Articles | Volume 19, issue 1
https://doi.org/10.5194/os-19-169-2023
© 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-19-169-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
22 Feb 2023
Research article |
| 22 Feb 2023
| 22 Feb 2023
Observation-based estimates of volume, heat, and freshwater exchanges between the subpolar North Atlantic interior, its boundary currents, and the atmosphere
Sam C. Jones
CORRESPONDING AUTHOR
Scottish Association for Marine Science, Oban, UK
Neil J. Fraser
Scottish Association for Marine Science, Oban, UK
Stuart A. Cunningham
Scottish Association for Marine Science, Oban, UK
Alan D. Fox
Scottish Association for Marine Science, Oban, UK
Mark E. Inall
Scottish Association for Marine Science, Oban, UK
Related authors
Kristin Burmeister, Neil James Fraser, Sam C. Jones, Stuart A. Cunningham, Lewis A. Drysdale, Mark E. Inall, Tiago S. Dotto, and N. Penny Holliday
EGUsphere, https://doi.org/10.5194/egusphere-2025-3167, https://doi.org/10.5194/egusphere-2025-3167, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
The Rockall Trough carries key ocean currents that affect Europe’s climate and seas. Researchers combined data from underwater sensors and robotic gliders to track water, heat, and freshwater flow from 2014 to 2022. They created a new method to merge this data, producing the first long-term record of one important current. This improves ocean monitoring and helps us better understand climate-related changes.
Alan D. Fox, Neil J. Fraser, and Stuart A. Cunningham
Ocean Sci., 21, 1735–1760, https://doi.org/10.5194/os-21-1735-2025, https://doi.org/10.5194/os-21-1735-2025, 2025
Short summary
Short summary
Understanding the seasonality of the overturning circulation is important for mitigating the impacts of Atlantic meridional overturning circulation (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 understanding AMOC.
Kristin Burmeister, Neil James Fraser, Sam C. Jones, Stuart A. Cunningham, Lewis A. Drysdale, Mark E. Inall, Tiago S. Dotto, and N. Penny Holliday
EGUsphere, https://doi.org/10.5194/egusphere-2025-3167, https://doi.org/10.5194/egusphere-2025-3167, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
The Rockall Trough carries key ocean currents that affect Europe’s climate and seas. Researchers combined data from underwater sensors and robotic gliders to track water, heat, and freshwater flow from 2014 to 2022. They created a new method to merge this data, producing the first long-term record of one important current. This improves ocean monitoring and helps us better understand climate-related changes.
Donald Alexander Slater, Eleanor Johnstone, Martim Mas e Braga, Neil Fraser, Tom Cowton, and Mark Inall
EGUsphere, https://doi.org/10.5194/egusphere-2024-3934, https://doi.org/10.5194/egusphere-2024-3934, 2025
Short summary
Short summary
Glacial fjords connect ice sheets to the ocean, controlling heat delivery to glaciers, which impacts ice sheet melt, and freshwater discharge to the ocean, affecting ocean circulation. However, their dynamics are not captured in large-scale climate models. We designed a simplified, computationally efficient model – FjordRPM – which accurately captures key fjord processes. It has direct applications for improving projections of ice melt, ocean circulation and sea-level rise.
Kristin Burmeister, Franziska U. Schwarzkopf, Willi Rath, Arne Biastoch, Peter Brandt, Joke F. Lübbecke, and Mark Inall
Ocean Sci., 20, 307–339, https://doi.org/10.5194/os-20-307-2024, https://doi.org/10.5194/os-20-307-2024, 2024
Short summary
Short summary
We apply two different forcing products to a high-resolution ocean model to investigate their impact on the simulated upper-current field in the tropical Atlantic. Where possible, we compare the simulated results to long-term observations. We find large discrepancies between the two simulations regarding the wind and current fields. We propose that long-term observations, once they have reached a critical length, need to be used to test the quality of wind-driven simulations.
