Articles | Volume 18, issue 4
https://doi.org/10.5194/os-18-953-2022
© Author(s) 2022. 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-18-953-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
06 Jul 2022
Research article |
| 06 Jul 2022
| 06 Jul 2022
Causes of the 2015 North Atlantic cold anomaly in a global state estimate
British Antarctic Survey, NERC, UKRI, Cambridge, UK
Daniel C. Jones
British Antarctic Survey, NERC, UKRI, Cambridge, UK
Simon A. Josey
National Oceanography Centre, Southampton, UK
Bablu Sinha
National Oceanography Centre, Southampton, UK
Gael Forget
EAPS, MIT, Cambridge, MA, USA
Related authors
Rachael N. C. Sanders, Elaine L. McDonagh, Siv K. Lauvset, Charles E. Turner, Thomas W. N. Haine, Nadine Goris, and Richard Sanders
EGUsphere, https://doi.org/10.5194/egusphere-2025-3729, https://doi.org/10.5194/egusphere-2025-3729, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
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Oxygen is essential to marine life, but the amount of oxygen in the ocean has been decreasing in recent decades. Using observations of oxygen concentration interpolated across a section of the subtropical North Atlantic Ocean, we show that deoxygenation in the region is primarily driven by an increase in oxygen being consumed during remineralisation of organic matter. The impact of this is strongest at depths of around 600 m, where the process drives up to 70 % of the total deoxygenation.
Rachael N. C. Sanders, Elaine L. McDonagh, Siv K. Lauvset, Charles E. Turner, Thomas W. N. Haine, Nadine Goris, and Richard Sanders
EGUsphere, https://doi.org/10.5194/egusphere-2025-3729, https://doi.org/10.5194/egusphere-2025-3729, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
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Oxygen is essential to marine life, but the amount of oxygen in the ocean has been decreasing in recent decades. Using observations of oxygen concentration interpolated across a section of the subtropical North Atlantic Ocean, we show that deoxygenation in the region is primarily driven by an increase in oxygen being consumed during remineralisation of organic matter. The impact of this is strongest at depths of around 600 m, where the process drives up to 70 % of the total deoxygenation.
Andreas Schiller, Simon A. Josey, John Siddorn, and Ibrahim Hoteit
State Planet, 5-opsr, 18, https://doi.org/10.5194/sp-5-opsr-18-2025, https://doi.org/10.5194/sp-5-opsr-18-2025, 2025
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The study illustrates the way atmospheric fields are used in ocean models as boundary conditions for the provisioning of the exchanges of heat, freshwater, and momentum fluxes. Such fluxes can be based on remote sensing instruments or provided directly by numerical weather prediction systems. Air–sea flux datasets are defined by their spatial and temporal resolutions and are limited by associated biases. Air–sea flux datasets for ocean models should be chosen with the applications in mind.
Catherine Guiavarc'h, David Storkey, Adam T. Blaker, Ed Blockley, Alex Megann, Helene Hewitt, Michael J. Bell, Daley Calvert, Dan Copsey, Bablu Sinha, Sophia Moreton, Pierre Mathiot, and Bo An
Geosci. Model Dev., 18, 377–403, https://doi.org/10.5194/gmd-18-377-2025, https://doi.org/10.5194/gmd-18-377-2025, 2025
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The Global Ocean and Sea Ice configuration version 9 (GOSI9) is the new UK hierarchy of model configurations based on the Nucleus for European Modelling of the Ocean (NEMO) and available at three resolutions. It will be used for various applications, e.g. weather forecasting and climate prediction. It improves upon the previous version by reducing global temperature and salinity biases and enhancing the representation of Arctic sea ice and the Antarctic Circumpolar Current.
Alex T. Archibald, Bablu Sinha, Maria R. Russo, Emily Matthews, Freya A. Squires, N. Luke Abraham, Stephane J.-B. Bauguitte, Thomas J. Bannan, Thomas G. Bell, David Berry, Lucy J. Carpenter, Hugh Coe, Andrew Coward, Peter Edwards, Daniel Feltham, Dwayne Heard, Jim Hopkins, James Keeble, Elizabeth C. Kent, Brian A. King, Isobel R. Lawrence, James Lee, Claire R. Macintosh, Alex Megann, Bengamin I. Moat, Katie Read, Chris Reed, Malcolm J. Roberts, Reinhard Schiemann, David Schroeder, Timothy J. Smyth, Loren Temple, Navaneeth Thamban, Lisa Whalley, Simon Williams, Huihui Wu, and Mingxi Yang
Earth Syst. Sci. Data, 17, 135–164, https://doi.org/10.5194/essd-17-135-2025, https://doi.org/10.5194/essd-17-135-2025, 2025
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Here, we present an overview of the data generated as part of the North Atlantic Climate System Integrated Study (ACSIS) programme that 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). The datasets described here cover the North Atlantic Ocean, the atmosphere above (it including its composition), and Arctic sea ice.
