Vertical heat fluxes diagnosed from airborne observations

Submesoscale eddies (smaller than 50 km) are ubiquitous in all oceans, as revealed by satellite infrared images. Diagnosing their impact on the ocean energetics from observations remains a challenge. This study analyzes a turbulent field of submesoscale eddies using airborne observations of surface currents and sea surface temperature, with high spatial resolution, collected during the S-MODE experiment in October 2022. Assuming surface current divergence and temperature are homogeneous down to a given depth, we show that more than 80\% of the upward vertical heat fluxes, reaching $\sim$220 W~m$^{-2}$, is explained by the smallest eddies (with a size smaller than 15 km). This emphasizes the contribution of small-scale eddies, poorly taken into account in numerical models, to the ocean heat budget and, therefore, to the climate system.