Articles | Volume 19, issue 3
https://doi.org/10.5194/os-19-857-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-19-857-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Unsupervised classification identifies coherent thermohaline structures in the Weddell Gyre region
British Antarctic Survey, NERC, UKRI, Cambridge, UK
Maike Sonnewald
Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ, USA
NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA
School of Oceanography, University of Washington, Seattle, WA, USA
Shenjie Zhou
British Antarctic Survey, NERC, UKRI, Cambridge, UK
Ute Hausmann
British Antarctic Survey, NERC, UKRI, Cambridge, UK
Andrew J. S. Meijers
British Antarctic Survey, NERC, UKRI, Cambridge, UK
Isabella Rosso
Scripps Institution of Oceanography, UCSD, La Jolla, CA, USA
GeoOptics Switzerland SA, Lausanne, Switzerland
Lars Boehme
SMRU, University of St. Andrews, St. Andrews, UK
Michael P. Meredith
British Antarctic Survey, NERC, UKRI, Cambridge, UK
Alberto C. Naveira Garabato
Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK
Related authors
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
Short summary
Short summary
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.
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
Short summary
Short summary
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.
Rachael N. C. Sanders, Daniel C. Jones, Simon A. Josey, Bablu Sinha, and Gael Forget
Ocean Sci., 18, 953–978, https://doi.org/10.5194/os-18-953-2022, https://doi.org/10.5194/os-18-953-2022, 2022
Short summary
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.
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
Short summary
Short summary
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.
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
Short summary
Short summary
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.
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
Short summary
Short summary
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.
Benjamin J. Davison, Anna E. Hogg, Carlos Moffat, Michael P. Meredith, and Benjamin J. Wallis
The Cryosphere, 18, 3237–3251, https://doi.org/10.5194/tc-18-3237-2024, https://doi.org/10.5194/tc-18-3237-2024, 2024
Short summary
Short summary
Using a new dataset of ice motion, we observed glacier acceleration on the west coast of the Antarctic Peninsula. The speed-up began around January 2021, but some glaciers sped up earlier or later. Using a combination of ship-based ocean temperature observations and climate models, we show that the speed-up coincided with a period of unusually warm air and ocean temperatures in the region.
Ben J. Fisher, Alex J. Poulton, Michael P. Meredith, Kimberlee Baldry, Oscar Schofield, and Sian F. Henley
EGUsphere, https://doi.org/10.5194/egusphere-2024-990, https://doi.org/10.5194/egusphere-2024-990, 2024
Short summary
Short summary
The Southern Ocean is a rapidly warming environment, with subsequent impacts on ecosystems and biogeochemical cycling. This study examines changes in phytoplankton and biogeochemistry using a range of climate models. Under climate change the Southern Ocean will be warmer, more acidic, more productive and have reduced nutrient availability by 2100. However, there is substantial variability between models across key productivity parameters, we propose ways of reducing this uncertainty.
Clara Celestine Douglas, Nathan Briggs, Peter Brown, Graeme MacGilchrist, and Alberto Naveira Garabato
Ocean Sci., 20, 475–497, https://doi.org/10.5194/os-20-475-2024, https://doi.org/10.5194/os-20-475-2024, 2024
Short summary
Short summary
We use data from satellites and robotic floats to assess what drives year-to-year variability in primary production in the Weddell Gyre. We find that the maximum area of ice-free water in the summer is important in determining the total primary production in the region but that areas that are ice free for longer than 120 d become nutrient limited. This has potential implications for ecosystem health in a warming world, where a decline in sea ice cover will affect total primary production.
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
Short summary
Short summary
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.
Jennifer Cocks, Alessandro Silvano, Alice Marzocchi, Oana Dragomir, Noémie Schifano, Anna E. Hogg, and Alberto C. Naveira Garabato
EGUsphere, https://doi.org/10.5194/egusphere-2023-3050, https://doi.org/10.5194/egusphere-2023-3050, 2023
Short summary
Short summary
Heat and freshwater fluxes in the Southern Ocean mediate global ocean circulation and abyssal ventilation. These fluxes manifest as changes in steric height: sea level anomalies from changes in ocean density. We compute the steric height anomaly of the Southern Ocean using satellite data and validate it against in-situ observations. We analyse interannual patterns, drawing links to climate variability, and discuss the effectiveness of the method, highlighting issues and suggesting improvements.