Alan D. Fox, Patricia Handmann, Christina Schmidt, Neil Fraser, Siren Rühs, Alejandra Sanchez-Franks, Torge Martin, Marilena Oltmanns, Clare Johnson, Willi Rath, N. Penny Holliday, Arne Biastoch, Stuart A. Cunningham, and Igor Yashayaev
Ocean Sci., 18, 1507–1533, https://doi.org/10.5194/os-18-1507-2022, https://doi.org/10.5194/os-18-1507-2022, 2022
Short summary
Short summary
Observations of the eastern subpolar North Atlantic in the 2010s show exceptional freshening and cooling of the upper ocean, peaking in 2016 with the lowest salinities recorded for 120 years. Using results from a high-resolution ocean model, supported by observations, we propose that the leading cause is reduced surface cooling over the preceding decade in the Labrador Sea, leading to increased outflow of less dense water and so to freshening and cooling of the eastern subpolar North Atlantic.
Benjamin R. Loveday, Timothy Smyth, Anıl Akpinar, Tom Hull, Mark E. Inall, Jan Kaiser, Bastien Y. Queste, Matt Tobermann, Charlotte A. J. Williams, and Matthew R. Palmer
Earth Syst. Sci. Data, 14, 3997–4016, https://doi.org/10.5194/essd-14-3997-2022, https://doi.org/10.5194/essd-14-3997-2022, 2022
Short summary
Short summary
Using a new approach to combine autonomous underwater glider data and satellite Earth observations, we have generated a 19-month time series of North Sea net primary productivity – the rate at which phytoplankton absorbs carbon dioxide minus that lost through respiration. This time series, which spans 13 gliders, allows for new investigations into small-scale, high-frequency variability in the biogeochemical processes that underpin the carbon cycle and coastal marine ecosystems in shelf seas.
Tillys Petit, M. Susan Lozier, Simon A. Josey, and Stuart A. Cunningham
Ocean Sci., 17, 1353–1365, https://doi.org/10.5194/os-17-1353-2021, https://doi.org/10.5194/os-17-1353-2021, 2021
Short summary
Short summary
Recent work has highlighted the dominant role of the Irminger and Iceland basins in the production of North Atlantic Deep Water. From our analysis, we find that air–sea fluxes and the ocean surface density field are both key determinants of the buoyancy-driven transformation in the Iceland Basin. However, the spatial distribution of the subpolar mode water (SPMW) transformation is most sensitive to surface density changes as opposed to the direct influence of the air–sea fluxes.
Cited articles
Barnier, B., Madec, G., Penduff, T., Molines, J.M., Treguier, A.M., Le
Sommer, J., Beckmann, A., Biastoch, A., Böning, C., Dengg, J., and
Derval, C.: Impact of partial steps and momentum advection schemes in a
global ocean circulation model at eddy-permitting resolution, Ocean
Dynam., 56, 543–567, https://doi.org/10.1007/s10236-006-0082-1, 2006.
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.
Biastoch, A., Schwarzkopf, F. U., Getzlaff, K., Rühs, S., Martin, T., Scheinert, M., Schulzki, T., Handmann, P., Hummels, R., and Böning, C. W.: Regional imprints of changes in the Atlantic Meridional Overturning Circulation in the eddy-rich ocean model VIKING20X, Ocean Sci., 17, 1177–1211, https://doi.org/10.5194/os-17-1177-2021, 2021.
Boyer, T. P., Baranova, O. K., Coleman, C., Garcia, H. E., Grodsky, A., Locarnini, R. A., Mishonov, A. V., Paver, C.R., Reagan, J. R., Seidov, D., Smolyar, I. V., Weathers, K., and Zweng, M. M.: World Ocean Database 2018, NOAA Atlas NESDIS 87 [data set], https://www.ncei.noaa.gov/access/world-ocean-database-select/dbsearch.html (last access: 3 September 2019), 2018.
Brambilla, E. and Talley, L. D.: Subpolar Mode Water in the northeastern
Atlantic: 1. Averaged properties and mean circulation, J. Geophys. Res.-Oceans, 113, C04025, doi:10.1029/2006JC004062, 2008.
Brambilla, E., Talley, L. D., and Robbins, P. E.: Subpolar mode water in the
northeastern Atlantic: 2. Origin and transformation, J. Geophys. Res.-Oceans, 113, C04026, doi:10.1029/2006JC004063, 2008.
Brüggemann, N. and Katsman, C. A.: Dynamics of downwelling in an eddying
marginal sea: Contrasting the Eulerian and the isopycnal perspective, J.
Phys. Oceanogr., 49, 3017–3035, https://doi.org/10.1175/JPO-D-19-0090.1, 2019.
