UK Overturning in the Subpolar North Atlantic Programme

The transport of heat and freshwater by the North Atlantic Subpolar Gyre greatly affects the climate of the North Atlantic and Europe through its impact on air temperature, precipitation and wind strength. It is highly significant to the region's marine ecosystems, the formation of hurricanes, and rainfall in places like the Sahel, the Amazon and parts of USA. However the Subpolar Gyre is presently inadequately measured, and no ocean general circulation or climate model represents it accurately. UK-OSNAP will deliver enhanced understanding of processes critical to the improvement of physics in climate models through sustained observation of ocean circulation and fluxes together with modelling and analysis.

Led by NOC, UK-OSNAP is a partnership between NOC, SAMS, University of Oxford and University of Liverpool. It is part of international OSNAP that is led by USA and includes 10 further partner groups in Canada, France, Germany, the Netherlands and China. The project will run for seven years from October 2013 and involves fieldwork at sea and model studies. UK-OSNAP is funded by the Natural Environment Research Council (NERC) and builds on National Capability underpinning observations.

Website: www.ukosnap.org

Principal Investigators:

Prof. Penny Holliday, NOC (penny.holliday (at) noc.ac.uk)
Prof. Sheldon Bacon, NOC (s.bacon (at) noc.ac.uk)
Prof. Stuart Cunningham, SAMS (stuart.cunningham (at) sams.ac.uk)
Prof. Mark Inall, SAMS (mark.inall (at) sams.ac.uk)

Project Dates:

September 2013 to August 2020

Funding:

NERC – National Capability
NERC – Discovery Science

Project

Aim

UK OSNAP aims to relate the variability of the overturning circulation of the North Atlantic with formation of deep water and basin-scale wind forcing.

What is the Subpolar Gyre and why is it important?

The North Atlantic subpolar region lies between roughly 45°N and 65°N, between the subtropics to the south and the Nordic Seas to the north. A ‘gyre’ is a large system of rotating currents driven by winds, and the North Atlantic Subpolar Gyre circulates anti-clockwise.

Schematic map of UK OSNAP array, with RAPID array shown

At the southern edge of the gyre the North Atlantic Current brings warm subtropical water into the eastern Subpolar region; most of that warm water circulates around the gyre, but some escapes and flows northwards between Greenland and Scotland and into the Nordic Seas. The gyre is deep, with the whole upper 1km of the North Atlantic circling in this way. The gyre is a key component of the climate system because it is a region where the ocean warms the atmosphere (keeping North Europe relatively mild) and because it draws atmospheric carbon dioxide into the deep ocean.

The warm water brought into the Subpolar Gyre releases heat into the colder atmosphere as it makes its way round the gyre. The properties of the waters change en route; they cool, become fresher and absorb carbon dioxide. This change is called ‘water mass conversion’ and the resulting water masses are dense and sink below the surface layers, flowing southwards away from the Subpolar Gyre. Because of this water mass conversion the Subpolar Gyre is one of the places where the Atlantic Meridional Overturning Circulation (AMOC) is not simply warm surface water flowing north and cold deep water flowing south; here, like the Nordic Seas, the AMOC here also takes the form of water moving down from the surface to below 1000m deep.

The Subpolar Gyre is also influenced by water from the Arctic; cool fresh Arctic water is a major ingredient in the western boundary currents of the gyre. The presence of light surface Arctic water can greatly influence the water mass conversion and therefore the downward movement of NAC water.

What do we mean by ‘fluxes’ and ‘storage’?

Scene of ice-covered mountains and sea ice

We use the word ‘fluxes’ to describe the movement of heat and freshwater between the atmosphere and the ocean. For example, in the Subpolar Gyre the ocean cools, losing heat to the atmosphere and this transfer of energy is called heat flux. In the Arctic, heavy precipitation and river run-off means there is a flux of freshwater from the atmosphere to the ocean. The Subpolar Gyre though does not continually get colder and colder, and the Arctic ocean does not continually get fresher and fresher, because the ocean and atmosphere work together to move heat and freshwater across latitudes to maintain a relatively steady climate pattern. The AMOC and the large ocean gyres are the key physical features that perform this redistribution of heat and freshwater.

The amount of heat and freshwater held within a part of the ocean is called ‘storage’, and understanding (and modelling) the relationships between heat and freshwater storage, fluxes and circulation is crucial to understanding and predicting local and global climate.

Why is more research needed?

Knowledge and understanding of the functioning of the Subpolar Gyre have increased, but ocean measurements have been patchy in time and space, so that the new understanding they generate is usually local to the measurements and not readily transferred to regional scale and beyond (such as the AMOC). We lack even a single coast-to-coast and surface-to-sea-bed measurement of circulation and fluxes in the Subpolar Gyre between North America and Europe.

