Articles | Volume 16, issue 4
https://doi.org/10.5194/os-16-863-2020
© Author(s) 2020. 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-16-863-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
23 Jul 2020
Research article |
| 23 Jul 2020
| 23 Jul 2020
Pending recovery in the strength of the meridional overturning circulation at 26° N
National Oceanography Centre, University of Southampton Waterfront
Campus, European Way, Southampton, SO14 3ZH, UK
David A. Smeed
National Oceanography Centre, University of Southampton Waterfront
Campus, European Way, Southampton, SO14 3ZH, UK
Eleanor Frajka-Williams
National Oceanography Centre, University of Southampton Waterfront
Campus, European Way, Southampton, SO14 3ZH, UK
Damien G. Desbruyères
Ifremer, University of Brest, CNRS, IRD, Laboratoire d'Océanographie
Physique et Spatiale, IUEM, Ifremer centre de Bretagne, 29280
Plouzané,
France
Claudie Beaulieu
Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
William E. Johns
Rosenstiel School of Marine and Atmospheric Science, University of Miami,
Miami, FL, USA
Darren Rayner
National Oceanography Centre, University of Southampton Waterfront
Campus, European Way, Southampton, SO14 3ZH, UK
Alejandra Sanchez-Franks
National Oceanography Centre, University of Southampton Waterfront
Campus, European Way, Southampton, SO14 3ZH, UK
Molly O. Baringer
Atlantic Oceanographic and Meteorological Laboratory, NOAA, Miami, FL,
USA
Denis Volkov
Atlantic Oceanographic and Meteorological Laboratory, NOAA, Miami, FL,
USA
Cooperative Institute for Marine and Atmospheric Studies, University of
Miami, Miami, FL, USA
Laura C. Jackson
Met Office, Exeter, UK
Harry L. Bryden
School of Ocean and Earth Science, University of Southampton Waterfront
Campus, European Way, Southampton, SO14 3ZH, UK
Related authors
Marilena Oltmanns, N. Penny Holliday, James Screen, Ben I. Moat, Simon A. Josey, D. Gwyn Evans, and Sheldon Bacon
Weather Clim. Dynam., 5, 109–132, https://doi.org/10.5194/wcd-5-109-2024, https://doi.org/10.5194/wcd-5-109-2024, 2024
Short summary
Short summary
The melting of land ice and sea ice leads to freshwater input into the ocean. Based on observations, we show that stronger freshwater anomalies in the subpolar North Atlantic in winter are followed by warmer and drier weather over Europe in summer. The identified link indicates an enhanced predictability of European summer weather at least a winter in advance. It further suggests that warmer and drier summers over Europe can become more frequent under increased freshwater fluxes in the future.
Alexander T. Archibald, Bablu Sinha, Maria Russo, Emily Matthews, Freya Squires, N. Luke Abraham, Stephane Bauguitte, Thomas Bannan, Thomas Bell, David Berry, Lucy Carpenter, Hugh Coe, Andrew Coward, Peter Edwards, Daniel Feltham, Dwayne Heard, Jim Hopkins, James Keeble, Elizabeth C. Kent, Brian King, Isobel R. Lawrence, James Lee, Claire R. Macintosh, Alex Megann, Ben I. Moat, Katie Read, Chris Reed, Malcolm Roberts, Reinhard Schiemann, David Schroeder, Tim Smyth, Loren Temple, Navaneeth Thamban, Lisa Whalley, Simon Williams, Huihui Wu, and Ming-Xi Yang
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2023-405, https://doi.org/10.5194/essd-2023-405, 2024
Revised manuscript accepted for ESSD
Short summary
Short summary
Here we present an overview of the data generated as part of the North Atlantic Climate System Integrated Studies (ACSIS) programme which are available through dedicated repositories at the Centre for Environmental Data Analysis (CEDA, www.ceda.ac.uk) and the British Oceanographic Data Centre (BODC, bodc.ac.uk). ACSIS data cover the full North Atlantic System comprising: the North Atlantic Ocean, the atmosphere above it including its composition, Arctic Sea Ice and the Greenland Ice Sheet.
Marilena Oltmanns, N. Penny Holliday, James Screen, D. Gwyn Evans, Simon A. Josey, Sheldon Bacon, and Ben I. Moat
Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2021-79, https://doi.org/10.5194/wcd-2021-79, 2021
Revised manuscript not accepted
Short summary
Short summary
The Arctic is currently warming twice as fast as the global average. This results in enhanced melting and thus freshwater releases into the North Atlantic. Using a combination of observations and models, we show that atmosphere-ocean feedbacks initiated by freshwater releases into the North Atlantic lead to warmer and drier weather over Europe in subsequent summers. The existence of this dynamical link suggests that European summer weather can potentially be predicted months to years in advance.
Alejandra Sanchez-Franks, Eleanor Frajka-Williams, Ben I. Moat, and David A. Smeed
Ocean Sci., 17, 1321–1340, https://doi.org/10.5194/os-17-1321-2021, https://doi.org/10.5194/os-17-1321-2021, 2021
Short summary
Short summary
In the North Atlantic, ocean currents carry warm surface waters northward and return cooler deep waters southward. This type of ocean circulation, known as overturning, is important for the Earth’s climate. This overturning has been measured using a mooring array at 26° N in the North Atlantic since 2004. Here we use these mooring data and global satellite data to produce a new method for monitoring the overturning over longer timescales, which could potentially be applied to different latitudes.
Emma L. Worthington, Ben I. Moat, David A. Smeed, Jennifer V. Mecking, Robert Marsh, and Gerard D. McCarthy
Ocean Sci., 17, 285–299, https://doi.org/10.5194/os-17-285-2021, https://doi.org/10.5194/os-17-285-2021, 2021
Short summary
Short summary
The RAPID array has observed the Atlantic meridional overturning circulation (AMOC) since 2004, but the AMOC was directly calculated only five times from 1957–2004. Here we create a statistical regression model from RAPID data, relating AMOC changes to density changes within the different water masses at 26° N, and apply it to historical hydrographic data. The resulting 1981–2016 record shows that the AMOC from 2008–2012 was its weakest since the mid-1980s, but it shows no overall decline.
Yang Liu, Jisk Attema, Ben Moat, and Wilco Hazeleger
Earth Syst. Dynam., 11, 77–96, https://doi.org/10.5194/esd-11-77-2020, https://doi.org/10.5194/esd-11-77-2020, 2020
Short summary
Short summary
Poleward meridional energy transport (MET) has significant impact on the climate in the Arctic. In this study, we quantify and intercompare MET at subpolar latitudes from six reanalysis data sets. The results indicate that the spatial distribution and temporal variations of MET differ substantially among the reanalysis data sets. Our study suggests that the MET estimated from reanalyses is useful for the evaluation of energy transports but should be used with great care.
Robert Marsh, Ivan D. Haigh, Stuart A. Cunningham, Mark E. Inall, Marie Porter, and Ben I. Moat
Ocean Sci., 13, 315–335, https://doi.org/10.5194/os-13-315-2017, https://doi.org/10.5194/os-13-315-2017, 2017
Short summary
Short summary
To the west of Britain and Ireland, a strong ocean current follows the steep slope that separates the deep Atlantic and the continental shelf. This “Slope Current” exerts an Atlantic influence on the North Sea and its ecosystems. Using a combination of computer modelling and archived data, we find that the Slope Current weakened over 1988–2007, reducing Atlantic influence on the North Sea, due to a combination of warming of the subpolar North Atlantic and weakening winds to the west of Scotland.