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
Short summary
Short summary
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.
Ben J. Fisher, Alex J. Poulton, Michael P. Meredith, Kimberlee Baldry, Oscar Schofield, and Sian F. Henley
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-10, https://doi.org/10.5194/bg-2023-10, 2023
Revised manuscript not accepted
Short summary
Short summary
The Southern Ocean is warming faster than the global average. As a globally important carbon sink and nutrient source, climate driven changes in ecosystems can be expected to cause widespread changes to biogeochemical cycles. We analysed earth system models and showed that productivity is expected to increase across the Southern Ocean, driven by different phytoplankton groups at different latitudes. These predictions carry large uncertainties, we propose targeted studies to reduce this error.
Stefanie L. Ypma, Quinten Bohte, Alexander Forryan, Alberto C. Naveira Garabato, Andy Donnelly, and Erik van Sebille
Ocean Sci., 18, 1477–1490, https://doi.org/10.5194/os-18-1477-2022, https://doi.org/10.5194/os-18-1477-2022, 2022
Short summary
Short summary
In this research we aim to improve cleanup efforts on the Galapagos Islands of marine plastic debris when resources are limited and the distribution of the plastic on shorelines is unknown. Using a network that describes the flow of macroplastic between the islands we have identified the most efficient cleanup locations, quantified the impact of targeting these locations and showed that shorelines where the plastic is unlikely to leave are likely efficient cleanup locations.
Rachael N. C. Sanders, Daniel C. Jones, Simon A. Josey, Bablu Sinha, and Gael Forget
Ocean Sci., 18, 953–978, https://doi.org/10.5194/os-18-953-2022, https://doi.org/10.5194/os-18-953-2022, 2022
Short summary
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.
Gilles Reverdin, Claire Waelbroeck, Catherine Pierre, Camille Akhoudas, Giovanni Aloisi, Marion Benetti, Bernard Bourlès, Magnus Danielsen, Jérôme Demange, Denis Diverrès, Jean-Claude Gascard, Marie-Noëlle Houssais, Hervé Le Goff, Pascale Lherminier, Claire Lo Monaco, Herlé Mercier, Nicolas Metzl, Simon Morisset, Aïcha Naamar, Thierry Reynaud, Jean-Baptiste Sallée, Virginie Thierry, Susan E. Hartman, Edward W. Mawji, Solveig Olafsdottir, Torsten Kanzow, Anton Velo, Antje Voelker, Igor Yashayaev, F. Alexander Haumann, Melanie J. Leng, Carol Arrowsmith, and Michael Meredith
Earth Syst. Sci. Data, 14, 2721–2735, https://doi.org/10.5194/essd-14-2721-2022, https://doi.org/10.5194/essd-14-2721-2022, 2022
Short summary
Short summary
The CISE-LOCEAN seawater stable isotope dataset has close to 8000 data entries. The δ18O and δD isotopic data measured at LOCEAN have uncertainties of at most 0.05 ‰ and 0.25 ‰, respectively. Some data were adjusted to correct for evaporation. The internal consistency indicates that the data can be used to investigate time and space variability to within 0.03 ‰ and 0.15 ‰ in δ18O–δD17; comparisons with data analyzed in other institutions suggest larger differences with other datasets.
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
Short summary
Short summary
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.
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
Short summary
Short summary
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.
Pieter Demuynck, Toby Tyrrell, Alberto Naveira Garabato, Mark Christopher Moore, and Adrian Peter Martin
Biogeosciences, 17, 2289–2314, https://doi.org/10.5194/bg-17-2289-2020, https://doi.org/10.5194/bg-17-2289-2020, 2020
Short summary
Short summary
The availability of macronutrients N and Si is of key importance to sustain life in the Southern Ocean. N and Si are available in abundance at the southern boundary of the Southern Ocean due to constant supply from the deep ocean. In the more northern regions of the Southern Ocean, a decline in macronutrient concentration is noticed, especially strong for Si rather than N. This paper uses a simplified biogeochemical model to investigate processes responsible for this decline in concentration.