Phoebe A. Hudson, Adrien C. H. Martin, Simon A. Josey, Alice Marzocchi, and Athanasios Angeloudis
Ocean Sci., 20, 341–367, https://doi.org/10.5194/os-20-341-2024, https://doi.org/10.5194/os-20-341-2024, 2024
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Satellite salinity data are used for the first time to study variability in Arctic freshwater transport from the Lena River and are shown to be a valuable tool for studying this region. These data confirm east/westerly wind is the main control on fresh water and sea ice transport rather than the volume of river runoff. The strong role of the wind suggests understanding how wind patterns will change is key to predicting future Arctic circulation and sea ice concentration.
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
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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.
Lea Poropat, Dani Jones, Simon D. A. Thomas, and Céline Heuzé
Ocean Sci., 20, 201–215, https://doi.org/10.5194/os-20-201-2024, https://doi.org/10.5194/os-20-201-2024, 2024
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In this study we use a machine learning method called a Gaussian mixture model to divide part of the ocean (northwestern European seas and part of the Atlantic Ocean) into regions based on satellite observations of sea level. This helps us study each of these regions separately and learn more about what causes sea level changes there. We find that the ocean is first divided based on bathymetry and then based on other features such as water masses and typical atmospheric conditions.
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
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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.
Christoph Heinze, Thorsten Blenckner, Peter Brown, Friederike Fröb, Anne Morée, Adrian L. New, Cara Nissen, Stefanie Rynders, Isabel Seguro, Yevgeny Aksenov, Yuri Artioli, Timothée Bourgeois, Friedrich Burger, Jonathan Buzan, B. B. Cael, Veli Çağlar Yumruktepe, Melissa Chierici, Christopher Danek, Ulf Dieckmann, Agneta Fransson, Thomas Frölicher, Giovanni Galli, Marion Gehlen, Aridane G. González, Melchor Gonzalez-Davila, Nicolas Gruber, Örjan Gustafsson, Judith Hauck, Mikko Heino, Stephanie Henson, Jenny Hieronymus, I. Emma Huertas, Fatma Jebri, Aurich Jeltsch-Thömmes, Fortunat Joos, Jaideep Joshi, Stephen Kelly, Nandini Menon, Precious Mongwe, Laurent Oziel, Sólveig Ólafsdottir, Julien Palmieri, Fiz F. Pérez, Rajamohanan Pillai Ranith, Juliano Ramanantsoa, Tilla Roy, Dagmara Rusiecka, J. Magdalena Santana Casiano, Yeray Santana-Falcón, Jörg Schwinger, Roland Séférian, Miriam Seifert, Anna Shchiptsova, Bablu Sinha, Christopher Somes, Reiner Steinfeldt, Dandan Tao, Jerry Tjiputra, Adam Ulfsbo, Christoph Völker, Tsuyoshi Wakamatsu, and Ying Ye
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-182, https://doi.org/10.5194/bg-2023-182, 2023
Revised manuscript not accepted
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For assessing the consequences of human-induced climate change for the marine realm, it is necessary to not only look at gradual changes but also at abrupt changes of environmental conditions. We summarise abrupt changes in ocean warming, acidification, and oxygen concentration as the key environmental factors for ecosystems. Taking these abrupt changes into account requires greenhouse gas emissions to be reduced to a larger extent than previously thought to limit respective damage.
