielwicz, John Osborne, Colin Dietrich, Natalie Monacci, Jessica Cross, Randy Bott, Alex Kozyr, Andreas J. Andersson, Nicholas R. Bates, Wei-Jun Cai, Meghan F. Cronin, Eric H. De Carlo, Burke Hales, Stephan D. Howden, Charity M. Lee, Derek P. Manzello, Michael J. McPhaden, Melissa Meléndez, John B. Mickett, Jan A. Newton, Scott E. Noakes, Jae Hoon Noh, Solveig R. Olafsdottir, Joseph E. Salisbury, Uwe Send, Thomas W. Trull, Douglas C. Vandemark, and Robert A. Weller
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Long-term observations are critical records for distinguishing natural cycles from climate change. We present a data set of 40 surface ocean CO2 and pH time series that suggests the time length necessary to detect a trend in seawater CO2 due to uptake of atmospheric CO2 varies from 8 years in the least variable ocean regions to 41 years in the most variable coastal regions. This data set provides a tool to evaluate natural cycles of ocean CO2, with long-term trends emerging as records lengthen.
Gilles Reverdin, Nicolas Metzl, Solveig Olafsdottir, Virginie Racapé, Taro Takahashi, Marion Benetti, Hedinn Valdimarsson, Alice Benoit-Cattin, Magnus Danielsen, Jonathan Fin, Aicha Naamar, Denis Pierrot, Kevin Sullivan, Francis Bringas, and Gustavo Goni
Earth Syst. Sci. Data, 10, 1901–1924, https://doi.org/10.5194/essd-10-1901-2018, https://doi.org/10.5194/essd-10-1901-2018, 2018
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This paper presents the SURATLANT data set (SURveillance ATLANTique), consisting of individual data of temperature, salinity, parameters of the carbonate system, nutrients, and water stable isotopes (δ18O and δD) collected mostly from ships of opportunity since 1993 along transects between Iceland and Newfoundland. These data are used to quantify the seasonal cycle and can be used to investigate long-term tendencies in the surface ocean, including of pCO2 and pH.
Bogi Hansen, Karin Margretha Húsgarð Larsen, Steffen Malskær Olsen, Detlef Quadfasel, Kerstin Jochumsen, and Svein Østerhus
Ocean Sci., 14, 871–885, https://doi.org/10.5194/os-14-871-2018, https://doi.org/10.5194/os-14-871-2018, 2018
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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.
Mohamed H. Salim, K. Heinke Schlünzen, David Grawe, Marita Boettcher, Andrea M. U. Gierisch, and Björn H. Fock
Geosci. Model Dev., 11, 3427–3445, https://doi.org/10.5194/gmd-11-3427-2018, https://doi.org/10.5194/gmd-11-3427-2018, 2018
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This paper gives a detailed description of the model theory of the obstacle-resolving microscale meteorological model MITRAS version 2. Detailed descriptions of the model equations and their formulations and approximations are presented. Also, detailed parameterizations of buildings, wind turbines, and vegetation in the model are introduced. Some example applications of the model are shown to demonstrate the model capacities and potential.
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
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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
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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.
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
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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.
Adrienne J. Sutton, Christopher L. Sabine, Richard A. Feely, Wei-Jun Cai, Meghan F. Cronin, Michael J. McPhaden, Julio M. Morell, Jan A. Newton, Jae-Hoon Noh, Sólveig R. Ólafsdóttir, Joseph E. Salisbury, Uwe Send, Douglas C. Vandemark, and Robert A. Weller
Biogeosciences, 13, 5065–5083, https://doi.org/10.5194/bg-13-5065-2016, https://doi.org/10.5194/bg-13-5065-2016, 2016
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Ocean carbonate observations from surface buoys reveal that marine life is currently exposed to conditions outside preindustrial bounds at 12 study locations around the world. Seasonal conditions in the California Current Ecosystem and Gulf of Maine also exceed thresholds that may impact shellfish larvae. High-resolution observations place long-term change in the context of large natural variability: a necessary step to understand ocean acidification impacts under real-world conditions.
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
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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
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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
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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.
