Scientists uncover diversion of Gulf Stream path in late 2011

October 14, 2012 – MAINE – At a meeting with New England commercial fishermen last December, physical oceanographers Glen Gawarkiewicz and Al Plueddemann from the Woods Hole Oceanographic Institution (WHOI) were alerted by three fishermen about unusually high surface water temperatures and strong currents on the outer continental shelf south of New England. “I promised them I would look into why that was happening,” Gawarkiewicz says. The result of his investigation was a discovery that the Gulf Stream diverged well to the north of its normal path beginning in late October 2011, causing the warmer-than-usual ocean temperatures along the New England continental shelf. The researchers’ findings, “Direct interaction between the Gulf Stream and the shelfbreak south of New England,” were published in the August 2012 issue of the journal Scientific Reports. To begin to unravel the mystery, Gawarkiewicz and his colleagues assembled data from a variety of sources and recreated a record of the Gulf Stream path during the fall of 2011. “These are very dramatic events for the outer continental shelf, at least 2 degrees C warmer than we’ve seen since 2001,” says Gawarkiewicz. “Near-bottom temperatures of 18 degrees C on the outer shelf are extremely high for late autumn.” The maximum recorded temperature in December 2011 was the warmest bottom temperature recorded in 6 years of records at the OC01 site. Gawarkiewicz and his colleagues collected additional data on water temperature and salinity from December 4, 2011 through January 4, 2012, from instruments on temporary test moorings placed 12 km south of the shelfbreak by the Ocean Observatories Initiative (OOI). The researchers compared those salinity measurements to historical data, and discovered that high salinity levels – consistent with the salinity of waters carried by the Gulf Stream – coincided with the warming periods. –Terra Daily