In this work, we study a Mediterranean cyclone that occurred in February 2023 and its relationship with a particular seismic signal called microseism. By integrating the data recorded by seismic stations, satellites, HF radar and wavemeter buoy we are able to obtain information about this event. We show how an innovative monitoring system of the Mediterranean cyclones can be designed by integrating microseism information with other techniques routinely used to study meteorological phenomena.

Coastal floods occur due to extreme sea levels (ESLs) which are difficult to predict because of their rarity. Long records of accurate sea levels at the local scale increase ESL predictability. Here, we apply a machine learning technique to extend sea level observation data in the past based on a neighbouring tide gauge. We compared the results with a linear model. We conclude that both models give reasonable results with a better accuracy towards the extremes for the machine learning model.

Tuna fisheries in the Pacific often use drifting fish aggregating devices (dFADs) to attract fish that are advected by subsurface flow through underwater appendages. Using a particle advection model, we find that virtual particles advected by surface flow are displaced farther than virtual dFADs. We find a relation between El Niño–Southern Oscillation and circular motion in some areas, influencing dFAD densities. This information helps us to understand processes that drive dFAD distribution.

Twin simulations, with and without tides, are used to assess the impact of internal tides (ITs) on ocean temperature off the Amazon mouth at a seasonal scale. We found that in the surface layers, ITs and barotropic tides cause a cooling effect on sea surface temperature, subsequently leading to an increase in the net heat flux between the atmosphere and ocean. Vertical mixing is identified as the primary driver, followed by vertical and horizontal advection.

We studied circulation and transports in the Archipelago Sea (in the Baltic Sea) with a high-resolution hydrodynamic model. Transport dynamics show different variabilities in the north and south, so no single transect can represent transport through the whole area in all cases. The net transport in the surface layer is southward and follows the alignment of the deeper channels. In the lower layer, the net transport is southward in the northern part of the area and northward in the southern part.

The southeastern Weddell Sea is important for global ocean circulation due to the cross-shelf-break exchange of Dense Shelf Water and Warm Deep Water, but their exact circulation pathways remain elusive. Using Lagrangian model experiments in an eddy-permitting ocean model, we show how present circulation pathways and transit times of these water masses on the continental shelf are altered by 21st-century climate change, which has implications for local ice-shelf basal melt rates and ecosystems.

The Benguela upwelling region off the coast of Namibia supplies cold water from the deep ocean that is transported offshore in finger-like structures called filaments. We investigate one major filament using measurements from a ship that crossed it multiple times and with mutiple buoys that follow the ocean currents. We find that the motions associated with the filament enhance the kinetic energy at small scales and provide a pathway for mixing of water and turbulent dissipation of energy.

We collected observations of the ocean environment at depths over 6000 m in the Southern Ocean, Indian Ocean, and western Pacific using sensor-equipped landers. We found that trench locations impact the water characteristics over these depths. Moving northward, they generally warmed but differed due to their position along bottom water circulation paths. These insights stress the importance of further research in understanding the environment of these deep regions and their importance.

The Weddell Sea is one of the most studied marine ecosystems outside the Antarctic Peninsula in the Southern Ocean. Yet, few studies consider the complexity of the Weddell Sea food web, which comprises 490 species and 16041 predator–prey interactions. Here we analysed a quantitative version of the Weddell Sea food web, where the interactions’ intensity is explicitly considered. We found that only a few species of marine mammals, sea birds, and fishes are important for the food web stability.

This study contributes to the development of methods to estimate targeted ocean ecosystem indicators, including their uncertainty, in the framework of the Copernicus Marine Service. A simplified approach is introduced to perform a 4D ensemble analysis and forecast, directly targeting selected biogeochemical variables and indicators (phenology, trophic efficiency, downward flux of organic matter). Care is taken to present the methods and discuss the reliability of the solution proposed.

From 2021 to 2022, a particular sub-estuary (East River estuary) suffered greatly from an enhanced salt intrusion. We conducted observation analysis, numerical simulations, and analytical solution to unravel the underlying mechanisms. This study is of help in the investigation of salt dynamics in sub-estuaries connected to main estuaries and of implications for mitigating salt intrusion problems in the regions.

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.

Satellite observations offer valuable information on phytoplankton abundance and community structure. Here, we employ satellite observations to infer seven phytoplankton groups at a global scale based on a new molecular method from Tara Oceans. The link has been established using machine learning approaches. The output of this work provides excellent tools to collect essential biodiversity variables and a foundation to monitor the evolution of marine biodiversity.

Understanding internal tide generation and propagation is crucial for predicting large-scale circulation and climate change. Internal tides are prone to interacting with background currents with similar spatial scales during propagation. This paper investigates the physical mechanism of the interaction between semidiurnal internal tides and an anticyclonic eddy in the northeastern South China Sea using a numerical model with high spatial and temporal resolution.

Marine heatwaves are long periods of extremely warm ocean surface temperatures. Predicting such events a few months in advance would help decision-making to mitigate their impacts on marine ecosystems. This work investigates how well operational seasonal forecasts can predict marine heatwaves. Results show that such events can be predicted a few months in advance in the tropics but that extending the predictability skill to other regions will require additional work on the forecast models.

Satellite retrievals of sea surface salinity (SSS) offer insights into freshwater changes in the Arctic Ocean. This study evaluates freshwater content in the Beaufort Gyre using SMOS and reanalysis data, revealing underestimation with reanalysis alone. Incorporating satellite SSS measurements improves freshwater content estimation, especially near ice-melting areas. Adding remotely sensed salinity aids in monitoring Arctic freshwater content and in understanding its impact on global climate.