Seasonal and inter-annual variability of the ice cover in the Greenland Sea

The results of studies of seasonal and inter-annual variability of the Greenland Sea ice cover are presented for the period from 1950 to 2016. Statistical characteristics of seasonal and inter-annual changes in the ice-covered area were calculated. Three clusters of typical seasonal variability were identified from the whole totality of all seasonal cycles. The first cluster presented a group of seasonal cycles in the period of maximum, the second one - the middle, and the third group - minimum areas of the winter ice cover. The estimates of correlation between changes in the ice areas in winter (February-March) or in summer (August-September) and areas of the following two months of a current year as well as in succeeding years were obtained. Empirical regularity of a variability of the ice cover during the annual cycle was established. This regularity is characterized by an existence of a 'memory' in the state of the ice cover, when a prehistory of the ice conditions determines to a certain extent the following phase. Analysis of inter-annual variability of the Greenland Sea ice cover did show a linear negative tendency in both winter and summer ice conditions. One-two year fluctuations were the most pronounced in the spectral density of inter-annual variations in the summer ice conditions. However, fluctuations with a longer period do also exist. With respect to contribution of hydrometeorological factors, the summer ice area is determined: (a) by conditions in the preceding winter, (b) by the atmospheric circulation, and (c) by the influence of warm Atlantic waters (about 20% of the total dispersion). Changes in the winter ice area depend: (a) mainly on the pre-winter state of ices (October-November), (b) on the influence of the Atlantic waters (about 30% of the total dispersion), and (c) on the heat balance and the atmospheric circulation (20% of the total dispersion). The results of this study may be used as a basis for the development of statistical models for analysis and prediction of long-term and climatic changes in the state of the ice cover in the Greenland Sea.