Stefania A. Ciliberti, Enrique Alvarez Fanjul, Jay Pearlman, Kirsten Wilmer-Becker, Pierre Bahurel, Fabrice Ardhuin, Alain Arnaud, Mike Bell, Segolene Berthou, Laurent Bertino, Arthur Capet, Eric Chassignet, Stefano Ciavatta, Mauro Cirano, Emanuela Clementi, Gianpiero Cossarini, Gianpaolo Coro, Stuart Corney, Fraser Davidson, Marie Drevillon, Yann Drillet, Renaud Dussurget, Ghada El Serafy, Katja Fennel, Marcos Garcia Sotillo, Patrick Heimbach, Fabrice Hernandez, Patrick Hogan, Ibrahim Hoteit, Sudheer Joseph, Simon Josey, Pierre-Yves Le Traon, Simone Libralato, Marco Mancini, Pascal Matte, Angelique Melet, Yasumasa Miyazawa, Andrew M. Moore, Antonio Novellino, Andrew Porter, Heather Regan, Laia Romero, Andreas Schiller, John Siddorn, Joanna Staneva, Cecile Thomas-Courcoux, Marina Tonani, Jose Maria Garcia-Valdecasas, Jennifer Veitch, Karina von Schuckmann, Liying Wan, John Wilkin, and Romane Zufic
State Planet, 1-osr7, 2, https://doi.org/10.5194/sp-1-osr7-2-2023, https://doi.org/10.5194/sp-1-osr7-2-2023, 2023
Bror F. Jönsson, Christopher L. Follett, Jacob Bien, Stephanie Dutkiewicz, Sangwon Hyun, Gemma Kulk, Gael L. Forget, Christian Müller, Marie-Fanny Racault, Christopher N. Hill, Thomas Jackson, and Shubha Sathyendranath
Geosci. Model Dev., 16, 4639–4657, https://doi.org/10.5194/gmd-16-4639-2023, https://doi.org/10.5194/gmd-16-4639-2023, 2023
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While biogeochemical models and satellite-derived ocean color data provide unprecedented information, it is problematic to compare them. Here, we present a new approach based on comparing probability density distributions of model and satellite properties to assess model skills. We also introduce Earth mover's distances as a novel and powerful metric to quantify the misfit between models and observations. We find that how 3D chlorophyll fields are aggregated can be a significant source of error.
Dani C. Jones, Maike Sonnewald, Shenjie Zhou, Ute Hausmann, Andrew J. S. Meijers, Isabella Rosso, Lars Boehme, Michael P. Meredith, and Alberto C. Naveira Garabato
Ocean Sci., 19, 857–885, https://doi.org/10.5194/os-19-857-2023, https://doi.org/10.5194/os-19-857-2023, 2023
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Machine learning is transforming oceanography. For example, unsupervised classification approaches help researchers identify underappreciated structures in ocean data, helping to generate new hypotheses. In this work, we use a type of unsupervised classification to identify structures in the temperature and salinity structure of the Weddell Gyre, which is an important region for global ocean circulation and for climate. We use our method to generate new ideas about mixing in the Weddell Gyre.
Fouzia Fahrin, Daniel C. Jones, Yan Wu, James Keeble, and Alexander T. Archibald
Atmos. Chem. Phys., 23, 3609–3627, https://doi.org/10.5194/acp-23-3609-2023, https://doi.org/10.5194/acp-23-3609-2023, 2023
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We use a machine learning technique called Gaussian mixture modeling (GMM) to classify vertical ozone profiles into groups based on how the ozone concentration changes with pressure. Even though the GMM algorithm was not provided with spatial information, the classes are geographically coherent. We also detect signatures of tropical broadening in UKESM1 future climate scenarios. GMM may be useful for understanding ozone structures in modeled and observed datasets.
Oscar Dimdore-Miles, Lesley Gray, Scott Osprey, Jon Robson, Rowan Sutton, and Bablu Sinha
Atmos. Chem. Phys., 22, 4867–4893, https://doi.org/10.5194/acp-22-4867-2022, https://doi.org/10.5194/acp-22-4867-2022, 2022
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This study examines interactions between variations in the strength of polar stratospheric winds and circulation in the North Atlantic in a climate model simulation. It finds that the Atlantic Meridional Overturning Circulation (AMOC) responds with oscillations to sets of consecutive Northern Hemisphere winters, which show all strong or all weak polar vortex conditions. The study also shows that a set of strong vortex winters in the 1990s contributed to the recent slowdown in the observed AMOC.
Ehud Strobach, Andrea Molod, Donifan Barahona, Atanas Trayanov, Dimitris Menemenlis, and Gael Forget
Geosci. Model Dev., 15, 2309–2324, https://doi.org/10.5194/gmd-15-2309-2022, https://doi.org/10.5194/gmd-15-2309-2022, 2022
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The Green's functions methodology offers a systematic, easy-to-implement, computationally cheap, scalable, and extendable method to tune uncertain parameters in models accounting for the dependent response of the model to a change in various parameters. Herein, we successfully show for the first time that long-term errors in earth system models can be considerably reduced using Green's functions methodology. The method can be easily applied to any model containing uncertain parameters.
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
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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.