A. S. A. Ferreira, H. Hátún, F. Counillon, M. R. Payne, and A. W. Visser
Biogeosciences, 12, 3641–3653, https://doi.org/10.5194/bg-12-3641-2015, https://doi.org/10.5194/bg-12-3641-2015, 2015
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Our main objective was to assess which bottom-up processes can best predict changes in phytoplankton surface spring blooms in the North Atlantic. We applied new phenology algorithms to satellite-derived data and compared four different metrics based on physical drivers of phytoplankton. We show that there is a dominant physical mechanism - mixed layer shoaling - and that different regions are governed by different physical phenomena.
E. Jeansson, R. G. J. Bellerby, I. Skjelvan, H. Frigstad, S. R. Ólafsdóttir, and J. Olafsson
Biogeosciences, 12, 875–885, https://doi.org/10.5194/bg-12-875-2015, https://doi.org/10.5194/bg-12-875-2015, 2015
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Long-term mean monthly fluxes of carbon and nutrients to the surface layer of the Iceland Sea are presented. From these fluxes we estimate primary production based on newly added nitrate (i.e. new production) and net community production (NCP). The annual new production in the Iceland Sea is estimated to 0.45±0.09mol N/m2/yr, and the net annual NCP to 7.3±1.0mol C/m2/yr. The typical C:N ratio during biological uptake is 9.0, challenging the Redfield C:N as the conversion factor in the area.
V. Racapé, N. Metzl, C. Pierre, G. Reverdin, P. D. Quay, and S. R. Olafsdottir
Biogeosciences, 11, 1683–1692, https://doi.org/10.5194/bg-11-1683-2014, https://doi.org/10.5194/bg-11-1683-2014, 2014
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 | Properties and processes: Overturning circulation, gyres and water masses
Seasonality of meridional overturning in the subpolar North Atlantic: implications for relying on the streamfunction maximum as a metric of AMOC slowdown
Hydrographic section along 55° E in the Indian and Southern oceans
On Mode Water formation and erosion in the Arabian Sea: Forcing mechanisms, regionality, and seasonality
Circulation of Baffin Bay and Hudson Bay waters on the Labrador shelf and into the subpolar North Atlantic
Mechanisms of the Overturning Circulation in the Northern Red Sea, more than Convective Mixing
Continued warming of deep waters in the Fram Strait
Observed change and the extent of coherence in the Gulf Stream system
Anomalous North Pacific subtropical mode water volume and density decrease in a recent stable Kuroshio Extension period from Argo observations
New insights into the eastern subpolar North Atlantic meridional overturning circulation from OVIDE
The Southern Ocean deep mixing band emerges from a competition between winter buoyancy loss and upper stratification strength
Comparing observed and modelled components of the Atlantic Meridional Overturning Circulation at 26° N
Water properties and bottom water patterns in hadal trench environments
Long-term eddy modulation affects the meridional asymmetry of the halocline in the Beaufort Gyre
Technical note: Determining Arctic Ocean halocline and cold halostad depths based on vertical stability
Alan D. Fox, Neil J. Fraser, and Stuart A. Cunningham
EGUsphere, https://doi.org/10.5194/egusphere-2025-616, https://doi.org/10.5194/egusphere-2025-616, 2025
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Understanding seasonality of the overturning circulation is important for mitigating the impacts of AMOC changes on European weather and climate. We examine the seasonal cycle in various common measures of overturning and find each to be dominated by different processes, not necessarily reflective of the processes driving overturning. We advocate for the use of a density flux measure as a valuable addition to AMOC monitoring.
Katsuro Katsumata, Shigeru Aoki, Kay I. Ohshima, and Michiyo Yamamoto-Kawai
Ocean Sci., 21, 419–436, https://doi.org/10.5194/os-21-419-2025, https://doi.org/10.5194/os-21-419-2025, 2025
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Ship-based observations provide data of seawater properties like temperature, salinity, nutrients, and various gases, but some important world oceans have still not been covered. A voyage in 2019/20 in the southwest Indian Ocean along approximately 55° E from 30° S to Antarctica attempted to fill one such data-sparse region. The measured cross section of the Antarctic Circumpolar Current and accompanying eddies demonstrates various oceanic behaviours including fronts and eddy mixing.