The current generation of ocean circulation and climate models do not represent the Subpolar Gyre accurately, and existing measurement systems are inadequate for the task. The RAPID–MOCHA array at 26.5°N (http://www.rapid.ac.uk/rapidmoc) has opened our eyes to the surprisingly variable mid-latitude AMOC. So, to understand the contributions of the Subpolar Gyre and the AMOC to climate, observations of Subpolar Gyre circulation and fluxes are required, along with the modelling and analysis required to deliver new understanding of processes critical to the improvement of climate models.

What are we doing?

The UK-OSNAP team is developing a new observing system and innovative modelling techniques to characterise the circulation and fluxes of the North Atlantic Subpolar Gyre. We will provide a continuous record for four years (2014–18) of full-depth, trans-basin mass, heat, and freshwater fluxes in the Subpolar Gyre. UK-OSNAP will be part of an international collaboration to establish a transoceanic observing system in the subpolar North Atlantic (the OSNAP array). Our second aim is to quantify and understand the Subpolar Gyre’s response to local and remote forcing of mass, heat and freshwater fluxes, within the conceptual framework of the AMOC.

To achieve the aims, we have a suite of specific project objectives:

to contribute to the OSNAP array with measurements in the Deep Western Boundary Current in the Irminger Basin, and the Eastern Boundary,
to generate a seasonally-resolved time series of Subpolar Gyre circulation and isopycnal and diapyncal mixing rates and their contribution to net fluxes of heat and freshwater, from 2001, and for each of the Subpolar Gyre sub-basins. We will use a new inverse method applied to Argo data and supplemented by ECCO ocean state estimates,
to identify the link between Subpolar Gyre heat storage and convergence in ocean heat transport. We will use dynamical assimilation and forward model experiments to develop diagnostics of ocean heat content change and heat transport convergence, and to explore the link to atmospheric forcing regimes,
to quantify and understand the local and remote causes of the observed Subpolar Gyre variability using a combination of adjoint modelling at non-eddying resolution to determine sensitivities, and high resolution eddy-permitting forward modelling to test sensitivity robustness,
to develop metrics appropriate to the Subpolar Gyre mass, heat and freshwater fluxes, by exploring improvements to the ‘flat’ and ‘tilted’ metrics via inclusion of horizontal circulation and Ekman fluxes, and testing in models, inverse solutions and the OSNAP array.

Project Management

We make 6-monthly progress reports to our funding agency, NERC, and you can read those here:

Other reports:

People

NOC Staff involved:

Prof. Penny Holliday

Prof. Sheldon Bacon

Dr Chris Wilson

Dr Joanne Hopkins

Equipment

Gliders

Oceanographic Sampling (Sensor and mooring equipment)

Publications

Journal Articles

2023

Jones, S. C., N. J. Fraser, S. A. Cunningham, A. D. Fox, and M. E. Inall (2023), Observation-based estimates of volume, heat, and freshwater exchanges between the subpolar North Atlantic interior, its boundary currents, and the atmosphere, Ocean Sci., 19(1), 169-192, doi:10.5194/os-19-169-2023

Evans, D. G., Holliday, N. P., Bacon, S., and Le Bras, I. (2023) Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas, Ocean Sci., 19, 745–768, https://doi.org/10.5194/os-19-745-2023

Oliver John Tooth, Helen Louise Johnson, Chris Wilson, and Dafydd Gwyn Evans, 2023. Seasonal overturning variability in the eastern North Atlantic subpolar gyre: a Lagrangian perspective. Ocean Science, 19, 769–791. https://os.copernicus.org/articles/19/769/2023/

Yao Fu, M. Susan Lozier, Tiago Carrilho Biló, Amy S. Bower, Stuart A. Cunningham, Frédéric Cyr, M. Femke de Jong, Brad deYoung, Lewis Drysdale, Neil Fraser, Nora Fried, Heather H. Furey Guoqi Han, Patricia Handmann, N. Penny Holliday, James Holte, Mark E. Inall, William E. Johns, Sam Jones, Johannes Karstensen, Feili Li, Astrid Pacini, Robert S. Pickart, Darren Rayner, Fiammetta Straneo, Igor Yashayaev. Seasonality of the Meridional Overturning Circulation in the Subpolar North Atlantic. (2023) Commun Earth Environ 4, 181. https://doi.org/10.1038/s43247-023-00848-9