Simon D. A. Thomas, Daniel C. Jones, Anita Faul, Erik Mackie, and Etienne Pauthenet
Ocean Sci., 17, 1545–1562, https://doi.org/10.5194/os-17-1545-2021, https://doi.org/10.5194/os-17-1545-2021, 2021
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We propose a probabilistic method and a new inter-class comparison metric for highlighting fronts in the Southern Ocean. We compare it with an image processing method that provides a more localised view of fronts that effectively highlights sharp jets. These two complementary approaches offer two views of Southern Ocean structure: the probabilistic method highlights boundaries between coherent thermohaline structures across the entire Southern Ocean, whereas edge detection highlights local jets.
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
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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.
Axel Peytavin, Bruno Sainte-Rose, Gael Forget, and Jean-Michel Campin
Geosci. Model Dev., 14, 4769–4780, https://doi.org/10.5194/gmd-14-4769-2021, https://doi.org/10.5194/gmd-14-4769-2021, 2021
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We present a new algorithm developed at The Ocean Cleanup to update ocean plastic models based on measurements from the field to improve future cleaning operations. Prepared in collaboration with MIT researchers, this initial study presents its use in several analytical and real test cases in which two observers in a flow field record regular observations to update a plastic forecast. We demonstrate this improves the prediction, even with inaccurate knowledge of the water flows driving plastic.
Rachel Furner, Peter Haynes, Dave Munday, Brooks Paige, Daniel C. Jones, and Emily Shuckburgh
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2021-132, https://doi.org/10.5194/gmd-2021-132, 2021
Revised manuscript not accepted
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Traditional weather & climate models are built from physics-based equations, while data-driven models are built from patterns found in datasets using Machine Learning or statistics. There is growing interest in using data-driven models for weather & climate prediction, but confidence in their use depends on understanding the patterns they're finding. We look at this with a simple regression model of ocean temperature and see the patterns found by the regression model are similar to the physics.
Pablo Ortega, Jon I. Robson, Matthew Menary, Rowan T. Sutton, Adam Blaker, Agathe Germe, Jöel J.-M. Hirschi, Bablu Sinha, Leon Hermanson, and Stephen Yeager
Earth Syst. Dynam., 12, 419–438, https://doi.org/10.5194/esd-12-419-2021, https://doi.org/10.5194/esd-12-419-2021, 2021
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Deep Labrador Sea densities are receiving increasing attention because of their link to many of the processes that govern decadal climate oscillations in the North Atlantic and their potential use as a precursor of those changes. This article explores those links and how they are represented in global climate models, documenting the main differences across models. Models are finally compared with observational products to identify the ones that reproduce the links more realistically.
Adam T. Blaker, Manoj Joshi, Bablu Sinha, David P. Stevens, Robin S. Smith, and Joël J.-M. Hirschi
Geosci. Model Dev., 14, 275–293, https://doi.org/10.5194/gmd-14-275-2021, https://doi.org/10.5194/gmd-14-275-2021, 2021
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FORTE 2.0 is a flexible coupled atmosphere–ocean general circulation model that can be run on modest hardware. We present two 2000-year simulations which show that FORTE 2.0 is capable of producing a stable climate. Earlier versions of FORTE were used for a wide range of studies, ranging from aquaplanet configurations to investigating the cold European winters of 2009–2010. This paper introduces the updated model for which the code and configuration are now publicly available.
David Ian Duncan, Patrick Eriksson, Simon Pfreundschuh, Christian Klepp, and Daniel C. Jones
Atmos. Chem. Phys., 19, 6969–6984, https://doi.org/10.5194/acp-19-6969-2019, https://doi.org/10.5194/acp-19-6969-2019, 2019
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Raindrop size distributions have not been systematically studied over the oceans but are significant for remotely sensing, assimilating, and modeling rain. Here we investigate raindrop populations with new global in situ data, compare them against satellite estimates, and explore a new technique to classify the shapes of these distributions. The results indicate the inadequacy of a commonly assumed shape in some regions and the sizable impact of shape variability on satellite measurements.
David Storkey, Adam T. Blaker, Pierre Mathiot, Alex Megann, Yevgeny Aksenov, Edward W. Blockley, Daley Calvert, Tim Graham, Helene T. Hewitt, Patrick Hyder, Till Kuhlbrodt, Jamie G. L. Rae, and Bablu Sinha
Geosci. Model Dev., 11, 3187–3213, https://doi.org/10.5194/gmd-11-3187-2018, https://doi.org/10.5194/gmd-11-3187-2018, 2018
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We document the latest version of the shared UK global configuration of the
NEMO ocean model. This configuration will be used as part of the climate
models for the UK contribution to the IPCC 6th Assessment Report.