Jan D. Zika, Jean-Baptiste Sallée, Andrew J. S. Meijers, Alberto C. Naveira-Garabato, Andrew J. Watson, Marie-Jose Messias, and Brian A. King
Ocean Sci., 16, 323–336, https://doi.org/10.5194/os-16-323-2020, https://doi.org/10.5194/os-16-323-2020, 2020
Short summary
Short summary
The ocean can regulate climate by distributing heat and carbon dioxide into its interior. This work has resulted from a major experiment aimed at understanding how that distribution occurs. In the experiment an artificial tracer was released into the ocean. After release the tracer was tracked as it was distorted by ocean currents. Using novel methods we reveal how the tracer's distortions follow the movement of the underlying water masses in the ocean and we estimate the rate at which it mixes.
Anna Mikis, Katharine R. Hendry, Jennifer Pike, Daniela N. Schmidt, Kirsty M. Edgar, Victoria Peck, Frank J. C. Peeters, Melanie J. Leng, Michael P. Meredith, Chloe L. C. Jones, Sharon Stammerjohn, and Hugh Ducklow
Biogeosciences, 16, 3267–3282, https://doi.org/10.5194/bg-16-3267-2019, https://doi.org/10.5194/bg-16-3267-2019, 2019
Short summary
Short summary
Antarctic marine calcifying organisms are threatened by regional climate change and ocean acidification. Future projections of regional carbonate production are challenging due to the lack of historical data combined with complex climate variability. We present a 6-year record of flux, morphology and geochemistry of an Antarctic planktonic foraminifera, which shows that their growth is most sensitive to sea ice dynamics and is linked with the El Niño–Southern Oscillation.
Alexander Forryan, Sheldon Bacon, Takamasa Tsubouchi, Sinhué Torres-Valdés, and Alberto C. Naveira Garabato
The Cryosphere, 13, 2111–2131, https://doi.org/10.5194/tc-13-2111-2019, https://doi.org/10.5194/tc-13-2111-2019, 2019
Short summary
Short summary
We compare control volume and geochemical tracer-based methods of estimating the Arctic Ocean freshwater budget and find both methods in good agreement. Inconsistencies arise from the distinction between
Atlanticand
Pacificwaters in the geochemical calculations. The definition of Pacific waters is particularly problematic due to the non-conservative nature of the nutrients underpinning the definition and the low salinity characterizing waters entering the Arctic through Bering Strait.
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
Short summary
Short summary
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.
M. Dolores Pérez-Hernández, Alonso Hernández-Guerra, Isis Comas-Rodríguez, Verónica M. Benítez-Barrios, Eugenio Fraile-Nuez, Josep L. Pelegrí, and Alberto C. Naveira Garabato
Ocean Sci., 13, 577–587, https://doi.org/10.5194/os-13-577-2017, https://doi.org/10.5194/os-13-577-2017, 2017
Short summary
Short summary
The decadal differences between the ALBATROSS (April 1999) and MOC2-Austral (February 2010) hydrographic cruises are analyzed. Changes in the intermediate water masses beneath seem to be very sensitive to the wind conditions existing in their formation area. The Subantarctic Front is wider and weaker in 2010 than in 1999, while the Polar Front remains in the same position and strengthens.
L. Biermann, C. Guinet, M. Bester, A. Brierley, and L. Boehme
Ocean Sci., 11, 83–91, https://doi.org/10.5194/os-11-83-2015, https://doi.org/10.5194/os-11-83-2015, 2015
Short summary
Short summary
To protect from light stress, phytoplankton inhibit photosynthesis and suppress fluorescence through the process of quenching. This makes them invisible to fluorometers. Conventionally, quenching is corrected by taking maximum fluorescence yield in a surface mixed layer (MLD) and filling in the invisible proportion. This is only valid in waters where turbulence is high and phytoplankton are uniformly mixed. Here, we show that correcting from Zeu is a robust alternative to correcting from MLD
Cited articles
Abrahamsen, E. P., Meijers, A. J. S., Polzin, K. L., Naveira Garabato, A. C.,
King, B. A., Firing, Y. L., Sallée, J.-B., Sheen, K. L., Gordon, A. L.,
Huber, B. A., and Meredith, M. P.: Stabilization of dense Antarctic water
supply to the Atlantic Ocean overturning circulation, Nat. Clim.
