Articles | Volume 19, issue 6
https://doi.org/10.5194/os-19-1809-2023
© 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-19-1809-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
20 Dec 2023
Research article |
| 20 Dec 2023
| 20 Dec 2023
Observations of strong turbulence and mixing impacting water exchange between two basins in the Baltic Sea
Julia Muchowski
CORRESPONDING AUTHOR
Department of Geological Sciences, Stockholm University, Stockholm, 10691, Sweden
Martin Jakobsson
Department of Geological Sciences, Stockholm University, Stockholm, 10691, Sweden
Lars Umlauf
Department of Physical Oceanography, Institute for Baltic Sea Research, 18119 Warnemünde, Germany
Lars Arneborg
Department of Research and Development, Swedish Meteorological and Hydrological Institute, Gothenburg, 426 71, Sweden
Bo Gustafsson
Stockholm University Baltic Sea Centre, Stockholm University, Stockholm, 10691, Sweden
Peter Holtermann
Department of Physical Oceanography, Institute for Baltic Sea Research, 18119 Warnemünde, Germany
Christoph Humborg
Stockholm University Baltic Sea Centre, Stockholm University, Stockholm, 10691, Sweden
Christian Stranne
Department of Geological Sciences, Stockholm University, Stockholm, 10691, Sweden
Stockholm University Baltic Sea Centre, Stockholm University, Stockholm, 10691, Sweden
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Matteo Masini, Agnes Karlsson, Lars Arneborg, Bengt Karlson, and Inga Monika Koszalka
EGUsphere, https://doi.org/10.5194/egusphere-2026-1344, https://doi.org/10.5194/egusphere-2026-1344, 2026
This preprint is open for discussion and under review for Natural Hazards and Earth System Sciences (NHESS).
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On the 8th of August, Storm Hans swept through the Baltic Sea disturbing the operation of desalination plants producing drinking water from sea water. In this paper, we build upon reports from the desalination plants to analyze the operational ocean model outputs and observations to identify the coastal processes behind the reported hazards. The results show a potential for future development of forecast framework.
Göran Björk, Göran Broström, Lars Arneborg, Anis Elyouncha, Daniel Bergman-Sjöstrand, and Per Pemberton
EGUsphere, https://doi.org/10.5194/egusphere-2026-785, https://doi.org/10.5194/egusphere-2026-785, 2026
This preprint is open for discussion and under review for The Cryosphere (TC).
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During the 2023/2024 ice season, a high-resolution dataset of ice thickness was collected in the Bothnian Bay. The analysis of data revealed a significant frequency of thick deformed ice such that about 60 % was thicker than 1 m. Among the 5500 individually identified ice keels, 20 % had a keel depth larger than 5 m and 2 % a depth larger than 10 m. This type of high-resolution ice data can be of vital importance for design of offshore structures and evaluation of computer ice models.
Lars Arneborg, Magnus Hieronymus, Per Pemberton, Ye Liu, and Sam T. Fredriksson
Ocean Sci., 22, 761–775, https://doi.org/10.5194/os-22-761-2026, https://doi.org/10.5194/os-22-761-2026, 2026
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Climate change influences estuaries and their ecosystems not only by rising temperatures but also by salinity changes. This modeling study highlights the magnitude and causes of the Baltic Sea salinity sensitivity to fresh water forcing and changed ocean salinity. The large sensitivity to increased fresh water forcing is shown to be caused by dilution of fresh water within the estuary, recirculation of much of the outflow water back into the estuary, as well as decreasing inflows of ocean water.
Julika Zinke, Joakim P. Hansen, Martijn Hermans, Alexis Fonseca, Sofia A. Wikström, Linda Kumblad, Emil Rydin, Marc Geibel, Matthew E. Salter, and Christoph Humborg
Biogeosciences, 23, 1653–1680, https://doi.org/10.5194/bg-23-1653-2026, https://doi.org/10.5194/bg-23-1653-2026, 2026
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This study presents one of the few studies to simultaneously measure all three major greenhouse gases across multiple shallow coastal bays in the Baltic Sea. Our findings reveal that these bays are highly variable and significant sources of greenhouse gases, with fluxes strongly influenced by bay characteristics and seasonal variation. By linking concentrations to environmental drivers, our work provides novel insights into overlooked but important components of coastal greenhouse gas budgets.