30-year integrations forced with atmospheric forcing show that the new
configurations have an improved simulation in the Southern Ocean with the
near-surface temperatures and salinities and the sea ice all matching the
observations more closely.
Daniel B. Williamson, Adam T. Blaker, and Bablu Sinha
Geosci. Model Dev., 10, 1789–1816, https://doi.org/10.5194/gmd-10-1789-2017, https://doi.org/10.5194/gmd-10-1789-2017, 2017
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We present a method from the statistical science literature to assist in the tuning of global climate models submitted to CMIP. We apply the method to the NEMO ocean model and find choices of its free parameters that lead to improved representations of depth integrated global mean temperature and salinity. We argue against automatic tuning procedures that involve optimising certain outputs of a model and explain why our method avoids common difficulties with/arguments against automatic tuning.
Helene T. Hewitt, Malcolm J. Roberts, Pat Hyder, Tim Graham, Jamie Rae, Stephen E. Belcher, Romain Bourdallé-Badie, Dan Copsey, Andrew Coward, Catherine Guiavarch, Chris Harris, Richard Hill, Joël J.-M. Hirschi, Gurvan Madec, Matthew S. Mizielinski, Erica Neininger, Adrian L. New, Jean-Christophe Rioual, Bablu Sinha, David Storkey, Ann Shelly, Livia Thorpe, and Richard A. Wood
Geosci. Model Dev., 9, 3655–3670, https://doi.org/10.5194/gmd-9-3655-2016, https://doi.org/10.5194/gmd-9-3655-2016, 2016
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We examine the impact in a coupled model of increasing atmosphere and ocean horizontal resolution and the frequency of coupling between the atmosphere and ocean. We demonstrate that increasing the ocean resolution from 1/4 degree to 1/12 degree has a major impact on ocean circulation and global heat transports. The results add to the body of evidence suggesting that ocean resolution is an important consideration when developing coupled models for weather and climate applications.
Simona Aracri, Katrin Schroeder, Jacopo Chiggiato, Harry Bryden, Elaine McDonagh, Simon Josey, Yann Hello, and Mireno Borghini
Ocean Sci. Discuss., https://doi.org/10.5194/os-2016-65, https://doi.org/10.5194/os-2016-65, 2016
Preprint withdrawn
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The abyssal velocity of the Northern Current, in the north-western Mediterranean has been estimated using for the first time MERMAIDs, i.e. submarine drifting instruments that record seismic waves. In this study the Northern Current shows an intense activity even in deep layers of the water column. Through pseudo-eulerian statistics different components of the observed variability are analysed and described, revealing the turbulent nature of the Liguro-Provençal basin abyssal circulation.
G. Forget, D. Ferreira, and X. Liang
Ocean Sci., 11, 839–853, https://doi.org/10.5194/os-11-839-2015, https://doi.org/10.5194/os-11-839-2015, 2015
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Results from the ECCO v4 ocean state estimate identify the constraint of fitting Argo profiles as an effective observational basis for inverse estimation of regional turbulent transport rates. The estimated parameters' geography is physically plausible and exhibits close connections with the observed upper-ocean stratification. They yield a clear reduction in the model drift away from observations over multi-century-long simulations, including for independent biochemistry variables.
G. Forget, J.-M. Campin, P. Heimbach, C. N. Hill, R. M. Ponte, and C. Wunsch
Geosci. Model Dev., 8, 3071–3104, https://doi.org/10.5194/gmd-8-3071-2015, https://doi.org/10.5194/gmd-8-3071-2015, 2015
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The ECCO v4 non-linear inverse modeling framework and its reference solution are made publicly available. The inverse estimate of ocean physics and atmospheric forcing yields a dynamically consistent and global state estimate without unidentified sources of heat and salt that closely fits in situ and satellite data. Any user can reproduce it accurately. Parametric and external model uncertainties are of comparable magnitudes and generally exceed structural model uncertainties.