Change, 9, 742–746, https://doi.org/10.1038/s41558-019-0561-2, 2019. a
Argo: Argo float data and metadata from Global Data Assembly Centre (Argo GDAC), SEANOE [data set], https://doi.org/10.17882/42182, 2020. a
Belkina, A. C., Ciccolella, C. O., Anno, R., Halpert, R., Spidlen, J., and
Snyder-Cappione, J. E.: Automated optimized parameters for T-distributed
stochastic neighbor embedding improve visualization and analysis of large
datasets, Nat. Commun., 10, 5415, https://doi.org/10.1038/s41467-019-13055-y, 2019. a
Boehme, L. and Rosso, I.: Classifying Oceanographic Structures in the
Amundsen Sea, Antarctica, Geophys. Res. Lett., 48, e2020GL089412,
https://doi.org/10.1029/2020GL089412, 2021. a
Boyer, T. P., Baranova, O. K., Coleman, C., Garcia, H. E., Grodsky, A., Locarnini, R. A., Mishonov, A. V., Paver, C. R., Reagan, J. R., Seidov, D., Smolyar, I. V., Weathers, K., Zweng, M. M.: World Ocean Database 2018, A.V. Mishonov, Technical Ed., NOAA Atlas NESDIS 87, [data set], https://www.ncei.noaa.gov/sites/default/files/2020-04/wod_intro_0.pdf (last access: 14 June 2023), 2018. a
Campbell, E. C., Wilson, E. A., Moore, G. W. K., Riser, S. C., Brayton, C. E.,
Mazloff, M. R., and Talley, L. D.: Antarctic offshore polynyas linked to
Southern Hemisphere climate anomalies, Nature, 570, 319–325,
https://doi.org/10.1038/s41586-019-1294-0, 2019. a
Chapman, C. C., Lea, M.-A., Meyer, A., Sallée, J.-B., and Hindell, M.:
Defining Southern Ocean fronts and their influence on biological and
physical processes in a changing climate, Nat. Clim. Change, 10, 209–219,
https://doi.org/10.1038/s41558-020-0705-4, 2020. a, b
Couchman, M. M. P., Wynne-Cattanach, B., Alford, M. H., Caulfield, C.-C. P.,
Kerswell, R. R., MacKinnon, J. A., and Voet, G.: Data-Driven
Identification of Turbulent Oceanic Mixing From Observational
Microstructure Data, Geophys. Res. Lett., 48, e2021GL094978,
https://doi.org/10.1029/2021GL094978, 2021. a
Desbruyères, D., Chafik, L., and Maze, G.: A shift in the ocean circulation
has warmed the subpolar North Atlantic Ocean since 2016, Communications
Earth & Environment, 2, 1–9, https://doi.org/10.1038/s43247-021-00120-y, 2021. a
Dotto, T. S., Naveira Garabato, A., Bacon, S., Tsamados, M., Holland, P. R.,
Hooley, J., Frajka-Williams, E., Ridout, A., and Meredith, M. P.: Variability
of the Ross Gyre, Southern Ocean: Drivers and Responses
Revealed by Satellite Altimetry, Geophys. Res. Lett., 45,
6195–6204, https://doi.org/10.1029/2018GL078607, 2018. a, b, c
Fahrbach, E., Rohardt, G., Schröder, M., and Strass, V.: Transport and structure of the Weddell Gyre, Ann. Geophys., 12, 840–855, https://doi.org/10.1007/s00585-994-0840-7, 1994. a, b
Forget, G., Campin, J.-M., Heimbach, P., Hill, C. N., Ponte, R. M., and Wunsch, C.: ECCO version 4: an integrated framework for non-linear inverse modeling and global ocean state estimation, Geosci. Model Dev., 8, 3071–3104, https://doi.org/10.5194/gmd-8-3071-2015, 2015. a
Foster, T. D. and Carmack, E. C.: Frontal zone mixing and Antarctic Bottom
water formation in the southern Weddell Sea, Deep-Sea Research and
Oceanographic Abstracts, 23, 301–317, https://doi.org/10.1016/0011-7471(76)90872-X,
1976. a
Gill, A.: Circulation and bottom water production in the Weddell Sea, Deep-Sea Research and Oceanographic Abstracts, 20, 111–140,
https://doi.org/10.1016/0011-7471(73)90048-X,
1973. a
Gordon, A. L. and Huber, B. A.: Southern ocean winter mixed layer, J. Geophys. Res., 95, 11655–11672, https://doi.org/10.1029/JC095iC07p11655, 1990. a
Gordon, A. L.: Deep Antarctic Convection West of Maud Rise, J. Phys. Oceanogr., 8, 600–612,
https://doi.org/10.1175/1520-0485(1978)008<0600:DACWOM>2.0.CO;2, 1978. a
Gordon, A. L., Visbeck, M., and Huber, B.: Export of Weddell Sea deep and
bottom water, J. Geophys. Res.-Oceans, 106, 9005–9017,
https://doi.org/10.1029/2000JC000281, 2001. a
Haumann, F. A., Gruber, N., Münnich, M., Frenger, I., and Kern, S.: Sea-ice
transport driving Southern Ocean salinity and its recent trends, Nature,
537, 89–92, https://doi.org/10.1038/nature19101, 2016. a, b
Houghton, I. A. and Wilson, J. D.: El Niño Detection Via Unsupervised
Clustering of Argo Temperature Profiles, J. Geophys.