Estel Font, Sebastiaan Swart, Puthenveettil Narayana Vinayachandran, and Bastien Y. Queste
EGUsphere, https://doi.org/10.5194/egusphere-2025-468, https://doi.org/10.5194/egusphere-2025-468, 2025
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Mode water is formed annually and sits between the warm surface water and deeper older waters. In the Arabian Sea, it plays a crucial role in regulating ocean heat and oxygen variability by acting as a doorway between the surface and deeper waters. Using observations and models, we show its formation is primarily driven by atmospheric forcing, though ocean currents, eddies, and biological heating also influence its life cycle. This water mass contributes up to 30% to the region's oxygen content.
Elodie Duyck, Nicholas P. Foukal, and Eleanor Frajka-Williams
Ocean Sci., 21, 241–260, https://doi.org/10.5194/os-21-241-2025, https://doi.org/10.5194/os-21-241-2025, 2025
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This study uses drifters – instruments that follow surface ocean currents – to investigate the pathways of Arctic origin waters that enter the North Atlantic west of Greenland. It shows that these waters remain close to the coast as they flow over the Labrador shelf and only spread into the open ocean south of the Labrador Sea. These results contribute to better understanding how the North Atlantic will be affected by additional freshwater from Greenland and the Arctic in the coming decades.
Lina Eyouni, Zoi Kokkini, Nikolaos D. Zarokanellos, and Burton H. Jones
EGUsphere, https://doi.org/10.5194/egusphere-2024-3319, https://doi.org/10.5194/egusphere-2024-3319, 2024
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This study examines how multiple processes in the Northern Red Sea form the Red Sea Outflow Water and affect biogeochemical fluxes. Using glider data, wind and air-sea flux reanalysis, and satellite observations, it highlights seasonal evolution. Eddy-driven upwelling exposes cool water to heat loss and evaporation, fueling primary productivity. Circulation patterns block inflows, extend cooling, and subduct water into the ocean interior, influencing regional dynamics.
Salar Karam, Céline Heuzé, Mario Hoppmann, and Laura de Steur
Ocean Sci., 20, 917–930, https://doi.org/10.5194/os-20-917-2024, https://doi.org/10.5194/os-20-917-2024, 2024
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A long-term mooring array in the Fram Strait allows for an evaluation of decadal trends in temperature in this major oceanic gateway into the Arctic. Since the 1980s, the deep waters of the Greenland Sea and the Eurasian Basin of the Arctic have warmed rapidly at a rate of 0.11°C and 0.05°C per decade, respectively, at a depth of 2500 m. We show that the temperatures of the two basins converged around 2017 and that the deep waters of the Greenland Sea are now a heat source for the Arctic Ocean.
Helene Asbjørnsen, Tor Eldevik, Johanne Skrefsrud, Helen L. Johnson, and Alejandra Sanchez-Franks
Ocean Sci., 20, 799–816, https://doi.org/10.5194/os-20-799-2024, https://doi.org/10.5194/os-20-799-2024, 2024
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The Gulf Stream system is essential for northward ocean heat transport. Here, we use observations along the path of the extended Gulf Stream system and an observationally constrained ocean model to investigate variability in the Gulf Stream system since the 1990s. We find regional differences in the variability between the subtropical, subpolar, and Nordic Seas regions, which warrants caution in using observational records at a single latitude to infer large-scale circulation change.
Jing Sheng, Cong Liu, Yanzhen Gu, Peiliang Li, Fangguo Zhai, and Ning Zhou
Ocean Sci., 20, 817–834, https://doi.org/10.5194/os-20-817-2024, https://doi.org/10.5194/os-20-817-2024, 2024
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The homogeneous water column, named mode water, retains atmosphere conditions and biogeochemical elements from the deep winter mixed layer and became weaker and warmer in the North Pacific subtropical ocean in 2018–2021 even though the Kuroshio Extension was stable. Locally anomalous east wind transporting warm water to the north and enhanced near-surface stratification hinder the deepening of the winter mixed layer. This study has broad implications for climate change and biogeochemical cycles.