2022

Berx, Barbara; Volkov, Denis; Baehr, Johanna; Baringer, Molly; Brandt, Peter; Burmeister, Kristin; Cunningham, Stuart; de Jong, Marieke; de Steur, Laura; Dong, Shenfu; Frajka-Williams, Eleanor ; Goni, Gustavo; Holliday, Penny ; Hummels, Rebecca; Ingvaldsen, Randi; Jochumsen, Kerstin; Johns, William; Jónsson, Steingrimur; Karstensen, Johannes; Kieke, Dagmar; Krishfield, Richard; Lankhorst, Matthias; Larsen, Karin; Le Bras, Isabela; Lee, Craig; Li, Feili; Lozier, Susan; Macrander, Andreas; McCarthy, Gerard; Mertens, Christian; Moat, Ben ; Moritz, Martin; Perez, Renellys; Polyakov, Igor; Proshutinsky, Andrey; Rabe, Berit; Rhein, Monika; Schmid, Claudia; Skagseth, Øystein; Smeed, David ; Timmermans, Mary-Louise; von Appen, Wilken-Jon; Williams, Bill; Woodgate, Rebecca; Yashayaev, Igor. 2022 Climate-relevant ocean transport measurements in the Atlantic and arctic oceans. Oceanography. 10-11. https://doi.org/10.5670/oceanog.2021.supplement.02-04

Fraser, Neil J.; Cunningham, Stuart A.; Drysdale, Lewis A.; Inall, Mark E.; Johnson, Clare; Jones, Sam C.; Burmeister, Kristin; Fox, Alan D.; Dumont, Estelle; Porter, Marie; Holliday, N. Penny . 2022 North Atlantic current and European slope current circulation in the Rockall Trough observed using moorings and gliders. Journal of Geophysical Research: Oceans, 127 (12). https://doi.org/10.1029/2022JC019291

Chafik, L., & Holliday, N. P., 2022. Rapid communication of upper-ocean salinity anomaly to deep waters of the Iceland Basin indicates an AMOC short-cut (Commentary). Geophysical Research Letters, 49, e2021GL097570. https://doi.org/10.1029/2021GL097570

Chafik, L., Holliday, N. P., Bacon, S., & Rossby, T. (2022). Irminger Sea is the center of action for subpolar AMOC variability. Geophysical Research Letters, 49, e2022GL099133. https://doi.org/10.1029/2022GL099133

Fox, A. D., Biastoch, A., Cunningham, S. A., Fraser, N., Handmann, P., Holliday, N. P., Johnson, C., Martin, T., Oltmanns, M., Rath, W., Rühs, S., Sanchez-Franks, A., and Schmidt, C., Yashayaev, I.: (2022) Exceptional freshening and cooling in the eastern subpolar North Atlantic caused by reduced Labrador Sea surface heat loss, Ocean Sci. https://doi.org/10.5194/os-2022-18

Koman, G, Johns, WE, Houk, A , Houpert, L, Li, F, (2022) Circulation and overturning in the eastern North Atlantic subpolar gyre, Progress in Oceanography, 208, 102884, https://doi.org/10.1016/j.pocean.2022.102884

Kostov, Y., M.-J. Messias, H. Mercier, H. L. Johnson and D. P. Marshall (2022) Fast mechanisms linking the Labrador Sea with subtropical Atlantic overturning. Climate Dynamics, https://doi.org/10.1007/s00382-022-06459-y

Roussenov, V. M., Williams, R. G., Lozier, M. S., Holliday, N. P., & Smith, D. M. (2022). Historical reconstruction of subpolar North Atlantic overturning and its relationship to density. Journal of Geophysical Research: Oceans, 127, e2021JC017732. https://doi.org/10.1029/2021JC017732

West, G., K. Burmeister and S. A. Cunningham (2022). Reinventing Observations of the Atlantic Meridional Overturning Circulation with Fetch AZA. Journal of Ocean Technology 17: 1-9. https://www.thejot.net/archive-issues/?id=78 (Subscription required for access)

2021

Fraser, N. J., & Cunningham, S. A. (2021). 120 years of AMOC variability reconstructed from observations using the Bernoulli inverse. Geophysical Research Letters, 48, e2021GL093893. https://doi.org/10.1029/2021GL093893

Desbruyères Damien, Chafik Léon, Maze Guillaume (2021). A shift in the ocean circulation has warmed the subpolar North Atlantic Ocean since 2016 . Nature Communications Earth & Environment , 2(1), 48 (9p.) https://doi.org/10.1038/s43247-021-00120-y

Petit T., M.S. Lozier, S.A. Josey, S.A. Cunningham. (2021) 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 Science, 17(5), pp. 1353–1365. doi: 10.5194/os-17-1353-2021. https://doi.org/10.5194/os-17-1353-2021

