Impacts of "Storis" on the Thermohaline Stratification off West Greenland

Abstract

This paper examines the variability in the hydrographic conditions in the waters off West Greenland with a focus on the influence of the Polar Water off East Greenland and its associated sea ice or "Storis". During the mid-1970s, mid-1980s and early-1990s, maxima of Polar Water were observed in the upper water layers off Fyllas Bank, West Greenland. At a station located on the offshore bank slope in about 900 m of water, the upper 75 m of the water column are primarily influenced by the Polar Water and the "Storis". There, monthly mean temperatures are maximum and salinities a minimum during August-September. In years of larger than usual amounts of "Storis", cold diluted surface waters appear along the west coast of Greenland. Observations of sea surface temperature anomalies off Fyllas Bank during July indicate strong warming from 1989 to 2008, going from what appears to be the coldest year to close to the warmest. Warm anomalies were actually re-established in 1996. Warmer-than-normal sub-surface conditions peaked in 2003, a year with no "Storis". From 2002 onwards, a phenomenon is observed which seems to indicate a new structure in the distribution of SST anomalies: a band of colder-than-normal waters on the shelves off East and West Greenland. It is assumed that the continuous warming has led to massive sea ice melt off East Greenland, and the ice drifts with the East Greenland Current along the shelves off East and West Greenland, strongly influencing the temperature and salinity characteristics of the surface waters.