We use data assimilation (DA) to optimally merge information from observations of ocean variables and a numerical model of the north-western Mediterranean Sea. Data come from satellites, coastal high-frequency radars and fixed & movable devices. DA decreases model errors associated to all observed variables. The volume transport across the Corsica Channel, which connects the Tyrrhenian and Ligurian waters, is differently modified based on the typology and location of the assimilated observation.

We present a unique dataset of underwater measurements collected by an autonomous glider in the western Mediterranean Sea. It reveals how ocean layers mix over seasons and years. Using sensors to detect small scale water movements, we estimated how energy and heat are transferred in the ocean. These data help scientists better understand ocean circulation and climate effects. All files and methods are openly shared to support future research.

Over 1468 hydrological vertical profiles were acquired in 21 years in the Mediterranean Sea. This allowed us to follow the diffusion of the Western Mediterranean Transient along all western seas or make some important repetitions across straits, channels, or at defined locations. These data are now available in four open-access online datasets, including profiles of water temperature, conductivity, dissolved oxygen, chlorophyll α fluorescence, and, after 2004, turbidity and pH.