Long-Term Sea Surface Temperature Variability along the US East Coast

Sea surface temperature variations along the entire U. S. East Coast from 1875 to 2007 are characterized using a collection of historical observations from lighthouses and lightships combined with recent buoy and shore-based measurements. Long-term coastal temperature trends are warming in the Gulf of Maine [1.0 degrees +/- 0.3 degrees C (100 yr)(-1)] and Middle Atlantic Bight [0.7 degrees +/- 0.3 degrees C (100 yr)(-1)], whereas trends are weakly cooling or not significant in the South Atlantic Bight [-0.1 degrees +/- 0.3 degrees C (100 yr)(-1)] and off Florida [-0.3 degrees +/- 0.2 degrees C (100 yr)(-1)]. Over the last century, temperatures along the northeastern U. S. coast have warmed at a rate 1.8-2.5 times the regional atmospheric temperature trend but are comparable to warming rates for the Arctic and Labrador, the source of coastal ocean waters north of Cape Hatteras (36 degrees N). South of Cape Hatteras, coastal ocean temperature trends match the regional atmospheric temperature trend. The observations and a simple model show that along-shelf transport, associated with the mean coastal current system running from Labrador to Cape Hatteras, is the mechanism controlling long-term temperature changes for this region and not the local air-sea exchange of heat.