Herlé Mercier, Damien Desbruyères, Pascale Lherminier, Antón Velo, Lidia Carracedo, Marcos Fontela, and Fiz F. Pérez
Ocean Sci., 20, 779–797, https://doi.org/10.5194/os-20-779-2024, https://doi.org/10.5194/os-20-779-2024, 2024
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We study the Atlantic Meridional Overturning Circulation (AMOC) measured between Greenland and Portugal between 1993–2021. We identify changes in AMOC limb volume and velocity as two major drivers of AMOC variability at subpolar latitudes. Volume variations dominate on the seasonal timescale, while velocity variations are more important on the decadal timescale. This decomposition proves useful for understanding the origin of the differences between AMOC time series from different analyses.
Romain Caneill, Fabien Roquet, and Jonas Nycander
Ocean Sci., 20, 601–619, https://doi.org/10.5194/os-20-601-2024, https://doi.org/10.5194/os-20-601-2024, 2024
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In winter, heat loss increases density at the surface of the Southern Ocean. This increase in density creates a mixed layer deeper than 250 m only in a narrow deep mixing band (DMB) located around 50° S. North of the DMB, the stratification is too strong to be eroded, so mixed layers are shallower. The density of cold water is almost not impacted by temperature changes. Thus, heat loss does not significantly increase the density south of the DMB, so no deep mixed layers are produced.
Harry Bryden, Jordi Beunk, Sybren Drijfhout, Wilco Hazeleger, and Jennifer Mecking
Ocean Sci., 20, 589–599, https://doi.org/10.5194/os-20-589-2024, https://doi.org/10.5194/os-20-589-2024, 2024
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There is widespread interest in whether the Gulf Stream will decline under global warming. We analyse 19 coupled climate model projections of the AMOC over the 21st century. The model consensus is that the AMOC will decline by about 40 % due to reductions in northward Gulf Stream transport and southward deep western boundary current transport. Whilst the wind-driven Gulf Stream decreases by 4 Sv, most of the decrease in the Gulf Stream is due to a reduction of 7 Sv in its thermohaline component.
Jessica Kolbusz, Jan Zika, Charitha Pattiaratchi, and Alan Jamieson
Ocean Sci., 20, 123–140, https://doi.org/10.5194/os-20-123-2024, https://doi.org/10.5194/os-20-123-2024, 2024
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We collected observations of the ocean environment at depths over 6000 m in the Southern Ocean, Indian Ocean, and western Pacific using sensor-equipped landers. We found that trench locations impact the water characteristics over these depths. Moving northward, they generally warmed but differed due to their position along bottom water circulation paths. These insights stress the importance of further research in understanding the environment of these deep regions and their importance.
Jinling Lu, Ling Du, and Shuhao Tao
Ocean Sci., 19, 1773–1789, https://doi.org/10.5194/os-19-1773-2023, https://doi.org/10.5194/os-19-1773-2023, 2023
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With the recent developments in observations and reanalysis data in the Beaufort Gyre, we investigate an improved understanding of eddy activity and asymmetrical halocline variability in the upper ocean. The halocline structures on the southern and northern sides of the central gyre have tended to be identical since 2014. The results suggest that enhanced eddy modulation through eddy fluxes influences oceanic stratification, resulting in reduced meridional asymmetry of the halocline.
Enrico P. Metzner and Marc Salzmann
Ocean Sci., 19, 1453–1464, https://doi.org/10.5194/os-19-1453-2023, https://doi.org/10.5194/os-19-1453-2023, 2023
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The Arctic Ocean cold halocline separates the cold surface mixed layer from the underlying warm Atlantic Water, and thus provides a precondition for sea ice formation. Here, we introduce a new method for detecting the halocline base and compare it to two existing methods. We show that the largest differences between the methods are found in the regions that are most prone to a halocline retreat in a warming climate, and we discuss the advantages and disadvantages of the three methods.
