North Atlantic Subpolar Gyre Warming - Impacts on Greenland Offshore Waters

摘要

Sea-surface temperature anomalies in the North Atlantic Subpolar Gyre indicate cold conditions in the 1980s and warming from the mid-1990s onwards, with maximum temperatures observed during October 2003. The latter is consistent with air temperaturesat Nuuk, Greenland, which document that 2003 was the warmest year since 1950. Ocean temperatures off West Greenland show a significant upward trend (0.096 deg C y~(-1) in 0-300 m layer during 1983-2004), which is considerably higher than that for the North Atlantic Basin over the period 1955-2003. Long-term (1964-2004) observations from Fyllas Bank off West Greenland also reveal warm conditions during the 1960s, although the highest temperatures on record are from the recent years of the present century. Geostrophic transports estimated from autumn 2004 hydrographic data suggest increased northward transport of the West Greenland Current. Ocean properties at this time were more saline and up to 2 deg C warmer-than-normal. Volume transports were + 2.4 Sv in the core of the West Greenland Current, + 0.5 Sv on the West Greenland shelf, and - 1.9 Sv in the Baffin Island Current. While the northward (+) transport figures are in the range of the mean October and November transport values (+ 1.6 Sv to + 3.0Sv), the southward (-) transport figure is considerably smaller than earlier published values (-3.1 Sv to -4.6 Sv).