Vertical Velocity and Vertical Heat Flux Observed within Loop Current Eddies in the Central Gulf of Mexico

Abstract

Sixteen months of observations from a surface-to-bottom mooring in the central Gulf of Mexico show that acoustic Doppler current profilers (ADCPs) are useful for directly measuring the vertical velocity within mesoscale anticyclonic eddies, such as those shed from the Loop Current; and combining simultaneous temperature measurements, vertical heat flux can also be estimated (as a covariance of both variables). There is evidence of significant and coherent signals of vertical velocity ?2?3 mm s?1 and vertical heat (temperature) transport ?10?3 °C m s?1 during the presence of three anticyclones. A simple analysis shows downward flow near the eddies? centers above 350 m and essentially upward flow in the peripheries, but below 700-m depth the pattern is indeed the opposite; however, further study is necessary to determine the eddies? interior structures. The observations also suggest the existence of a vertical convergence of heat somewhere around 600-m depth, and estimations of adiabatic heat flux suggest that part of the converged heat, which is not recirculated within the eddy, must escape from the eddy and flow upward along the isopycnals up to the surface layers. This is in good agreement with previous results that have suggested that an excess heat gained by the Gulf in the intermediate levels through exchanges with the Caribbean Sea must be exported to the upper layers by an upward mean heat flux.