Cited articles
Arias, P. A., Bellouin, N., Coppola, E., Jones, R. G., Krinner, G., Marotzke, J., Naik, V., Palmer, M. D., Plattner, G.-K., Rogelj, J., Rojas, M., Sillmann, J., Storelvmo, T., Thorne, P. W., Trewin, B., Achuta Rao, K., Adhikary, B., Allan, R. P., Armour, K., Bala, G., Barimalala, R., Berger, S., Canadell, J. G., Cassou, C., Cherchi, A., Collins, W., Collins, W. D., Connors, S. L., Corti, S., Cruz, F., Dentener, F. J., Dereczynski, C., Di Luca, A., Diongue Niang, A., Doblas-Reyes, F. J., Dosio, A., Douville, H., Engelbrecht, F., Eyring, V., Fischer, E., Forster, P., Fox-Kemper, B., Fuglestvedt, J. S., Fyfe, J. C., Gillett, N. P., Goldfarb, L., Gorodetskaya, I., Gutierrez, J. M., Hamdi, R., Hawkins, E., Hewitt, H. T., Hope, P., Islam, A. S., Jones, C., Kaufman, D. S., Kopp, R. E., Kosaka, Y., Kossin, J., Krakovska, S., Lee, J.-Y., Li, J., Mauritsen, T., Maycock, T. K., Meinshausen, M., Min, S.-K., Monteiro, P. M. S., Ngo-Duc, T., Otto, F., Pinto, I., Pirani, A., Raghavan, K., Ranasinghe, R., Ruane, A. C., Ruiz, L., Sallée, J.-B., Samset, B. H., Sathyendranath, S., Seneviratne, S. I., Sörensson, A. A., Szopa, S., Takayabu, I., Tréguier, A.-M., van den Hurk, B., Vautard, R., von Schuckmann, K., Zaehle, S., Zhang, X., and Zickfeld, K.: Technical Summary, in: Climate Change 2021: The
Physical Science Basis. Contribution of Working Group I to the Sixth
Assessment Report of the Intergovernmental Panel on Climate Change, edited
by: Masson-Delmotte, V., Zhai, P., Pirani, A., Connors, S. L., Péan, C., Berger, S., Caud, N., Chen, Y., Goldfarb, Z., Gomis, M. I., Huang, M., Leitzell, K., Lonnoy, E., Matthews, J. B. R., Maycock, T. K., Waterfield, T., Yelekçi, O., Yu, R., and Zhou, B., Cambridge University Press, Cambridge, United
Kingdom and New York, NY, USA, 33–144,
https://doi.org/10.1017/9781009157896.002, 2021.
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.
Berx, B., Hansen, B., Østerhus, S., Larsen, K. M., Sherwin, T., and Jochumsen, K.: Combining in situ measurements and altimetry to estimate volume, heat and salt transport variability through the Faroe–Shetland Channel, Ocean Sci., 9, 639–654, https://doi.org/10.5194/os-9-639-2013, 2013.
Darelius, E., Fer, I., and Quadfasel, D.: Faroe Bank Channel overflow:
mesoscale variability, J. Phys. Oceanogr., 41, 2137–2154,
https://doi.org/10.1175/JPO-D-11-035.1, 2011.
Darelius, E., Fer, I., Rasmussen, T., Guo, C., and Larsen, K. M. H.: On the modulation of the periodicity of the Faroe Bank Channel overflow instabilities, Ocean Sci., 11, 855–871, https://doi.org/10.5194/os-11-855-2015, 2015.
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: ENVOFAR, http://www.envofar.fo, last access: 10 August 2023.
Geyer, F., Østerhus, S., Hansen, B., and Quadfasel, D.: Observations of
highly regular oscillations in the overflow plume downstream of the Faroe
Bank Channel, J. Geophys. Res., 111, C12020,
https://doi.org/10.1029/2006JC003693, 2006.
Hansen, B. and Meincke, J.: Eddies and meanders in the Iceland-Faroe Ridge
area, Deep-Sea Res, 26, 1067–1082,
https://doi.org/10.1016/0198-0149(79)90048-7, 1979.
Hansen, B. and Østerhus, S.: North Atlantic–Nordic Seas exchanges, Prog.
Oceanogr., 45, 109–208, https://doi.org/10.1016/s0079-6611(99)00052-x,
2000.
Hansen, B., Østerhus, S., Hátún, H., Kristiansen, R., and Larsen,
K. M. H.: The Iceland-Faroe inflow of Atlantic water to the Nordic Seas,
Prog. Oceanogr., 59, 4, 443–474,
https://doi.org/10.1016/j.pocean.2003.10.003, 2003.
Hansen, B., Hátún, H., Kristiansen, R., Olsen, S. M., and Østerhus, S.: Stability and forcing of the Iceland-Faroe inflow of water, heat, and salt to the Arctic, Ocean Sci., 6, 1013–1026, https://doi.org/10.5194/os-6-1013-2010, 2010.
