The Gulf of Mexico has several oceanographic phenomena that are important to interpreting effects of the oil spill. One of these is the Gulf Loop Current. This warm-water current runs north through the Yucatan Channel between Mexico and Cuba into the Gulf of Mexico then exits the Gulf as part of the Florida Current just south of the Florida Keys and north of Cuba into the Atlantic Ocean as the Gulf Stream. What’s more, there are cycles that this Loop Current goes through at random intervals – it varies in speed, depth, and extent into the Gulf. The waters carried by the Current are much warmer than the waters in the Gulf and can affect (or be affected by) hurricanes as they enter. These cycles cause the current to vary in size and reach at any given time of the year.

The cycle of the Gulf Loop Current includes four phases. The first phase of the cycle starts with the Current shallowly entering the Gulf of Mexico from the Caribbean Sea, wrapping around Cuba and immediately heading out to the Atlantic. Over time, the Loop grows in size, reaching farther into the Gulf more and more in the second phase of the cycle. After reaching into the Gulf, a portion of the Loop detaches to create an eddy vortex that circles south of the U.S. Gulf Coast. This is the third phase of the cycle. This eddy starts to slowly drift toward Texas and Mexico, gradually decreasing in size and intensity. The Loop recedes back toward the western tip of Cuba during this stage. In the final fourth phase, the Loop retreats back to its original position and the eddy diminishes as it drifts west.

Loop Current and Eddies as of June 27, 2010[1]

Loop Current Effects on Hurricanes

The Loop Current and its eddies are believed to boost the strength of hurricanes entering the Gulf. This was the case for hurricanes Katrina and Rita in 2005. Both hurricanes passed over the warm waters of the Gulf Loop Current and an eddy created by the Loop, enabling each to grow to category five hurricanes. Some residents fear that a hurricane passing over the oil spill might draw in the oil and then spread it over land.

Loop Current Effects on Oil Spill

The Loop Current and its eddies could interact with the oil spill in two ways. First, the oil could enter the Loop Current (already detected in small amounts in May 2010) and enter the Atlantic Ocean traveling toward Europe and Greenland via the Gulf Stream. If the oil were to become trapped in an eddy, this could drift the oil toward Mexico and Texas. However, oil trapped within an eddy, circling within the Gulf of Mexico, will do less damage to the coastline and the marine life that currently flourishes there. If this were to happen, the damaging effects of the oil toxins might be reduced and the toxins would disperse becoming “relatively inert and not nearly as toxic as liquid crude.”[2] The plants and animals in the Loop Current will not be so lucky.

Oil from the Deepwater Horizon accident was reported in small amounts in the Loop Current in May 2010 by University of South Florida scientists. Communities along West Florida and the Florida Keys continue to monitor reports for signs of approaching danger. One such effort includes the use of a robot named Waldo to detect oil in the current. The Loop Current, the eddies, and the surrounding sea temperatures are all being monitored by the National Data Buoy Center, part of the National Oceanic and Atmospheric Administration (NOAA).

Resources on the Loop Current

[1] Colorado Center for Astrodynamics Research (CCAR) generated by: Global NearReal-Time Altimeter Geostrophic Velocity Viewer.

[2] How bad could BP oil spill get for the Gulf and the nation? -