Internal tides are perturbations of the density and current in the ocean that are generated when the astronomical flows over the irregular bottom topography, and propagate in the stratified ocean under the form of waves. They then interact with other types of currents, which disturb their properties – phase and amplitude – and results in a loss of regularity, called incoherence. This paper investigates this mechanism using numerical simulations.

Thirty years of in situ hydrographic measurements combined with satellite observations reveal that Atlantic Water flowing northward along Norway is cooling less than before. We find that reduced surface heat loss and faster advection are likely drivers, though their relative effect varies over time. These changes result in more ocean heat reaching the Arctic, with likely impacts on climate, sea ice, and marine ecosystems.

We studied internal tides in the Gulf of Oman, where they had not been observed in detail before. Using seabed instruments, we found that these underwater waves travel far inshore, strengthen as the season shifts toward fall, and stay predictable for weeks. They may bring cooler, low-oxygen water to coastal areas, influencing marine ecosystems and reef health.

We study how tides, wind, and waves interact at the ocean surface by tracking ultra-thin drifters released in the southern North Sea for two months. Using model data together with data-driven machine learning models, we determine the relative contribution of each forcing mechanism in driving the drifters' velocity and improve the prediction of their trajectories. We also test the generalisability of this method by applying it to the same drifters in the Tyrrhenian Sea.

Measuring total alkalinity in seawater is essential for understanding and monitoring the ocean carbonate system. To improve the reliability of these measurements, we developed reference materials and tested them in an inter-laboratory comparison. We also thoroughly quantified, for the first time, the uncertainty of the standard measurement method. These results, as well as the key metrological tools developed, support more accurate long-term monitoring of the ocean carbonate system.