Climatic changes of seasonal and inter-annual variability of the ice cover of the Greenland and Barents Seas

Abstract

The structure of the long-period variability of the ice cover of the Barents and Greenland Seas over a long series of observations from 1930 to 2017 is analyzed. In both seas, there is a significant negative linear trend of ice cover for both the winter and summer seasons. Average for the period of 1950–2016 intra-annual changes in ice coverings demonstrate the conjugacy of the seasonal cycles of the Greenland and Barents Seas, but with certain differences. Three homogeneous groups with a similar character of intra-annual changes in the ice area are identified for each sea. Identified succession in a state of ice cover for 2 years.The conjugacy of changes in the average decadal values of sea ice cover in April and August with the average decadal indices of atmospheric circulation AO, AD, PNA, NAO and the index of the thermal state of the North Atlantic AMO is shown. Spectral analysis of the winter and summer ice cover of the Greenland and Barents Seas for the period 1930–2016 confirmed earlier received cyclical fluctuations of 22, 9–11 and 6–7 years.Cross-correlation analysis established a close relationship between the longitudinal changes in the ice cover and the average annual values of the following astrogeophysical parameters, the longitude coordinate of the Earth pole position Y, the Earth axis nutation indices dEps and dPsi, the Earth rotation speed index lod (length of day), Sun solar activity index (annual Wolf number) , the average for six months, the distance from the Sun to Earth in the summer SX-III and the winter SX-III periods. Significant correlation coefficients are quite large (R = |0,30| – |0,56|) for both seas, comparable to the correlation coefficients between the ice cover and average annual air temperature T, show the reality of the ice cover mediated reaction to changes in astrophysical factors. Statistical equations relating the sea ice cover to hydrometeorological and astrogeophysical factors were obtained by multiple correlation. The overall correlation coefficient varies from R = 0,80 to R = 0,87 AT. The Greenland Sea, the share of astrogeophysical factors in the long-term changes in the ice cover of both the winter and summer seasons exceeded the contribution of hydrometeorological factors by 3–4 times. In the Barents Sea, the contribution to the total dispersion of astrogeophysical factors in the winter period is somewhat less than that of hydrometeorological factors, and in the summer period they exceed only 1.4 times. The authors’ approach opens up the possibility of using it to obtain statistical equations for the diagnosis and forecast of long-term and climatic changes in sea-ice cover.