Sofia Allende, post-doctorante à l’IRPHE, invitée par Baptiste Néel (MIO), donnera un séminaire le vendredi 20 février 2026 à 13h00, à l’Amphithéâtre OCEANOMED, sur le thème : Melting dynamics and mixing layer growth near the ice-ocean interface.
Résumé
At the ice–ocean interface, one of the key physical processes is double-diffusive convection, a mechanism describing the convective mixing of fluids driven by the interplay between salinity and temperature gradients. This phenomenon is thought to play a critical role in regulating the salt and heat balance in polar regions but remains poorly parameterized in global climate models. I will here describe recent numerical work using highly resolved simulations, where we study the melt-driven growth of temperature and salinity mixing layers beneath a rigid ice interface. By varying the ambient salinity and the salt diffusivity, we identify a transition from convective to diffusion-dominated dynamics close to the interface, which decouples the melting dynamics from the turbulent transport. We demonstrate that the mixing layer grows super-diffusively in all regimes, thereby challenging the commonly assumed picture of a fully diffusive regime at high salinity. These results highlight potential limitations of diagnostics based on fixed concentration thresholds in oceanographic applications.