Bryden, H. L., Johns, W. E., King, B. A., McCarthy, G., McDonagh, E. L., Moat,
B. I., and Smeed, D. A.: Reduction in ocean heat transport at 26∘ N
since 2008 cools the eastern subpolar gyre of the North Atlantic Ocean, J.
Climate, 33, 1677–1689, https://doi.org/10.5194/os-16-863-2020, 2020.
Caínzos, V., Hernández-Guerra, A., McCarthy, G.D., McDonagh, E.L.,
Cubas Armas, M., and Pérez-Hernández, M. D.: Thirty years of GOSHIP
and WOCE data: Atlantic overturning of mass, heat, and freshwater transport,
Geophys. Res. Lett., 49, e2021GL096527, https://doi.org/10.1029/2021GL096527, 2022.
GEBCO Compilation Group: GEBCO 2019 Grid, GEBCO [data set], https://doi.org/10.5285/836f016a-33be-6ddc-e053-6c86abc0788e, 2019.
Chafik, L. and Rossby, T.: Volume, heat, and freshwater divergences in the
subpolar North Atlantic suggest the Nordic Seas as key to the state of the
meridional overturning circulation, Geophys. Res. Lett., 46,
4799–4808, https://doi.org/10.1029/2019GL082110, 2019.
Chen, X. and Tung, K. K.: Varying planetary heat sink led to global-warming
slowdown and acceleration, Science, 345, 897–903,
https://doi.org/10.1126/science.1254937, 2014.
Copernicus Climate Change Service (C3S): Climate Data Store: Sea level daily gridded data from satellite observations for the global ocean from 1993 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS) [data set], doi:10.24381/cds.4c328c78, 2018.
Davis, R. E.: Preliminary results from directly measuring middepth
circulation in the tropical and South Pacific, J. Geophys. Res.-Oceans,
103, 24619–24639, https://doi.org/10.1029/98JC01913, 1998.
De Jong, M. F., Oltmanns, M., Karstensen, J., and De Steur, L.: Deep Convection
in the Irminger Sea observed with a dense mooring array, Oceanography, 31,
50–59, 2018.
De Steur, L., Hansen, E., Gerdes, R., Karcher, M., Fahrbach, E., and Holfort,
J.: Freshwater fluxes in the East Greenland Current: A decade of
observations, Geophys. Res. Lett., 36, L23611, https://doi.org/10.1029/2009GL041278, 2009.
De Steur, L., Pickart, R.S., Macrander, A., Våge, K., Harden, B.,
Jónsson, S., Østerhus, S., and Valdimarsson, H.: Liquid freshwater
transport estimates from the East Greenland Current based on continuous
measurements north of Denmark Strait, J. Geophys. Res.-Oceans, 122,
93–109, https://doi.org/10.1002/2016JC012106, 2017.
Desbruyères, D. G., Sinha, B., McDonagh, E. L., Josey, S. A., Holliday,
N. P., Smeed, D. A., New, A. L., Megann, A., and Moat, B. I.: Importance of
boundary processes for heat uptake in the subpolar North Atlantic, J.
Geophys. Res.-Oceans, 125, e2020JC016366, https://doi.org/10.1029/2020JC016366, 2020.
Dickson, R. R. and Brown, J.: The production of North Atlantic Deep Water:
sources, rates, and pathways, J. Geophys. Res.-Oceans, 99, 12319–12341,
https://doi.org/10.1029/94JC00530, 1994.
Dickson, B., Dye, S., Jónsson, S., Köhl, A., Macrander, A., Marnela,
M., Meincke, J., Olsen, S., Rudels, B., Valdimarsson, H., and Voet, G.: The
overflow flux west of Iceland: Variability, origins and forcing, in
Arctic-Subarctic Ocean Fluxes: Defining the Role of the Northern Seas in
Climate, Springer Netherlands, 443–474, 2008.
Fox, A. D., Handmann, P., Schmidt, C., Fraser, N., Rühs, S., Sanchez-Franks, A., Martin, T., Oltmanns, M., Johnson, C., Rath, W., Holliday, N. P., Biastoch, A., Cunningham, S. A., and Yashayaev, I.: Exceptional freshening and cooling in the eastern subpolar North Atlantic caused by reduced Labrador Sea surface heat loss, Ocean Sci., 18, 1507–1533, https://doi.org/10.5194/os-18-1507-2022, 2022.
