Characterization of air-sea turbulent heat fluxes associated to submesoscale eddies in the South Brazil Bight

Air-sea heat exchanges are critical for Earth's climate, influencing precipitation, cloud formation, and atmospheric storms. The role of submesoscale eddies (SMEs) on the lower atmosphere and how they impact these processes remains unclear. In this study, satellite and reanalysis products were used to analyze air-sea latent heat flux (LHF) and sensible heat flux (SHF) in the South Brazil Bight (SBB) and to investigate the influence of SMEs on these fluxes. This region is characterized by high SMEs activity, predominantly cyclonic eddies with radii ranging from 1–3 km, mainly located over the continental shelf. Our findings revealed that LHF and SHF exhibit regional and seasonal variability within the SBB, with milder fluxes in the northern and central areas compared to the southern sector, and heightened fluxes during fall and winter. A composite analysis within the eddies showed stronger values near the eddy center, with average magnitudes of − 15.4 W m⁻² (− 9.3 W m⁻²) of LHF and − 2.0 W m⁻² (− 1.3 W m⁻²) of SHF for cyclonic (anticyclonic) eddies, indicating that both features contribute to ocean heat gain on average. Notably, SMEs exhibited turbulent heat flux magnitudes comparable to or even surpassing those associated with mesoscale eddies reported in previous studies. The highest values were primarily located over oceanic regions and areas influenced by the Brazil Current. Interestingly, the same eddy could display LHF and SHF with opposing signals. These findings highlight the significant role of SMEs in surface heat exchange processes, suggesting important implications for enhancing weather forecasts and oceanic models.