The role of ocean mesoscale variability on upper ocean temperature flux and air-sea interactions in the Gulf of Mexico

Mesoscale variability of the current system in the Intra-Americas Sea affects heat advection and the distribution of heat anomalies over the Gulf of Mexico (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. Hence, we employ a coupled land-atmosphere-ocean-sea-ice model with 0.1 deg ocean resolution (high resolution; HR) and perform a comparative study with its low resolution counterpart (1 deg ocean resolution with the same atmosphere resolution; LR). Similar to observations, we find positive correlation between SST and ocean-to-atmosphere heat flux anomalies in HR, indicating an ocean SST forcing on turbulent surface heat fluxes, while LR exhibits the negative correlation. For HR, we decompose the heat fluxes in the budget for the upper ocean heat content (OHC) into the mean and mesoscale-eddy components. We find that while the magnitude of heat fluxes by the mean currents is larger, eddy OHC divergence/convergence dominates the heat budget. We also find that variability of turbulent fluxes correlate well with the eddy heat flux divergence. Additionally, we identify anticyclonic eddies related to the Loop Current and Loop rings, which have an average diameter of about 350 km. The warm anomaly associated with these anticyclones has an identifiable imprint on surface turbulent heat flux, atmospheric circulation and convective precipitation in the northwest quadrant of the eddy composite. We find that the warm anomaly is also supported by eddy heat convergence. Collectively, these results highlight the importance of mesoscale variability for the upper ocean heat budget and air-sea interactions, which has potentially important implications for climate variability in the United States.