Dana Hellemann, Xiaole Sun, Tom Jilbert, Eva Ehrnsten, Lora Harris, Bo Gustafsson, Christoph Humborg, and Alf Norkko
EGUsphere, https://doi.org/10.5194/egusphere-2026-959, https://doi.org/10.5194/egusphere-2026-959, 2026
This preprint is open for discussion and under review for Biogeosciences (BG).
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Using model-simulations and field data, we assess the effect of past eutrophication on present and future ammonium dynamics in coastal sediments of the Baltic Sea and their impact on the coastal ecosystem. Our results indicate a clear eutrophication legacy effect on the persistence of ammonium being released from the sediment to the water column, particularly under oxygen deficiency, with long-lasting effects into the far future and thus important implications for ecosystem recovery measures.
Jamie Barnett, Felicity A. Holmes, Sarah L. Greenwood, Mathieu Morlighem, Nina Kirchner, and Martin Jakobsson
EGUsphere, https://doi.org/10.5194/egusphere-2026-436, https://doi.org/10.5194/egusphere-2026-436, 2026
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Computer models used to predict future change of the Greenland Ice Sheet are uncertain, especially in how they represent iceberg calving. We compare several calving approaches by testing model results against satellite observations of changes at three unique floating ice shelves in Greenland. We then extend the simulations to the year 2300 to explore future ice loss, finding that warming of the atmosphere or ocean is more important than the choice of calving method.
Abigail E. Robinson, Anna Scaini, Francisco J. Peña, Peter A. Hambäck, Christoph Humborg, and Fernando Jaramillo
Hydrol. Earth Syst. Sci., 29, 5975–6001, https://doi.org/10.5194/hess-29-5975-2025, https://doi.org/10.5194/hess-29-5975-2025, 2025
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Wetlands provide vital benefits like flood control, drought resilience, and carbon storage, but these depend on how water moves and is stored within the wetland. Using satellite imagery and AI, we mapped water patterns in 43 Swedish wetlands, identifying five hydrological types. This approach reveals differences in flooding and drying, linking wetland water behaviour to the benefits they provide, offering a practical way to understand wetland functions.
Jamie Barnett, Felicity A. Holmes, Joshua Cuzzone, Henning Åkesson, Mathieu Morlighem, Matt O'Regan, Johan Nilsson, Nina Kirchner, and Martin Jakobsson
The Cryosphere, 19, 3631–3653, https://doi.org/10.5194/tc-19-3631-2025, https://doi.org/10.5194/tc-19-3631-2025, 2025
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Understanding how ice sheets have changed in the past can allow us to make better predictions for the future. By running a state-of-the-art model of Ryder Glacier, North Greenland, over the past 12 000 years we find that both a warming atmosphere and the ocean play a key role in the evolution of the glacier. Our conclusions stress that accurately quantifying the ice sheet’s interactions with the ocean is required to predict future changes and reliable sea level rise estimates.
Felicity A. Holmes, Jamie Barnett, Henning Åkesson, Mathieu Morlighem, Johan Nilsson, Nina Kirchner, and Martin Jakobsson
The Cryosphere, 19, 2695–2714, https://doi.org/10.5194/tc-19-2695-2025, https://doi.org/10.5194/tc-19-2695-2025, 2025
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Northern Greenland contains some of the ice sheet's last remaining glaciers with floating ice tongues. One of these is Ryder Glacier, which has been relatively stable in recent decades, in contrast to nearby glaciers. Here, we use a computer model to simulate Ryder Glacier until 2300 under both a low- and a high-emissions scenario. Very high levels of surface melt under a high-emissions future lead to a sea level rise contribution that is an order of magnitude higher than under a low-emissions future.
