Articles | Volume 21, issue 4
https://doi.org/10.5194/os-21-1609-2025
© Author(s) 2025. 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-21-1609-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
30 Jul 2025
Research article |
| 30 Jul 2025
| 30 Jul 2025
Satellite-derived steric height in the Southern Ocean: trends, variability, and climate drivers
National Oceanography Centre, Southampton, SO14 3ZH, UK
Institute for Climate and Atmospheric Science, University of Leeds, Leeds, LS2 9JT, UK
Alessandro Silvano
School of Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
Alberto C. Naveira Garabato
School of Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
Oana Dragomir
School of Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
Balearic Islands Coastal Observing and Forecasting System, 07121 Palma, Balearic Islands, Spain
Noémie Schifano
Laboratoire d’Océanographie Physique et Spatiale (LOPS), Univ Brest, CNRS, IUEM, Brest, France
Anna E. Hogg
Institute for Climate and Atmospheric Science, University of Leeds, Leeds, LS2 9JT, UK
Alice Marzocchi
National Oceanography Centre, Southampton, SO14 3ZH, UK
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Isabelle F. M. White, Oana Dragomir, Alessandro Silvano, Alberto C. Naveira Garabato, Anna E. Hogg, Pierre Dutrieux, Laura Herraiz-Borreguero, and Jennifer Cocks
EGUsphere, https://doi.org/10.5194/egusphere-2026-4414, https://doi.org/10.5194/egusphere-2026-4414, 2026
This preprint is open for discussion and under review for Earth Observation (EO).
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We present a 22-year sea surface height product in the ice-covered Southern Ocean from Envisat and CryoSat-2 satellite altimetry data. Our product is 1° longitude by 0.5° latitude from 50° S to the Antarctic coast. Validation with in-situ, independent satellite and reanalysis data shows it captures seasonal and interannual variability. This supports long-term study of large-scale sea level trends and processes in the Southern Ocean, a region that is observing rapid sea ice and ice sheet melting.
Isabelle F. M. White, Oana Dragomir, Alessandro Silvano, Alberto C. Naveira Garabato, Anna E. Hogg, Pierre Dutrieux, Laura Herraiz-Borreguero, and Jennifer Cocks
EGUsphere, https://doi.org/10.5194/egusphere-2026-4414, https://doi.org/10.5194/egusphere-2026-4414, 2026
This preprint is open for discussion and under review for Earth Observation (EO).
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We present a 22-year sea surface height product in the ice-covered Southern Ocean from Envisat and CryoSat-2 satellite altimetry data. Our product is 1° longitude by 0.5° latitude from 50° S to the Antarctic coast. Validation with in-situ, independent satellite and reanalysis data shows it captures seasonal and interannual variability. This supports long-term study of large-scale sea level trends and processes in the Southern Ocean, a region that is observing rapid sea ice and ice sheet melting.
Benjamin J. Davison, Andrew J. Sole, Gregoire Guillet, Douglas I. Benn, Jonathan Kingslake, Jeremy C. Ely, Stephen J. Livingstone, Christopher D. Stringer, Jonathan L. Carrivick, and Anna E. Hogg
The Cryosphere, 20, 4293–4311, https://doi.org/10.5194/tc-20-4293-2026, https://doi.org/10.5194/tc-20-4293-2026, 2026
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Some glaciers flow slowly for many years before dramatically accelerating. This is usually a sign of a surge. Theory and observations suggest that surges occur in certain climates. The Antarctic Peninsula has such a climate yet only one surge has been observed there. We present detailed observations of three glaciers that surged recently. We explore how climate change over the past hundred years, and projected climate change up to 2150, has and will affect surging behaviour on the Peninsula.
