Articles | Volume 4-osr8
https://doi.org/10.5194/sp-4-osr8-16-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/sp-4-osr8-16-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
30 Sep 2024
| OSR8 | Chapter 4.4
| 30 Sep 2024 | OSR8 | Chapter 4.4
Baltic Sea surface temperature analysis 2022: a study of marine heatwaves and overall high seasonal temperatures
Anja Lindenthal
CORRESPONDING AUTHOR
Marine Sciences Department, Federal Maritime and Hydrographic Agency, 20539 Hamburg, Germany
Marine Sciences Department, Federal Maritime and Hydrographic Agency, 20539 Hamburg, Germany
Simon Jandt-Scheelke
Marine Sciences Department, Federal Maritime and Hydrographic Agency, 20539 Hamburg, Germany
Tim Kruschke
Marine Sciences Department, Federal Maritime and Hydrographic Agency, 20539 Hamburg, Germany
Priidik Lagemaa
Department of Marine Systems, Tallinn University of Technology, Tallinn, 12618, Estonia
Eefke M. van der Lee
Marine Sciences Department, Federal Maritime and Hydrographic Agency, 18057 Rostock, Germany
Ilja Maljutenko
Department of Marine Systems, Tallinn University of Technology, Tallinn, 12618, Estonia
Helen E. Morrison
Marine Sciences Department, Federal Maritime and Hydrographic Agency, 18057 Rostock, Germany
Tabea R. Panteleit
Marine Sciences Department, Federal Maritime and Hydrographic Agency, 20539 Hamburg, Germany
Urmas Raudsepp
Department of Marine Systems, Tallinn University of Technology, Tallinn, 12618, Estonia
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Lena Spruch, Anja Lindenthal, Peter Holtermann, Simon Jandt-Scheelke, Arjun Kumar, Michael Naumann, and Uwe Krumme
State Planet Discuss., https://doi.org/10.5194/sp-2026-16, https://doi.org/10.5194/sp-2026-16, 2026
Preprint under review for SP
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In September 2025, fish kills occurred at multiple sites along Germany’s western Baltic Sea coast. Using model data and measurements, we show that they were caused by upwelling of hypoxic bottom water. Coastal hypoxia is a known environmental issue in the region and mainly caused by ongoing eutrophication and rising water temperatures. We find that marine heatwaves preceded the fish kills, contributing to increased stress on the fish both through high temperature and by increasing deoxynation.
Vijith Vijayakumaran, Rebecca Millington, Jorn Bruggeman, Josefine Hahn, Helen Powley, Gennadi Lessin, Anja Lindenthal, Corinna Schrum, and Ute Daewel
EGUsphere, https://doi.org/10.5194/egusphere-2026-3078, https://doi.org/10.5194/egusphere-2026-3078, 2026
This preprint is open for discussion and under review for Geoscientific Model Development (GMD).
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We present ECOSMO End-to-End v2.0, a set of fish and macrobenthos functional-group modules that can be two-way coupled to lower-trophic-level marine ecosystem models. Using a one-dimensional setup, we tested these plug-and-play modules coupled to three models used in the Copernicus Marine Service framework. Simulations show that macrobenthos increase bottom-layer nutrients and are essential for realistic fish production, while fish and macrobenthos strengthen top-down control on plankton.
Tuomas Kärnä, Patrik Ljungemyr, Saeed Falahat, Ida Ringgaard, Lars Axell, Vasily Korabel, Jens Murawski, Ilja Maljutenko, Anja Lindenthal, Simon Jandt-Scheelke, Svetlana Verjovkina, Ina Lorkowski, Priidik Lagemaa, Jun She, Laura Tuomi, Adam Nord, and Vibeke Huess
Geosci. Model Dev., 14, 5731–5749, https://doi.org/10.5194/gmd-14-5731-2021, https://doi.org/10.5194/gmd-14-5731-2021, 2021
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We present Nemo-Nordic 2.0, a novel operational marine model for the Baltic Sea. The model covers the Baltic Sea and the North Sea with approximately 1 nmi resolution. We validate the model's performance against sea level, water temperature, and salinity observations, as well as sea ice charts. The skill analysis demonstrates that Nemo-Nordic 2.0 can reproduce the hydrographic features of the Baltic Sea.