E. Frajka-Williams, C. S. Meinen, W. E. Johns, D. A. Smeed, A. Duchez, A. J. Lawrence, D. A. Cuthbertson, G. D. McCarthy, H. L. Bryden, M. O. Baringer, B. I. Moat, and D. Rayner
Ocean Sci., 12, 481–493, https://doi.org/10.5194/os-12-481-2016, https://doi.org/10.5194/os-12-481-2016, 2016
Short summary
Short summary
The ocean meridional overturning circulation (MOC) is predicted by climate models to slow down in this century, resulting in reduced transport of heat northward to mid-latitudes. At 26° N, the Atlantic MOC has been measured continuously for the past decade (2004–2014). In this paper, we discuss the 10-year record of variability, identify the origins of the continued weakening of the circulation, and discuss high-frequency (subannual) compensation between transport components.
P. Achtert, I. M. Brooks, B. J. Brooks, B. I. Moat, J. Prytherch, P. O. G. Persson, and M. Tjernström
Atmos. Meas. Tech., 8, 4993–5007, https://doi.org/10.5194/amt-8-4993-2015, https://doi.org/10.5194/amt-8-4993-2015, 2015
Short summary
Short summary
Doppler lidar wind measurements were obtained during a 3-month Arctic cruise in summer 2014. Ship-motion effects were compensated by combining a commercial Doppler lidar with a custom-made motion-stabilisation platform. This enables the retrieval of wind profiles in the Arctic boundary layer with uncertainties comparable to land-based lidar measurements and standard radiosondes. The presented set-up has the potential to facilitate continuous ship-based wind profile measurements over the oceans.
J. Prytherch, M. J. Yelland, I. M. Brooks, D. J. Tupman, R. W. Pascal, B. I. Moat, and S. J. Norris
Atmos. Chem. Phys., 15, 10619–10629, https://doi.org/10.5194/acp-15-10619-2015, https://doi.org/10.5194/acp-15-10619-2015, 2015
Short summary
Short summary
Signals at scales associated with wave and platform motion are often apparent in ship-based turbulent flux measurements, but it has been uncertain whether this is due to measurement error or to wind-wave interactions. We show that the signal has a dependence on horizontal ship velocity and that removing the signal reduces the dependence of the momentum flux on the orientation of the ship to the wind. We conclude that the signal is a bias due to time-varying motion-dependent flow distortion.
D. A. Smeed, G. D. McCarthy, S. A. Cunningham, E. Frajka-Williams, D. Rayner, W. E. Johns, C. S. Meinen, M. O. Baringer, B. I. Moat, A. Duchez, and H. L. Bryden
Ocean Sci., 10, 29–38, https://doi.org/10.5194/os-10-29-2014, https://doi.org/10.5194/os-10-29-2014, 2014
S. J. Norris, I. M. Brooks, B. I. Moat, M. J. Yelland, G. de Leeuw, R. W. Pascal, and B. Brooks
Ocean Sci., 9, 133–145, https://doi.org/10.5194/os-9-133-2013, https://doi.org/10.5194/os-9-133-2013, 2013
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
Short summary
Short summary
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.
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
Short summary
Short summary
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.
Marilena Oltmanns, N. Penny Holliday, James Screen, Ben I. Moat, Simon A. Josey, D. Gwyn Evans, and Sheldon Bacon
Weather Clim. Dynam., 5, 109–132, https://doi.org/10.5194/wcd-5-109-2024, https://doi.org/10.5194/wcd-5-109-2024, 2024
Short summary
Short summary
The melting of land ice and sea ice leads to freshwater input into the ocean. Based on observations, we show that stronger freshwater anomalies in the subpolar North Atlantic in winter are followed by warmer and drier weather over Europe in summer. The identified link indicates an enhanced predictability of European summer weather at least a winter in advance. It further suggests that warmer and drier summers over Europe can become more frequent under increased freshwater fluxes in the future.
Alexander T. Archibald, Bablu Sinha, Maria Russo, Emily Matthews, Freya Squires, N. Luke Abraham, Stephane Bauguitte, Thomas Bannan, Thomas Bell, David Berry, Lucy Carpenter, Hugh Coe, Andrew Coward, Peter Edwards, Daniel Feltham, Dwayne Heard, Jim Hopkins, James Keeble, Elizabeth C. Kent, Brian King, Isobel R. Lawrence, James Lee, Claire R. Macintosh, Alex Megann, Ben I. Moat, Katie Read, Chris Reed, Malcolm Roberts, Reinhard Schiemann, David Schroeder, Tim Smyth, Loren Temple, Navaneeth Thamban, Lisa Whalley, Simon Williams, Huihui Wu, and Ming-Xi Yang
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2023-405, https://doi.org/10.5194/essd-2023-405, 2024
Revised manuscript accepted for ESSD
Short summary
Short summary
Here we present an overview of the data generated as part of the North Atlantic Climate System Integrated Studies (ACSIS) programme which are available through dedicated repositories at the Centre for Environmental Data Analysis (CEDA, www.ceda.ac.uk) and the British Oceanographic Data Centre (BODC, bodc.ac.uk). ACSIS data cover the full North Atlantic System comprising: the North Atlantic Ocean, the atmosphere above it including its composition, Arctic Sea Ice and the Greenland Ice Sheet.
Sina Loriani, Yevgeny Aksenov, David Armstrong McKay, Govindasamy Bala, Andreas Born, Cristiano M. Chiessi, Henk Dijkstra, Jonathan F. Donges, Sybren Drijfhout, Matthew H. England, Alexey V. Fedorov, Laura Jackson, Kai Kornhuber, Gabriele Messori, Francesco Pausata, Stefanie Rynders, Jean-Baptiste Salée, Bablu Sinha, Steven Sherwood, Didier Swingedouw, and Thejna Tharammal
EGUsphere, https://doi.org/10.5194/egusphere-2023-2589, https://doi.org/10.5194/egusphere-2023-2589, 2023
Short summary
Short summary
In this work, we draw on paleoreords, observations and modelling studies to review tipping points in the ocean overturning circulations, monsoon systems and global atmospheric circulations. We find indications for tipping in the ocean overturning circulations and the West African monsoon, with potentially severe impacts on the Earth system and humans. Tipping in the other considered systems is considered conceivable but currently not sufficiently supported by evidence.
Jonathan Andrew Baker, Richard Renshaw, Laura Claire Jackson, Clotilde Dubois, Doroteaciro Iovino, Hao Zuo, Renellys C. Perez, Shenfu Dong, Marion Kersalé, Michael Mayer, Johannes Mayer, Sabrina Speich, and Tarron Lamont
State Planet, 1-osr7, 4, https://doi.org/10.5194/sp-1-osr7-4-2023, https://doi.org/10.5194/sp-1-osr7-4-2023, 2023
Short summary
Short summary
We use ocean reanalyses, in which ocean models are combined with observations, to infer past changes in ocean circulation and heat transport in the South Atlantic. Comparing these estimates with other observation-based estimates, we find differences in their trends, variability, and mean heat transport but closer agreement in their mean overturning strength. Ocean reanalyses can help us understand the cause of these differences, which could improve estimates of ocean transports in this region.