Yikai Zhu, Anna E. Hogg, Benjamin J. Wallis, Ross A. W. Slater, and Oliver J. Marsh
EGUsphere, https://doi.org/10.5194/egusphere-2026-3795, https://doi.org/10.5194/egusphere-2026-3795, 2026
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Luisa E. Avilés-Podgurski, Patrick Martineau, Hua Lu, Ayako Yamamoto, Amanda C. Maycock, Andrew Orr, Tony Phillips, Thomas J. Bracegirdle, Anna E. Hogg, Grzegorz Muszynski, and Andrew Fleming
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Evridiki Chrysagi, Lars Umlauf, Ulf Gräwe, Hans Burchard, and Alberto C. Naveira Garabato
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High-resolution numerical simulations of the Baltic Sea reveal that fine-scale motions known as submesoscales are widespread in the deeper layers of the basin, especially near its boundaries. These features are linked to strong mixing and, in this wind-driven system, are found to intensify during storms, with wind reversals shifting the location of mixing hotspots. Our results suggest that storm-modulated submesoscales may be important in other wind-driven coastal seas and lakes.
Hugues Goosse, Cecile Davrinche, Benjamin Richaud, Dániel Topál, Stephy Libera, Alberto C. Naveira Garabato, Alessandro Silvano, Martin Vancoppenolle, and Pablo Ortega
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The variability of the winter sea ice edge is much higher in regions close to the main topographic features of the Southern Ocean than over the smoother abyssal plain. The oceanic bathymetry influences mesoscale eddy activity and the Antarctic Circumpolar Current jets, affecting both oceanic heat transport and sea ice velocity and subsequently sea ice variability.
Harry J. Davis, Robert G. Bingham, Carlos Martín, Elizabeth R. Thomas, Andrew S. Hein, and Anna E. Hogg
The Cryosphere, 20, 2735–2756, https://doi.org/10.5194/tc-20-2735-2026, https://doi.org/10.5194/tc-20-2735-2026, 2026
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Miriam F. Sterl, Carlo J. Mans, Alberto C. Naveira Garabato, and Sjoerd Groeskamp
EGUsphere, https://doi.org/10.5194/egusphere-2026-2566, https://doi.org/10.5194/egusphere-2026-2566, 2026
This preprint is open for discussion and under review for Ocean Science (OS).
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Alberto C. Naveira Garabato, Carl P. Spingys, Andrew J. Lucas, Tiago S. Dotto, Christian T. Wild, Scott W. Tyler, Ted A. Scambos, Christopher B. Kratt, Giuseppe Cappelli, Ethan F. Williams, Mariona Claret, Hannah E. Glover, Meagan E. Wengrove, Madison M. Smith, Michael G. Baker, Giuseppe Marra, Max Tamussino, Zitong Feng, David Lloyd, Liam Taylor, Mikael Mazur, Maria-Daphne Mangriotis, Aaron Micallef, Jennifer Ward Neale, Oleg A. Godin, Matthew H. Alford, Emma P. M. Gregory, Michael A. Clare, Hamid Shiri, Angel Ruiz Angulo, Kathryn L. Gunn, Ben I. Moat, Isobel A. Yeo, Afonso Loureiro, Alessandro Silvano, Arthur Hartog, and Mohammad Belal
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Sarah Leibrock, Ross A. W. Slater, Anna E. Hogg, and Celia A. Baumhoer
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Hugues Goosse, Stephy Libera, Alberto C. Naveira Garabato, Benjamin Richaud, Alessandro Silvano, and Martin Vancoppenolle
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Trystan Surawy-Stepney, Stephen L. Cornford, and Anna E. Hogg
The Cryosphere, 19, 5531–5545, https://doi.org/10.5194/tc-19-5531-2025, https://doi.org/10.5194/tc-19-5531-2025, 2025
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Shenjie Zhou, Pierre Dutrieux, Claudia F. Giulivi, Adrian Jenkins, Alessandro Silvano, Christopher Auckland, E. Povl Abrahamsen, Michael Meredith, Irena Vaňková, Keith Nicholls, Peter E. D. Davis, Svein Østerhus, Arnold L. Gordon, Christopher J. Zappa, Tiago S. Dotto, Ted Scambos, Kathryn L. Gunn, Stephen R. Rintoul, Shigeru Aoki, Craig Stevens, Chengyan Liu, Sukyoung Yun, Tae-Wan Kim, Won Sang Lee, Markus Janout, Tore Hattermann, Julius Lauber, Elin Darelius, Anna Wåhlin, Leo Middleton, Pasquale Castagno, Giorgio Budillon, Karen J. Heywood, Jennifer Graham, Stephen Dye, Daisuke Hirano, and Una Kim Miller