Lena Spruch, Anja Lindenthal, Peter Holtermann, Simon Jandt-Scheelke, Arjun Kumar, Michael Naumann, and Uwe Krumme
State Planet Discuss., https://doi.org/10.5194/sp-2026-16, https://doi.org/10.5194/sp-2026-16, 2026
Preprint under review for SP
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In September 2025, fish kills occurred at multiple sites along Germany’s western Baltic Sea coast. Using model data and measurements, we show that they were caused by upwelling of hypoxic bottom water. Coastal hypoxia is a known environmental issue in the region and mainly caused by ongoing eutrophication and rising water temperatures. We find that marine heatwaves preceded the fish kills, contributing to increased stress on the fish both through high temperature and by increasing deoxynation.
Vijith Vijayakumaran, Rebecca Millington, Jorn Bruggeman, Josefine Hahn, Helen Powley, Gennadi Lessin, Anja Lindenthal, Corinna Schrum, and Ute Daewel
EGUsphere, https://doi.org/10.5194/egusphere-2026-3078, https://doi.org/10.5194/egusphere-2026-3078, 2026
This preprint is open for discussion and under review for Geoscientific Model Development (GMD).
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We present ECOSMO End-to-End v2.0, a set of fish and macrobenthos functional-group modules that can be two-way coupled to lower-trophic-level marine ecosystem models. Using a one-dimensional setup, we tested these plug-and-play modules coupled to three models used in the Copernicus Marine Service framework. Simulations show that macrobenthos increase bottom-layer nutrients and are essential for realistic fish production, while fish and macrobenthos strengthen top-down control on plankton.
Ali Hayatijozani, Amirhossein Barzandeh, Ilja Maljutenko, Priidik Lagemaa, and Urmas Raudsepp
State Planet Discuss., https://doi.org/10.5194/sp-2026-4, https://doi.org/10.5194/sp-2026-4, 2026
Preprint under review for SP
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Using long-term regional reanalysis, this study shows that Baltic Sea warming is spatially organized rather than basin-uniform. Heat content anomalies form recurrent regimes, including basin-wide warm/cold states and contrasted patterns with opposite anomalies across regions. Positive regimes increase after the mid-2010s, while regional contrasts persist, highlighting the limits of basin-mean heat metrics.
Marilaure Grégoire, Gianpiero Cossarini, Corinne Derval, Elodie Gutknecht, Susan Kay, Julien Lamouroux, Helen Morrison, Coralie Perruche, Annette Samuelsen, Lena Spruch, Anna Teruzzi, Luc Vandenbulcke, Karina Von Schuckmann, and Tsuyoshi Wakamatsu
EGUsphere, https://doi.org/10.5194/egusphere-2026-813, https://doi.org/10.5194/egusphere-2026-813, 2026
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We review the advancements in our capabilities to predict the green ocean in the frame of the European Copernicus Marine Service since its start in 2015 and for the five European seas, the Arctic and Global oceans. The evolutions of the prediction systems, delivered products and computing resources requirements are reviewed. Recommendations for future developments are proposed based on a SWOT analysis of current CMEMS green ocean prediction systems and products.
Vera Maurer, Wibke Düsterhöft-Wriggers, Rebekka Beddig, Janna Meyer, Claudia Hinrichs, Ha Thi Minh Ho-Hagemann, Joanna Staneva, Birte-Marie Ehlers, and Frank Janssen
Geosci. Model Dev., 19, 543–578, https://doi.org/10.5194/gmd-19-543-2026, https://doi.org/10.5194/gmd-19-543-2026, 2026
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With CORDEX-CMIP6, ensembles of regional climate projections enable analyses on regional climate change. We present a regional coupled ocean-atmosphere model setup for Europe, tailored to provide consistent climate change information for the North and Baltic Seas. The simulation effectively captures the mean climate, variability, and extremes such as storm surges and marine heatwaves. Using this setup, we will contribute climate projections to EURO-CORDEX.
Shakti Singh, Ilja Maljutenko, and Rivo Uiboupin
The Cryosphere, 19, 4741–4758, https://doi.org/10.5194/tc-19-4741-2025, https://doi.org/10.5194/tc-19-4741-2025, 2025
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The sea ice statistics study highlights the bias in model estimations compared to satellite data and provides a simple approach to minimise that. During the study period, the model estimates sea ice forming slightly earlier but aligns well with the satellite data for ice season's end. Rapid decrease in the sea ice parameters is observed across the Baltic Sea, especially the ice thickness in the Bothnian Bay sub-basin. These statistics could be crucial for regional adaptation strategies.