Victor Rousseau, Robin Fraudeau, Matthew Hammond, Odilon Joël Houndegnonto, Michaël Ablain, Alejandro Blazquez, Fransisco Mir Calafat, Damien Desbruyères, Giuseppe Foti, William Llovel, Florence Marti, Benoît Meyssignac, Marco Restano, and Jérôme Benveniste
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2023-236, https://doi.org/10.5194/essd-2023-236, 2023
Preprint withdrawn
Short summary
Short summary
The estimation of regional Ocean Heat Content (OHC) is crucial for climate analysis and future climate predictions. In our study, we accurately estimate regional OHC changes in the Atlantic Ocean using satellite and in situ data. Findings reveal significant warming in the Atlantic basin from 2002 to 2020 with a mean trend of 0.17W/m², representing 230 times the power of global nuclear plants. The product has also been successfully validated in the North Atlantic basin using in situ data.
Karina von Schuckmann, Audrey Minière, Flora Gues, Francisco José Cuesta-Valero, Gottfried Kirchengast, Susheel Adusumilli, Fiammetta Straneo, Michaël Ablain, Richard P. Allan, Paul M. Barker, Hugo Beltrami, Alejandro Blazquez, Tim Boyer, Lijing Cheng, John Church, Damien Desbruyeres, Han Dolman, Catia M. Domingues, Almudena García-García, Donata Giglio, John E. Gilson, Maximilian Gorfer, Leopold Haimberger, Maria Z. Hakuba, Stefan Hendricks, Shigeki Hosoda, Gregory C. Johnson, Rachel Killick, Brian King, Nicolas Kolodziejczyk, Anton Korosov, Gerhard Krinner, Mikael Kuusela, Felix W. Landerer, Moritz Langer, Thomas Lavergne, Isobel Lawrence, Yuehua Li, John Lyman, Florence Marti, Ben Marzeion, Michael Mayer, Andrew H. MacDougall, Trevor McDougall, Didier Paolo Monselesan, Jan Nitzbon, Inès Otosaka, Jian Peng, Sarah Purkey, Dean Roemmich, Kanako Sato, Katsunari Sato, Abhishek Savita, Axel Schweiger, Andrew Shepherd, Sonia I. Seneviratne, Leon Simons, Donald A. Slater, Thomas Slater, Andrea K. Steiner, Toshio Suga, Tanguy Szekely, Wim Thiery, Mary-Louise Timmermans, Inne Vanderkelen, Susan E. Wjiffels, Tonghua Wu, and Michael Zemp
Earth Syst. Sci. Data, 15, 1675–1709, https://doi.org/10.5194/essd-15-1675-2023, https://doi.org/10.5194/essd-15-1675-2023, 2023
Short summary
Short summary
Earth's climate is out of energy balance, and this study quantifies how much heat has consequently accumulated over the past decades (ocean: 89 %, land: 6 %, cryosphere: 4 %, atmosphere: 1 %). Since 1971, this accumulated heat reached record values at an increasing pace. The Earth heat inventory provides a comprehensive view on the status and expectation of global warming, and we call for an implementation of this global climate indicator into the Paris Agreement’s Global Stocktake.
Laura C. Jackson, Eduardo Alastrué de Asenjo, Katinka Bellomo, Gokhan Danabasoglu, Helmuth Haak, Aixue Hu, Johann Jungclaus, Warren Lee, Virna L. Meccia, Oleg Saenko, Andrew Shao, and Didier Swingedouw
Geosci. Model Dev., 16, 1975–1995, https://doi.org/10.5194/gmd-16-1975-2023, https://doi.org/10.5194/gmd-16-1975-2023, 2023
Short summary
Short summary
The Atlantic meridional overturning circulation (AMOC) has an important impact on the climate. There are theories that freshening of the ocean might cause the AMOC to cross a tipping point (TP) beyond which recovery is difficult; however, it is unclear whether TPs exist in global climate models. Here, we outline a set of experiments designed to explore AMOC tipping points and sensitivity to additional freshwater input as part of the North Atlantic Hosing Model Intercomparison Project (NAHosMIP).
Denis L. Volkov, Claudia Schmid, Leah Chomiak, Cyril Germineaud, Shenfu Dong, and Marlos Goes
Ocean Sci., 18, 1741–1762, https://doi.org/10.5194/os-18-1741-2022, https://doi.org/10.5194/os-18-1741-2022, 2022
Short summary
Short summary
Ocean and atmosphere dynamics redistribute heat and freshwater, which drives regional sea level changes. This study reports on the east-to-west propagation of sea level anomalies in the subpolar North Atlantic as an important component of the interannual to decadal regional sea level variability. It is demonstrated that this variability is the result of a complex interplay between the local wind forcing, surface heat fluxes, and the advection of heat and freshwater by ocean currents.
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.
Marion Kersalé, Denis L. Volkov, Kandaga Pujiana, and Hong Zhang
Ocean Sci., 18, 193–212, https://doi.org/10.5194/os-18-193-2022, https://doi.org/10.5194/os-18-193-2022, 2022
Short summary
Short summary
The southern Indian Ocean is one of the major basins for regional heat accumulation and sea level rise. The year-to-year changes of regional sea level are influenced by water exchange with the Pacific Ocean via the Indonesian Throughflow. Using a general circulation model, we show that the spatiotemporal pattern of these changes is primarily set by local wind forcing modulated by El Niño–Southern Oscillation, while oceanic signals originating in the Pacific can amplify locally forced signals.
Marilena Oltmanns, N. Penny Holliday, James Screen, D. Gwyn Evans, Simon A. Josey, Sheldon Bacon, and Ben I. Moat
Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2021-79, https://doi.org/10.5194/wcd-2021-79, 2021
Revised manuscript not accepted
Short summary
Short summary
The Arctic is currently warming twice as fast as the global average. This results in enhanced melting and thus freshwater releases into the North Atlantic. Using a combination of observations and models, we show that atmosphere-ocean feedbacks initiated by freshwater releases into the North Atlantic lead to warmer and drier weather over Europe in subsequent summers. The existence of this dynamical link suggests that European summer weather can potentially be predicted months to years in advance.
Helen E. Phillips, Amit Tandon, Ryo Furue, Raleigh Hood, Caroline C. Ummenhofer, Jessica A. Benthuysen, Viviane Menezes, Shijian Hu, Ben Webber, Alejandra Sanchez-Franks, Deepak Cherian, Emily Shroyer, Ming Feng, Hemantha Wijesekera, Abhisek Chatterjee, Lisan Yu, Juliet Hermes, Raghu Murtugudde, Tomoki Tozuka, Danielle Su, Arvind Singh, Luca Centurioni, Satya Prakash, and Jerry Wiggert
Ocean Sci., 17, 1677–1751, https://doi.org/10.5194/os-17-1677-2021, https://doi.org/10.5194/os-17-1677-2021, 2021
Short summary
Short summary
Over the past decade, understanding of the Indian Ocean has progressed through new observations and advances in theory and models of the oceanic and atmospheric circulation. This review brings together new understanding of the ocean–atmosphere system in the Indian Ocean, describing Indian Ocean circulation patterns, air–sea interactions, climate variability, and the critical role of the Indian Ocean as a clearing house for anthropogenic heat.