A. Megann, D. Storkey, Y. Aksenov, S. Alderson, D. Calvert, T. Graham, P. Hyder, J. Siddorn, and B. Sinha
Geosci. Model Dev., 7, 1069–1092, https://doi.org/10.5194/gmd-7-1069-2014, https://doi.org/10.5194/gmd-7-1069-2014, 2014
J. J.-M. Hirschi, A. T. Blaker, B. Sinha, A. Coward, B. de Cuevas, S. Alderson, and G. Madec
Ocean Sci., 9, 805–823, https://doi.org/10.5194/os-9-805-2013, https://doi.org/10.5194/os-9-805-2013, 2013
Cited articles
Alexander, M. A., Deser, C., and Timlin, M. S.: The reemergence of SST
anomalies in the North Pacific Ocean, J. Climate, 12, 2419–2433,
https://doi.org/10.1175/1520-0442(1999)012<2419:TROSAI>2.0.CO;2, 1999. a
Asbjørnsen, H., Årthun, M., Skagseth, Ø., and Eldevik, T.:
Mechanisms of ocean heat anomalies in the Norwegian Sea, J.
Geophys. Res.-Oceans, 124, 2908–2923, https://doi.org/10.1029/2018JC014649,
2019. a
Barnston, A. G. and Livezey, R. E.: Classification, seasonality and
persistence of low-frequency atmospheric circulation patterns, Mon.
Weather Rev., 115, 1083–1126,
https://doi.org/10.1175/1520-0493(1987)115<1083:CSAPOL>2.0.CO;2, 1987. a
Buckley, M. W., Ponte, R. M., Forget, G., and Heimbach, P.: Low-frequency SST
and upper-ocean heat content variability in the North Atlantic, J.
Climate, 27, 4996–5018, https://doi.org/10.1175/JCLI-D-13-00316.1, 2014. a, b
Buckley, M. W., Ponte, R. M., Forget, G., and Heimbach, P.: Determining the
origins of advective heat transport convergence variability in the North
Atlantic, J. Climate, 28, 3943–3956,
https://doi.org/10.1175/JCLI-D-14-00579.1, 2015. a
Cassou, C., Deser, C., and Alexander, M. A.: Investigating the impact of
reemerging sea surface temperature anomalies on the winter atmospheric
circulation over the North Atlantic, J. Climate, 20, 3510–3526,
https://doi.org/10.1175/JCLI4202.1, 2007. a, b
Chakraborty, A. and Campin, J.-M.: Heat and salt budgets in MITgcm, Tech.
rep., Atmospheric and Oceanic Sciences Group, Space Applications Centre,
Indian Space Research Organization, Ahmedabad, India, http://mitgcm.org/download/daily_snapshot/MITgcm/doc/Heat_Salt_Budget_MITgcm.pdf (last access: 4 July 2022), 2013. a
de Jong, M. F. and de Steur, L.: Strong winter cooling over the Irminger Sea
in winter 2014–2015, exceptional deep convection, and the emergence of
anomalously low SST, Geophys. Res. Lett., 43, 7106–7113,
https://doi.org/10.1002/2016GL069596, 2016. a, b
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. a, b, c
Dong, S., Gille, S. T., and Sprintall, J.: An assessment of the Southern Ocean
mixed layer heat budget, J. Climate, 20, 4425–4442,
https://doi.org/10.1175/JCLI4259.1, 2007. a, b
Doyle, J. D. and Shapiro, M. A.: Flow response to large-scale topography: The
Greenland tip jet, Tellus A, 51, 728–748,
https://doi.org/10.1034/j.1600-0870.1996.00014.x, 1999. a
Drijfhout, S., Van Oldenborgh, G. J., and Cimatoribus, A.: Is a decline of
AMOC causing the warming hole above the North Atlantic in observed and
modeled warming patterns?, J. Climate, 25, 8373–8379,
https://doi.org/10.1175/JCLI-D-12-00490.1, 2012. a
Duchez, A., Frajka-Williams, E., Josey, S., Evans, D., Grist, J., Marsh, R.,
McCarthy, G., Sinha, B., Berry, D., 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. a, b, c, d
ECCO Consortium, Fukumori, I., Wang, O., Fenty, I., Forget, G., Heimbach, P.,
and Ponte, R.: Synopsis of the ECCO central production global ocean and
sea-ice state estimate, version 4 release 4, Zenodo [data set], https://doi.org/10.5281/zenodo.3765929, 2021. a, b
Forget, G., Ferreira, D., and Liang, X.: On the observability of turbulent transport rates by Argo: supporting evidence from an inversion experiment, Ocean Sci., 11, 839–853, https://doi.org/10.5194/os-11-839-2015, 2015b. a, b
Foukal, N. P. and Lozier, M. S.: Examining the origins of ocean heat content
variability in the eastern North Atlantic subpolar gyre, Geophys.
