potential vorticity at intermediate depths in the Labrador Sea, the Irminger Sea, and the
Iceland Basin have been constructed by combining the hydrographic sections crossing the
sub-arctic gyre of the North Atlantic Ocean from the coast of Labrador to Europe, occupied
nearly annually since 1990, and historic hydrographic data from the preceding years since
1950. The temperature data of the last 60 years mainly reflect a multi-decadal variability …