Igor A. Dmitrenko, Denis L. Volkov, Tricia A. Stadnyk, Andrew Tefs, David G. Babb, Sergey A. Kirillov, Alex Crawford, Kevin Sydor, and David G. Barber
Ocean Sci., 17, 1367–1384, https://doi.org/10.5194/os-17-1367-2021, https://doi.org/10.5194/os-17-1367-2021, 2021
Short summary
Short summary
Significant trends of sea ice in Hudson Bay have led to a considerable increase in shipping activity. Therefore, understanding sea level variability is an urgent issue crucial for safe navigation and coastal infrastructure. Using the sea level, atmospheric and river discharge data, we assess environmental factors impacting variability of sea level at Churchill. We find that it is dominated by wind forcing, with the seasonal cycle generated by the seasonal cycle in atmospheric circulation.
Alejandra Sanchez-Franks, Eleanor Frajka-Williams, Ben I. Moat, and David A. Smeed
Ocean Sci., 17, 1321–1340, https://doi.org/10.5194/os-17-1321-2021, https://doi.org/10.5194/os-17-1321-2021, 2021
Short summary
Short summary
In the North Atlantic, ocean currents carry warm surface waters northward and return cooler deep waters southward. This type of ocean circulation, known as overturning, is important for the Earth’s climate. This overturning has been measured using a mooring array at 26° N in the North Atlantic since 2004. Here we use these mooring data and global satellite data to produce a new method for monitoring the overturning over longer timescales, which could potentially be applied to different latitudes.
Jack Giddings, Karen J. Heywood, Adrian J. Matthews, Manoj M. Joshi, Benjamin G. M. Webber, Alejandra Sanchez-Franks, Brian A. King, and Puthenveettil N. Vinayachandran
Ocean Sci., 17, 871–890, https://doi.org/10.5194/os-17-871-2021, https://doi.org/10.5194/os-17-871-2021, 2021
Short summary
Short summary
Little is known about the impact of chlorophyll on SST in the Bay of Bengal (BoB). Solar irradiance measured by an ocean glider and three Argo floats is used to determine the effect of chlorophyll on BoB SST during the 2016 summer monsoon. The Southwest Monsoon Current has high chlorophyll concentrations (∼0.5 mg m−3) and shallow solar penetration depths (∼14 m). Ocean mixed layer model simulations show that SST increases by 0.35°C per month, with the potential to influence monsoon rainfall.
Emma L. Worthington, Ben I. Moat, David A. Smeed, Jennifer V. Mecking, Robert Marsh, and Gerard D. McCarthy
Ocean Sci., 17, 285–299, https://doi.org/10.5194/os-17-285-2021, https://doi.org/10.5194/os-17-285-2021, 2021
Short summary
Short summary
The RAPID array has observed the Atlantic meridional overturning circulation (AMOC) since 2004, but the AMOC was directly calculated only five times from 1957–2004. Here we create a statistical regression model from RAPID data, relating AMOC changes to density changes within the different water masses at 26° N, and apply it to historical hydrographic data. The resulting 1981–2016 record shows that the AMOC from 2008–2012 was its weakest since the mid-1980s, but it shows no overall decline.
Bogi Hansen, Karin Margretha Húsgarð Larsen, Hjálmar Hátún, Steingrímur Jónsson, Sólveig Rósa Ólafsdóttir, Andreas Macrander, William Johns, N. Penny Holliday, and Steffen Malskær Olsen
Ocean Sci. Discuss., https://doi.org/10.5194/os-2021-14, https://doi.org/10.5194/os-2021-14, 2021
Preprint withdrawn
Short summary
Short summary
Compared to other freshwater sources, runoff from Iceland is small and usually flows into the Nordic Seas. Under certain wind conditions, it can, however, flow into the Iceland Basin and this occurred after 2014, when this region had already freshened from other causes. This explains why the surface freshening in this area became so extreme. The local and shallow character of this runoff allows it to have a disproportionate effect on vertical mixing, winter convection, and biological production.
Karina von Schuckmann, Lijing Cheng, Matthew D. Palmer, James Hansen, Caterina Tassone, Valentin Aich, Susheel Adusumilli, Hugo Beltrami, Tim Boyer, Francisco José Cuesta-Valero, Damien Desbruyères, Catia Domingues, Almudena García-García, Pierre Gentine, John Gilson, Maximilian Gorfer, Leopold Haimberger, Masayoshi Ishii, Gregory C. Johnson, Rachel Killick, Brian A. King, Gottfried Kirchengast, Nicolas Kolodziejczyk, John Lyman, Ben Marzeion, Michael Mayer, Maeva Monier, Didier Paolo Monselesan, Sarah Purkey, Dean Roemmich, Axel Schweiger, Sonia I. Seneviratne, Andrew Shepherd, Donald A. Slater, Andrea K. Steiner, Fiammetta Straneo, Mary-Louise Timmermans, and Susan E. Wijffels
Earth Syst. Sci. Data, 12, 2013–2041, https://doi.org/10.5194/essd-12-2013-2020, https://doi.org/10.5194/essd-12-2013-2020, 2020
Short summary
Short summary
Understanding how much and where the heat is distributed in the Earth system is fundamental to understanding how this affects warming oceans, atmosphere and land, rising temperatures and sea level, and loss of grounded and floating ice, which are fundamental concerns for society. This study is a Global Climate Observing System (GCOS) concerted international effort to obtain the Earth heat inventory over the period 1960–2018.
Torben Koenigk, Ramon Fuentes-Franco, Virna Meccia, Oliver Gutjahr, Laura C. Jackson, Adrian L. New, Pablo Ortega, Christopher Roberts, Malcolm Roberts, Thomas Arsouze, Doroteaciro Iovino, Marie-Pierre Moine, and Dmitry V. Sein
Ocean Sci. Discuss., https://doi.org/10.5194/os-2020-41, https://doi.org/10.5194/os-2020-41, 2020
Revised manuscript not accepted
Short summary
Short summary
The mixing of water masses into the deep ocean in the North Atlantic is important for the entire global ocean circulation. We use seven global climate models to investigate the effect of increasing the model resolution on this deep ocean mixing. The main result is that increased model resolution leads to a deeper mixing of water masses in the Labrador Sea but has less effect in the Greenland Sea. However, most of the models overestimate the deep ocean mixing compared to observations.
Yang Liu, Jisk Attema, Ben Moat, and Wilco Hazeleger
Earth Syst. Dynam., 11, 77–96, https://doi.org/10.5194/esd-11-77-2020, https://doi.org/10.5194/esd-11-77-2020, 2020
Short summary
Short summary
Poleward meridional energy transport (MET) has significant impact on the climate in the Arctic. In this study, we quantify and intercompare MET at subpolar latitudes from six reanalysis data sets. The results indicate that the spatial distribution and temporal variations of MET differ substantially among the reanalysis data sets. Our study suggests that the MET estimated from reanalyses is useful for the evaluation of energy transports but should be used with great care.
