Three-Dimensional In Situ Measurements of a Large Anticyclonic Eddy and Surrounding Waters in the Eastern Caribbean Sea

Previous studies of anticyclonic Caribbean eddies illustrate their pathways, horizontal scales, amplitudes and their relationship with the Caribbean Current. However, their vertical structure has remained unresolved from in situ observations and has not been thoroughly explained in literature. While these studies show that warm-core eddies (WCE) in the basin can evolve from North Brazil Current (NBC) rings together with current instabilities within the Caribbean, this finding hasn’t been investigated using water mass characteristics. The vertical structure of a large anticyclonic eddy and the background flow in the Caribbean is examined using oceanic profilers deployed during a NOAA research aircraft study in September 2014 in the Eastern Caribbean Sea. Measurements of the overlying atmospheric boundary layer are also collected to examine air-sea processes over the warm feature. These novel measurements highlight three-dimensional temperature and salinity profiles for eddy and background regimes, including anomalous thermal structure compared to climatology, upper ocean buoyancy frequency, a residing barrier layer (BL), velocity structure, and water mass characteristics. Focus is directed towards how these observations compare to the Gulf of Mexico (GoM) given the connectivity of the two basins. Results suggest that the eddy’s vertical structure is similar to WCEs in the GoM whereas its upper ocean stratification is relatively stronger due in part to a prevalent BL. Given the eddy’s trajectory prior to sampling and the freshwater anomalies contained within, NBC ring influence is suspected. Atmospheric measurements show a somewhat unstable, moist boundary layer over the eddy. Three-dimensional in situ ocean measurements in these Caribbean eddies are key to furthering knowledge of the dominant air-sea interaction processes in the Intra-American Seas and their potential relationship with atmospheric boundary layer processes including tropical cyclone passage.