Res.-Oceans, 125, e2019JC015947, https://doi.org/10.1029/2019JC015947, 2020. a
IPCC: The Ocean and Cryosphere in a Changing Climate: Special
Report of the Intergovernmental Panel on Climate Change, Cambridge
University Press, https://doi.org/10.1017/9781009157964, 2022. a
Johnson, G. C.: Quantifying Antarctic Bottom Water and North Atlantic
Deep Water volumes, J. Geophys. Res.-Oceans, 113, C05027,
https://doi.org/10.1029/2007JC004477, 2008. a
Johnson, G. C., Purkey, S. G., and Toole, J. M.: Reduced Antarctic meridional
overturning circulation reaches the North Atlantic Ocean, Geophys.
Res. Lett., 35, L22601, https://doi.org/10.1029/2008GL035619, 2008. a
Jones, D.: so-wise/weddell_gyre_clusters: Third release,
https://doi.org/10.5281/zenodo.7465388, 2023. a, b
Jones, D. and Zhou, S.: SO-WISE South Atlantic Ocean and Indian
Ocean Observational Constraints, Zenodo, https://doi.org/10.5281/zenodo.7468656, 2022. a, b
Jones, D. C. and Ito, T.: Gaussian mixture modeling describes the geography of
the surface carbon budget, in: Proceedings of the 9th International
Workshop on Climate Informatics, p. 6, Paris, France,
https://doi.org/10.5065/y82j-f154, 2019. a, b
Jones, D. C., Holt, H. J., Meijers, A. J. S., and Shuckburgh, E.: Unsupervised
Clustering of Southern Ocean Argo Float Temperature Profiles,
J. Geophys. Res.-Oceans, 40, 390–402,
https://doi.org/10.1029/2018JC014629, 2019. a, b
Jones, D. and Zhou, S.: South Atlantic Ocean profile dataset: identification of near-Antarctic profiles using unsupervised classification, Zenodo [data set], https://doi.org/10.5281/zenodo.7465132, 2022b. a
Jullion, L., Garabato, A. C. N., Bacon, S., Meredith, M. P., Brown, P. J.,
Torres-Valdés, S., Speer, K. G., Holland, P. R., Dong, J., Bakker, D.,
Hoppema, M., Loose, B., Venables, H. J., Jenkins, W. J., Messias, M.-J., and
Fahrbach, E.: The contribution of the Weddell Gyre to the lower limb of
the Global Overturning Circulation, J. Geophys. Res.-Oceans, 119, 3357–3377, https://doi.org/10.1002/2013JC009725, 2014. a, b
Kaiser, B. E., Saenz, J. A., Sonnewald, M., and Livescu, D.: Automated
identification of dominant physical processes, Eng. Appl.
Artif. Intell., 116, 105496, https://doi.org/10.1016/j.engappai.2022.105496,
2022. a
Killworth, P.: An equivalent-barotropic mode in the Fine Resolution
Antarctic Model, J. Phys. Oceanogr., 22, 1379–1387, 1992. a
Killworth, P. D.: Deep convection in the World Ocean, Rev.
Geophys., 21, 1–26, https://doi.org/10.1029/RG021i001p00001, 1983. a
Kim, Y. S. and Orsi, A. H.: On the Variability of Antarctic Circumpolar
Current Fronts Inferred from 1992–2011 Altimetry*, J.