Earth Syst. Sci. Data, 17, 5693–5706, https://doi.org/10.5194/essd-17-5693-2025, https://doi.org/10.5194/essd-17-5693-2025, 2025
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Katie Lowery, Pierre Dutrieux, Paul R. Holland, Anna E. Hogg, Noel Gourmelen, and Benjamin J. Wallis
The Cryosphere, 19, 4893–4911, https://doi.org/10.5194/tc-19-4893-2025, https://doi.org/10.5194/tc-19-4893-2025, 2025
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Matilda Weatherley, Chris R. Stokes, Stewart S. R. Jamieson, Sindhu Ramanath, and Alessandro Silvano
EGUsphere, https://doi.org/10.5194/egusphere-2025-4100, https://doi.org/10.5194/egusphere-2025-4100, 2025
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Parts of the East Antarctic Ice Sheet rest on a bed below sea level, making them vulnerable to ice dynamic changes and instability, but few glaciers have been studied in detail. Here we report on glaciers draining into Porpoise Bay, Wilkes Land, overlying the Aurora Subglacial Basin. We find ice surface thinning, grounding line retreat and ice surface velocity increase over recent decades, consistent with warm ocean waters intrusion. This highlights this region's vulnerability to future warming.
Verónica González-Gambau, Estrella Olmedo, Aina García-Espriu, Cristina González-Haro, Antonio Turiel, Carolina Gabarró, Alessandro Silvano, Aditya Narayanan, Alberto Naveira-Garabato, Rafael Catany, Nina Hoareau, Marta Umbert, Giuseppe Aulicino, Yuri Cotroneo, Roberto Sabia, and Diego Fernández-Prieto
Earth Syst. Sci. Data, 17, 5089–5111, https://doi.org/10.5194/essd-17-5089-2025, https://doi.org/10.5194/essd-17-5089-2025, 2025
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This paper introduces a new Sea Surface Salinity product for the Southern Ocean, based on SMOS data and developed by the Barcelona Expert Center. It offers 9 d maps on a 25 km EASE-SL grid, from 2011 to 2023, covering areas south of 30° S. The product is accurate beyond 150 km from sea ice, with nearly zero bias and a ~0.22 STD. It tracks well seasonal and interannual changes and will contribute to the understanding of processes influenced by upper-ocean salinity, including ice formation/melt.
Yikai Zhu, Anna E. Hogg, Andrew Hooper, and Benjamin J. Wallis
The Cryosphere, 19, 3971–3989, https://doi.org/10.5194/tc-19-3971-2025, https://doi.org/10.5194/tc-19-3971-2025, 2025
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This study investigates the long- and short-term changes in the grounding line of the Amery Ice Shelf in East Antarctica, using satellite observations and a method called Differential Range Offset Tracking (DROT). Our findings show how the grounding line behaves in response to tides and other environmental factors, with implications for understanding ice shelf stability.
Zanna Chase, Karen E. Kohfeld, Amy Leventer, David Lund, Xavier Crosta, Laurie Menviel, Helen C. Bostock, Matthew Chadwick, Samuel L. Jaccard, Jacob Jones, Alice Marzocchi, Katrin J. Meissner, Elisabeth Sikes, Louise C. Sime, and Luke Skinner
EGUsphere, https://doi.org/10.5194/egusphere-2025-3504, https://doi.org/10.5194/egusphere-2025-3504, 2025
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The impact of recent dramatic declines in Antarctic sea ice on the Earth system are uncertain. We reviewed how sea ice affects ocean circulation, ice sheets, winds, and the carbon cycle by considering theory and modern observations alongside paleo-proxy reconstructions. We found evidence for connections between sea ice and these systems but also conflicting results, which point to missing knowledge. Our work highlights the complex role of sea ice in the Earth system.
