The importance of ocean mesoscale variability for air-sea interactions and heat anomaly distribution in the Gulf of Mexico

Circulation of the Intra-Americas Sea (IAS) in the Gulf of Mexico (GoM) is mainly composed of the Caribbean Current that enters the GoM via the Yucatan Channel, continues as the Loop Current in the GoM and exits through the Florida Straits as the Florida Current. Variability of the current system in the IAS affects heat advection and the distribution of heat anomalies over the GoM and Atlantic Warm Pool, which in turn has profound implications on climate extremes over North America, particularly precipitation events and hurricane development. However, current generation global coupled climate models (GCM) are unable to resolve these mesoscale circulations and variability, which are expected to play a significant role in heat anomaly distribution. Hence, we employ an eddy-resolving GCM with 0.1 deg ocean resolution (high resolution; HR) and perform a comparative study with a low resolution GCM (1 deg ocean resolution with the same atmosphere resolution of 0.5 deg; LR) to evaluate the contributions of mesoscale currents and eddies to air-sea interactions and heat anomaly distribution in the GoM. Similar to observations, HR indicates an ocean SST forcing on turbulent surface heat fluxes while LR shows the contrary. For HR, we decompose upper ocean heat content (OHC) advection terms into mean and eddy components. We find that while the magnitude of heat transport is larger in the mean, eddy OHC divergence/convergence dominates heat advection. We also find that variability of turbulent fluxes correlate well with variability of ocean heat advection, and more precisely, eddy heat advection, which highlights the importance of mesoscale variability for air-sea interactions, heat distribution and consequently climate.