Phys. Oceanogr., 44, 3054–3071, https://doi.org/10.1175/JPO-D-13-0217.1, 2014. a, b
Kobak, D. and Berens, P.: The art of using t-SNE for single-cell
transcriptomics, Nat. Commun., 10, 5416,
https://doi.org/10.1038/s41467-019-13056-x, 2019. a
Krupitsky, A., Kamenkovich, V., Naik, N., and Cane, M.: A linear equivalent
barotropic model of the Antarctic Circumpolar Current with realistic
coastlines and bottom topography, J. Phys. Oceanogr., 26,
1803–1824, 1996. a
Maaten, L. v. d. and Hinton, G.: Visualizing Data using t-SNE, J.
Mach. Learn. Res., 9, 2579–2605, 2008. a
Marshall, D.: Influence of topography on the large-scale ocean circulation,
J. Phys. Oceanogr., 25, 1622–1635, 1995. a
Martinson, D. G.: Evolution of the southern ocean winter mixed layer and sea
ice: Open ocean deepwater formation and ventilation, J. Geophys.
Res.-Oceans, 95, 11641–11654, https://doi.org/10.1029/JC095iC07p11641, 1990. a
Maze, G., Mercier, H., Fablet, R., Tandeo, P., Radcenco, M. L., Lenca, P.,
Feucher, C., and Le Goff, C.: Coherent heat patterns revealed by unsupervised
classification of Argo temperature profiles in the North Atlantic
Ocean, Prog. Oceanogr., 151, 275–292,
https://doi.org/10.1016/j.pocean.2016.12.008, 2017. a, b
Mazloff, M. R., Heimbach, P., and Wunsch, C.: An Eddy-Permitting Southern
Ocean State Estimate, J. Phys. Oceanogr., 40, 880–899,
https://doi.org/10.1175/2009jpo4236.1, 2010. a, b
Mazloff, M.: Scripps Institution of Oceanography,
Southern Ocean State Estimate [Iteration 100], [data set], http://sose.ucsd.edu/sose_stateestimation_data_05to10.html last access: 4 June 2023. a
McDougall, T. and Barker, P.: Getting started with TEOS-10 and the Gibbs
Seawater (GSW) Oceanographic Toolbox, SCOR/IAPSO WG127, ISBN 978-0-646-55621-5, 2011. a
McLachlan, G. and Basford, K.: Mixture Models: Inference and Applications
to Clustering, Dekker, ISBN-13 9780824776916, 1988. a
Meier, W. N., Fetterer, F., Windnagel, A. K., and Stewart, J. S.: NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 4 [data set], Boulder, Colorado USA, National Snow and Ice Data Center, https://doi.org/10.7265/efmz-2t65, 2021. a
Meijers, A. J. S., Klocker, A., Bindoff, N. L., Williams, G. D., and Marsland,
S. J.: The circulation and water masses of the Antarctic shelf and
continental slope between 30 and 80∘ E, Deep-Sea Res. Pt. II, 57, 723–737, https://doi.org/10.1016/j.dsr2.2009.04.019,
2010. a
Naveira Garabato, A. C., McDonagh, E. L., Stevens, D. P., Heywood, K. J., and
Sanders, R. J.: On the export of Antarctic Bottom Water from the
Weddell Sea, Deep-Sea Res. Pt. II,
49, 4715–4742, https://doi.org/10.1016/S0967-0645(02)00156-X, 2002. a
Naveira Garabato, A. C., Zika, J. D., Jullion, L., Brown, P. J., Holland,
P. R., Meredith, M. P., and Bacon, S.: The thermodynamic balance of the
Weddell Gyre, Geophys. Res. Lett., 43, 317–325,
https://doi.org/10.1002/2015GL066658, 2016. a, b
Park, Y.-H., Charriaud, E., Craneguy, P., and Kartavtseff, A.: Fronts,
transport, and Weddell Gyre at 30∘ E between Africa and Antarctica,
J. Geophys. Res.-Oceans, 106, 2857–2879,
https://doi.org/10.1029/2000JC900087, 2001. a
Patmore, R. D., Holland, P. R., Munday, D. R., Garabato, A. C. N., Stevens,
D. P., and Meredith, M. P.: Topographic Control of Southern Ocean
Gyres and the Antarctic Circumpolar Current: A Barotropic
Perspective, J. Phys. Oceanogr., 49, 3221–3244,
https://doi.org/10.1175/JPO-D-19-0083.1, 2019. a, b
Patterson, S. L. and Sievers, H. A.: The Weddell-Scotia Confluence,
J. Phys. Oceanogr., 10, 1584–1610,
https://doi.org/10.1175/1520-0485(1980)010<1584:TWSC>2.0.CO;2, 1980. a, b, c
Pauthenet, E., Roquet, F., Madec, G., and Nerini, D.: A linear decomposition of
the Southern Ocean thermohaline structure, J. Phys.