Urmas Raudsepp, Ilja Maljutenko, Priidik Lagemaa, and Karina von Schuckmann
State Planet, 6-osr9, 6, https://doi.org/10.5194/sp-6-osr9-6-2025, https://doi.org/10.5194/sp-6-osr9-6-2025, 2025
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Over the past 3 decades, the Baltic Sea has warmed and become saltier, reflecting broader atmospheric trends. Heat content changes are mainly driven by subsurface temperature variations in the upper 100 m, influenced by air temperature, evaporation, and wind stress. Freshwater content changes are largely controlled by salinity shifts in the halocline (40–120 m), with key drivers being saline inflows, precipitation, and zonal wind stress.
Urmas Raudsepp, Ulvi Ahmadov, Ilja Maljutenko, Amirhossein Barzandeh, Mariliis Kõuts, and Priidik Lagemaa
State Planet Discuss., https://doi.org/10.5194/sp-2025-7, https://doi.org/10.5194/sp-2025-7, 2025
Revised manuscript accepted for SP
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Over the past 30 years, the Baltic Sea’s surface mixed layer has changed unevenly: it is shoaling in the southwest due to warming and increased stratification, while deepening in the northeast as ice loss allows more winter mixing. These shifts affect marine ecosystems—shallower mixing in the south limits oxygen supply to deep waters, worsening hypoxia, while deeper mixing in the north may enhance spring algal blooms. Climate impacts in the Baltic are regionally diverse.
Urmas Raudsepp, Ilja Maljutenko, Jan-Victor Björkqvist, Amirhossein Barzandeh, Sander Rikka, Aarne Männik, Siim Pärt, Priidik Lagemaa, Victor Alari, Kaimo Vahter, and Rivo Uiboupin
State Planet Discuss., https://doi.org/10.5194/sp-2025-8, https://doi.org/10.5194/sp-2025-8, 2025
Revised manuscript under review for SP
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The study identified key extreme metocean conditions relevant for Floating Storage and Regasification Unit design on Estonia’s coast, using statistical approaches like GPD and GEV to estimate return values. These thresholds inform infrastructure safety margins. The analysis was extended across the Baltic Sea using harmonized methods, enabling consistent risk assessment, cross-border planning, and climate-resilient design for major maritime infrastructure sites.
Laura Tuomi, Milla Johansson, Andrew Twelves, Mika Rantanen, Priidik Lagemaa, Hedi Kanarik, Jani Särkkä, Urmas Raudsepp, and Antti Westerlund
State Planet Discuss., https://doi.org/10.5194/sp-2025-12, https://doi.org/10.5194/sp-2025-12, 2025
Revised manuscript accepted for SP
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A record low sea level of -153 cm, 34 cm below the previous minimum, was measured in the Bothnian Bay in November 2024. This extreme event was caused by a strong and long-lasting windstorm that followed an unusual track. The BAL MFC NRT physical forecast system was able to accurately predict this sea level event 3–4 days in advance. However, forecasts with longer lead times failed to predict the record low sea level, although they did indicate a significant drop in sea levels during the storm.
Amirhossein Barzandeh, Matjaž Ličer, Marko Rus, Matej Kristan, Ilja Maljutenko, Jüri Elken, Priidik Lagemaa, and Rivo Uiboupin
Ocean Sci., 21, 1315–1327, https://doi.org/10.5194/os-21-1315-2025, https://doi.org/10.5194/os-21-1315-2025, 2025
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We evaluated a deep-learning model, HIDRA2, for predicting sea levels along the Estonian coast and compared it to traditional numerical models. HIDRA2 performed better overall, offering faster forecasts and valuable uncertainty estimates using ensemble predictions.
Laura Schaffer, Andreas Boesch, Johanna Baehr, and Tim Kruschke
Nat. Hazards Earth Syst. Sci., 25, 2081–2096, https://doi.org/10.5194/nhess-25-2081-2025, https://doi.org/10.5194/nhess-25-2081-2025, 2025
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We developed a simple and effective model to predict storm surges in the German Bight, using wind data and a multiple linear regression approach. Trained on historical data from 1959 to 2022, our storm surge model demonstrates high predictive skill and performs as well as more complex models, despite its simplicity. It can predict both moderate and extreme storm surges, making it a valuable tool for future climate change studies.