Benjamin J. Davison, Anna E. Hogg, Thomas Slater, Richard Rigby, and Nicolaj Hansen
Earth Syst. Sci. Data, 17, 3259–3281, https://doi.org/10.5194/essd-17-3259-2025, https://doi.org/10.5194/essd-17-3259-2025, 2025
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Grounding line discharge is a measure of the amount of ice entering the ocean from an ice mass. This paper describes a dataset of grounding line discharge for the Antarctic Ice Sheet and each of its glaciers. The dataset shows that Antarctic Ice Sheet grounding line discharge has increased since 1996.
Heather L. Selley, Anna E. Hogg, Benjamin J. Davison, Pierre Dutrieux, and Thomas Slater
The Cryosphere, 19, 1725–1738, https://doi.org/10.5194/tc-19-1725-2025, https://doi.org/10.5194/tc-19-1725-2025, 2025
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We used satellite observations to measure recent changes in ice speed and flow direction in the Pope, Smith, and Kohler region of West Antarctica (2005–2022). We found substantial speed-up on seven ice streams of up to 87 %. However, Kohler West Glacier has slowed by 10 %, due to the redirection of ice flow into its rapidly thinning neighbour. This process of “ice piracy” has not previously been directly observed on this rapid timescale and may influence future ice shelf and sheet mass changes.
Benjamin J. Wallis, Anna E. Hogg, Yikai Zhu, and Andrew Hooper
The Cryosphere, 18, 4723–4742, https://doi.org/10.5194/tc-18-4723-2024, https://doi.org/10.5194/tc-18-4723-2024, 2024
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The grounding line, where ice begins to float, is an essential variable to understand ice dynamics, but in some locations it can be challenging to measure with established techniques. Using satellite data and a new method, Wallis et al. measure the grounding line position of glaciers and ice shelves in the Antarctic Peninsula and find retreats of up to 16.3 km have occurred since the last time measurements were made in the 1990s.
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
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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.
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
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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.
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.
Trystan Surawy-Stepney, Anna E. Hogg, Stephen L. Cornford, Benjamin J. Wallis, Benjamin J. Davison, Heather L. Selley, Ross A. W. Slater, Elise K. Lie, Livia Jakob, Andrew Ridout, Noel Gourmelen, Bryony I. D. Freer, Sally F. Wilson, and Andrew Shepherd
The Cryosphere, 18, 977–993, https://doi.org/10.5194/tc-18-977-2024, https://doi.org/10.5194/tc-18-977-2024, 2024
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Here, we use satellite observations and an ice flow model to quantify the impact of sea ice buttressing on ice streams on the Antarctic Peninsula. The evacuation of 11-year-old landfast sea ice in the Larsen B embayment on the East Antarctic Peninsula in January 2022 was closely followed by major changes in the calving behaviour and acceleration (30 %) of the ocean-terminating glaciers. Our results show that sea ice buttressing had a negligible direct role in the observed dynamic changes.
Trystan Surawy-Stepney, Anna E. Hogg, Stephen L. Cornford, and David C. Hogg
The Cryosphere, 17, 4421–4445, https://doi.org/10.5194/tc-17-4421-2023, https://doi.org/10.5194/tc-17-4421-2023, 2023
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The presence of crevasses in Antarctica influences how the ice sheet behaves. It is important, therefore, to collect data on the spatial distribution of crevasses and how they are changing. We present a method of mapping crevasses from satellite radar imagery and apply it to 7.5 years of images, covering Antarctica's floating and grounded ice. We develop a method of measuring change in the density of crevasses and quantify increased fracturing in important parts of the West Antarctic Ice Sheet.