Zou, S., Bower, A.S, Furey, H., Pickart, R.S., Houpert, L., Holliday, N.P. 2021 Observed Deep Overflow Cyclones around Greenland. Journal of Physical Oceanography, https://doi.org/10.1175/JPO-D-20-0288.1

F. Li, M. S. Lozier, N. P. Holliday, W. E. Johns, I. A. Le Bras, B. Moat, S. A. Cunningham, M. F. de Jong. 2021. Observation-based estimates of heat and freshwater exchanges from the subtropical North Atlantic to the Arctic. Progress in Oceanography, 197, https://doi.org/10.1016/j.pocean.2021.102640

F. Li, M.S. Lozier, S. Bacon, A. Bower, S.A. Cunningham, M.F. de Jong, B. DeYoung, N. Fraser, N. Fried, G. Han, N.P. Holliday, J. Holte, L. Houpert, M.E. Inall, W.E. Johns, S. Jones, C. Johnson, J. Karstensen, I.A. LeBras, P. Lherminier, X. Lin, H. Mercier, M. Oltmanns, A. Pacini, T. Petit, R.S. Pickart, D. Rayner, F. Straneo, V. Thierry, M. Visbeck, I. Yashayaev, C. Zhou. 2021. Subpolar North Atlantic western boundary density anomalies and the Meridional Overturning Circulation. Nat Commun 12, 3002 (2021). https://doi.org/10.1038/s41467-021-23350-2

Kostov, Y., Johnson, H.L., Marshall, D.P., Heimbach, P., Forget, G, Holliday, N.P., Lozier, M.S., Li, F., Pillar, H.R., Smith, T. 2021, Contrasting sources of variability in subtropical and subpolar Atlantic overturning. Nature Geosciences 10.1038/s41561-021-00759-4

Gould, J. W., and S. A. Cunningham (2021), Global-scale patterns of observed sea surface salinity intensified since the 1870s, Nature Communications Earth & Environment, doi.org/10.1038/s43247-021-00161-3.

Pacini, A., Pickart, R., Le Bras, I., Straneo, F. Holliday, N.P. 2021, Cyclonic eddies in the West Greenland Boundary Current System. JPO, https://doi.org/10.1175/JPO-D-20-0255.1

Le Bras, I., Straneo, F., Muilwijk, M., Smedsrud, L.H., Li, Feili, Lozier, M.S., Holliday, N.P.. 2021, How much Arctic fresh water participates in the subpolar overturning circulation? JPO, 51(3), 955-973. https://doi.org/10.1175/JPO-D-20-0240.1

MacGilchrist, Johnson, Lique and Marshall (2021) Demons in the North Atlantic: Variability of Deep Ocean Ventilation, GRL, https://doi.org/10.1029/2020GL092340

Tsubouchi, T., K. Våge, B. Hansen, K. M. H. Larsen, S. Østerhus, C. Johnson, S. Jónsson and H. Valdimarsson (2021). Increased ocean heat transport into the Nordic Seas and Arctic Ocean over the period 1993–2016. Nature Climate Change 11(1): 21-26. https://www.nature.com/articles/s41558-020-00941-3

2020

Petit, T., Lozier, M. S., Josey, S. A., & Cunningham, S. A. 2020. Atlantic deep water formation occurs primarily in the Iceland Basin and Irminger Sea by local buoyancy forcing. Geophysical Research Letters, 47, e2020GL091028. https://doi.org/10.1029/2020GL091028

Desbruyères, D. G.; Sinha, B.; McDonagh, E. L.; Josey, S. A.; Holliday, N. P.; Smeed, D. A. ; New, A. L.; Megann, A.; Moat, B. I. . 2020 Importance of boundary processes for heat uptake in the Subpolar North Atlantic. Journal of Geophysical Research: Oceans, 125 (9), e2020JC016366. https://doi.org/10.1029/2020JC016366

Houpert, L. Cunningham, S.; Fraser, N.; Johnson, C.; Holliday, N. P., Jones, S.; Moat, B.; Rayner, D., 2020 Observed variability of the North Atlantic current in the Rockall Trough from four years of mooring measurements. Journal of Geophysical Research: Oceans, 125 (10), e2020JC016403. https://doi.org/10.1029/2020JC016403

Rossby, T., Chafik, L., & Houpert, L, 2020. What can hydrography tell us about the strength of the Nordic Seas MOC over the last 70 to 100 years?.Geophysical Research Letters, 47,e2020GL087456. https://doi.org/10.1029/2020GL087456

Mackay, N., Wilson, C., Holliday, N.P., Zika, J.D., 2020. The observation-based application of a Regional Thermohaline Inverse Method to diagnose the formation and transformation of water masses north of the OSNAP array from 2013-2015. JPO, 50, 1533-1555. https://doi.org/10.1175/JPO-D-19-0188.1

Huthnance, J.M., Inall, M.E., Fraser, N.J., 2020, Oceanic density/pressure gradients and slope currents. Journal of Physical Oceanography, DOI: 10.1175/JPO-D-19-0134.1

Johnson, C., M. Inall, S. Gary and S. Cunningham, 2020, Significance of climate indices to benthic conditions across the northern North Atlantic and adjacent shelf seas, Frontiers in Marine Science, 7, doi: 10.3389/fmars.2020.00002.

