OS - recent papers

Seasonal and interannual drivers of Sargassum inundations in the Northern Gulf of Guinea

Wed, 16 Sep 2026 03:14:30 +0200

Seasonal and interannual drivers of Sargassum inundations in the Northern Gulf of Guinea
Clovis Thouvenin-Masson and Julien Jouanno
Ocean Sci., 22, 2835–2862, https://doi.org/10.5194/os-22-2835-2026, 2026
We studied why floating Sargassum seaweed repeatedly reaches the northern Gulf of Guinea, where it affects coastal activities such as fishing. By combining satellite observations with computer simulations, we found two main arrival seasons, in spring and autumn. Most events are driven by seaweed transported from the eastern tropical Atlantic, while winds push it toward the coast and beaching limits how long it persists. Year-to-year changes are linked to shifts in Atlantic climate.

Evaluation of a coupled regional reanalysis for the Mediterranean region covering the period 1993–2024

Mon, 14 Sep 2026 03:14:30 +0200

Evaluation of a coupled regional reanalysis for the Mediterranean region covering the period 1993–2024
Andrea Storto, Vincenzo de Toma, and Chunxue Yang
Ocean Sci., 22, 2809–2834, https://doi.org/10.5194/os-22-2809-2026, 2026
The Mediterranean region is one of the fastest-warming areas on Earth, and understanding its changes is thus crucial. We produced a new reconstruction of the Mediterranean climate for the 1993–2024 period, using a modelling system that combines weather, ocean, and hydrology information with observations. This new reanalysis offers a clearer picture of how the region has been warming, drying, and changing over the past 30 years, supporting better studies of extreme events and climate impacts.

Enhanced water mass mixing in Fram Strait in 2020 and elevated circulation timescales of Atlantic-derived waters in 2021 based on transient tracers I-129 and U-236

Fri, 11 Sep 2026 03:14:30 +0200

Enhanced water mass mixing in Fram Strait in 2020 and elevated circulation timescales of Atlantic-derived waters in 2021 based on transient tracers I-129 and U-236
Marcel Scheiwiller, Anne-Marie Wefing, Habacuc Pérez-Tribouillier, Christof Vockenhuber, Paul A. Dodd, Justin P. Gwynn, and Núria Casacuberta
Ocean Sci., 22, 2779–2808, https://doi.org/10.5194/os-22-2779-2026, 2026
We used man-made chemical markers to study how warm Atlantic origin water moves through the Arctic Ocean. Comparing Fram Strait observations from 2016 to 2021, we found stronger mixing in 2020 and longer transit times in 2021. This variability matters because these waters carry heat into the Arctic Ocean, intensifying its warming. Our findings help improve predictions of the Arctic Ocean climate response and its wider effects on ocean circulation.

Phytoplankton community structure responses to episodic summer storms in a temperate coastal ecosystem

Wed, 09 Sep 2026 03:14:30 +0200

Phytoplankton community structure responses to episodic summer storms in a temperate coastal ecosystem
Harshal Chavan, Urania Christaki, Luis Felipe Artigas, and Francois G. Schmitt
Ocean Sci., 22, 2743–2777, https://doi.org/10.5194/os-22-2743-2026, 2026
We found that fluctuations in the marine environment during summer can trigger bloom formation in the nutrient-depleted eastern English Channel. Different storm impacts played various roles in promoting the growth of certain phytoplankton. Surplus nutrients supplied by rivers caused diatom blooms, while wind-driven storms supported the growth of pico- and nano-sized phytoplankton.

The added value of Med-CORDEX coupled high-resolution regional climate models in representing sea surface temperature and marine heatwaves in the Mediterranean Sea

Wed, 09 Sep 2026 03:14:30 +0200

The added value of Med-CORDEX coupled high-resolution regional climate models in representing sea surface temperature and marine heatwaves in the Mediterranean Sea
Francesco De Rovere, Giulia Bonino, Ronan McAdam, Enrico Scoccimarro, Samuel Somot, Iván M. Parras-Berrocal, Bodo Ahrens, Vladimir Djurdjevic, Laurent Li, and Simona Masina
Ocean Sci., 22, 2725–2742, https://doi.org/10.5194/os-22-2725-2026, 2026
Marine heatwaves in the Mediterranean Sea are intensifying, posing growing threats to marine life and coastal communities. We evaluated if high-resolution regional climate models better capture these extremes compared to the global models driving them. Regional models reliably improve sea surface temperature patterns and marine heatwave duration, but struggle more with heatwave intensity. Higher horizontal resolution alone is not enough, advances in other model components are equally needed.