Bryony I. D. Freer, Oliver J. Marsh, Anna E. Hogg, Helen Amanda Fricker, and Laurie Padman
The Cryosphere, 17, 4079–4101, https://doi.org/10.5194/tc-17-4079-2023, https://doi.org/10.5194/tc-17-4079-2023, 2023
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We develop a method using ICESat-2 data to measure how Antarctic grounding lines (GLs) migrate across the tide cycle. At an ice plain on the Ronne Ice Shelf we observe 15 km of tidal GL migration, the largest reported distance in Antarctica, dominating any signal of long-term migration. We identify four distinct migration modes, which provide both observational support for models of tidal ice flexure and GL migration and insights into ice shelf–ocean–subglacial interactions in grounding zones.
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.
Julia R. Andreasen, Anna E. Hogg, and Heather L. Selley
The Cryosphere, 17, 2059–2072, https://doi.org/10.5194/tc-17-2059-2023, https://doi.org/10.5194/tc-17-2059-2023, 2023
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There are few long-term, high spatial resolution observations of ice shelf change in Antarctica over the past 3 decades. In this study, we use high spatial resolution observations to map the annual calving front location on 34 ice shelves around Antarctica from 2009 to 2019 using satellite data. The results provide a comprehensive assessment of ice front migration across Antarctica over the last decade.
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
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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.
Xavier Crosta, Karen E. Kohfeld, Helen C. Bostock, Matthew Chadwick, Alice Du Vivier, Oliver Esper, Johan Etourneau, Jacob Jones, Amy Leventer, Juliane Müller, Rachael H. Rhodes, Claire S. Allen, Pooja Ghadi, Nele Lamping, Carina B. Lange, Kelly-Anne Lawler, David Lund, Alice Marzocchi, Katrin J. Meissner, Laurie Menviel, Abhilash Nair, Molly Patterson, Jennifer Pike, Joseph G. Prebble, Christina Riesselman, Henrik Sadatzki, Louise C. Sime, Sunil K. Shukla, Lena Thöle, Maria-Elena Vorrath, Wenshen Xiao, and Jiao Yang
Clim. Past, 18, 1729–1756, https://doi.org/10.5194/cp-18-1729-2022, https://doi.org/10.5194/cp-18-1729-2022, 2022
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Despite its importance in the global climate, our knowledge of Antarctic sea-ice changes throughout the last glacial–interglacial cycle is extremely limited. As part of the Cycles of Sea Ice Dynamics in the Earth system (C-SIDE) Working Group, we review marine- and ice-core-based sea-ice proxies to provide insights into their applicability and limitations. By compiling published records, we provide information on Antarctic sea-ice dynamics over the past 130 000 years.
Martin Horwath, Benjamin D. Gutknecht, Anny Cazenave, Hindumathi Kulaiappan Palanisamy, Florence Marti, Ben Marzeion, Frank Paul, Raymond Le Bris, Anna E. Hogg, Inès Otosaka, Andrew Shepherd, Petra Döll, Denise Cáceres, Hannes Müller Schmied, Johnny A. Johannessen, Jan Even Øie Nilsen, Roshin P. Raj, René Forsberg, Louise Sandberg Sørensen, Valentina R. Barletta, Sebastian B. Simonsen, Per Knudsen, Ole Baltazar Andersen, Heidi Ranndal, Stine K. Rose, Christopher J. Merchant, Claire R. Macintosh, Karina von Schuckmann, Kristin Novotny, Andreas Groh, Marco Restano, and Jérôme Benveniste
Earth Syst. Sci. Data, 14, 411–447, https://doi.org/10.5194/essd-14-411-2022, https://doi.org/10.5194/essd-14-411-2022, 2022
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Global mean sea-level change observed from 1993 to 2016 (mean rate of 3.05 mm yr−1) matches the combined effect of changes in water density (thermal expansion) and ocean mass. Ocean-mass change has been assessed through the contributions from glaciers, ice sheets, and land water storage or directly from satellite data since 2003. Our budget assessments of linear trends and monthly anomalies utilise new datasets and uncertainty characterisations developed within ESA's Climate Change Initiative.
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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 trends and variability in steric height, drawing links to climate variability, and discuss the effectiveness of the method, highlighting issues with its application.
Heat and freshwater fluxes in the Southern Ocean mediate global ocean circulation and abyssal...