Holliday, N. Penny; Bersch, Manfred; Berx, Barbara; Chafik, Léon; Cunningham, Stuart; Florindo-López, Cristian; Hátún, Hjálmar; Johns, William; Josey, Simon A.; Larsen, Karin Margretha H.; Mulet, Sandrine; Oltmanns, Marilena; Reverdin, Gilles; Rossby, Tom; Thierry, Virginie; Valdimarsson, Hedinn; Yashayaev, Igor. 2020 Ocean circulation causes the largest freshening event for 120 years in eastern subpolar North Atlantic. Nature Communications, 11 (1), 585. https://doi.org/10.1038/s41467-020-14474-y

Le Bras, I. A.‐A.; Straneo, F.; Holte, J.; Jong, M. F.; Holliday, N. P.. 2020 Rapid export of waters formed by convection near the Irminger Sea's western boundary. Geophysical Research Letters, 47 (3), e2019GL085989. https://doi.org/10.1029/2019GL085989

2019

Benetti, M.; Reverdin, G.; Clarke, J.S.; Tynan, E.; Holliday, N.P.; Torres‐Valdes, S.; Lherminier, P.; Yashayaev, I.. 2019 Sources and distribution of fresh water around Cape Farewell in 2014. Journal of Geophysical Research: Oceans. Journal of Geophysical Research Oceans, 124, 9404–9416.https://doi.org/10.1029/2019JC015080

González-Pola, César; Fratantoni, Paula; Larsen, Karin M. H.; Holliday, N. Penny; Dye, Stephen; Mork, Kjell Arne; Beszczynska-Möller, Agnieszka; Valdimarsson, Hedinn; Trofimov, Alexander; Parner, Hjalte; Klein, Holger; Cisewski, Boris; Fontán, Almudena; Lyons, Kieran; Kolodziejczyk, Nicolas; Graña, Rocío; Linders, Johanna; Wodzinowski, Tycjan; Goszczko, Ilona; Cusack, Caroline. 2019 The ICES Working Group on Oceanic Hydrography: A Bridge From In-situ Sampling to the Remote Autonomous Observation Era. Frontiers in Marine Science, 6. https://doi.org/10.3389/fmars.2019.00103

Kostov, Y., Johnson, H.L., Marshall, D.P. (2019) AMOC sensitivity to surface buoyancy fluxes: the role of air-sea feedback mechanisms. Climate Dynamics. doi: https://doi.org/10.1007/s00382-019-04802-4

Moat; B. Sinha; S. A. Josey; J. Robson; P. Ortega; F. Sévellec; N. P. Holliday; G. D. McCarthy; A. L. New; J. J.-M. Hirschi. 2019. New insights into decadal North Atlantic sea surface temperature and ocean heat content variability from a high-resolution coupled climate model, Journal of Climate. 32 (18). 6137-6161.https://doi.org/10.1175/JCLI-D-18-0709.1

Eleanor Frajka-Williams, Isabelle J Ansorge, Johanna Baehr, Harry L Bryden, Maria Paz Chidichimo, Stuart A Cunningham, Gokhan Danabasoglu, Shenfu Dong, Kathleen A Donohue, Shane Elipot, N. Penny Holliday, Rebecca Hummels, Laura C Jackson, Johannes Karstensen, Matthias Lankhorst, Isabela Le Bras, M. Susan Lozier, Elaine L McDonagh, Christopher S Meinen, Herle Mercier, Bengamin I Moat, Renellys C Perez, Christopher G Piecuch, Monika Rhein, Meric Srokosz, Kevin Edward Trenberth, Sheldon Bacon, Gael Forget, Gustavo Jorge Goni, Patrick Heimbach, Dagmar Kieke, Jannes Koelling, Tarron Lamont, Gerard McCarthy, Christian Mertens, Uwe Send, David A Smeed, Marcel van den Berg, Denis Volkov, Chris Wilson, 2019, Atlantic Meridional Overturning Circulation: observed transport and variability. Frontiers in Marine Science, Ocean Observations, 6:260, https://doi.org/10.3389/fmars.2019.00260

