Inter-seasonal and inter-decadal variability of freshwater and heat content in the Arctic Ocean

Arctic Ocean salinity, temperature and density data drawn from the Environmental Working Group (EWG) Atlas were used to compute freshwater thickness (FT) and heat content (HC) for both Atlantic water and Arctic surface water over a 40-year period. Both FT and HC exhibited strong seasonal variability when the decadal mean winter (DJFMAM) maps were compared with summer (JJASON) maps for each of four decades from 1950 to 1989. Maps of climatological values of FT and HC for both seasons were constructed, and FT and HC anomalies were calculated for each of four decades: 1950-1959, 1960-1969, 1970-1979 and 1980-1989.

In addition to strong seasonality, the signature of inter-decadal variability of HC and FT was evident, based on both HC and FT anomalies for each of the four decades studied. FT anomalies had two well-defined highs and two lows in the 1950s and 1960s, which shifted to a single well defined high and low anomaly during the 1970s and continued through the 1980s. To evaluate climate trends of Arctic atmospheric variables and sea ice extent, the corresponding observed data from the 1990s will be used when this data set becomes available to the scientific community.