Fraser, N. J. and Cunningham, S. A.: 120 years of AMOC variability
reconstructed from observations using the Bernoulli inverse, Geophys. Res.
Lett., 48, e2021GL093893, https://doi.org/10.1029/2021GL093893, 2021.
Fratantoni, D. M.: North Atlantic surface circulation during the 1990's
observed with satellite-tracked drifters, J. Geophys. Res.-Oceans, 106,
22067–22093, https://doi.org/10.1029/2000JC000730, 2001.
GEBCO Compilation Group: GEBCO 2019 Grid, GEBCO [data set],
https://doi.org/10.5285/836f016a-33be-6ddc-e053-6c86abc0788e, 2019.
Girton, J. B., Sanford, T. B., and Käse, R. H.: Synoptic sections of the
Denmark Strait overflow, Geophys. Res. Lett., 28, 1619–1622, 2001.
Good, S. A., Martin, M. J., and Rayner, N. A.: EN4: Quality controlled ocean
temperature and salinity profiles and monthly objective analyses with
uncertainty estimates, J. Geophys. Res.-Oceans, 118, 6704–6716, 2013.
Good, S. A., Martin, M. J., and Rayner, N. A.: EN4: Quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates, J. Geophys. Res.-Oceans, 118, 6704–6716, https://doi.org/10.1002/2013JC009067, 2013.
Gouretski, V. and Reseghetti, F.: On depth and temperature biases in bathythermograph data: Development of a new correction scheme based on analysis of a global ocean database, Deep Sea Res. Pt. I, 57, 812–833, https://doi.org/10.1016/J.DSR.2010.03.011, 2010.
Gouretski, V. and Cheng, L.: Correction for Systematic Errors in the Global Dataset of Temperature Profiles from Mechanical Bathythermographs, J. Atmos. Ocean. Tech., 37, 841–855, https://doi.org/10.1175/JTECH-D-19-0205.1, 2020.
Gurvan, M., Bourdallé-Badie, R., Bouttier, P.-A., Bricaud, C., Bruciaferri, D., Calvert, D., Chanut, J., Clementi, E., Coward, A., Delrosso, D., Ethé, C., Flavoni, S., Graham, T., Harle, J., Iovino, D., Lea, D., Lévy, C., Lovato, T., Martin, N., Masson, S., Mocavero, S., Paul, J., Rousset, C., Storkey, D., Storto, A., and Vancoppenolle, M.: NEMO ocean engine, Zenodo [code], https://doi.org/10.5281/zenodo.3248739, 2017.
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.
Harden, B. E., Pickart, R. S., Valdimarsson, H., Våge, K., de Steur, L.,
Richards, C., Bahr, F., Torres, D., Børve, E., Jónsson, S., and
Macrander, A.: Upstream sources of the Denmark Strait Overflow: Observations
from a high-resolution mooring array, Deep-Sea Res. Pt. I, 112, 94–112,
https://doi.org/10.1016/j.dsr.2016.02.007, 2016.
Hersbach, H., Bell, B., Berrisford, P., Biavati, G., Horányi, A., Muñoz Sabater, J., Nicolas, J., Peubey, C., Radu, R., Rozum, I., Schepers, D., Simmons, A., Soci, C., Dee, D., and Thépaut, J.-N.: ERA5 monthly averaged data on single levels from 1959 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS) [data set], doi:10.24381/cds.f17050d7, 2019.
Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horányi, A.,
Muñoz-Sabater, J., Nicolas, J., Peubey, C., Radu, R., Schepers, D., and
Simmons, A.: The ERA5 global reanalysis, Q. J. Roy. Meteor. Soc., 146,
1999–2049, 2020.
Hirschi, J. J. M., Barnier, B., Böning, C., Biastoch, A., Blaker, A. T.,
Coward, A., Danilov, S., Drijfhout, S., Getzlaff, K., Griffies, S. M., and
Hasumi, H.: The Atlantic meridional overturning circulation in
high-resolution models, J. Geophys. Res.-Oceans, 125, e2019JC015522,
https://doi.org/10.1029/2019JC015522, 2020.