Daniel L. Pönisch, Henry C. Bittig, Martin Kolbe, Ingo Schuffenhauer, Stefan Otto, Peter Holtermann, Kusala Premaratne, and Gregor Rehder
Biogeosciences, 22, 3583–3614, https://doi.org/10.5194/bg-22-3583-2025, https://doi.org/10.5194/bg-22-3583-2025, 2025
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Rewetted peatlands exhibit natural spatiotemporal biogeochemical heterogeneity, influenced by water level and vegetation. This study investigated the variability of greenhouse gas distribution in a peatland rewetted with brackish water. Two innovative sensor-equipped platforms were used to measure a wide range of marine physicochemical variables at high temporal resolution. The measurements revealed strong fluctuations in CO2 and CH4, expressed as multi-day, diurnal, and event-based variability.
Flor Vermassen, Clare Bird, Tirza M. Weitkamp, Kate F. Darling, Hanna Farnelid, Céline Heuzé, Allison Y. Hsiang, Salar Karam, Christian Stranne, Marcus Sundbom, and Helen K. Coxall
Biogeosciences, 22, 2261–2286, https://doi.org/10.5194/bg-22-2261-2025, https://doi.org/10.5194/bg-22-2261-2025, 2025
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We provide the first systematic survey of planktonic foraminifera in the high Arctic Ocean. Our results describe the abundance and species composition under summer sea ice. They indicate that the polar specialist N. pachyderma is the only species present, with subpolar species absent. The data set will be a valuable reference for continued monitoring of the state of planktonic foraminifera communities as they respond to the ongoing sea-ice decline and the “Atlantification” of the Arctic Ocean.
Erik Gustafsson, Bo G. Gustafsson, Martijn Hermans, Christoph Humborg, and Christian Stranne
Geosci. Model Dev., 17, 7157–7179, https://doi.org/10.5194/gmd-17-7157-2024, https://doi.org/10.5194/gmd-17-7157-2024, 2024
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Methane (CH4) cycling in the Baltic Proper is studied through model simulations, enabling a first estimate of key CH4 fluxes. A preliminary budget identifies benthic CH4 release as the dominant source and two main sinks: CH4 oxidation in the water (92 % of sinks) and outgassing to the atmosphere (8 % of sinks). This study addresses CH4 emissions from coastal seas and is a first step toward understanding the relative importance of open-water outgassing compared with local coastal hotspots.
Itzel Ruvalcaba Baroni, Elin Almroth-Rosell, Lars Axell, Sam T. Fredriksson, Jenny Hieronymus, Magnus Hieronymus, Sandra-Esther Brunnabend, Matthias Gröger, Ivan Kuznetsov, Filippa Fransner, Robinson Hordoir, Saeed Falahat, and Lars Arneborg
Biogeosciences, 21, 2087–2132, https://doi.org/10.5194/bg-21-2087-2024, https://doi.org/10.5194/bg-21-2087-2024, 2024
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The health of the Baltic and North seas is threatened due to high anthropogenic pressure; thus, different methods to assess the status of these regions are urgently needed. Here, we validated a novel model simulating the ocean dynamics and biogeochemistry of the Baltic and North seas that can be used to create future climate and nutrient scenarios, contribute to European initiatives on de-eutrophication, and provide water quality advice and support on nutrient load reductions for both seas.
Johan Nilsson, Eef van Dongen, Martin Jakobsson, Matt O'Regan, and Christian Stranne
The Cryosphere, 17, 2455–2476, https://doi.org/10.5194/tc-17-2455-2023, https://doi.org/10.5194/tc-17-2455-2023, 2023
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We investigate how topographical sills suppress basal glacier melt in Greenlandic fjords. The basal melt drives an exchange flow over the sill, but there is an upper flow limit set by the Atlantic Water features outside the fjord. If this limit is reached, the flow enters a new regime where the melt is suppressed and its sensitivity to the Atlantic Water temperature is reduced.