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., 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: 27 June 2023), 2017.
Hansen, B., Larsen, K. M. H., Olsen, S. M., Quadfasel, D., Jochumsen, K., and Østerhus, S.: Overflow of cold water across the Iceland–Faroe Ridge through the Western Valley, Ocean Sci., 14, 871–885, https://doi.org/10.5194/os-14-871-2018, 2018.
Hansen, B., Larsen, K. M. H., and Hátún, H.: Monitoring the velocity
structure of the Faroe Current, Havstovan Technical Report Nr.: 19-01,
http://www.hav.fo/PDF/Ritgerdir/2019/TechRep1901.pdf (last access: 27 June 2023), 2019.
Hansen, B., Larsen, K. M. H., Hátún, H., and Østerhus, S.:
Atlantic water extent on the Faroe Current monitoring section, Havstovan
Technical Report Nr.: 20-03,
http://www.hav.fo/PDF/Ritgerdir/2020/TechRep2003.pdf (last access: 27 June 2023), 2020.
Hátún, H., Hansen, B., and Haugan, P.: Using an ”inverse dynamic
method” to determine temperature and salinity fields from ADCP
measurements, J. Atmos. Ocean. Tech., 21, 527–534,
https://doi.org/10.1175/1520-0426(2004)021<0527:UAIDMT>2.0.CO;2, 2004.
Helland-Hansen, B. and Nansen, F.: The Norwegian Sea, its physical
oceanography. Based on the Norwegian researches 1900–1904, Report on
Norwegian fishery and marine-investigations Vol. 11 1909 No.2, 390 pp. +
325 plates, https://imr.brage.unit.no/imr-xmlui/handle/11250/114874 (last access: 10 August 2023), 1909.
Hermann, F.: Hydrographic Conditions in the South-Western Part of the
Norwegian Sea, Ann. Biol. Cons. Int. Explor. Mer., 5, 19–21, 1949.
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.
Heuzé, C. and Årthun, M.: The Atlantic inflow across the
Greenland-Scotland ridge in global climate models (CMIP5), Elem. Sci. Anth.,
7, 16, https://doi.org/10.1525/elementa.354, 2019.
Jónsson, S. and Valdimarsson, H.: Water mass transport variability to
the North Icelandic shelf, 1994–2010, ICES J. Mar. Sci., 69, 809–815,
https://doi.org/10.1093/icesjms/fss024, 2012.
Knudsen, M.: Den Danske Ingolf-expedition, Bianco Lunos Kgl. Hof-Bogtrykkeri
(F. Dreyer), København, 1, 21–154, 1898.
Koman, G., Johns, W. E., Houk, A., Houpert, L., and Li, F.: Circulation and
overturning in the eastern North Atlantic subpolar gyre, Prog. Oceanogr.,
208, 102884, https://doi.org/10.1016/j.pocean.2022.102884, 2022.
Larsen, K. M. H., Hátún, H., Hansen, B., and Kristiansen, R.:
Atlantic water in the Faroe area: sources and variability, ICES J. Mar.
Sci., 69, 802–808, https://doi.org/10.1093/icesjms/fss028, 2012.
Logemann, K., Ólafsson, J., Snorrason, Á., Valdimarsson, H., and Marteinsdóttir, G.: The circulation of Icelandic waters – a modelling study, Ocean Sci., 9, 931–955, https://doi.org/10.5194/os-9-931-2013, 2013.
Lozier, M. S., Li, F., Bacon, S., Bahr, F., Bower, A. S., Cunningham, S. A.,
de Jong, M. F., de Steur, L., deYoung, B., Fischer, J., Gary, S. F.,
Greenan, B. J. W., Holliday, N. P., Houk, A., Houpert, L., Inall, M. E.,
Johns, W. E., Johnson, H. L., Johnson, C., Karstensen, J., Koman, G., Le
Bras, I. A., Lin, X., Mackay, N., Marshall, D. P., Mercier, H., Oltmanns,
M., Pickart, R. S., Ramsey, A. L., Rayner, D., Straneo, F., Thierry, V.,
Torres, D. J., Williams, R. G., Wilson, C., Yang, J., Yashayaev, I., and
Zhao, J.: A sea change in our view of overturning in the subpolar North
Atlantic, Science, 363, 516–521, https://doi.org/10.1126/science.aau6592,
2019.