Seasonal stratification regulates carbon allocation between particulate and dissolved pathways in the Gulf of Aqaba

Tue, 08 Sep 2026 03:14:30 +0200

Seasonal stratification regulates carbon allocation between particulate and dissolved pathways in the Gulf of Aqaba
Eyal Rahav and Adina Paytan
Ocean Sci., 22, 2711–2723, https://doi.org/10.5194/os-22-2711-2026, 2026
To understand how ocean warming may alter carbon storage, we examined seasonal carbon cycling in the northern Red Sea over five months. As summer warming intensified water-column stratification and reduced nutrient supply, carbon fixation by microscopic algae declined, while a larger fraction of newly produced carbon was released as dissolved material and rapidly respired by bacteria. This near-surface recycling may reduce carbon transfer to depth and weaken ocean carbon storage.

An improvement to short term variability in Global Mean Sea Level reconstruction

Mon, 07 Sep 2026 03:14:30 +0200

An improvement to short term variability in Global Mean Sea Level reconstruction
Andrew G. P. Shaw, Svetlana Jevrejeva, and Francisco M. Calafat
Ocean Sci., 22, 2673–2689, https://doi.org/10.5194/os-22-2673-2026, 2026
This study shows a novel approach to improve a short term variability in Global Mean Sea level (GMSL) reconstruction. The GMSL is an important measure to assess the health of the planet and good GMSL variability (trend removed) measurements are vital to understanding the sea level budget.

Current status of ocean observation, ensemble reanalysis and CMIP6 models in describing Antarctic Bottom Water

Mon, 07 Sep 2026 03:14:30 +0200

Current status of ocean observation, ensemble reanalysis and CMIP6 models in describing Antarctic Bottom Water
Siran Chen, Jiping Liu, and Xianxian Han
Ocean Sci., 22, 2691–2709, https://doi.org/10.5194/os-22-2691-2026, 2026
Antarctic Bottom Water influences global ocean circulation, heat storage, and carbon uptake. We compared an observational atlas, an ocean reconstruction, and 16 climate models by separating this water into three regional types. The reconstruction matched the observed large-scale patterns well, but many climate models showed substantial regional temperature and salinity errors. Correcting average biases improved some models, although errors in spatial structure remained.

Asymmetric response of coastal currents to oscillating alongshore wind stress over a coastal bank

Wed, 02 Sep 2026 03:14:30 +0200

Asymmetric response of coastal currents to oscillating alongshore wind stress over a coastal bank
Jihun Jung, Yang-Ki Cho, Gwang-Ho Seo, and Kwang-Young Jeong
Ocean Sci., 22, 2659–2672, https://doi.org/10.5194/os-22-2659-2026, 2026
This study investigates ocean currents over a coastal bank along the southern coast of Korea, focusing on their asymmetric response to alongshore wind stress. Variability is larger in the western region of the bank, driven by enhanced cross-shore sea level gradients associated with vertically integrated transport over bank topography. The asymmetry remains robust despite offshore currents and changes in wind conditions.

The vertical structure of mesoscale eddies in the Azores Current corridor: a combined altimetry-Argo analysis

Fri, 28 Aug 2026 03:14:30 +0200

The vertical structure of mesoscale eddies in the Azores Current corridor: a combined altimetry-Argo analysis
Susana M. Silva-Fernandes and Álvaro J. Peliz
Ocean Sci., 22, 2637–2657, https://doi.org/10.5194/os-22-2637-2026, 2026
The instability of the Azores Current often generates large eddies that can transport heat, salt, and biological properties. Using 10 000 Argo profiles and 20 years of satellite data, this study shows that eddy cores deepen and intensify westward. Anticyclones have warm and salty cores, while cyclones are cold and fresh. In general, the vertical movement of the density surfaces shapes their vertical structure, while the interior transport of different water masses dominates near the surface.