Holliday, N. P., Meyer, A., Bacon, S., Alderson, S. G., and de Cuevas, B.:
Retroflection of part of the east Greenland current at Cape Farewell,
Geophys. Res. Lett., 34, 7609, https://doi.org/10.1029/2006GL029085, 2007.
Huthnance, J. M., Inall, M. E., and Fraser, N. J.: Oceanic density/pressure
gradients and slope currents, J. Phys. Oceanogr., 50, 1643–1654,
https://doi.org/10.1175/JPO-D-19-0134.1, 2020.
Huthnance, J., Hopkins, J., Berx, B., Dale, A., Holt, J., Hosegood, P.,
Inall, M., Jones, S., Loveday, B. R., Miller, P. I., and Polton, J.: Ocean
shelf exchange, NW European shelf seas: Measurements, estimates and
comparisons, Prog. Oceanogr., 202, 102760, https://doi.org/10.1016/j.pocean.2022.102760,
2022.
Jochumsen, K., Quadfasel, D., Valdimarsson, H. and Jónsson, S.:
Variability of the Denmark Strait overflow: Moored time series from
1996–2011, J. Geophys. Res.-Oceans, 117, C12003, https://doi.org/10.1029/2012JC008244,
2012.
Jochumsen, K., Moritz, M., Nunes, N., Quadfasel, D., Larsen, K.M., Hansen,
B., Valdimarsson, H., and Jonsson, S.: Revised transport estimates of the D
enmark S trait overflow, J. Geophys. Res.-Oceans, 122, 3434–3450,
https://doi.org/10.1002/2017JC012803, 2017.
Johns, W. E., Devana, M., Houk, A., and Zou, S.: Moored Observations of the
Iceland-Scotland Overflow Plume Along the Eastern Flank of the Reykjanes
Ridge, J. Geophys. Res.-Oceans, 126, e2021JC017524,
https://doi.org/10.1029/2021JC017524, 2021.
Johnson, C., Sherwin, T., Cunningham, S., Dumont, E., Houpert, L., and
Holliday, N. P.: Transports and pathways of overflow water in the Rockall
Trough, Deep-Sea Res. Pt. I, 122, 48–59, https://doi.org/10.1016/j.dsr.2017.02.004,
2017.
Johnson, H. L., Cessi, P., Marshall, D. P., Schloesser, F., and Spall, M. A.:
Recent contributions of theory to our understanding of the Atlantic
meridional overturning circulation, J. Geophys. Res.-Oceans, 124,
5376–5399, https://doi.org/10.1029/2019JC015330, 2019.
Jones, S., Cottier, F., Inall, M., and Griffiths, C.: Decadal variability on
the Northwest European continental shelf, Prog. Oceanogr., 161,
131–151, https://doi.org/10.1016/j.pocean.2018.01.012, 2018.
Jones, S., Inall, M., Porter, M., Graham, J. A., and Cottier, F.: Storm-driven across-shelf oceanic flows into coastal waters, Ocean Sci., 16, 389–403, https://doi.org/10.5194/os-16-389-2020, 2020.
Jones, S. C.: Code used in transport and flux analysis for Jones et al. 2023. “Observation-based estimates of volume, heat and freshwater exchanges between the subpolar North Atlantic interior, its boundary currents and the atmosphere”, Zenodo [code], doi:10.5281/zenodo.7566026, 2023.
Josey, S. A., Jong, M. F., Oltmanns, M., Moore, G. K., and Weller, R. A.:
Extreme variability in Irminger Sea winter heat loss revealed by ocean
observatories initiative mooring and the ERA5 reanalysis, Geophys. Res.
Lett., 46, 293–302, https://doi.org/10.1029/2018GL080956, 2019.
Käse, R. H., Girton, J. B., and Sanford, T. B.: Structure and variability of
the Denmark Strait Overflow: Model and observations, J. Geophys. Res.-Oceans, 108, 3181, doi:10.1029/2002JC001548, 2003.
Kostov, Y., Johnson, H. L., Marshall, D. P., Heimbach, P., Forget, G.,
Holliday, N. P., Lozier, M. S., Li, F., Pillar, H. R., and Smith, T.: Distinct
sources of interannual subtropical and subpolar Atlantic overturning
variability, Nat. Geosci., 14, 491–495, https://doi.org/10.1038/s41561-021-00759-4,
2021.
