High-resolution numerical modeling of the Strait of Gibraltar: Exploring fine-scale dynamics

– Jean-Baptiste Roustan, SHOM –

Résumé :

For several years, LAERO and SHOM have developed a high-resolution ocean circulation model of the Strait of Gibraltar based on the non-hydrostatic,
non-Boussinesq core of the Coastal and Regional Ocean Community model (CROCO). The simulation uses three two-way nested grids, increasing the
resolution from 900 m in the surrounding basins to 60 m over Camarinal Sill, the main topographic feature of the Strait of Gibraltar.
This configuration has been extensively validated using data from a field campaign conducted by SHOM aboard R/V L’Atalante in October 2020,
dedicated to sampling fine-scale dynamics. The resulting dataset provides valuable insights into small-scale processes (Roustan et al., 2023; 2024a; 2024b).
After a brief review of these results, we first assess the model’s ability to reproduce the complex fine-scale structure of the flow and associated mixing.
Then, we focus on the impact of the nested grid, which enable to simulate the largest turbulent eddies.
Finally, preliminary indications of small-scale feedback on the large-scale circulation are discussed.

Beyond this topic, I will introduce my new reseach field essentially focused on mesoscale.
I will briefly present SHOOT, the new eddy detection algorithm developed with the SHOM team.