Recent  

Due to the need to obtain a greater amount of data in less time in areas with little in situ hydrographic data, an algorithm based on cluster analysis is proposed. This algorithm allows real-time quality control of Argo data which has patterns similar to data in delayed mode. To test this, a study area of high scientific interest but with little concentration of in situ data was chosen. In this area 80 % of the data normally discarded because of salinity drifts was recovered.

On top of forced changes such as human-caused global warming, unforced climate variability exists. Most multidecadal variability (MV) involves the oceans, but current climate models use non-turbulent, coarse-resolution oceans. We investigate the effect of resolving important turbulent ocean features on MV. We find that ocean heat content, ocean–atmosphere heat flux, and global mean surface temperature MV is more pronounced in the higher-resolution model relative to higher-frequency variability.

Mesoscale eddies are an important part of the turbulent motion in the oceans, constituting coherent structures that can live for years and store physical property anomalies. Analysis of anticyclone (clockwise-rotating eddies) tracks in the eastern Levantine Basin revealed statistical patterns over 19 years of data, in particular the presence of an anticyclone attractor above the Eratosthenes Seamount, with a strong heat content signature.

In this work we used a concept called geochemical fingerprinting, with isotopes of neodymium and lead as tools to recognize the main sources and the physical processes responsible for the transport and deposition of sediments on a large area of the South Atlantic margin. Distinct sources, such as Antarctica, the Andean Cordillera, the Río de la Plata basin, and old rocks from the Brazilian shield, are identified.

The Atlantic Meridional Overturning Circulation (AMOC) quantifies the impact of the ocean on climate and climate change. Here we show that a high-resolution ocean model is able to realistically simulate ocean currents. While the mean representation of the AMOC depends on choices made for the model and on the atmospheric forcing, the temporal variability is quite robust. Comparing the ocean model with ocean observations, we able to identify that the AMOC has declined over the past two decades.

Correct surface ocean circulation forecasts are highly relevant to search and rescue, oil spills, and ecological processes, among other things. High-frequency radar (HFR) is a remote sensing technology that measures surface currents in coastal areas with high temporal and spatial resolution. We performed a series of experiments in which we use HFR observations from the Ibiza Channel to improve the forecasts provided by a regional ocean model in the western Mediterranean.

We demonstrate that even sparse BGC-Argo profiles can substantially improve biogeochemical prediction via a priori model tuning. By assimilating satellite surface chlorophyll and physical observations, subsurface distributions of physical properties and nutrients were improved immediately. The improvement of subsurface chlorophyll was modest initially but was greatly enhanced after adjusting the parameterization for light attenuation through further a priori tuning.

Detailed ocean currents in the southeastern tropical Indian Ocean have not been fully explained because of limited observations. Here, zonal current characteristics in the region have been studied using 64-year HYCOM results (1950–2013). This study has revealed distinctive features of current variations on various timescales. Current vertical structures, their responses to remote forcings from the Pacific and Indian oceans, and contributions of each timescale have all been investigated.

We analyse the importance of local heat and freshwater fluxes for sea level variability in the tropical Pacific on interannual to decadal timescales by using a global ocean model. Our results suggest that they amplify sea level variability in the eastern part of the basin and dampen it in the central and western part of the domain. We demonstrate that the oceanic response allows local sea level anomalies to propagate zonally which enables remote effects of local heat and freshwater fluxes.

Freshwater in the Arctic Ocean plays a critical role in the global climate system by impacting ocean circulations, stratification, mixing, and emergent regimes. In this review paper we assess how Arctic Ocean freshwater changed in the 2010s relative to the 2000s. Estimates from observations and reanalyses show a qualitative stabilization in the 2010s due to a compensation between a freshening of the Beaufort Gyre and a reduction in freshwater in the Amerasian and Eurasian basins.

We estimate Agulhas leakage, water flowing from the Indian Ocean to the South Atlantic, in an ocean model with two different tools. The mean transport, variability and trend of Agulhas leakage is simulated comparably with both tools, emphasising the robustness of our method. If the experiments are designed differently, the mean transport of Agulhas leakage is altered, but not the trend. Agulhas leakage waters cool and become less salty south of Africa resulting in a density increase​.

This study presents three-dimensional imaging of the ocean interior with seismic surveying data. We found that the ocean's temporal variability barely affects imaging in the survey vessel's sailing direction but heavily affects the imaging perpendicular to the sailing direction. Most importantly, the obtained volume represents a series of snapshots of ocean structures, revealing the evolution of ocean dynamics over time. This study provides essential understanding for 3D seismic oceanography.

This study quantifies the influence of ocean eddies and other mesoscale phenomena (spanning 50–1000 km) on heat movement. The method used gives different results than earlier studies by classifying motions based on their variation in space, not time. The effect of major ocean currents on heat movement in the ocean depends on the currents' mesoscale structure. Mesoscale processes also impact year-to-year changes in heat movement, especially at middle latitudes and in the tropical Pacific.

In this work we explored design options for a future Atlantic-scale observational network enabling the release of carbon system estimates by combining data streams from various platforms. We used outputs of a physical–biogeochemical global ocean model at sites of real-world observations to reconstruct surface ocean pCO₂ by applying a non-linear feed-forward neural network. The results provide important information for future BGC-Argo deployment, i.e. important regions and the number of floats.

In our laboratory experiments we addressed the question of how surface standing waves in a closed stratified basin are damped by the interaction of the flow in the bulk with a sill-like bottom obstacle reaching up to a density interface between the more saline deep layer and the freshwater layer at the top. We quantify the decay rates of the surface waves and explore what types of internal waves can be excited in this process along the internal density interface.

We develop a method for monitoring zooplankton while controlling key environmental conditions at precise depths in the sea. We apply a profiler with an acoustic device to observe the sound-scattering layers formed by zooplankton species that descend for several tens of meters every day all year round and by persistent aggregations of the resting stage of copepods under very low concentrations of dissolved oxygen (below 10 μM L⁻¹) from spring to late autumn.

Experiments in rotating tanks can simulate the Earth system and help to represent the real ocean, where rotation plays an important role. We wanted to show the minor importance of the wind in driving the flow in the Ionian Sea. We did this by observing changes in the water current in a rotating tank affected only by the pumping of dense water into the system. The flow variations were similar to those in the real sea, confirming the scarce importance of the wind for the flow in the Ionian Sea.