Laurila, T. K., Sinclair, V. A., and Gregow, H.: Climatology, variability, and
trends in near-surface wind speeds over the North Atlantic and Europe during
1979–2018 based on ERA5, Int. J. Climatol., 41, 2253–2278,
https://doi.org/10.1002/joc.6957, 2021.
Lavender, K. L., Davis, R. E., and Owens, W. B.: Mid-depth recirculation
observed in the interior Labrador and Irminger seas by direct velocity
measurements, Nature, 407, 66–69, 2000.
Le Bras, I. A., Straneo, F., Holte, J., De Jong, M. F., and Holliday, N. P.:
Rapid export of waters formed by convection near the Irminger Sea's western
boundary, Geophys. Res. Lett., 47, e2019GL085989, https://doi.org/10.1029/2019GL085989, 2020.
Li, F. and Lozier, M. S.: On the linkage between Labrador Sea Water volume
and overturning circulation in the Labrador Sea: A case study on proxies, J.
Climate, 31, 5225–5241, https://doi.org/10.1175/JCLI-D-17-0692.1, 2018.
Li, F., Lozier, M. S., Bacon, S., Bower, A. S., Cunningham, S. A., de Jong,
M. F., deYoung, B., Fraser, N., Fried, N., Han, G., Holliday, N. P., Holte,
J., Houpert, L., Inall, M. E., Johns, W. E., Jones, S., Johnson, C.,
Karstensen, J., Le Bras, I. A., Lherminier, P., Lin, X., Mercier, H.,
Oltmanns, M., Pacini, A., Petit, T., Pickart, R. S., Rayner, D., Straneo,
F., Thierry, V., Visbeck, M., Yashayaev, I., and Zhou, C.: Subpolar North
Atlantic western boundary density anomalies and the Meridional Overturning
Circulation, Nat. Commun., 12, 3002, https://doi.org/10.1038/s41467-021-23350-2,
2021a.
Li, F., Lozier, M. S., Holliday, N. P., Johns, W. E., Le Bras, I. A., Moat,
B. I., Cunningham, S. A., and De Jong, M. F.: Observation-based estimates of
heat and freshwater exchanges from the subtropical North Atlantic to the
Arctic, Prog. Oceanogr., 197, 102640, https://doi.org/10.1016/j.pocean.2021.102640,
2021b.
Lin, P., Pickart, R. S., Torres, D. J., and Pacini, A.: Evolution of the
freshwater coastal current at the southern tip of Greenland, J. Phys.
Oceangr., 48, 2127–2140, https://doi.org/10.1175/JPO-D-18-0035.1, 2018.
Lin, P., Pickart, R. S., Jochumsen, K., Moore, G. W. K., Valdimarsson, H.,
Fristedt, T., and Pratt, L. J.: Kinematic structure and dynamics of the
Denmark Strait overflow from ship-based observations, J. Phys. Oceangr.,
50, 3235–3251, https://doi.org/10.1175/JPO-D-20-0095.1, 2020.
Liu, Y. J., Desbruyères, D. G., Mercier, H., and Spall, M. A.:
Observation-based estimates of Eulerian-mean boundary downwelling in the
western subpolar North Atlantic, Geophys. Res. Lett., 49, e2021GL097243,
https://doi.org/10.1029/2021GL097243, 2022.
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.
Marsh, R., Haigh, I. D., Cunningham, S. A., Inall, M. E., Porter, M., and Moat, B. I.: Large-scale forcing of the European Slope Current and associated inflows to the North Sea, Ocean Sci., 13, 315–335, https://doi.org/10.5194/os-13-315-2017, 2017.
Masson-Delmotte, V., Zhai, P., Pirani, A., Connors, S. L., Péan, C.,
Berger, S., Caud, N., Chen, Y., Goldfarb, L., 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. (Eds.): IPCC, 2021: Climate change
2021: The physical science basis. Contribution of working group I to the
sixth assessment report of the Intergovernmental Panel on Climate Change,
Cambridge University Press. In Press.
Mastropole, D., Pickart, R. S., Valdimarsson, H., Våge, K., Jochumsen, K.,
and Girton, J.: On the hydrography of Denmark Strait, J. Geophys. Res.-Oceans, 122, 306–321, 2017.