Mayer, M., Tsubouchi, T., Winkelbauer, S., Larsen, K. M. H., Berx, B.,
Macrander, A., Iovino, D., Jónsson, S., and Renshaw, R.: Recent
variations in oceanic transports across the Greenland-Scotland Ridge,
Copernicus Ocean State Report, 7, J.
Oper. Oceanogr., accepted, 2023.
McCartney, M. S. and Talley, L. D.: Warm-to-Cold Water Conversion in the
Northern North Atlantic Ocean, J. Phys. Oceanogr., 14, 922–935,
https://doi.org/10.1175/1520-0485(1984)014<0922:WTCWCI>2.0.CO;2, 1984.
Meincke, J.: The Hydrographic Section along the Iceland-Faroe Ridge carried
out by R.V. “Anton Dohrn” in 1959–1971, Ber. Dt. Wiss. Kommiss.
Meeresforsch., 22, 372—384, 1972.
Meincke, J.: On the distribution of low salinity intermediate waters around
the Faroes, Deutsche Hydrographische Zeitschrift, 31, 50–64,
https://doi.org/10.1007/bf02226000, 1978.
Meincke, J.: The Modern Current Regime Across the Greenland-Scotland Ridge,
in: Structure and Development of the Greenland-Scotland Ridge, edited by:
Bott, M. H. P., Saxov, S., Talwani, M., and Thiede, J., NATO Conference
Series (IV Marine Science), 8, Springer, Boston, MA, 637–650,
https://doi.org/10.1007/978-1-4613-3485-9_31, 1983.
Melnikov, S. P. and Popov, V. I.: The Distribution and Specific Features of
the Biology of Deepwater Redfish Sebastes mentella (Scorpaenidae) During
Mating in the Pelagial of the Northern Atlantic, J. Ichthyol., 2009,
300–312, https://doi.org/10.1134/S0032945209040031, 2009.
Moat, B. I., Smeed, D. A., Frajka-Williams, E., Desbruyères, D. G., Beaulieu, C., Johns, W. E., Rayner, D., Sanchez-Franks, A., Baringer, M. O., Volkov, D., Jackson, L. C., and Bryden, H. L.: Pending recovery in the strength of the meridional overturning circulation at 26° N, Ocean Sci., 16, 863–874, https://doi.org/10.5194/os-16-863-2020, 2020.
Mulet, S., Rio, M.-H., Etienne, H., Artana, C., Cancet, M., Dibarboure, G., Feng, H., Husson, R., Picot, N., Provost, C., and Strub, P. T.: The new CNES-CLS18 global mean dynamic topography, Ocean Sci., 17, 789–808, https://doi.org/10.5194/os-17-789-2021, 2021.
Nielsen, J. N.: Hydrography of the waters by the Faroe Islands and Iceland
during the cruises of the danish research steamer “Thor” in the summer 1903,
Medd. Komm. f. Havunders. Serie Hydrogr., Bind I Nr. 4, 42 pp., 1904.
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.
Orvik, K. A. and Niiler, P.: Major pathways of Atlantic water in the
northern North Atlantic and Nordic Seas toward Arctic, Geophys. Res. Lett.,
29, 1896, https://doi.org/10.1029/2002GL015002, 2002.
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.,
427–441, https://doi.org/10.1007/978-1-4020-6774-7_19, 2008.
Østerhus, S., Woodgate, R., Valdimarsson, H., Turrell, B., de Steur, L., Quadfasel, D., Olsen, S. M., Moritz, M., Lee, C. M., Larsen, K. M. H., Jónsson, S., Johnson, C., Jochumsen, K., Hansen, B., Curry, B., Cunningham, S., and Berx, B.: Arctic Mediterranean exchanges: a consistent volume budget and trends in transports from two decades of observations, Ocean Sci., 15, 379–399, https://doi.org/10.5194/os-15-379-2019, 2019.
Pacariz, S. V., Hátún, H., Jacobsen, J. A., Johnson, C., Eliasen,
S., and Rey, F.: Nutrient-driven poleward expansion of the Northeast
Atlantic mackerel (Scomber scombrus) stock: A new hypothesis, Elem. Sci.