Gabriel West, Darrell S. Kaufman, Martin Jakobsson, and Matt O'Regan
Geochronology, 5, 285–299, https://doi.org/10.5194/gchron-5-285-2023, https://doi.org/10.5194/gchron-5-285-2023, 2023
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We report aspartic and glutamic acid racemization analyses on Neogloboquadrina pachyderma and Cibicidoides wuellerstorfi from the Arctic Ocean (AO). The rates of racemization in the species are compared. Calibrating the rate of racemization in C. wuellerstorfi for the past 400 ka allows the estimation of sample ages from the central AO. Estimated ages are older than existing age assignments (as previously observed for N. pachyderma), confirming that differences are not due to taxonomic effects.
Eva Ehrnsten, Oleg Pavlovitch Savchuk, and Bo Gustav Gustafsson
Biogeosciences, 19, 3337–3367, https://doi.org/10.5194/bg-19-3337-2022, https://doi.org/10.5194/bg-19-3337-2022, 2022
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We studied the effects of benthic fauna, animals living on or in the seafloor, on the biogeochemical cycles of carbon, nitrogen and phosphorus using a model of the Baltic Sea ecosystem. By eating and excreting, the animals transform a large part of organic matter sinking to the seafloor into inorganic forms, which fuel plankton blooms. Simultaneously, when they move around (bioturbate), phosphorus is bound in the sediments. This reduces nitrogen-fixing plankton blooms and oxygen depletion.
Karol Kuliński, Gregor Rehder, Eero Asmala, Alena Bartosova, Jacob Carstensen, Bo Gustafsson, Per O. J. Hall, Christoph Humborg, Tom Jilbert, Klaus Jürgens, H. E. Markus Meier, Bärbel Müller-Karulis, Michael Naumann, Jørgen E. Olesen, Oleg Savchuk, Andreas Schramm, Caroline P. Slomp, Mikhail Sofiev, Anna Sobek, Beata Szymczycha, and Emma Undeman
Earth Syst. Dynam., 13, 633–685, https://doi.org/10.5194/esd-13-633-2022, https://doi.org/10.5194/esd-13-633-2022, 2022
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The paper covers the aspects related to changes in carbon, nitrogen, and phosphorus (C, N, P) external loads; their transformations in the coastal zone; changes in organic matter production (eutrophication) and remineralization (oxygen availability); and the role of sediments in burial and turnover of C, N, and P. Furthermore, this paper also focuses on changes in the marine CO2 system, the structure of the microbial community, and the role of contaminants for biogeochemical processes.
Jaclyn Clement Kinney, Karen M. Assmann, Wieslaw Maslowski, Göran Björk, Martin Jakobsson, Sara Jutterström, Younjoo J. Lee, Robert Osinski, Igor Semiletov, Adam Ulfsbo, Irene Wåhlström, and Leif G. Anderson
Ocean Sci., 18, 29–49, https://doi.org/10.5194/os-18-29-2022, https://doi.org/10.5194/os-18-29-2022, 2022
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We use data crossing Herald Canyon in the Chukchi Sea collected in 2008 and 2014 together with numerical modelling to investigate the circulation in the western Chukchi Sea. A large fraction of water from the Chukchi Sea enters the East Siberian Sea south of Wrangel Island and circulates in an anticyclonic direction around the island. To assess the differences between years, we use numerical modelling results, which show that high-frequency variability dominates the flow in Herald Canyon.
Amanda T. Nylund, Lars Arneborg, Anders Tengberg, Ulf Mallast, and Ida-Maja Hassellöv
Ocean Sci., 17, 1285–1302, https://doi.org/10.5194/os-17-1285-2021, https://doi.org/10.5194/os-17-1285-2021, 2021
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Acoustic and satellite observations of turbulent ship wakes show that ships can mix the water column down to 30 m depth and that a temperature signature of the wake can last for tens of kilometres after ship passage. Turbulent wakes deeper than 12 m were frequently detected, which is deeper than previously reported. The observed extent of turbulent ship wakes implies that in areas with intensive ship traffic, ship mixing should be considered when assessing environmental impacts from shipping.