Hopkins, J. E. , N. P. Holliday, S. Bacon, D. Rayner, L. Houpert, I. Le Bras, F. Straneo, C. Wilson, Transport variability of the Irminger Sea Deep Western Boundary Current from a mooring array. 2019. Journal of Geophysical Research: Oceans, 124, 3246–3278. https://doi.org/10.1029/2018JC014730

Li, F., Lozier, M.S., Danabasoglu, G., Holliday, N.P., Kwon, Y.-O., Romanou, A., Yeager, S. G., Zhang, R., 2019. Local and downstream relationship between Labrador Sea Water volume and North Atlantic meridional overturning circulation variability. J. Climate, 32, 3883-3898. https://doi.org/10.1175/JCLI-D-18-0735.1

González-Pola C, Fratantoni P, Larsen KMH, Holliday NP, Dye S, Mork KA, Beszczynska-Möller A, Valdimarsson H, Trofimov A, Parner H, Klein H, Cisewski B, Fontán A, Lyons K, Kolodziejczyk N, Graña R, Linders J, Wodzinowski T, Goszczko I and Cusack C (2019) The ICES Working Group on Oceanic Hydrography: A Bridge From In-situ Sampling to the Remote Autonomous Observation Era. Front. Mar. Sci. 6:103. doi: 10.3389/fmars.2019.00103

Lozier, M.S., F. Li, S. Bacon, F. Bahr, A. Bower, S. Cunningham, F. de Jong, L. de Steur, Brad de Young, J. Fischer, S. Gary, B. Greenan, N.P. Holliday, A. Houk, L. Houpert, M. Inall, B. Johns, H. Johnson, C. Johnson, J. Karstensen, G. Koman, I. LeBras, X. Lin, N. Mackay, D. Marshall, H. Mercier, M. Oltmanns, R. Pickart, A. Ramsay, D. Rayner, F. Straneo, V. Thierry, D. Torres, R. Williams, C. Wilson, J. Yang, I. Yashayaev, J. Zhao. 2019. A sea change in our view of overturning in the Subpolar North Atlantic Program. Science 01 Feb 2019:Vol. 363, Issue 6426, pp. 516-521 DOI: 10.1126/science.aau6592

2018

Le Bras, I. A.-A., Straneo, F., Holte, J., & Holliday, N. P. (2018). Seasonality of freshwater in the East Greenland Current system from 2014 to 2016. Journal of Geophysical Research: Oceans, 123, 8828–8848. https://doi.org/10.1029/2018JC014511

Pillar, H. R., H. L. Johnson, D. P. Marshall, P. Heimbach, and S. Takao, 2018: Impacts of Atmospheric Reanalysis Uncertainty on AMOC Estimates at 25N. J. Climate, 31, 8719-8744.

Houpert L., M. Inall E. Dumont S. Gary C. Johnson M. Porter W. E. Johns S. A. Cunningham, 2018, Structure and Transport of the North Atlantic Current in the Eastern Subpolar Gyre from Sustained Glider Observations, Journal of Geophysical Research-Oceans, https://doi.org/10.1029/2018JC014162

Zhao, J., Bower, A., Yang, J., Lin, X., Holliday, N.P., 2018, Meridional heat transport variability induced by mesoscale processes in the subpolar North Atlantic, Nature Communications, 9:1124, doi:10.1038/s41467-018-03134-x

Holliday, N.P., Bacon, S., Cunningham, S., Gary, S.F., Karstensen, J., King, B.A., Li, F., McDonagh, E.L. 2018, Subpolar North Atlantic overturning and gyre-scale circulation in the summers of 2014 and 2016. JGR-Oceans, 123(7), 4538-4559, 10.1029/2018JC013841

Mackay, N, Wilson, C., Zika, J., Holliday, N.P., 2018, A regional thermohaline inverse method for estimating circulation and mixing in the Arctic, Journal of Ocean and Atmosphere Technology, DOI: 10.1175/JTECH-D-17-0198.1

Gary, S. F., Cunningham, S. A., Johnson, C., Houpert, L., Holliday, N.P., Behrens, E., Biastoch, A., Boning, C. 2018. Seasonal cycles of oceanic transport in the eastern subpolar North Atlantic. JGR-Oceans, 123 (2), 1471-1484, doi 10.1002/2017JC013350

2017

Ferrari, R., L.-P. Nadeau, D. P. Marshall, L .C. Allison, and H. L. Johnson, 2017: A model of the ocean overturning circulation with two closed basins and a re-entrant channel. J. Phys. Oceanogr., 47, 2887-2906.

