October 13, 2012 — The ocean waters around the New England continental shelf were warmer than usual thanks to a divergence in the Gulf Stream path that started about one year ago, researchers from the Woods Hole Oceanographic Institution (WHOI) announced on Thursday.
The study, which was published in the August edition of the journal Scientific Reports, began after local commercial fisherman met with WHOI members and alerted them to unusually high surface water temperature and strong currents in the area.
Physical oceanographer Glen Gawarkiewicz promised that he would launch an investigation into the phenomenon, and began collecting data and creating a record of the Gulf Stream’s path during the fall of 2011, the institute said in a prepared statement.
“First, they tapped into data collected by a program called eMOLT, a non-profit collaboration of fishing industry, research, academic and government entities, run by James Manning of National Oceanic and Atmospheric Administration’s Northeast Fisheries Science Center. For more than a decade the program has recorded near-bottom ocean temperatures by distributing temperature probes to lobstermen,” WHOI officials said.
Together with Manning, WHOI scientists Robert Todd and Magdalena Andres collected a series of temperature readings from a pair of different eMOLT sites located on the outer continental shelf. They discovered two separate events where the temperature of the waters increased by 6.2 degrees Celsius and 6.7 degrees Celsius, ultimately reaching highs in excess of 18 degrees Celsius as a result.
Gawarkiewicz called those temperature spikes “dramatic events for the outer continental shelf, at least 2°C warmer than we’ve seen since 2001,” and added that the 18 degree Celsius readings in that region in late fall were “extremely high” for that place at that time. In fact, WHOI reported that the maximum recorded temperature at one of the sites for the month of December was the warmest recorded in six years worth of observations at that location.
“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 institute said. “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.”
“The extent and duration of the two 2011 warming events combined with the high salinity observed by the researchers suggested the cause was not a transient warm core ring, but the Gulf Stream itself that carried warm, salty water to the outer shelf,” they added. “To solidify that finding, Gawarkiewicz received serendipitous help from students in the Marine Advanced Technology Education (MATE) program at Cape Fear Community College in Wilmington, NC, who had deployed a surface drifter during the period coinciding with the two warming events.”