Malcolm J. Roberts, Alex Baker, Ed W. Blockley, Daley Calvert, Andrew Coward, Helene T. Hewitt, Laura C. Jackson, Till Kuhlbrodt, Pierre Mathiot, Christopher D. Roberts, Reinhard Schiemann, Jon Seddon, Benoît Vannière, and Pier Luigi Vidale
Geosci. Model Dev., 12, 4999–5028, https://doi.org/10.5194/gmd-12-4999-2019, https://doi.org/10.5194/gmd-12-4999-2019, 2019
Short summary
Short summary
We investigate the role that horizontal grid spacing plays in global coupled climate model simulations, together with examining the efficacy of a new design of simulation experiments that is being used by the community for multi-model comparison. We found that finer grid spacing in both atmosphere and ocean–sea ice models leads to a general reduction in bias compared to observations, and that once eddies in the ocean are resolved, several key climate processes are greatly improved.
Damien G. Desbruyères, Herlé Mercier, Guillaume Maze, and Nathalie Daniault
Ocean Sci., 15, 809–817, https://doi.org/10.5194/os-15-809-2019, https://doi.org/10.5194/os-15-809-2019, 2019
Short summary
Short summary
In the North Atlantic, ocean currents transport warm waters northward in the upper water column, and cold waters southwards at depth. This circulation is here reconstructed from surface data and thermodynamics theory. Its driving role in recent temperature changes (1993–2017) in the North Atlantic is evidenced, and predictions of near-future variability (5 years) are provided and discussed.
Arseny A. Kubryakov, Sergey V. Stanichny, and Denis L. Volkov
Ocean Sci., 13, 443–452, https://doi.org/10.5194/os-13-443-2017, https://doi.org/10.5194/os-13-443-2017, 2017
Short summary
Short summary
The Black Sea dynamics impact on the local sea level rise. In recent decades, the increase of the wind curl induced the intensification of the cyclonic circulation and divergence in the basin center. As a result, the sea level rise in the coastal areas is 1.5–2 times higher than in the basin center. Additional heterogeneity of sea level trends is related to the changes of the mesoscale dynamics. The large-scale dynamic sea level and its rise can be estimated using atmospheric reanalysis data.
Robert Marsh, Ivan D. Haigh, Stuart A. Cunningham, Mark E. Inall, Marie Porter, and Ben I. Moat
Ocean Sci., 13, 315–335, https://doi.org/10.5194/os-13-315-2017, https://doi.org/10.5194/os-13-315-2017, 2017
Short summary
Short summary
To the west of Britain and Ireland, a strong ocean current follows the steep slope that separates the deep Atlantic and the continental shelf. This “Slope Current” exerts an Atlantic influence on the North Sea and its ecosystems. Using a combination of computer modelling and archived data, we find that the Slope Current weakened over 1988–2007, reducing Atlantic influence on the North Sea, due to a combination of warming of the subpolar North Atlantic and weakening winds to the west of Scotland.
Claudie Beaulieu, Harriet Cole, Stephanie Henson, Andrew Yool, Thomas R. Anderson, Lee de Mora, Erik T. Buitenhuis, Momme Butenschön, Ian J. Totterdell, and J. Icarus Allen
Biogeosciences, 13, 4533–4553, https://doi.org/10.5194/bg-13-4533-2016, https://doi.org/10.5194/bg-13-4533-2016, 2016
Short summary
Short summary
Regime shifts have been suggested in the late 1970s and late 1980s in the Gulf of Alaska with important consequences for fisheries. Here we investigate the ability of a suite of ocean biogeochemical models of varying complexity to simulate these regime shifts. Our results demonstrate that ocean models can successfully simulate regime shifts in the Gulf of Alaska region, thereby improving our understanding of how changes in physical conditions are propagated from lower to upper trophic levels.
E. Frajka-Williams, C. S. Meinen, W. E. Johns, D. A. Smeed, A. Duchez, A. J. Lawrence, D. A. Cuthbertson, G. D. McCarthy, H. L. Bryden, M. O. Baringer, B. I. Moat, and D. Rayner
Ocean Sci., 12, 481–493, https://doi.org/10.5194/os-12-481-2016, https://doi.org/10.5194/os-12-481-2016, 2016
Short summary
Short summary
The ocean meridional overturning circulation (MOC) is predicted by climate models to slow down in this century, resulting in reduced transport of heat northward to mid-latitudes. At 26° N, the Atlantic MOC has been measured continuously for the past decade (2004–2014). In this paper, we discuss the 10-year record of variability, identify the origins of the continued weakening of the circulation, and discuss high-frequency (subannual) compensation between transport components.
Wolfgang Buermann, Claudie Beaulieu, Bikash Parida, David Medvigy, George J. Collatz, Justin Sheffield, and Jorge L. Sarmiento
Biogeosciences, 13, 1597–1607, https://doi.org/10.5194/bg-13-1597-2016, https://doi.org/10.5194/bg-13-1597-2016, 2016
Short summary
Short summary
Recent analyses of the global carbon budget found a substantial increase in the land sink in the late 1980s whose origin remains unknown. Consistent with this shift, we find that plant growth increased in the late 1980s especially in Eurasia and northern Africa. There, climatic constraints on plant growth have eased possibly due to linked climate modes in the North Atlantic. Better understanding of North Atlantic climate may be essential for more credible projections of the land carbon sink.
P. Achtert, I. M. Brooks, B. J. Brooks, B. I. Moat, J. Prytherch, P. O. G. Persson, and M. Tjernström
Atmos. Meas. Tech., 8, 4993–5007, https://doi.org/10.5194/amt-8-4993-2015, https://doi.org/10.5194/amt-8-4993-2015, 2015
Short summary
Short summary
Doppler lidar wind measurements were obtained during a 3-month Arctic cruise in summer 2014. Ship-motion effects were compensated by combining a commercial Doppler lidar with a custom-made motion-stabilisation platform. This enables the retrieval of wind profiles in the Arctic boundary layer with uncertainties comparable to land-based lidar measurements and standard radiosondes. The presented set-up has the potential to facilitate continuous ship-based wind profile measurements over the oceans.
J. Prytherch, M. J. Yelland, I. M. Brooks, D. J. Tupman, R. W. Pascal, B. I. Moat, and S. J. Norris
Atmos. Chem. Phys., 15, 10619–10629, https://doi.org/10.5194/acp-15-10619-2015, https://doi.org/10.5194/acp-15-10619-2015, 2015
Short summary
Short summary
Signals at scales associated with wave and platform motion are often apparent in ship-based turbulent flux measurements, but it has been uncertain whether this is due to measurement error or to wind-wave interactions. We show that the signal has a dependence on horizontal ship velocity and that removing the signal reduces the dependence of the momentum flux on the orientation of the ship to the wind. We conclude that the signal is a bias due to time-varying motion-dependent flow distortion.