Krill defecation at depth reduces carbon flux attenuation in the Weddell Sea euphotic zone

Fri, 28 Aug 2026 03:14:30 +0200

Krill defecation at depth reduces carbon flux attenuation in the Weddell Sea euphotic zone
Florence Atherden, Emily Rowlands, Gareth Flint, Sophie Fielding, Katrin Schmidt, Elaine Fileman, Maren Richter, Bethany Wilkinson, Angus Atkinson, and Clara Manno
Ocean Sci., 22, 2621–2635, https://doi.org/10.5194/os-22-2621-2026, 2026
The Southern Ocean influences global climate, in part, through biological production of carbon-rich particles which trap atmospheric CO2 in the deep ocean. Our study highlights that krill defecating at 50–100 m and injecting carbon-rich pellets effectively counteracts the "typical" scenario where the quantity of particles rapidly decreases from the surface, ultimately increasing how much atmospheric carbon is stored. These processes are of global benefit, but vulnerable in a changing climate.

Water masses in the Atlantic Ocean: water mass ages and ventilation

Thu, 27 Aug 2026 03:14:30 +0200

Water masses in the Atlantic Ocean: water mass ages and ventilation
Mian Liu and Toste Tanhua
Ocean Sci., 22, 2595–2620, https://doi.org/10.5194/os-22-2595-2026, 2026
We measured the age of Atlantic waters using man-made gases and a radioactive isotope. Age increases with depth: young surface waters are about 30 years old, deep Antarctic water reaches 100 years, and the oldest bottom water is roughly 120 years. The western Atlantic is younger and better ventilated than the east. These patterns help estimate deep-sea oxygen use and are key for climate models and marine ecosystems.

An automated method for polynya detection using a geomorphon algorithm

Tue, 25 Aug 2026 03:14:30 +0200

An automated method for polynya detection using a geomorphon algorithm
Mia Hurst and Lars Boehme
Ocean Sci., 22, 2559–2594, https://doi.org/10.5194/os-22-2559-2026, 2026
Polynyas are areas of open water in sea ice that are important for ocean life and climate. We developed a new method to automatically find polynyas using morphological patterns in Antarctic sea ice data. The method reliably detected both large and small polynyas, produced results consistent with existing approaches, and remained accurate despite data uncertainty. This approach offers a promising way to build consistent long-term records and improve future studies of changing polar environments.

Data-driven enhancement of ocean surface forcing for accurate floating debris transport modelling in the East/Japan Sea

Fri, 21 Aug 2026 03:14:30 +0200

Data-driven enhancement of ocean surface forcing for accurate floating debris transport modelling in the East/Japan Sea
Hong Thi My Tran, Young-Gyu Park, and Jun Myoung Choi
Ocean Sci., 22, 2533–2558, https://doi.org/10.5194/os-22-2533-2026, 2026
We tracked 33 floating devices released off the Korean coast to understand how debris moves across the East/Japan Sea. Their paths showed a route toward Japan and an early split caused by ocean circulation. By comparing observations with computer simulations, we found that the best predictions combine geostrophic currents, Stoke drift, and windage, while deeper devices also require Ekman currents. Winter favored faster eastward transport and beaching, whereas summer caused wider spreading.

Chlorophyll a variation trends in marginal seas: assessing the impact of global warming and anthropogenic activities using time-series satellite data (1998–2020)

Mon, 17 Aug 2026 03:14:30 +0200

Chlorophyll a variation trends in marginal seas: assessing the impact of global warming and anthropogenic activities using time-series satellite data (1998–2020)
Nan Yao, Xiaoyu Zhang, Lei Bi, Shuchang Ma, Andrew B. Cundy, Haiyan Jin, and Renyi Liu
Ocean Sci., 22, 2503–2531, https://doi.org/10.5194/os-22-2503-2026, 2026
Analyzing 1998–2020 satellite data, this study finds global warming reduces offshore Chl a in open marginal seas, a trend extending nearshore. In contrast, Chl a in highly polluted enclosed seas remains unaffected by warming, dominated instead by nutrient inputs. Successful environmental policies reducing pollution may inadvertently accelerate the climate-driven Chl a decline, revealing a complex ecological trade-off.

