Why Do Inverse Eddy Surface Temperature Anomalies Emerge? The Case of the Mediterranean Sea

It is widely accepted that the signature of anticyclonic (cyclonic) eddies on sea surface temperature corresponds to a warm (cold) core anomaly. Nevertheless, this statement has been put question by recent regional studies showing existence inverse eddy SST anomalies: Cold Core anticyclones and, respectively, Warm cyclones. This study shows emergence these anomalies seasonal phenomenon affects life cycle mesoscale in Mediterranean Sea. We use remote sensing observations and situ data analyse eddy-induced anomaly over 3-year period (2016–2018). build an index quantify amount cyclones all year especially during spring re-stratification period. find 70% are May June both for anticyclones. Regular could reach 1.5 °C, while ones only present first 50 m oceanic layer hardly exceed 1 °C. In order understand underlying dynamical processes, we construct simple vertical column model impact air–sea fluxes stratification inside outside eddies. taking into account differential diapycnal mixing—increased reduced cyclones—that reproduce correctly, agreement with observations, inversion core. simplified suggests mixing modulation might be key mechanism leads eddy–SSTA ocean.