M. Borghini, H. Bryden, K. Schroeder, S. Sparnocchia, and A. Vetrano
Ocean Sci., 10, 693–700, https://doi.org/10.5194/os-10-693-2014, https://doi.org/10.5194/os-10-693-2014, 2014
H. L. Bryden, B. A. King, G. D. McCarthy, and E. L. McDonagh
Ocean Sci., 10, 683–691, https://doi.org/10.5194/os-10-683-2014, https://doi.org/10.5194/os-10-683-2014, 2014
D. A. Smeed, G. D. McCarthy, S. A. Cunningham, E. Frajka-Williams, D. Rayner, W. E. Johns, C. S. Meinen, M. O. Baringer, B. I. Moat, A. Duchez, and H. L. Bryden
Ocean Sci., 10, 29–38, https://doi.org/10.5194/os-10-29-2014, https://doi.org/10.5194/os-10-29-2014, 2014
S. J. Norris, I. M. Brooks, B. I. Moat, M. J. Yelland, G. de Leeuw, R. W. Pascal, and B. Brooks
Ocean Sci., 9, 133–145, https://doi.org/10.5194/os-9-133-2013, https://doi.org/10.5194/os-9-133-2013, 2013
Related subject area
Approach: In situ Observations | Depth range: Deep Ocean | Geographical range: Deep Seas: North Atlantic | Phenomena: Temperature, Salinity and Density Fields
Observed decline of the Atlantic meridional overturning circulation 2004–2012
D. A. Smeed, G. D. McCarthy, S. A. Cunningham, E. Frajka-Williams, D. Rayner, W. E. Johns, C. S. Meinen, M. O. Baringer, B. I. Moat, A. Duchez, and H. L. Bryden
Ocean Sci., 10, 29–38, https://doi.org/10.5194/os-10-29-2014, https://doi.org/10.5194/os-10-29-2014, 2014
Cited articles
Barber, D. C., Dyke, A., Hillaire-Marcel, C., Jennings, A. E., Andrews, J.
T., Kerwin, M. W., Bilodeau, F., McNeely, R., Southon, J., Morehead, M. D.,
and Gagnon, J.-M.: Forcing of the cold event of 8,200 years ago by
catastrophic drainage of Laurentide lakes, Nature, 400, 344–348,
https://doi.org/10.1038/22504, 1999.
Beaulieu, C. and Killick, R.: Distinguishing trends and shifts from memory
in climate data Distinguishing trends and shifts from memory in climate
data, J. Climate, 31, 9519–9543, https://doi.org/10.1175/jcli-d-17-0863.1, 2018.
Blockley, E. W., Martin, M. J., McLaren, A. J., Ryan, A. G., Waters, J., Lea, D. J., Mirouze, I., Peterson, K. A., Sellar, A., and Storkey, D.: Recent development of the Met Office operational ocean forecasting system: an overview and assessment of the new Global FOAM forecasts, Geosci. Model Dev., 7, 2613–2638, https://doi.org/10.5194/gmd-7-2613-2014, 2014.
Bower, A. S., Lozier M. S., Gary S. F., and Böning C. W.,: Interior
pathways of the North Atlantic Meridional Overturning Circulation, Nature,
459, 243–247, https://doi.org/10.1038/nature07979, 2009.
Bryden, H. L., Johns, W. E., King, B. A., McCarthy, G. A., 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/10.1175/JCLI-D-19-0323.1,
2020.
Calafat, F. M., Wahl, T., Lindsten, F., Williams, J., and Frajka-Williams, E.:
Coherent modulation of the sea-level annual cycle in the United States by
Atlantic Rossby waves, Nat. Comm., 9, 2571, https://doi.org/10.1038/s41467-018-04898-y,
2018.
Copernicus Climate Change Service (C3S) (2017): ERA5: Fifth generation of ECMWF atmospheric reanalyses of the global climate, Copernicus Climate Change Service Climate Data Store (CDS), available at: https://cds.climate.copernicus.eu/cdsapp#!/home, last access: 16 July 2020.
Cunningham, S. A., Kanzow, T. O., Rayner, D., Barringer, M. O., Johns, W. E.,
Marotzke, J., Longworth, H. R., Grant, E. M., Hirschi, J. J.-M., Beal, L. M.,
Meinen, C. S., and Bryden, H. L.: Temporal variability of the Atlantic
Meridional Overturning Circulation at 26.5∘ N, Science, 317,
935–938, https://doi.org/10.1126/science.1141304, 2007.
Delworth, T. L. and Mann, M. E.: Observed and simulated multidecadal
variability in the Northern Hemisphere, Clim. Dyn., 16, 661–676,
https://doi.org/10.1007/s003820000075, 2000.
Desbruyères, D. G., Mercier, H., Maze, G., and Daniault, N.: Surface predictor of overturning circulation and heat content change in the subpolar North Atlantic, Ocean Sci., 15, 809–817, https://doi.org/10.5194/os-15-809-2019, 2019.
Duchez, A., Frajka-Williams, E., Castro, N., Hirschi, J., and Coward, A.:
Seasonal to interannual variability in density around the Canary Islands and
their influence on the Atlantic meridional overturning circulation at
26∘ N, J. Geophys. Res.-Ocean., 119, 1843–1860,
https://doi.org/10.1002/2013JC009416, 2014.
Duchez, A., Frajka-Williams, E., Josey, S. A., Evans, D. G., Grist, J. P.,
Marsh, R., McCarthy, G. D., Sinha, B., Berry, D. I., and Hirschi, J. J.-M.:
Drivers of exceptionally cold North Atlantic Ocean temperatures and their
link to the 2015 European heat wave, Environ. Res. Lett., 11, 074004, https://doi.org/10.1088/1748-9326/11/7/074004, 2016.
Enfield, D. B., Mestas-Nunez, A. M., and Trimble, P. J.: The Atlantic
Multidecadal Oscillation and its relationship to rainfall and river flows in
the continental U.S., Geophys. Res. Lett., 28, 2077–2080,
https://doi.org/10.1029/2000GL012745, 2001.
Frajka-Williams, E., Meinen, C. S., Johns, W. E., Smeed, D. A., Duchez, A., Lawrence, A. J., Cuthbertson, D. A., McCarthy, G. D., Bryden, H. L., Baringer, M. O., Moat, B. I., and Rayner, D.: Compensation between meridional flow components of the Atlantic MOC at 26∘ N, Ocean Sci., 12, 481–493, https://doi.org/10.5194/os-12-481-2016, 2016.
Frajka-Williams, E., Beaulieu, C., and Duchez, A.: Emerging negative Atlantic
Multidecadal Oscillation in spite of warm subtropics, Scientific Reports,
7, 11224, https://doi.org/10.1038/s41598-017-11046-x, 2017.
Frajka-Williams, E., Ansorge, I. J., Baehr, J., Bryden, H. L., Chidichimo,
M. P., Cunningham, S. A., Danabasoglu, G., Dong, S., Donohue, K. A., Elipot,
S., Heimbach, P., Holliday, N. P., Hummels, R., Jackson, L. C., Karstensen,
J., Lankhorst, M., Bras, I. A. L., Lozier, M. S., McDonagh, E. L., Meinen,
C. S., Mercier, H., Moat, B. I., Perez, R. C., Piecuch, C. G., Rhein, M.,
Srokosz, M. A., Trenberth, K. E., Bacon, S., Forget, G., Goni, G., Kieke,
D., Koelling, J., Lamont, T., McCarthy, G. D., Mertens, C., Send, U., Smeed,
D. A., Speich, S., van den Berg, M., Volkov, D., and Wilson, C.: OceanObs19:
Atlantic meridional overturning circulation: Observed transports and
variability, Front. Mar. Sci., 6, 260,
https://doi.org/10.3389/fmars.2019.00260, 2019.
