Argo in boundary currents: study cases using the VirtualFleet software

The Argo Program is a key component of the Global Ocean Observing System. The core program consists of drifting floats that make a 2000m profile of temperature and salinity every 10 days. The global ocean has been sampled on target since 2007, with a spatially uniform array of floats providing, at least, one profile every 10 days on a 3x3-degree global grid. But this core mission has been recognised as sub-optimal for turbulent regions, including the equatorial band and Western Boundary Currents. Boundary current (BC) regions are hot spots of the ocean’s variability, they host strong currents constantly instable, hence turbulent, which concentrate large signals (e.g. of mean/eddy meridional heat transport or surface heat transfer). The Argo Program thus need to improve its observation strategy for turbulent BC regions in order to better capture their complex ocean interior structure and variability. Historically, the Argo Program has recommended a doubling of the profile density in BC regions. In this study, we tested this recommendation and further follow on new approaches based on several simulations studies using the VirtualFleet software, a python tool that simulate the trajectories and sampling of virtual floats. Simulations were done for the Gulf Stream Extension, the East Greenland Current and the West Spitzbergen Current in the Nordic Seas, the Western Mediterranean Sea and the Gulf of Cadiz. Several optimization strategies were tested. Our results show how to improve the Argo mission in those areas and provide recommendations for the sampling strategies (deployment plans and configuration parameters) to be possibly adopted by the core Argo Program.

Angel-Benavides, I., Balem, K., Díaz-Barroso, L., Klein, B., Le, M., Maze, G., van, C., & Piecho-Santos, A. (2022, Oct). <i>Argo in boundary currents: study cases using the VirtualFleet software</i>&nbsp;[Poster presentation]. 7ᵗʰ Argo Science Workshop, Brussels, Belgium. https://premc.org/doc/ASW7/Posters/Benavides_Poster.pdf