Henrieka Detlef, Brendan Reilly, Anne Jennings, Mads Mørk Jensen, Matt O'Regan, Marianne Glasius, Jesper Olsen, Martin Jakobsson, and Christof Pearce
The Cryosphere, 15, 4357–4380, https://doi.org/10.5194/tc-15-4357-2021, https://doi.org/10.5194/tc-15-4357-2021, 2021
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Here we examine the Nares Strait sea ice dynamics over the last 7000 years and their implications for the late Holocene readvance of the floating part of Petermann Glacier. We propose that the historically observed sea ice dynamics are a relatively recent feature, while most of the mid-Holocene was marked by variable sea ice conditions in Nares Strait. Nonetheless, major advances of the Petermann ice tongue were preceded by a shift towards harsher sea ice conditions in Nares Strait.
Matt O'Regan, Thomas M. Cronin, Brendan Reilly, Aage Kristian Olsen Alstrup, Laura Gemery, Anna Golub, Larry A. Mayer, Mathieu Morlighem, Matthias Moros, Ole L. Munk, Johan Nilsson, Christof Pearce, Henrieka Detlef, Christian Stranne, Flor Vermassen, Gabriel West, and Martin Jakobsson
The Cryosphere, 15, 4073–4097, https://doi.org/10.5194/tc-15-4073-2021, https://doi.org/10.5194/tc-15-4073-2021, 2021
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Ryder Glacier is a marine-terminating glacier in north Greenland discharging ice into the Lincoln Sea. Here we use marine sediment cores to reconstruct its retreat and advance behavior through the Holocene. We show that while Sherard Osborn Fjord has a physiography conducive to glacier and ice tongue stability, Ryder still retreated more than 40 km inland from its current position by the Middle Holocene. This highlights the sensitivity of north Greenland's marine glaciers to climate change.
Tobias Peter Bauer, Peter Holtermann, Bernd Heinold, Hagen Radtke, Oswald Knoth, and Knut Klingbeil
Geosci. Model Dev., 14, 4843–4863, https://doi.org/10.5194/gmd-14-4843-2021, https://doi.org/10.5194/gmd-14-4843-2021, 2021
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We present the coupled atmosphere–ocean model system ICONGETM. The added value and potential of using the latest coupling technologies are discussed in detail. An exchange grid handles the different coastlines from the unstructured atmosphere and the structured ocean grids. Due to a high level of automated processing, ICONGETM requires only minimal user input. The application to a coastal upwelling scenario demonstrates significantly improved model results compared to uncoupled simulations.
Qing Li, Jorn Bruggeman, Hans Burchard, Knut Klingbeil, Lars Umlauf, and Karsten Bolding
Geosci. Model Dev., 14, 4261–4282, https://doi.org/10.5194/gmd-14-4261-2021, https://doi.org/10.5194/gmd-14-4261-2021, 2021
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Different ocean vertical mixing schemes are usually developed in different modeling framework, making the comparison across such schemes difficult. Here, we develop a consistent framework for testing, comparing, and applying different ocean mixing schemes by integrating CVMix into GOTM, which also extends the capability of GOTM towards including the effects of ocean surface waves. A suite of test cases and toolsets for developing and evaluating ocean mixing schemes is also described.
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Short summary
We show observational data of highly increased mixing and vertical salt flux rates in a sparsely sampled region of the northern Baltic Sea. Co-located acoustic observations complement our in situ measurements and visualize turbulent mixing with high spatial resolution. The observed mixing is generally not resolved in numerical models of the area but likely impacts the exchange of water between the adjacent basins as well as nutrient and oxygen conditions in the Bothnian Sea.
We show observational data of highly increased mixing and vertical salt flux rates in a sparsely...