Ganopolski, A. and Rahmstorf, S.: Rapid changes of glacial climate simulated
in a coupled climate model, Nature, 409, 153–158, https://doi.org/10.1038/35051500,
2001.
Gulev, S. K., Latif, M., Keenlyside, N., Park, W., and Koltermann, K. P.: North
Atlantic Ocean control on surface heat flux on multidecadal timescales,
Nature, 499, 464–467, https://doi.org/10.1038/nature12268, 2013.
IPCC: Observations: Ocean, in: Climate Change 2013: The Physical Science
Basis. Contribution of Working Group I to the Fifth Assess- ment Report of
the Intergovernmental Panel on Climate Change, edited by: Stocker, T. F.,
Qin, D., Plattner, G.-K., Tignor, M., Allen, S., Boschung, J., Nauels, A.,
Xia, Y., Bex, V., and Midgley, P., 1535 pp, Cambridge University Press,
Cambridge, United Kingdom, https://doi.org/10.1017/CBO9781107415324, 2013.
Jackson, L. C., Peterson, K. A., Roberts, C. D., and Wood, R. A.: Recent
slowing of Atlantic overturning circulation as a recovery from earlier
strengthening, Nat. Geosci., 9, 518–522, 2016.
Jackson, J. C., Dubois, C., Forget, G., Haines, K., Harrison, M., Iovino, D., Kohl,
A., Mignac, D., Mashina, S., Peterson, K. A., Piecuch, C. G., Roberts, C., Robson,
J., Storto, A., Toyoda, T., Valdivieso, M., Wilson, C., Wang, Y., and Zuo, H.: The
mean state and variability of the north Atlantic circulation: a perspective
from ocean reanalyses, J. Geophys. Res.-Ocean., 124, 9141–9170,
https://doi.org/10.1029/2019JC015210, 2019.
Johns, W. E., Baringer, M. O., Beal, L. M., Cunningham, S. A., Kanzow, T.,
Bryden, H. L., Hirschi, J. J.-M., Marotzke, J., Meinen, C. S., Shaw, B., and
Curry, R.: Continuous, Array-Based Estimates of Atlantic Ocean Heat
Transport at 26.5∘ N, J. Climate, 24, 2429–2449, https://doi.org/10.1175/2010JCLI3997.1, 2011.
Johnson, H. L. and Marshall, D. P.: A theory for the surface Atlantic
response to thermohaline variability, J. Phys. Oceanogr., 32, 1121–1132, https://doi.org/10.1175/1520-0485(2002)032<1121:ATFTSA>2.0.CO;2, 2002.
Josey, S. A., Hirschi, J. J.-M., Sinha, B., Duchez, A., Grist, J. P., and Marsh,
R.: The Recent Atlantic Cold Anomaly: Causes, Consequences, and Related
Phenomena, Ann. Rev. Mar. Sci., 10, 475–501,
https://doi.org/10.1146/annurev-marine-121916-063102, 2018.
Kanzow, T., Cunningham, S. A., Rayner, D., Hirschi, J. J.-M., Johns, W. E.,
Baringer, M. O., Bryden, H. L., Beal, L. M., Meinen, C. S., and Marotzke, J.:
Observed flow compensation associated with the MOC at 26.5∘ N in
the Atlantic, Science, 317, 938–941, https://doi.org/10.1126/science.1141293, 2007.
Kanzow, T., Johnson, H., Marshall, D., Cunningham, S. A., Hirschi, J. J.-M.,
Mujahid, A., Bryden, H. L., and Johns, W. E.: Basin-wide integrated volume
transports in an eddy-filled ocean, J. Phys. Oceanogr., 39,
3091–3110, https://doi.org/10.1175/2009JPO4185.1, 2009.
Kanzow, T., Cunningham, S. A., Johns, W. E., Hirschi, J. J.-M., Marotzke,
J., Baringer, M. O., Meinen, C. S., Chidichimo, M. P., Atkinson, C., Beal,
L. M., Bryden, H. L., and Collins, J.: Seasonal variability of the Atlantic
meridional overturning circulation at 26.5∘ N, J. Climate, 23,
5678–5698, https://doi.org/10.1175/2010JCLI3389.1, 2010.
Killick, R., Fearnhead, P., and Eckley, I. A.: Optimal Detection of Changepoints With a Linear
Computational Cost, J. Am. Stat. Assoc., 107, 1590–1598, https://doi.org/10.1080/01621459.2012.737745, 2012.
Killick, R., Beaulieu, C., Taylor, S., and Hullait, H.: Envcpt: Detection of
structural changes in climate and environment time series (Version version
1.1.1), CRAN, retrieved from: https://CRAN.R-project.org/package=EnvCpt (last access: 16 July 2020),
2018.
Lozier, M. S.: Deconstructing the Conveyor Belt, Science, 328, 1507–1511,
https://doi.org/10.1126/science.1189250, 2010.
Lozier, M. S., Li, F., Bacon, S., Bahr, F., Bower, A. S., Cunningham, S. A.,
de Jong, M. F., de Steur, L., de Young, 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.
McCarthy, G., Frajka-Williams, E., Johns, W. E., Baringer, M. O., Meinen, C.
S., Bryden, H. L., Rayner, D., Duchez, A., Roberts, C. D., and Cunningham, S.
A.: Observed Interannual Variability of the Atlantic Meridional Overturning
Circulation at 26.5∘ N, Geophys. Res. Lett., 39, L19609,
https://doi.org/10.1029/2012GL052933, 2012.
McCarthy, G. D., Smeed, D. A., Johns, W. E., Frajka-Williams, E., Moat, B.
I., Rayner, D., Baringer, M. O., Meinen, C. S., and Bryden, H. L.: Measuring
the Atlantic meridional overturning circulation at 26∘ N, Prog.
Oceanogr., 130, 91–111, https://doi.org/10.1016/j.pocean.2014.10.006, 2015.
Megann, A., Storkey, D., Aksenov, Y., Alderson, S., Calvert, D., Graham, T., Hyder, P., Siddorn, J., and Sinha, B.: GO5.0: the joint NERC–Met Office NEMO global ocean model for use in coupled and forced applications, Geosci. Model Dev., 7, 1069–1092, https://doi.org/10.5194/gmd-7-1069-2014, 2014.
Meinen, C. S., Johns, W. E., Moat, B. I., Smith, R. H., Johns, E., Rayner, D.,
Frajka-Williams, E., Garcia, R. F., and Garzoli, S. L.: Structure and variability
of the Antilles Current at 26.5∘ N, J. Geophys. Res.-Ocean., 124,
3700–3723, https://doi.org/10.1029/2018JC014836, 2019.
Mercier, H., Lherminier, P., Sarajanov, A., Gaillard, F., Daniault, N.,
Desbruyères, D. G., Falina, A., Ferron, B., Gourcuff, C., Huck, T., and
Thierry, V.: Variability of the meridional circulation at the
Greenland-Portugal OVIDE section from 1993 to 2010, Prog. Oceanogr., 132,
250–261, https://doi.org/10.1016/j.pocean.2013.11.001, 2015.
