3D Atmospheric Imprint of Mesoscale Eddies Driven by the Thermal Feedback in the Gulf Stream Region

Abstract The 3D imprint of mesoscale ocean eddies on the overlying atmosphere is investigated using coupled ocean‐atmosphere high‐resolution simulation of the Gulf Stream region, distinguishing cyclones and anticyclones. Sea surface temperature (SST) anomalies are predominantly warm for anticyclones and cold for cyclones, driving a Thermal Feedback (TFB) to the atmosphere. Wind‐rotated eddy composites method reveals significant modulation by eddies in wind speed, planetary boundary layer height (PBLH), cloud cover and vertical velocities. However, no significant precipitation anomalies are retrieved. The wind derivatives reveal different vertical scales: wind curl anomalies extend straight above the eddies up to about 600 m, while wind divergence anomalies are significant only in near‐surface. Furthermore, vertical velocity anomalies extend up to twice above the mean PBLH. The TFB impacts significantly the wind speed, wind divergence, PBLH and vertical wind anomalies, through downward‐momentum mixing and pressure adjustment processes. It has a top‐down effect: the planetary boundary layer (PBL) stability is affected by the heat fluxes anomalies driven by the TFB directly above the eddy. Planetary boundary layer height modulation further goes along vertical velocities and wind divergence in near‐surface, lagged downstream of the eddy by about 2–3 hr, suggesting important non‐local ocean‐atmosphere coupling impacts. The coupling of PBLH modulation to SST anomalies is about , about 30% lower than previous studies using coarser resolution simulations that consider only large eddies. This suggests the PBLH response to mesoscale eddies was overestimated due to poor representation of smaller eddies.