Marshall, D. P., and H. L. Johnson, 2017: Relative strength of the Antarctic Circumpolar Current and Atlantic Meridional Overturning Circulation. Tellus A, 69, 1338884.

Johnson, C., Cunningham, S., Sherwin, T., Dumont, E., Houpert, L., Holliday, N.P., Gary, S., (2017). Pathways and transports of overflow water in the Rockall Trough. doi: 10.1016/j.dsr.2017.02.004,

Benetti, M., Reverdin, G., Yashayaev, I., Holliday, N.P., Tynan, E., Torres-Valdes, S., Lherminier, P., Treguer, P., Sarthou, G., Lique, C., (2017), Composition of freshwater in the spring 2014 on the southern Labrador shelf and slope. JGR, doi: 10.1002/2016JC012244

2016

Lozier, M. S. Bacon, S., Bower, A. S., Cunningham, S. A. de Jong, M. F., de Steur, L., deYoung, B., Fischer, J., Gary, S. F., Greenan, B. J.W., Heimbach, P., Holliday, N. P., Houpert, L., Inall, M.E., Johns, W. E., Johnson, H. L., Karstensen, J.,Li, Feili; Lin, X., Mackay, N., Marshall, D. P., Mercier, H., Myers, P. G., Pickart, R. S., Pillar, H. R. Straneo, F., Thierry, V., Weller, R A., Williams, R. G., Wilson, C., Yang, J., Zhao, J., Zika, J. D., 2016 Overturning in the Subpolar North Atlantic Program: a new international ocean observing system. Bulletin of the American Meteorological Society, 10.1175/BAMS-D-16-0057.1

Doddridge, E. W., D. P. Marshall, and A. McC. Hogg, 2016: Eddy cancellation of the Ekman cell in subtropical gyres. J. Phys. Oceanogr., 46, 2995-3010.

Pillar, H., Heimbach, P., Johnson, H. and Marshall, D. (2016), Dynamical attribution of recent variability in Atlantic overturning, Journal of Climate, 29, 3339-3352, 10.1175/JCLI-D-15-0727.1

2015

Munday, D. R., H. L. Johnson, and D. P. Marshall, 2015: The role of ocean gateways in the dynamics and sensitivity to wind stress of the early Antarctic Circumpolar Current. Paleoceanography, 30, 284–302.

Williams, R.G., V. Roussenov, M.S. Lozier, D. Smith (2015). Mechanisms of heat content and thermocline change in the subtropical and subpolar North Atlantic. J. Climate, 10.1175/JCLI-D-15-0097.1

Holliday, N. P., S. A. Cunningham, C. Johnson, S. Gary, C. Griffiths, J. F. Read, and T. Sherwin (2015), Multi-decadal variability of potential temperature, salinity and transport in the eastern subpolar North Atlantic, J. Geophys. Res. - Oceans, 10.1002/2015JC010762.

Sherwin, T. J., Aleynik, D. L., Inall, M. E. & Dumont, E. (2015) Deep drivers of mesoscale circulation in the central Rockall Trough. Ocean Science, doi:10.5194/os-11-343-2015

Marzocchi, A., J. Hirschi, J.-M, N. P. Holliday, S. A. Cunningham, A. T. Blaker, and A. C. Coward (2015), The North Atlantic subpolar circulation in an eddy-resolving global ocean model, Journal of Marine Systems, 142, 126-143, doi:10.1016/j.jmarsys.2014.10.007.

2014

Williams et al, 2014. Decadal evolution of ocean thermal anomalies in the North Atlantic: the effects of Ekman, overturning, and horizontal transport. Journal of Climate, 27, 2, 698-719.

2013

Cunningham, S. A., C. D. Roberts, E. Frajka-Williams, W. E. Johns, W. Hobbs, M. Palmer, D. Rayner, D. A. Smeed, and G. McCarthey (2013), Atlantic Meridional Overturning Circulation slowdown causes widespread cooling in the Atlantic, Geophys. Res. Letters, 40, 6202-6207, doi:6210.1002/2013GL058464.

Johnson, C., M. Inall, and S. Häkkinen (2013), Declining nutrient concentrations in the northeast Atlantic as a result of a weakening Subpolar Gyre, Deep Sea Research I, 82, 95-107.

Reports

Holliday et al, 2017, RRS Discovery Cruise DY078 06 - 28 May 2017, Southampton to Reykjavik. Extended Ellett Line 2017 occupation and OSNAP Rockall Trough mooring refurbishment cruise. Southampton, National Oceanography Centre, 118pp. (National Oceanography Centre Cruise Report 48)

Cunningham, S., Houpert, L., et al, (2016), RRS Discovery Cruise DY053, 26 Jun - 23 Jul 2016, Glasgow to Reykjavik. OSNAP 2016 mooring refurbishment cruise, Leg 1. SAMS Report, 121pp.