Mehdi Pasha Karami, Torben Koenigk, Shiyu Wang, René Navarro Labastida, Tim Kruschke, Aude Carreric, Pablo Ortega, Klaus Wyser, Ramon Fuentes Franco, Agatha M. de Boer, Marie Sicard, and Aitor Aldama Campino
EGUsphere, https://doi.org/10.5194/egusphere-2025-2653, https://doi.org/10.5194/egusphere-2025-2653, 2025
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This study uses a high-resolution global climate model to simulate future climate, focusing on the Arctic and North Atlantic. The model captures observed sea ice loss and Atlantic circulation trends, projecting a nearly ice-free Arctic by 2040. It introduces a new method to quantify deep water formation, revealing how different ocean regions contribute to the weakening of overturning circulation in a warming climate.
Jüri Elken, Ilja Maljutenko, Priidik Lagemaa, Rivo Uiboupin, and Urmas Raudsepp
State Planet, 4-osr8, 9, https://doi.org/10.5194/sp-4-osr8-9-2024, https://doi.org/10.5194/sp-4-osr8-9-2024, 2024
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Baltic deep water is generally warmer than surface water during winter when district heating is required. Depending on the location, depth, and oceanographic situation, bottom water of Tallinn Bay can be used as an energy source for seawater heat pumps until the end of February, covering the major time interval when heating is needed. Episodically, there are colder-water events when seawater heat extraction has to be complemented by other sources of heating energy.
Karina von Schuckmann, Lorena Moreira, Mathilde Cancet, Flora Gues, Emmanuelle Autret, Jonathan Baker, Clément Bricaud, Romain Bourdalle-Badie, Lluis Castrillo, Lijing Cheng, Frederic Chevallier, Daniele Ciani, Alvaro de Pascual-Collar, Vincenzo De Toma, Marie Drevillon, Claudia Fanelli, Gilles Garric, Marion Gehlen, Rianne Giesen, Kevin Hodges, Doroteaciro Iovino, Simon Jandt-Scheelke, Eric Jansen, Melanie Juza, Ioanna Karagali, Thomas Lavergne, Simona Masina, Ronan McAdam, Audrey Minière, Helen Morrison, Tabea Rebekka Panteleit, Andrea Pisano, Marie-Isabelle Pujol, Ad Stoffelen, Sulian Thual, Simon Van Gennip, Pierre Veillard, Chunxue Yang, and Hao Zuo
State Planet, 4-osr8, 1, https://doi.org/10.5194/sp-4-osr8-1-2024, https://doi.org/10.5194/sp-4-osr8-1-2024, 2024
Karina von Schuckmann, Lorena Moreira, Mathilde Cancet, Flora Gues, Emmanuelle Autret, Ali Aydogdu, Lluis Castrillo, Daniele Ciani, Andrea Cipollone, Emanuela Clementi, Gianpiero Cossarini, Alvaro de Pascual-Collar, Vincenzo De Toma, Marion Gehlen, Rianne Giesen, Marie Drevillon, Claudia Fanelli, Kevin Hodges, Simon Jandt-Scheelke, Eric Jansen, Melanie Juza, Ioanna Karagali, Priidik Lagemaa, Vidar Lien, Leonardo Lima, Vladyslav Lyubartsev, Ilja Maljutenko, Simona Masina, Ronan McAdam, Pietro Miraglio, Helen Morrison, Tabea Rebekka Panteleit, Andrea Pisano, Marie-Isabelle Pujol, Urmas Raudsepp, Roshin Raj, Ad Stoffelen, Simon Van Gennip, Pierre Veillard, and Chunxue Yang
State Planet, 4-osr8, 2, https://doi.org/10.5194/sp-4-osr8-2-2024, https://doi.org/10.5194/sp-4-osr8-2-2024, 2024
Jan Åström, Fredrik Robertsen, Jari Haapala, Arttu Polojärvi, Rivo Uiboupin, and Ilja Maljutenko
The Cryosphere, 18, 2429–2442, https://doi.org/10.5194/tc-18-2429-2024, https://doi.org/10.5194/tc-18-2429-2024, 2024
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The HiDEM code has been developed for analyzing the fracture and fragmentation of brittle materials and has been extensively applied to glacier calving. Here, we report on the adaptation of the code to sea-ice dynamics and breakup. The code demonstrates the capability to simulate sea-ice dynamics on a 100 km scale with an unprecedented resolution. We argue that codes of this type may become useful for improving forecasts of sea-ice dynamics.