Menary, M. B., Jackson, L. C., and Lozier, M. S.: Reconciling the relationship
between the AMOC and Labrador Sea in OSNAP observations and climate models,
Geophys. Res. Lett., 47, e2020GL089793, https://doi.org/10.1029/2020GL089793, 2020.
Munk, W. H.: On the wind-driven ocean circulation, J. Atmos.
Sci., 7, 80–93, 1950.
Østerhus, S., Sherwin, T., Quadfasel, D., and Hansen, B.: The overflow
transport east of Iceland, in Arctic-subarctic ocean fluxes: Defining the
role of the northern seas in climate, Springer Netherlands, 427–441, 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.
Petit, T., Mercier, H., and Thierry, V.: First direct estimates of volume and
water mass transports across the Reykjanes Ridge, J. Geophys. Res.-Oceans,
123, 6703–6719, https://doi.org/10.1029/2018JC013999, 2018.
Petit, T., Lozier, M. S., Josey, S. A., and Cunningham, S. A.: Atlantic deep
water formation occurs primarily in the Iceland Basin and Irminger Sea by
local buoyancy forcing, Geophys. Res. Lett., 47, e2020GL091028,
https://doi.org/10.1029/2020GL091028, 2020.
Petit, T., Lozier, M. S., Josey, S. A., and Cunningham, S. A.: Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North Atlantic, Ocean Sci., 17, 1353–1365, https://doi.org/10.5194/os-17-1353-2021, 2021.
Petrie, B. and Buckley, J.: Volume and freshwater transport of the Labrador
Current in Flemish Pass, J. Geophys. Res.-Oceans, 101, 28335–28342,
https://doi.org/10.1029/96JC02779, 1996.
Pickart, R. S. and Spall, M. A.: Impact of Labrador Sea convection on the
North Atlantic meridional overturning circulation, J. Phys. Oceangr., 37,
2207–2227, https://doi.org/10.1175/JPO3178.1, 2007.
Pickart, R. S., Spall, M. A., and Lazier, J. R.: Mid-depth ventilation in the
western boundary current system of the Subpolar Gyre, Deep-Sea Res. Pt. I,
44, 1025–1054, https://doi.org/10.1016/S0967-0637(96)00122-7, 1997.
Porter, M., Dale, A. C., Jones, S., Siemering, B., and Inall, M. E.:
Cross-slope flow in the Atlantic Inflow Current driven by the on-shelf
deflection of a slope current, Deep-Sea Res. Pt. I, 140, 173–185,
https://doi.org/10.1016/J.DSR.2018.09.002, 2018.
Prater, M. D.: Eddies in the Labrador Sea as observed by profiling RAFOS
floats and remote sensing, J. Phys. Oceangr., 32, 411–427, 2002.
Rhein, M., Kieke, D., Hüttl-Kabus, S., Roessler, A., Mertens, C.,
Meissner, R., Klein, B., Böning, C. W., and Yashayaev, I.: Deep water
formation, the subpolar gyre, and the meridional overturning circulation in
the subpolar North Atlantic, Deep-Sea. Res. Pt. II, 58, 1819–1832,
https://doi.org/10.1016/j.dsr2.2010.10.061, 2011.
Rossby, T., Reverdin, G., Chafik, L., and Søiland, H.: A direct estimate
of poleward volume, heat, and freshwater fluxes at 59.5∘ N between
Greenland and Scotland, J. Geophys. Res.-Oceans, 122, 5870–5887,
https://doi.org/10.1002/2017JC012835, 2017.
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.-Oceans, 117, https://doi.org/10.1029/2011JC007572,
2012.
Semper, S., Våge, K., Pickart, R. S., Jónsson, S., and Valdimarsson,
H.: Evolution and transformation of the North Icelandic Irminger Current
along the North Iceland shelf, J. Geophys. Res.-Oceans, 127,
e2021JC017700, https://doi.org/10.1029/2021JC017700, 2022.
Simpson, J. H. and McCandliss, R. R.: “The Ekman Drain”: a conduit to the
deep ocean for shelf material, Ocean Dynam., 63, 1063–1072,
https://doi.org/10.1007/s10236-013-0644-y, 2013.
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.
Souza, A. J., Simpson, J. H., Harikrishnan, M., and Malarkey, J.: Flow
structure and seasonality in the Hebridean slope current, Oceanol. Acta, 24,
63–76, https://doi.org/10.1016/s0399-1784(00)01103-8, 2001.