Evaluate the impact of a 4 h tandem phase on the continuity of nadir altimetry measurements between S3 and S3NG-T

Mon, 17 Aug 2026 03:14:30 +0200

Evaluate the impact of a 4 h tandem phase on the continuity of nadir altimetry measurements between S3 and S3NG-T
Noémie Lalau, Michaël Ablain, Thomas Vaujour, François Boy, Gerald Dibarboure, and Alejandro Egido
Ocean Sci., 22, 2491–2501, https://doi.org/10.5194/os-22-2491-2026, 2026
We investigated how to maintain continuous sea level measurements between current Sentinel-3 constellation and the upcoming Sentinel-3 Next Generation Topography mission. Because of new satellite designs, a 4-hour delay will exists between observations during the calibration phase. By simulating this time lag, we found that, despite increased uncertainty, reliable calibration is possible. Extending this phase to one year ensures a stable, long-term record for climate and ocean monitoring.

Intraseasonal variability and eddy-induced structural modulation of the North Pacific intermediate water revealed by multi-mooring observations

Mon, 17 Aug 2026 03:14:30 +0200

Intraseasonal variability and eddy-induced structural modulation of the North Pacific intermediate water revealed by multi-mooring observations
Qiang Ren, Yansong Liu, Yansheng Zhang, Shumin Tu, Wei Huang, Feng Nan, Ran Wang, Xinyuan Diao, Jianfeng Wang, Xinchuang Liu, Zifei Chen, and Fei Yu
Ocean Sci., 22, 2449–2469, https://doi.org/10.5194/os-22-2449-2026, 2026
This study reveals how mesoscale eddies modulate the North Pacific Intermediate Water (NPIW) using three long-term mooring observations. By introducing “intermediate water thickness” as a new structural indicator, it shows that eddies compress or expand the NPIW layer, producing 60–80-day intraseasonal variability. Thickness and salinity are strongly inversely related, providing the first quantitative evidence of eddy-induced structural changes in mid-depth waters.

High current speed events in a harbor channel driven by resonant sub-hourly sea level dynamics: an example from Varna, Black Sea

Mon, 17 Aug 2026 03:14:30 +0200

High current speed events in a harbor channel driven by resonant sub-hourly sea level dynamics: an example from Varna, Black Sea
Jüri Elken, Laura Piho, and Maarja Kruusmaa
Ocean Sci., 22, 2471–2490, https://doi.org/10.5194/os-22-2471-2026, 2026
Three novel Hydromast stations revealed occasional high-amplitude current and water-level oscillations in the 2.4-km-long navigation channel, with dominant periods of 37 and 19 minutes. The oscillation events reflect resonant long-wave forcing from the open sea. The maximum changes in currents and sea level – 0.8 m s−1 and 0.8 m – are harmful to ship navigation, harbor operations, and coastal management. Approaches for detecting and forecasting strong sub-hourly oscillations are discussed.

Thermohaline gradients and frontal regimes in the northwestern Tropical Atlantic

Thu, 13 Aug 2026 03:14:30 +0200

Thermohaline gradients and frontal regimes in the northwestern Tropical Atlantic
Dante C. Napolitano, Jonathan Gula, Solange Coadou-Chaventon, Sabrina Speich, Cesar B. Rocha, James C. McWilliams, Dongxiao Zhang, and Xavier Carton
Ocean Sci., 22, 2425–2447, https://doi.org/10.5194/os-22-2425-2026, 2026
The Amazon River plume interaction with the North Brazil Current creates sharp temperature-salinity differences called fronts that are important for modulating air-sea interactions and biogeochemical cycles. This study uses data from robotic sailboats and a numerical model to provide a comprehensive picture of these fronts associated with the local dynamics. We characterize three distinct frontal regimes and the temperature-salinity relations linked to the Amazon discharge and current strength.

Water mass modification of the warm Atlantic Inflow towards the Arctic across the Iceland-Faroe Ridge

Wed, 12 Aug 2026 03:14:30 +0200

Water mass modification of the warm Atlantic Inflow towards the Arctic across the Iceland-Faroe Ridge
Guðrið Eriksdóttir, Bogi Hansen, Karin Margretha H. Larsen, Steffen M. Olsen, Andrea M. U. Gierisch, and Sólveig Rósa Ólafsdóttir
Ocean Sci., 22, 2405–2423, https://doi.org/10.5194/os-22-2405-2026, 2026
The Atlantic inflow across the Iceland-Faroe Ridge carries almost half of the warm water towards the Arctic. This study explores the modifications of the Atlantic water on its way to and across this underwater ridge. While crossing the ridge, the water is strongly cooled and freshened, which can reduce the ability for deep-water formation. Understanding these processes is important for improving ocean and climate models so more realistic forecasts can be made in a warming climate.