Alexandra Marki, Xin Li, and Simon Jandt-Scheelke
EGUsphere, https://doi.org/10.5194/egusphere-2023-3092, https://doi.org/10.5194/egusphere-2023-3092, 2024
Preprint archived
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Aim of the Oxygen Deficiency Index (ODI) blueprint is to inform about the water-quality in the North and Baltic Seas by using observations and model-simulations. The ODI helps us to calculate the probability if low-oxygen conditions might occur, with low ODI values indicating a low risk and vice-versa. We show that the ODI is able to forecast oxygen deficiency zones between 30 to 75 days. Important points in our study were the simplicity of application, deployment and an easy interpretation.
Urmas Raudsepp, Ilja Maljutenko, Amirhossein Barzandeh, Rivo Uiboupin, and Priidik Lagemaa
State Planet, 1-osr7, 7, https://doi.org/10.5194/sp-1-osr7-7-2023, https://doi.org/10.5194/sp-1-osr7-7-2023, 2023
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The freshwater content in the Baltic Sea has wide sub-regional variability characterized by the local climate dynamics. The total freshwater content trend is negative due to the recent increased inflows of saltwater, but there are also regions where the increase in runoff and decrease in ice content have led to an increase in the freshwater content.
Claudia Hinrichs, Peter Köhler, Christoph Völker, and Judith Hauck
Biogeosciences, 20, 3717–3735, https://doi.org/10.5194/bg-20-3717-2023, https://doi.org/10.5194/bg-20-3717-2023, 2023
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This study evaluated the alkalinity distribution in 14 climate models and found that most models underestimate alkalinity at the surface and overestimate it in the deeper ocean. It highlights the need for better understanding and quantification of processes driving alkalinity distribution and calcium carbonate dissolution and the importance of accounting for biases in model results when evaluating potential ocean alkalinity enhancement experiments.
Annika Drews, Wenjuan Huo, Katja Matthes, Kunihiko Kodera, and Tim Kruschke
Atmos. Chem. Phys., 22, 7893–7904, https://doi.org/10.5194/acp-22-7893-2022, https://doi.org/10.5194/acp-22-7893-2022, 2022
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Solar irradiance varies with a period of approximately 11 years. Using a unique large chemistry–climate model dataset, we investigate the solar surface signal in the North Atlantic and European region and find that it changes over time, depending on the strength of the solar cycle. For the first time, we estimate the potential predictability associated with including realistic solar forcing in a model. These results may improve seasonal to decadal predictions of European climate.
Urmas Raudsepp and Ilja Maljutenko
Geosci. Model Dev., 15, 535–551, https://doi.org/10.5194/gmd-15-535-2022, https://doi.org/10.5194/gmd-15-535-2022, 2022
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A model's ability to reproduce the state of a simulated object is always a subject of discussion. A new method for the multivariate assessment of numerical model skills uses the K-means algorithm for clustering model errors. All available data that fall into the model domain and simulation period are incorporated into the skill assessment. The clustered errors are used for spatial and temporal analysis of the model accuracy. The method can be applied to different types of geoscientific models.
Tuomas Kärnä, Patrik Ljungemyr, Saeed Falahat, Ida Ringgaard, Lars Axell, Vasily Korabel, Jens Murawski, Ilja Maljutenko, Anja Lindenthal, Simon Jandt-Scheelke, Svetlana Verjovkina, Ina Lorkowski, Priidik Lagemaa, Jun She, Laura Tuomi, Adam Nord, and Vibeke Huess
Geosci. Model Dev., 14, 5731–5749, https://doi.org/10.5194/gmd-14-5731-2021, https://doi.org/10.5194/gmd-14-5731-2021, 2021
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We present Nemo-Nordic 2.0, a novel operational marine model for the Baltic Sea. The model covers the Baltic Sea and the North Sea with approximately 1 nmi resolution. We validate the model's performance against sea level, water temperature, and salinity observations, as well as sea ice charts. The skill analysis demonstrates that Nemo-Nordic 2.0 can reproduce the hydrographic features of the Baltic Sea.
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Short summary
In 2022, large parts of the Baltic Sea experienced the third-warmest to warmest summer and autumn temperatures since 1997 and several marine heatwaves (MHWs). Using remote sensing, reanalysis, and in situ data, this study characterizes regional differences in MHW properties in the Baltic Sea in 2022. Furthermore, it presents an analysis of long-term trends and the relationship between atmospheric warming and MHW occurrences, including their propagation into deeper layers.
In 2022, large parts of the Baltic Sea experienced the third-warmest to warmest summer and...
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