Res. Lett., 45, 11–275, https://doi.org/10.1029/2018GL079122, 2018. a, b
Frankignoul, C.: Sea surface temperature anomalies, planetary waves, and
air-sea feedback in the middle latitudes, Rev. Geophys., 23,
357–390, https://doi.org/10.1029/RG023i004p00357, 1985. a, b
Gaspar, P., Grégoris, Y., and Lefevre, J.-M.: A simple eddy-kinetic-energy model for
simulations of the ocean vertical mixing: tests at station Papa and long-term
upper ocean study site, J. Geophys. Res., 95, 16–179,
https://doi.org/10.1029/JC095iC09p16179, 1990. a
Gent, P. R. and McWilliams, J. C.: Isopycnal mixing in ocean circulation
models, J. Phys. Oceanogr., 20, 150–155,
https://doi.org/10.1175/1520-0485(1990)020<0150:IMIOCM>2.0.CO;2, 1990. a, b
Grist, J. P. and Josey, S. A.: Inverse analysis adjustment of the SOC air–sea
flux climatology using ocean heat transport constraints, J.
Climate, 16, 3274–3295,
https://doi.org/10.1175/1520-0442(2003)016<3274:IAAOTS>2.0.CO;2, 2003. a
Grist, J. P., Josey, S. A., Jacobs, Z. L., Marsh, R., Sinha, B., and
Van Sebille, E.: Extreme air–sea interaction over the North Atlantic
subpolar gyre during the winter of 2013–2014 and its sub-surface legacy,
Clim. Dynam., 46, 4027–4045, https://doi.org/10.1007/s00382-015-2819-3, 2016. a, b, c
Hátún, H., Olsen, B., and Pacariz, S.: The dynamics of the North
Atlantic subpolar gyre introduces predictability to the breeding success of
kittiwakes, Front. Mar. Sci., 4, 123,
https://doi.org/10.3389/fmars.2017.00123, 2017. a
Holliday, N. P., Bersch, M., Berx, B., Chafik, L., Cunningham, S., Florindo-López, C., Hátún, H., Johns, W., Josey, S. A., Larsen, K. M. H., Mulet, S., Oltmanns, M., Reverdin, G., Rossby, T., Thierry, V., Valdimarsson, H., and Yashayaev, I.: Ocean circulation causes the largest freshening event for
120 years in eastern subpolar North Atlantic, Nat. Commun., 11,
1–15, https://doi.org/10.1038/s41467-020-14474-y, 2020. a, b, c
Josey, S. A., De Jong, M., Oltmanns, M., Moore, G., and Weller, R.: 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. a, b, c
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. a, b
Lamb, P. J. and Peppler, R. A.: North Atlantic Oscillation: concept and an
application, B. Am. Meteorol. Soc., 68,
1218–1225, https://doi.org/10.1175/1520-0477(1987)068<1218:NAOCAA>2.0.CO;2, 1987. a
Large, W. and Yeager, S.: The global climatology of an interannually varying
air–sea flux data set, Clim. Dynam., 33, 341–364,
https://doi.org/10.1007/s00382-008-0441-3, 2009. a
Lindsay, R., Wensnahan, M., Schweiger, A., and Zhang, J.: Evaluation of seven different atmospheric reanalysis products in the Arctic, J.
Climate, 27, 2588–2606, https://doi.org/10.1175/JCLI-D-13-00014.1, 2014. a, b
Losch, M., Menemenlis, D., Campin, J.-M., Heimbach, P., and Hill, C.: On the
formulation of sea-ice models. Part 1: Effects of different solver
implementations and parameterizations, Ocean Model., 33, 129–144,
https://doi.org/10.1016/j.ocemod.2009.12.008, 2010. a
Maroon, E. A., Yeager, S. G., Danabasoglu, G., and Rosenbloom, N.: Was the
2015 North Atlantic subpolar cold anomaly predictable?, J.
Climate, 34, 5403–5423, https://doi.org/10.1175/JCLI-D-20-0750.1, 2021. a, b
Marshall, J., Johnson, H., and Goodman, J.: A study of the interaction of the
North Atlantic Oscillation with ocean circulation, J. Climate, 14,
1399–1421, https://doi.org/10.1175/1520-0442(2001)014<1399:ASOTIO>2.0.CO;2, 2001. a
Mecking, J., Drijfhout, S., Hirschi, J. J., and Blaker, A.: Ocean and
atmosphere influence on the 2015 European heatwave, Environ. Res.
