Loop Current Dynamics

Gulf of Mexico Hybrid Coordinate Ocean Model (GoM-HYCOM) Loop Current Dynamics

Strong oceanic flows form a continuous link between the Southern and Northern Atlantic through the Caribbean Sea and the Gulf of Mexico. The Loop Current (LC) forms the origin of the Gulf Stream and it owes its unique shape to the Gulf geometry. It exhibits strong variability in extension and overall “shape”. At one extreme (“young” stage), the LC has an almost direct path to the Florida Current, causing the shear in the flow to set up a quasi-permanent clockwise recirculation known as the Cuban Vortex. At the other extreme (“extended” stage), it intrudes into the Gulf of Mexico, forming an intense clockwise flow as far north as 29°N, near the shelf-break of the Northern Gulf of Mexico (see NGoM-HYCOM model domain). Transition between these extremes is usually achieved through the shedding of anticyclonic rings that travel westward. Occasionally Loop Current-Mississippi River plume interactions have been observed / simulated, marked by the removal of Mississippi River waters along the LC front all the way to the Straits of Florida.


Intrusions of the Loop Current on the West Florida Shelf and indirect effects on shelf circulation in the Gulf of Mexico have also been studied. Eddies traveling around the LC front play a role in the ring shedding process (see below). They also promote the connectivity among remote coastal ecosystems, such as coral reefs, as they can travel by upstream reefs south of the Yucatan peninsula to downstream reefs in the Florida Keys (see Eddies in the Straits of Florida).


GoM plots provided by Pat Hogan and Ole-Martin Smedstad, Naval Research Lab - Stennis Space Center Satellite data and composite image provided by Viva Benzon, RSMAS satellite group


Sea Surface Height (SSH) fields from GoM-HYCOM (with the NCODA data assimilation system) for May 27, 2004 (upper left) and May 29, 2004 (right) and 7-day composite (May 24 to 31, 2004) from the Aqua-satellite chl-a data (bottom left). The model predicts a realistic shape for the Loop Current and the simulation helps studies of LC dynamics, such as the processes that lead to ring formation and change in LC extension, as well as the influence of LC dynamics on the dynamics of the West Florida Shelf and South Florida shelf and coastal regions.


A cyclonic eddy (marked by low SSH, blue color) around 25°N, 85°W is promoting the formation and detachment of a Loop Current ring, which will eventually cause a retreat of the LC to a “young” position south of 25°N.


Villy Kourafalou — vkourafalou@rsmas.miami.edu
George Halliwell — ghalliwell@rsmas.miami.edu