Oceanogr., 47, 29–47, https://doi.org/10.1175/JPO-D-16-0083.s1, 2017. a
Pedregosa, F., Varoquaux, G., Gramfort, A., Michel, V., Thirion, B., Grisel,
O., Blondel, M., Prettenhofer, P., Weiss, R., Dubourg, V., Vanderplas, J.,
Passos, A., Cournapeau, D., Brucher, M., Perrot, M., and Duchesnay, E.:
Scikit-learn: Machine Learning in Python, J. Mach. Learn.
Res., 12, 2825–2830, 2011. a
Reeve, K. A., Boebel, O., Kanzow, T., Strass, V., Rohardt, G., and Fahrbach, E.: A gridded data set of upper-ocean hydrographic properties in the Weddell Gyre obtained by objective mapping of Argo float measurements, Earth Syst. Sci. Data, 8, 15–40, https://doi.org/10.5194/essd-8-15-2016, 2016. a, b
Reeve, K. A., Boebel, O., Strass, V., Kanzow, T., and Gerdes, R.: Horizontal
circulation and volume transports in the Weddell Gyre derived from Argo
float data, Prog. Oceanogr., 175, 263–283,
https://doi.org/10.1016/j.pocean.2019.04.006, 2019. a, b
Rintoul, S. R. and Garabato, A. C. N.: Chapter 18 – Dynamics of the
Southern Ocean Circulation, in: Ocean Circulation and Climate,
edited by: Siedler, G., Griffies, S. M., Gould, J., and Church, J. A., Vol. 103 of International Geophysics, 471–492, Academic Press,
https://doi.org/10.1016/B978-0-12-391851-2.00018-0, 2013. a
Roquet, F., Ferreira, D., Caneill, R., Schlesinger, D., and Madec, G.: Unique
thermal expansion properties of water key to the formation of sea ice on
Earth, Sci. Adv., 8, eabq0793, https://doi.org/10.1126/sciadv.abq0793,
2022. a
Rosso, I., Mazloff, M. R., Talley, L. D., Purkey, S. G., Freeman, N. M., and
Maze, G.: Water Mass and Biogeochemical Variability in the Kerguelen
Sector of the Southern Ocean: A Machine Learning Approach for a
Mixing Hot Spot, J. Geophys. Res.-Oceans, 125,
e2019JC015877, https://doi.org/10.1029/2019JC015877, 2020. a
Rousseeuw, P. J.: Silhouettes: A graphical aid to the interpretation and
validation of cluster analysis, J. Comput. Appl.
Math., 20, 53–65, https://doi.org/10.1016/0377-0427(87)90125-7, 1987. a
Sambe, F. and Suga, T.: Unsupervised Clustering of Argo Temperature and
Salinity Profiles in the Mid-Latitude Northwest Pacific Ocean
and Revealed Influence of the Kuroshio Extension Variability on the
Vertical Structure Distribution, J. Geophys. Res.-Oceans, 127, e2021JC018138, https://doi.org/10.1029/2021JC018138, 2022. a
Schmidtko, S., Heywood, K. J., Thompson, A. F., and Aoki, S.: Multidecadal
warming of Antarctic waters, Science, 346, 1227–1231,
https://doi.org/10.1126/science.1256117, 2014. a
Sokolov, S. and Rintoul, S. R.: Circumpolar structure and distribution of the
Antarctic Circumpolar Current fronts: 2. Variability and relationship
to sea surface height, J. Geophys. Res.-Oceans, 114, C11019,
https://doi.org/10.1029/2008JC005248, 2009. a
Sonnewald, M. and Lguensat, R.: Revealing the Impact of Global Heating on
North Atlantic Circulation Using Transparent Machine Learning,
J. Adv. Model. Earth Sy., 13, e2021MS002496,
https://doi.org/10.1029/2021MS002496, 2021. a
Sonnewald, M., Wunsch, C., and Heimbach, P.: Unsupervised Learning Reveals
Geography of Global Ocean Dynamical Regions, Earth Space
Sci., 6, 784–794, https://doi.org/10.1029/2018EA000519, 2019. a, b
Sonnewald, M., Dutkiewicz, S., Hill, C., and Forget, G.: Elucidating ecological
complexity: Unsupervised learning determines global marine eco-provinces,
Sci. Adv., 6, eaay4740, https://doi.org/10.1126/sciadv.aay4740, 2020. a
Sonnewald, M., Lguensat, R., Jones, D. C., Dueben, P. D., Brajard, J., and
Balaji, V.: Bridging observations, theory and numerical simulation of the
ocean using machine learning, Environ. Res. Lett., 16, 073008,
https://doi.org/10.1088/1748-9326/ac0eb0, 2021. a, b
Thomas, E. E. and Müller, M.: Characterizing vertical upper ocean temperature
structures in the European Arctic through unsupervised machine learning,
Ocean Model., 177, 102092, https://doi.org/10.1016/j.ocemod.2022.102092, 2022. a
Thompson, A. F., Stewart, A. L., Spence, P., and Heywood, K. J.: The
Antarctic Slope Current in a Changing Climate, Rev.
