Oceanic Eddy Modulation of Wintertime Air-Sea Coupling and Marine Atmospheric Boundary Layer Winds over the East China Sea

This study examined the effects of air-sea coupling and oceanic mesoscale eddies on wintertime low-level wind events within the marine atmospheric boundary layer (MABL) over the Kuroshio front zone in the East China Sea. High-resolution (eddy-resolving, 5 km) and low-resolution (50 km) simulations were conducted, using prescribed sea surface temperature (SST) forcing and air-sea coupled simulations in both resolutions. Among all simulations, the eddy-resolved air-sea coupled (EC) one exhibited the strongest atmosphere-to-SST feedback, closest to reanalysis data. In the EC simulation, complex interactions of numerous oceanic eddies enhanced oceanic front intensity. Compared with uncoupled and low-resolution simulations, it better reproduced wind event statistics from reanalysis. Highly-resolved eddy pairs with positive northwest-to-southeast SST anomalies strengthened SST gradients, altering sea surface heat fluxes and MABL stability, and thereby distinctly modulating wind event durations. Specifically, short-lived events were suppressed while long-lived ones persisted, consistent with reanalysis. These effects are attributed to the influence of numerous oceanic eddy pairs, by enhancing oceanic front intensity, air-sea temperature differences, sea surface heat fluxes, and lower atmospheric stability. Anomalous winds were restrained during initiation but prolonged as events evolved.