Environmental Controls on the Seasonal and Spatial Variability of Submesoscale Thermal Air–Sea Coupling Over the Gulf Stream

Abstract Using an ocean‐atmosphere coupled simulation, we investigate the seasonal variability of the low‐level wind response to submesoscale (O(1–10 km)) sea surface temperature (SST) anomalies over the Gulf Stream, focusing on the respective roles of the downwind momentum mixing (DMM) and pressure adjustment (PA) mechanisms. The wind response to submesoscale SST anomalies exhibits a strong seasonal cycle, with larger coupling in summer and pronounced spatial heterogeneity—significant north of the Gulf Stream but weak to the south. We furthermore show that the DMM dominates the coupling. Background atmospheric stability and wind speed control the seasonal modulation by driving the sensitivity of winds to SST perturbations. The spatial heterogeneity arises from the weak SST gradients south of the Gulf Stream. Two distinct regimes are found: (a) unstable conditions and weak winds, favoring a primarily divergent response, and (b) near‐stable conditions with moderate to strong winds, yielding both divergent and rotational response.