Geophys., 56, 741–770, https://doi.org/10.1029/2018RG000624, 2018.
a
Thomson, R. E. and Fine, I. V.: Estimating Mixed Layer Depth from
Oceanic Profile Data, J. Atmos. Ocean. Tech.,
20, 319–329, https://doi.org/10.1175/1520-0426(2003)020<0319:EMLDFO>2.0.CO;2, 2003. a, b
Tschudi, M., Meier, W., Stewart, N. J. S., Fowler, C., and Maslanik, J.: Polar Pathfinder Daily 25 km EASE-Grid Sea Ice Motion Vectors, Version 4 [data set], Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center, https://doi.org/10.5067/INAWUWO7QH7B, 2019. a
van der Maaten, L. and Hinton, G.: Visualizing Data using t-SNE, J.
Mach. Learn. Res., 9, 2579–2605, 2008. a
Vernet, M., Geibert, W., Hoppema, M., Brown, P. J., Haas, C., Hellmer, H. H.,
Jokat, W., Jullion, L., Mazloff, M., Bakker, D. C. E., Brearley, J. A.,
Croot, P., Hattermann, T., Hauck, J., Hillenbrand, C.-D., Hoppe, C. J. M.,
Huhn, O., Koch, B. P., Lechtenfeld, O. J., Meredith, M. P., Naveira Garabato,
A. C., Nöthig, E.-M., Peeken, I., Rutgers van der Loeff, M. M., Schmidtko,
S., Schröder, M., Strass, V. H., Torres-Valdés, S., and Verdy, A.: The
Weddell Gyre, Southern Ocean: Present Knowledge and Future
Challenges, Rev. Geophys., 57, 623–708,
https://doi.org/10.1029/2018RG000604, 2019. a, b, c, d, e, f, g, h, i
Whitworth, T., Nowlin, W. D., Orsi, A. H., Locarnini, R. A., and Smith, S. G.:
Weddell Sea shelf water in the Bransfield Strait and Weddell-Scotia
Confluence, Deep-Sea Res. Pt. I, 41,
629–641, https://doi.org/10.1016/0967-0637(94)90046-9, 1994. a, b
Wilson, E. A., Thompson, A. F., Stewart, A. L., and Sun, S.: Bathymetric
Control of Subpolar Gyres and the Overturning Circulation in the
Southern Ocean, J. Phys. Oceanogr., 52, 205–223,
https://doi.org/10.1175/JPO-D-21-0136.1, 2022. a
Xia, X., Hong, Y., Du, Y., and Xiu, P.: Three Types of Antarctic
Intermediate Water Revealed by a Machine Learning Approach,
Geophys. Res. Lett., 49, e2022GL099445,
https://doi.org/10.1029/2022GL099445, 2022. a
Zhang, Q., Qian, C., and Dong, C.: A machine learning approach to
quality-control Argo temperature data, Atmos. Ocean. Sci.
Lett., https://doi.org/10.1016/j.aosl.2022.100292, online first, 2022. a
Short summary
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.
Machine learning is transforming oceanography. For example, unsupervised classification...