Anth., 4, 105, https://doi.org/10.12952/journal.elementa.000105, 2016.
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, https://doi.org/10.1029/98JC00890,
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.
Rio, M. H., Guinehut, S., and Larnicol, G.: New CNES-CLS09 global mean
dynamic topography computed from the combination of GRACE data, altimetry,
and in situ measurements, J. Geophys. Res., 116,
C07018, https://doi.org/10.1029/2010JC006505, 2011.
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.
Rossby, T., Flagg, C., Chafik, L., Harden, B., and Søiland, H.: A Direct
Estimate of Volume, Heat, and Freshwater Exchange Across the
Greenland-Iceland-Faroe-Scotland Ridge, J. Geophys. Res.-Oceans, 123,
7139–7153, https://doi.org/10.1029/2018jc014250, 2018.
Sarafanov, A., Falina, A., Mercier, H., Sokov, A., Lherminier, P., Gourcuff,
C., Gladyshev, S., Gaillard, F., and Daniault, N.: Mean full-depth summer
circulation and transports at the northern periphery of the Atlantic Ocean
in the 2000s, J. Geophys. Res., 117, C01014,
https://doi.org/10.1029/2011JC007572, 2012.
Smeed, D. A., McCarthy, G. D., Cunningham, S. A., Frajka-Williams, E., Rayner, D., Johns, W. E., Meinen, C. S., Baringer, M. O., Moat, B. I., Duchez, A., and Bryden, H. L.: Observed decline of the Atlantic meridional overturning circulation 2004–2012, Ocean Sci., 10, 29–38, https://doi.org/10.5194/os-10-29-2014, 2014.
Smeed, D. A., Josey, S. A., Beaulieu, C., Johns, W. E., Moat, B. I.,
Frajka-Williams, E., Rayner, D., Meinen, C. S., Baringer, M. O., Bryden, H.
L., and McCarthy, G. D.: The North Atlantic Ocean Is in a State of Reduced
Overturning, Geophys. Res. Lett., 45, 1527–1533,
https://doi.org/10.1002/2017gl076350, 2018.
Tait, J. B., Lee, A. J., Stefansson, U., and Hermann, F.: Temperature and
salinity distributions and water-masses of the region, Rapp. PV Reun. Cons.
Int. Explor. Mer., 157, 38–149, 1967.
Tsubouchi, T., Våge, K., Hansen, B., Larsen, K. M. H., Østerhus, S.,
Johnson, C., Joìnsson, S., and Valdimarsson, H.: Increased ocean heat
transport into the Nordic Seas and Arctic Ocean over the period 1993–2016,
Nat. Clim. Change, 11, 21–26, https://doi.org/10.1038/s41558-020-00941-3,
2021.
Ullgren, J. E., Darelius, E., and Fer, I.: Volume transport and mixing of the Faroe Bank Channel overflow from one year of moored measurements, Ocean Sci., 12, 451–470, https://doi.org/10.5194/os-12-451-2016, 2016.
Voet, G.: On the Nordic Overturning Circulation, Dissertation zur Erlangung
des Doktorgrades der Naturwissenschaften im Fachbereich Geowissenschaften
der Universität Hamburg, Hamburg, https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=a39f14525c76072f3b4f93fc56b32aaa4b8bd06f (last access: 14 August 2023), 98 pp., 2010.
von Storch, H.: Misuses of Statistical Analysis in Climate Research, in:
Analysis of Climate Variability, edited by: von Storch, H. and Navarra, A.,
Springer, Berlin, Heidelberg,
https://doi.org/10.1007/978-3-662-03744-7_2, 1999.
Worthington, E. L., Moat, B. I., Smeed, D. A., Mecking, J. V., Marsh, R., and McCarthy, G. D.: A 30-year reconstruction of the Atlantic meridional overturning circulation shows no decline, Ocean Sci., 17, 285–299, https://doi.org/10.5194/os-17-285-2021, 2021.
Worthington, L. V.: The Norwegian Sea as a mediterranean basin, Deep-Sea
Res. Pt. I, 17, 77–84, https://doi.org/10.1016/0011-7471(70)90088-4, 1970.
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.
Based on in situ observations combined with sea level anomaly (SLA) data from satellite...