Spall, M. A.: Buoyancy-forced downwelling in boundary currents, J. Phys.
Oceanog., 38, 2704–2721, https://doi.org/10.1175/2008JPO3993.1, 2008.
Spall, M. A. and Pickart, R. S.: Where does dense water sink? A subpolar
gyre example, J. Phys. Oceanogr., 31, 810–826,
2000.
Spall, M. A., Pickart, R. S., Lin, P., von Appen, W. J., Mastropole, D.,
Valdimarsson, H., Haine, T. W., and Almansi, M.: Frontogenesis and variability
in Denmark Strait and its influence on overflow water, J. Phys. Oceanogr.,
49, 1889–1904, https://doi.org/10.1175/JPO-D-19-0053.1, 2019.
Stommel, H.: A survey of ocean current theory, Deep-Sea Res., 4, 149–184,
1957.
Straneo, F.: On the connection between dense water formation, overturning,
and poleward heat transport in a convective basin, J. Phys. Oceanogr., 36, 1822–1840,
https://doi.org/10.1175/JPO2932.1, 2006.
Sverdrup, H. U.: Wind-driven currents in a baroclinic ocean; with application
to the equatorial currents of the eastern Pacific, P. Natl. Acad. Sci. USA, 33,
318–326, 1947.
Tréguier, A. M., Lique, C., Deshayes, J., and Molines, J. M.: The North
Atlantic eddy heat transport and its relation with the vertical tilting of
the Gulf Stream axis, J. Phys. Oceanogr., 47, 1281–1289,
https://doi.org/10.1175/JPO-D-16-0172.1, 2017.
Tsubouchi, T., Våge, K., Hansen, B., Larsen, K.M.H., Østerhus, S.,
Johnson, C., Jónsson, 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.
Tsujino, H., Urakawa, S., Nakano, H., Small, R. J., Kim, W. M., Yeager, S. G.,
Danabasoglu, G., Suzuki, T., Bamber, J. L., Bentsen, M., and Böning, C.W.:
JRA-55 based surface dataset for driving ocean–sea-ice models
(JRA55-do), Ocean Model., 130, 79–139, https://doi.org/10.1016/j.ocemod.2018.07.002,
2018.
Williams, R. G., Roussenov, V., Lozier, M. S., and Smith, D.: Mechanisms of
heat content and thermocline change in the subtropical and subpolar North
Atlantic, J. Climate, 28, 9803–9815, https://doi.org/10.1175/JCLI-D-15-0097.1, 2015.
Yashayaev, I.: Hydrographic changes in the Labrador Sea, 1960–2005, Prog.
Oceanogr., 73, 242–276, https://doi.org/10.1016/j.pocean.2007.04.015, 2007.
Yashayaev, I. and Loder, J. W.: Further intensification of deep convection in
the Labrador Sea in 2016, Geophys. Res. Lett., 44, 1429–1438,
https://doi.org/10.1002/2016GL071668, 2017.
Zantopp, R., Fischer, J., Visbeck, M., and Karstensen, J.: From interannual
to decadal: 17 years of boundary current transports at the exit of the
Labrador Sea, J. Geophys. Res.-Oceans, 122, 1724–1748, https://doi.org/10.1002/2016JC012271, 2017.
Zhai, X., Johnson, H. L., Marshall, D. P., and Wunsch, C.: On the wind power
input to the ocean general circulation, J. Phys. Oceanogr., 42, 1357–1365,
https://doi.org/10.1175/JPO-D-12-09.1, 2012.
Zhang, R. and Thomas, M.: Horizontal circulation across density surfaces
contributes substantially to the long-term mean northern Atlantic meridional
overturning circulation, Commun. Earth Environ., 2, 1–12,
https://doi.org/10.1038/s43247-021-00182-y, 2021.
Short summary
Warm water is transported from the tropical Atlantic towards western Europe and the Arctic. It loses heat to the atmosphere on the way, which strongly influences the climate. We construct a dataset encircling the North Atlantic basin north of 47° N. We calculate how and where heat enters and leaves the basin and how much cooling must happen in the interior. We find that cooling in the north-eastern Atlantic is a crucial step in controlling the conversion of water to higher densities.
Warm water is transported from the tropical Atlantic towards western Europe and the Arctic. It...
