Wednesday, May 26, 2010

Could the oil spill reach Virginia?

As officials make another attempt to cap the well spilling oil into the Gulf of Mexico, Virginians might be asking, “Could oil show up here?” As of now, it appears a large oil slick on Virginia waterways is unlikely, but oil residue in the form of tar balls could wash up on local beaches. How could oil that’s currently in the Gulf of Mexico end up in Virginia?
The Earth’s oceans are always on the move, their motion influenced by atmospheric circulation patterns, water temperature and salinity, ocean floor topography, and the Earth’s rotation. These ocean currents can occur both at the surface and deep in the ocean; they often travel great distances and have an enormous effect on regional climates.
As far as the oil spill goes, the Loop Current is the first culprit that could carry oil toward the East Coast. This current flows north between the Yucatan Peninsula and Cuba into the Gulf of Mexico, loops east and then south along the west coast of Florida. The Florida Current would take up where the Loop Current left off, carrying the oil around Florida. Then the Gulf Stream would take over and carry it up the southeast coast.
The Gulf Stream is an enormous river of warm water averaging 60 miles in width and 3000 feet in depth. At Cape Hatteras, the current’s flow rate is an incredible 85 million cubic meters per second, equivalent to over 1 billion fire hoses! (By comparison, the Mississippi River moves water at roughly 0.6 million cubic meters per second.) A major influence on East Coast weather, the Gulf Stream sometimes breeds Nor’easters in the winter and intensifies hurricanes in the summer, as happened with Hurricane Hugo off the coast of South Carolina in 1989.
At present, disruptions in the Loop Current appear to be keeping oil away from Florida and the Gulf Stream. Eddies often form and then break off from the main body of the current; the majority of the oil that had drifted into the Loop Current in recent weeks appears to be caught in an eddy and cut off from the main body of the current. Satellite pictures even suggest that the current itself may soon sever entirely, lessening the imminent threat of oil coming ashore in Florida and beyond.
This afternoon BP began an attempt to plug the leak with a method called top kill, an ambitious procedure intended to clog the well with thousands of pounds of heavy fluids pumped through extremely long pipes. This procedure has never been attempted so far beneath the surface; it could take several days to determine if it was successful. For everyone’s sake, let’s hope they succeed.
Satellite image courtesy of NASA. Colors indicate water temperature: darker colors = cooler temperatures, lighter colors = warmer temperatures.

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