Lett., 14, 114035, https://doi.org/10.1088/1748-9326/ab4d33, 2019. a, b
Met Office Hadley Centre: EN.4.2.2 data, Met Office Hadley Centre [data set], https://www.metoffice.gov.uk/hadobs/en4/, last access: January 2019. a
Moore, G.: Gale force winds over the Irminger Sea to the east of Cape
Farewell, Greenland, Geophys. Res. Lett., 30, 1894,
https://doi.org/10.1029/2003GL018012, 2003. a
Peter, A.-C., Le Hénaff, M., Du Penhoat, Y., Menkes, C. E., Marin, F.,
Vialard, J., Caniaux, G., and Lazar, A.: A model study of the seasonal mixed
layer heat budget in the equatorial Atlantic, J. Geophys.
Res.-Oceans, 111, C06014, https://doi.org/10.1029/2005JC003157, 2006. a, b
Piecuch, C. G.: A note on practical evaluation of budgets in ECCO version 4
release 3, Tech. rep., http://hdl.handle.net/1721.1/111094 (last access: September 2021),
2017. a
Piecuch, C. G., Ponte, R. M., Little, C. M., Buckley, M. W., and Fukumori, I.:
Mechanisms underlying recent decadal changes in subpolar North Atlantic
Ocean heat content, J. Geophys. Res.-Oceans, 122,
7181–7197, https://doi.org/10.1002/2017JC012845, 2017. a
Piron, A., Thierry, V., Mercier, H., and Caniaux, G.: Gyre-scale deep
convection in the subpolar North Atlantic Ocean during winter 2014–2015,
Geophys. Res. Lett., 44, 1439–1447, https://doi.org/10.1002/2016GL071895,
2017. a, b, c
Rahmstorf, S., Box, J. E., Feulner, G., Mann, M. E., Robinson, A., Rutherford,
S., and Schaffernicht, E. J.: Exceptional twentieth-century slowdown in
Atlantic Ocean overturning circulation, Nat. Clim. Change, 5,
475–480, https://doi.org/10.1038/nclimate2554, 2015. a
Rayner, N., Parker, D. E., Horton, E., Folland, C. K., Alexander, L. V.,
Rowell, D., Kent, E., and Kaplan, A.: Global analyses of sea surface
temperature, sea ice, and night marine air temperature since the late
nineteenth century, J. Geophys. Res.-Atmos., 108, 4407,
https://doi.org/10.1029/2002JD002670, 2003 (data available at: https://www.metoffice.gov.uk/hadobs/hadisst/data/download.html, last access: March 2021). a
Rogers, J. C.: The association between the North Atlantic Oscillation and the
Southern Oscillation in the northern hemisphere, Mon. Weather Rev.,
112, 1999–2015, https://doi.org/10.1175/1520-0493(1984)112<1999:TABTNA>2.0.CO;2, 1984. a
Sutton, R. and Mathieu, P.-P.: Response of the atmosphere–ocean mixed-layer
system to anomalous ocean heat-flux convergence, Q. J.
Roy. Meteor. Soc., 128, 1259–1275,
https://doi.org/10.1256/003590002320373283, 2002. a
Taws, S. L., Marsh, R., Wells, N. C., and Hirschi, J.: Re-emerging ocean
temperature anomalies in late-2010 associated with a repeat negative NAO,
Geophys. Res. Lett., 38, L20601, https://doi.org/10.1029/2011GL048978, 2011. a, b
Tesdal, J.-E., Abernathey, R. P., Goes, J. I., Gordon, A. L., and Haine, T. W.:
Salinity trends within the upper layers of the subpolar North Atlantic,
J. Climate, 31, 2675–2698, https://doi.org/10.1175/JCLI-D-17-0532.1, 2018. a
Wallace, J. M. and Gutzler, D. S.: Teleconnections in the geopotential height
field during the Northern Hemisphere winter, Mon. Weather Rev., 109,
784–812, https://doi.org/10.1175/1520-0493(1981)109<0784:TITGHF>2.0.CO;2, 1981. a
Short summary
In 2015, record low temperatures were observed in the North Atlantic. Using an ocean model, we show that surface heat loss in December 2013 caused 75 % of the initial cooling before this "cold blob" was trapped below the surface. The following summer, the cold blob re-emerged due to a strong temperature difference between the surface ocean and below, driving vertical diffusion of heat. Lower than average surface warming then led to the coldest temperature anomalies in August 2015.
In 2015, record low temperatures were observed in the North Atlantic. Using an ocean model, we...
