Timing of deep convection in the Greenland and Iceland Seas

This paper reviews published information on the timing of hydrographic and atmospheric variations in the Iceland and Greenland Seas. Large scale variations in hydrography, advection features, regional convection and their general impact or connection with climate and hydro-biological conditions will be considered briefly in the area of the Subarctic Gyre in the northern North Atlantic and the Nordic Seas. The intermediate convection in the Iceland Sea may have ceased during the so-called ''ice years'' in North Icelandic waters in the late sixties (1965-1970). Convection to the bottom in the Greenland Sea seems to have ceased in the seventies or after 1972. A clear linkage between the period of the ''Great Salinity Anomaly'', that was first observed in the Iceland Sea around 1968 and was advected through the Subarctic Gyre and returned to East Greenland waters and North Icelandic waters in 1981, and the timing of reduction of convection in the Greenland Sea is thus not obvious. Further detailed analysis is needed to resolve the questions about processes involved in the variability of hydrographic conditions in the northern North Atlantic and the Nordic Seas. It should be noted that conditions for convection may not only be related to atmospheric conditions or large scale advection of water characteristics but also to regional or local hydrographic conditions. (C) 1997 International Council for the Exploration of the Sea.