Holliday, N.P.; et al, (2016), RRS Discovery Cruise DY054, 27 Jul - 17 Aug 2016, Reykjavik to Southampton. OSNAP 2016 mooring refurbishment cruise, Leg 2. Southampton, National Oceanography Centre, 77pp. (National Oceanography Centre Cruise Report 40)

Johnson, C., S. Cunningham, J. Fischer, S. Gary, J. Karstensen, T. Liblik, and L. de Steur (2016a), Report on the upper and lower transport variability at NACLIM key section in the Subpolar gyre of the North Atlantic, NACLIM Deliverable D22.31 Rep., http://naclim.zmaw.de/index.php?id=2247.

Cunningham, S. A. (2015), R/V Knorr Cruise KN221-02,Rep 288., 1-50pp, SAMS. 

King, B.A.; Holliday, N.P.; et al, .. 2015 RRS James Clark Ross Cruise 302, 06 Jun - 21 Jul 2014, The 2015 RAGNARRoC, OSNAP AND Extended Ellett Line cruise report. Southampton, National Oceanography Centre, 76pp. (National Oceanography Centre Cruise Report 35)

Cunningham, S. A. (2014), The Oceans, in The Times Comprehensive Atlas of the World 14th edition, edited, pp. 32-33, HarperCollins, Glasgow.

Pickart, R. (2014), R/V Knorr Cruise KN221-03, 1-64pp, WHOI

Karstensen, J., and C. Johnson (2014), Report on the technical characteristic of the observing system operated in NACLIM south of the sills, Work package 2.2, Deliverable 22.8Rep., 33pp pp, University of Hamburg, Hamburg.

Impact

UK-OSNAP will showcase physical science and technology through the use of social media, blogs and press releases.

You can watch a range of short films made for the North Atlantic Story Project and featuring UK OSNAP researchers.

We’ve posted some videos from our cruises on the UK OSNAP youtube channel.

UK OSNAP has a blog about our adventures at sea.

Watch this really great film about making OSNAP observations at sea – made by our partners at NIOZ, and featuring UK OSNAP scientists https://www.youtube.com/watch?v=a-lhCIQjE4c&feature=youtu.be

There are loads of interesting animations and videos of ocean data at the University of Liverpool’s Ocean Climate YouTube Channel.

In particular we like the videos that consider different perspectives of sea level change, drawing upon the history of sea-level measurements at Liverpool and our ongoing work on understanding past and present sea-level variability and projections for the future.

Part 1: Personal Perspective www.youtube.com/watch?v=je_wqNSc3Hs

Part 2: Historical Perspective www.youtube.com/watch?v=mbzf4SgbZao

Part 3: Future Perspective? www.youtube.com/watch?v=-8ZpARgVlFI

Listen to a NERC Planet Earth Online podcast about OSNAP.

UK-OSNAP is a partner in NAVIS, the North Atlantic Virtual Institute that seeks to advance scientific understanding of this key component of our climate system by fostering interaction, exchange, collaboration and education.

Who benefits from UK-OSNAP?

The UK-OSNAP programme will generate a large amount of data and information that will have many uses. Some specific groups that will directly benefit are:

Decadal and seasonal forecasters

Knowledge of the sub-polar North Atlantic Ocean is crucial to the skill of emerging seasonal and decadal forecasting systems. OSNAP will increase the quantity and quality of in-situ observations needed to initialise such forecasts. This will be of direct benefit to the UK Meteorological Office.

UK, European and international climate modellers

Observations of ocean heat, freshwater and mass transports within the sub-polar North Atlantic will provide further valuable data to enable assessment, and subsequent refinement, of coupled ocean/climate models used for prediction. The ability of models to simulate ocean transports within the complex sub-polar region is a candid measure of their performance, and affects simulation of related climate processes.

International and domestic climate policy and decision makers

The reduction of the uncertainty of seasonal, decadal and longer-term model forecasts will ultimately contribute to increasingly reliable projections of future climate, thereby underpinning mitigation and adaptation strategies. New understanding of environmental variability is highly valuable to organisations that provide advice for maintaining healthy and productive seas. Combination of OSNAP results with data from other locations will aid detection of any large-scale change in the system that may be underway, or evolve, in the coming years, likely to influence regional climate and require modified adaptation and mitigation policies to those currently in place.

Access to UK-OSNAP data and products

Links to OSNAP data can be found at the international OSNAP website