Mesoscale eddies are ubiquitous turbulent structures in the ocean, influencing the upper mixed layer. The mixed layer is the ocean surface layer mixed through air–sea exchanges. Using Argo profiling floats inside large Mediterranean anticyclones, we investigate the induced winter mixed-layer depth anomalies. Mixed-layer depth was observed to be greatly influenced by the eddy preexisting subsurface structure to which it possibly connects and can also create double-core anticyclones.

Altimeter-derived currents are used here to revisit the seasonal and interannual variability of all surface currents involved in the western tropical Atlantic circulation. A new approach based on the calculation of the current strengths and core positions is used to investigate the relationship between the currents, the remote wind variability, and the tropical Atlantic modes. The results show relationships at the seasonal and interannual timescale depending on the location of the currents.

Sea ice melt, together with other freshwater sources, has effects on the Arctic environment. Sea surface salinity (SSS) plays a key role in representing water mixing. Recently the satellite SSS from SMOS was developed in the Arctic region. In this study, we first evaluate the impact of assimilating these satellite data in an Arctic reanalysis system. It shows that SSS errors are reduced by 10–50 % depending on areas, encouraging its use in a long-time reanalysis to monitor the Arctic water cycle.

The Chukchi continental slope is one of the most energetic regions in the western Arctic Ocean as it is populated with strong boundary currents and mesoscale eddies. Using a set of experiments with an idealized primitive equation numerical model, we find that the ice friction can cause the loss of energy of both the Chukchi Slope Current and mesoscale eddies over a vertical scale of 100 m through Ekman pumping. Some scales for measuring the effects of ice friction are also provided.

Data assimilation techniques are important for combining observations with numerical models. Here, we approximate the adjoint of viscous-plastic dynamics (adjoint-VP) to replace the adjoint of free-drift dynamics (adjoint-FD) for developing an advanced Arctic Ocean and sea ice modeling and adjoint-based assimilation system. We find that adjoint-VP provides a better ocean and sea ice estimation than adjoint-FD, considering the residual errors and adjustments of the atmospheric states.

The increase in ocean mass due to land ice melting is responsible for about two-thirds of the global mean sea level rise. The ocean mass variations are monitored by GRACE and GRACE Follow-On gravimetry satellites that faced instrumental issues over the last few years. In this work, we assess the robustness of these data by comparing the ocean mass gravimetry estimates to independent observations (other satellite observations, oceanographic measurements and land ice and water models).

To understand the circulation pattern in the Gulf of Thailand (GoT) and the local wind effect, satellite and in situ observations are used. The flow is highly variable at the western boundary and the GoT mouth. Seasonally, it is dominated by the monsoon winds and sea surface level set up by local wind rotation. Surprisingly, interannual variation in the current over each region in the GoT responds to different climate modes (El Niño–Southern Oscillation and the Indian Ocean Dipole) differently.

This study aims to analyse the changes of the vertical structure of the ocean during upwelling and the role of climate patterns in the Canary Current (25–35°N) over a period of 25 years (1993–2017). Ocean mixing is enhanced during upwelling events and extends deeper (shallower) in the winters of positive (negative) North Atlantic Oscillation. It is enhanced during coupled, opposite phases of the East Atlantic pattern, suggesting stronger upwelling activity independent of climate patterns.

Recent advances allow us to observe the ocean from space with increasingly higher detail, challenging our knowledge of the ocean's surface height signature. We use a statistical approach to determine the spatial scale at which the sea surface height signal is no longer dominated by geostrophic turbulence but in turn becomes dominated by wave-type motions. This information helps us to better use the data provided by ocean-observing satellites and to gain knowledge on climate-driving processes.

This study explores the variability of water mass transformation within the Weddell Gyre (WG). The WG is the largest source of Antarctic Bottom Water (AABW). Changes to our climate can modify the mechanisms that transform waters to become AABW. In this study, we computed water mass transformation volume budgets by using three ocean models and a mathematical framework developed by Walin. Out of the three models, we found one to be most useful in studying the interannual variability of AABW.

Melt from the Greenland ice sheet and sea ice both influence light and nutrient availability in the Arctic coastal ocean. We use a 3D coupled hydrodynamic–biogeochemical model to evaluate the relative importance of these processes for timing, distribution, and magnitude of phytoplankton production in Disko Bay, west Greenland. Our study indicates that decreasing sea ice and more freshwater discharge can work synergistically and increase primary productivity of the coastal ocean around Greenland.

The El Niño Southern Oscillation (ENSO) has a global influence on weather and climate. Over most of the equatorial Pacific, where ENSO is focused, variations in sea surface height, such as measured by satellite, are strongly influenced by vertical displacements of the ocean thermocline. We show that linearly removing this influence leads to a time series of sea surface height that capture ENSO dynamics in the central Pacific, where ENSO variability has become more active in recent decades.

Based on the latest satellite observations published by the French space agency CNES, we present the current state of the sea level at the scale of the planet and assess its rise and acceleration over the past 29 years. To support scientific research we provide updated estimations of our confidence in our estimations and highlight key technological and scientific fields. Making progress on that will help to better characterize the sea level in the future.

The South Vietnam upwelling develops in summer along and off the Vietnamese coast. It brings cold and nutrient-rich waters to the surface, allowing photosynthesis essential to marine ecosystems and fishing resources. We show here that its daily variations are mainly due to the wind, thus predictable, in the southern shelf and coastal regions. However, they are more chaotic in the offshore area, and especially in the northern area, due to the influence of eddies of a highly chaotic nature.

This study reports the existence of a relatively-low-productivity area of upwelling east of Hainan Island (UEH), which is inconsistent with previous cognition. The reason for this phenomenon is the crucial role of the Guangdong Coastal Current and precipitation. The current and precipitation would induce a high productivity, which is interrupted by the upwelling processes. Therefore, the upwelling has a relatively limited effect on the Chl a concentration in the UEH area.

We develop a forecasting system for marine-litter concentration (MLC) in the Mediterranean based on a simple statistical method. The idea is that similar meteorological situations yield similar MLC patterns. We train our model with a historical meteorological dataset and MLCs from numerical simulations to recognize these situations and patterns and use them to forecast the future MLC. The results are promising; the approach has potential to become a suitable, cost-effective forecasting method.

Climate change will alter heat and freshwater fluxes as well as ocean circulation, driving local changes in sea level. This sea-level change component is known as ocean dynamic sea level (DSL), and it is usually projected using computationally expensive global climate models. Statistical models are a cheaper alternative for projecting DSL but may contain significant errors. Here, we partly remove those errors (driven by internal climate variability) by using pattern recognition techniques.

Volcanic meteotsunamis (VMTs) are global with impacts dependent on local topography. The impacts of a volcanic meteotsunami may occur where the oceanic tsunami is not present. Tsunami warning systems do not consider VMTs which can arrive first and may be several meters for a large volcanic eruption at locations with ideal topographical or bathymetric conditions. Here, we analyzed this event using high-frequency tide gauge data along with deep-water buoys and air pressure gauges worldwide.