Overturning Instabilities Across a Warm Core Ring From Glider Observations

This work presents new evidence for conducive conditions the existence of overturning instabilities in mixed layer across a mesoscale anticyclonic Loop Current Eddy (LCE) and surrounding cyclonic eddies Gulf Mexico (GoM). The LCE was intensively sampled using four gliders during 12 months. is characterized by strong anomaly fresh warm water center strain at periphery. Mixed layers prone to are diagnosed from gradients buoyancy. In GoM, reduction potential vorticity (PV) driven surface cooling year-round persistent negative turbulent heat fluxes, eventually reaching −700 W m−2 extreme winter wind events. Lateral buoyancy associated with submesoscale filaments fronts periphery enhance frictional torque supplied stress when aligned geostrophic jet current. Negative PV occurs simultaneously fluxes events Ekman that reduce stratification. These regions susceptible mixed-layer gravitational-symmetric instability preferentially winter. Extreme equivalent flux (≤−10,000 m−2) 1.2 N coincides development inertial-symmetric vorticity. observations might have several implications restratification processes, kinetic energy budget, biogeochemical cycles inside LCEs can contribute formation low-PV waters could feed mode GoM.