Last EuroSea deep Argo float deployed in the North Atlantic during BOCATS-OVIDE cruise

During the BOCATS-OVIDE cruise, held in June-July 2023, five deep Argo floats were deployed to contribute to the observation of water mass property changes, circulation, and acidification in the North Atlantic (NA) subpolar gyre. 

The BOCATS-OVIDE cruise, which was realized in June-July 2023, is the 11th occupation of the biennial section A25-OVIDE, which started in 2002, within the framework of the international GO-SHIP programme. It contributes to the observation of water mass property changes, circulation, and acidification in the North Atlantic (NA) subpolar gyre. Indeed, the ocean currently accumulates 93% of the excess heat and 25% of the excess COgenerated by human activities. The Atlantic Meridional Overturning Circulation (AMOC) influences the climate of Europe on interannual to decadal time scales and contributes to the capture of anthropogenic CO2. In the subpolar gyre of the NA, ocean acidification reaches abyssal depths (>3 500m), endangering ecosystems supported by cold water coral structures. A recent weakening of the AMOC has been reported at mid-latitudes and it is expected that the slow-down of the AMOC becomes more pronounced in the coming decades (IPCC, 2019).

During the cruise, a particular focus was given to the new challenge of assessing the variability of the deep circulation in the NA, improving the spatial-temporal resolution of deep currents and water mass characteristics by sustaining a regional Deep-Argo array. To that aim, five deep Argo floats were deployed.

Among the five floats, one deep Argo float (WMO 1902621) has been deployed in the frame of the EuroSea project (WP7) and complements the five deep floats deployed in 2021 for the task on carbon audit of the European relevant deep convection regions. All floats were equipped with an oxygen sensor that will bring new data to improve methods to monitor the uptake and storage of carbon in the Irminger Sea (Asselot et al. 2023) and its propagation within the deep circulation. 


Read the full abstract presented at EGU23-5422, during the session “The North Atlantic: natural variability and global change”: Asselot, R., Carracedo, L. I., Thierry, V., Mercier, H., Velo, A., Bajon, R., and Pérez, F. F.: Argo-based anthropogenic carbon concentration and inventory in the Labrador and Irminger Seas over 2011-2021, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5422,, 2023.

Deep Arvor deployment onboard BOCATS-OVIDE cruise. © Caroline Le Bihan / Ifremer

Map of the Deep Argo floats deployments during the 2021 and 2023 BOCATS cruises.

Note that some green dots may correspond to the same deployment positions. © OceanOPS