Moat, B. I., Josey, S. A., Sinha, B., Blaker, A. T., Smeed, D. A., McCarthy,
G., Johns, W. E., Hirschi, J. J.-M., Frajka-Williams, E., Rayner, D.,
Duchez, A., and Coward, A. C.: Major variations in subtropical North Atlantic
heat transport at short (5 day) timescales and their causes, J. Geophys.
Res.-Ocean., 121, 3237–3249, https://doi.org/10.1002/2016JC011660, 2016.
Moat, B. I., Sinha, B., Josey, S. A., Robson, J., Ortega, P., Sévellec,
F., Holliday, N. P., McCarthy, G. D., New, A. L., and Hirschi, J. J.-M.:
Insights into decadal North Atlantic sea surface temperature and ocean heat
content variability from an eddy-permitting coupled climate model, J.
Climate, 32, 6137–6161, https://doi.org/10.1175/JCLI-D-18-0709.1, 2019.
Molinari, R. L., Fine R. A., Wilson W. D., Curry R. G., Abell, J., and
McCartney, M. S.: The arrival of recently formed Labrador Sea Water in the
Deep Western Boundary Current at 26.5∘ N, Geophys. Res. Lett., 25,
2249–2252, https://doi.org/10.1029/98GL01853, 1998.
Pickart, R. S. and Spall, M. A.: Impact of Labrador Sea convection on the
North Atlantic Meridional Overturning circulation, J. Phys. Oceanogr.,
37, 2207–2227, https://doi.org/10.1175/JPO3178.1, 2007.
Roberts, C. D., Waters, J., Peterson, K. A., Palmer, M., McCarthy, G. D.,
Frajka-Williams, E., Haines, K., Lea, D. J., Martin, M. J., Storkey, D.,
Blockley, E. W., and Zuo, H.: Atmosphere drives observed interannual
variability of the Atlantic meridional overturning circulation at
26.5∘ N, Geophys. Res. Lett., 40, 5164–5170, https://doi.org/10.1002/grl.50930, 2013.
Robson, J., Sutton, R., and Smith, D.: Atlantic overturning in decline?, Nat.
Geosci., 7, 2–3, https://doi.org/10.1038/ngeo2050, 2014.
Sinha, B., Smeed, D. A., McCarthy, G., Moat, B. I., Josey, S. A., Hirschi,
J. J.-M., Frajka-Williams, E., Blaker, A. T., Rayner, D., and Madec, G.: The
accuracy of estimates of the overturning circulation from basin-wide mooring
arrays, Prog. Oceanogr., 160, 101–123,
https://doi.org/10.1016/j.pocean.2017.12.001, 2018.
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., Johns, W., Moat, B., Frajka-Williams, E., Rayner,
D., Meinen, C., Baringer, M., Bryden, H., and McCarthy, G.: The North
Atlantic Ocean is in a state of reduced overturning, Geophys. Res. Lett.,
45, 1527–1533, https://doi.org/10.1002/2017GL076350, 2018.
Smeed, D., Moat, B. I., Rayner, D., Johns, W. E., Baringer, M. O., Volkov, D. L.,
and Frajka-Williams, E.: Atlantic meridional overturning circulation
observed by the RAPID-MOCHA-WBTS (RAPID-Meridional Overturning Circulation
and Heatflux Array-Western Boundary Time Series) array at 26∘ N
from 2004 to 2018, British Oceanographic Data Centre, National Oceanography
Centre, NERC, UK, https://doi.org/10.5285/8cd7e7bb-9a20-05d8-e053-6c86abc012c2, 2019.
Srokosz, M., Baringer, M., Bryden, H., Cunningham, S., Delworth, T., Lozier,
S., Marotzke, J., and Sutton, R.: Past, Present, and Future Changes in the
Atlantic Meridional Overturning Circulation, B. Am.
Meteorol. Soc., 93, 1663–1676, https://doi.org/10.1175/BAMS-D-11-00151.1, 2012.
Srokosz, M. A. and Bryden, H. L.: Observing the Atlantic Meridional
Overturning Circulation yields a decade of inevitable surprises, Science,
348, 1255575, https://doi.org/10.1126/science.1255575, 2015.
Sutton, R. T. and Dong, B.: Atlantic Ocean influence on a shift in European
climate in the 1990s, Nature Geosci., 5, 788–792, https://doi.org/10.1038/ngeo1595,
2012.
Sutton, R. T., McCarthy, G. D., Robson, J., Sinha, B., Archibald, A., and
Gray, L. J.: Atlantic multi-decadal variability and the UK ACSIS programme,
B. Am. Meteorol. Soc., 99, 415–425, https://doi.org/10.1175/BAMS-D-16-0266.1, 2018.
Trenberth, K. E. and Shea, D. J.: Atlantic hurricanes and natural
variability in 2005, Geophys. Res. Lett., 33, L12704,
https://doi.org/10.1029/2006GL026894, 2006.
van Sebille, E., Baringer, M. O., Johns, W. E., Meinen, C. S., Beal, L. M.,
de Jong, M. F., and van Aken, H. M.: Propagation pathways of classical
Labrador Sea water from its source region to 26∘ N, J. Geophys.
Res.-Ocean., 116, C12027, https://doi.org/10.1029/2011JC007171, 2011.
Waters, J., Lea, D. J., Martin, J., Mirouze, I., Weaver, A., and While, J.:
Implementing a variational data assimilation system in an operational 1/4
degree global ocean model, Q. J. Roy. Meteorol. Soc., 141, 333–349, 2015.
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, 2016.
Zhang, R.: Anticorrelated multidecadal variations between surface and
subsurface tropical North Atlantic, Geophys. Res. Lett., 34, L12713,
https://doi.org/10.1029/2007GL030225, 2007.
Zhang, R., Sutton, R., Danabasoglu, G., Kwon, Y.-O., Marsh, R., Yeager, S.
G., Amrhein, D. E., and Little, C. M.: A review of the role of the Atlantic
meridional overturning circulation in Atlantic Multidecadal Variability and
associated climate impacts, Rev. Geophys., 57, 316–375,
https://doi.org/10.1029/2019RG000644, 2019.
Zhao, J. and Johns, W. E.: Wind-driven seasonal cycle of the Atlantic
meridional overturning circulation, J. Phys. Oceanogr., 44, 1541–1562, https://doi.org/10.1175/JPO-D-13-0144.1, 2014a.
Zhao, J. and Johns, W. E.: Wind-forced interannual variability of the
Atlantic meridional overturning circulation at 26.5∘ N, J.
Geophys. Res.-Ocean., 119, 2403–2419, https://doi.org/10.1002/2013JC009407, 2014b.
Zou, S. and Lozier, M. S.: Breaking the linkage between Labrador Sea Water
production and its export to the subtropical gyre, J. Phys.
Oceanogr., 46, 2169–2182, https://doi.org/10.1175/JPO-D-15-0210.1, 2016.
Short summary
The RAPID 26° N array has been measuring the Atlantic meridional overturning circulation (AMOC) since 2004. Since 2009 the AMOC has, compared with previous years, been in a low state. In 2013–2015, in the northern North Atlantic, strong cooling was observed in the ocean and anticipated to intensify the strength of the AMOC some years later. Here, we analyse the latest results from 26° N and conclude that while the AMOC has increased since 2009, this increase is not statistically significant.
The RAPID 26° N array has been measuring the Atlantic meridional overturning circulation (AMOC)...
