The second leading mode of principal component analysis of the winter atmospheric pressure pattern in the North Atlantic-European region known as the East Atlantic Oscillation (EAO) is considered. The winter EAO pattern exhibits well-defined dipole at 500-hPa geopotential height (H 500 ) with centers over the North Atlantic and the Central Europe. The EAO phase-to-phase shifts reflect the general atmospheric circulation changes and the zonal (meridional) circulation dominates in positive (negative) EAO phase. This induces storm tracks spatial shift, heat and moisture transport redistribution, which in turn results in anomalous winter air temperature and precipitation in the Europe. The surface air temperature and precipitation interannual variability explained by EAO index is 25 -35 % and 15 -25 %, respectively. Positive EAO phase is associated with the higher winter air temperatures in Europe (mean anomalies are from +0.3 to +3.5 °C), and negative EAO phase is associated with the lower winter air temperatures (mean anomalies are from -1.5 to -0.5 °C). Basin-wide changes in the intensity and location of the North Atlantic polar jet stream are observed between the EAO opposite phases. Anomalous cyclonic (anticyclonic) circulation over the North Atlantic and southward (northward) shift of the North Atlantic jet stream is shown to be inherent in positive (negative) EAO phase.

The processes of interaction within the ocean-sea ice-atmosphere system which influence a multiyear ice cover dynamics in the Barents Sea are investigated. Being analyzed, the principal components of the sea ice concentration fields in the Barents Sea make it possible to distinguish three modes of interannual variability of the sea ice concentration. It is shown that the first mode describes 65.4 % of the sea ice concentration total variance and its multiyear trend. The second mode (10.8 %) is related to the variations of the heat inflow due to the sea currents governed by the atmospheric circulation. The third one (7.8 %) is associated with variability of the total turbulent heat flux from the ocean to the atmosphere at the boundary of the ice edge in the northern Barents Sea. Introduction. One of the most important regions for monitoring climatic changes in the Western Arctic is the Barents Sea [1, 2] which is attributed to the ice covered ones; but unlike the other Arctic seas, it is never completely covered by ice. Ice formation is usually observed in the north, east (off the archipelago Novaya Zemlya coast) and in the southeast of the sea. Depending on the hydrometeorological conditions, duration of the ice period is 6 -10 months [3]. Global increase of the air temperature observed during the past decades and especially pronounced in the Arctic region ("the effect of polar amplification") has already resulted in rapid reduction of the ice cover. At present, the ice area in the Barents Sea decreases much more rapidly (about 10.5 % during 10 years) than those in the other seas of the Arctic basin that demonstrates the worse negative trend in winter period [4 -6].Starting from the pilot paper [7], the basic factor conditioning climate of the Western Arctic seas including inter-annual variability of the ice cover area in the Barents Sea [8 -11] is considered to be heat advection by the North Atlantic Current. On the other hand, many authors emphasize the important role of the atmospheric factors, namely large-scale atmospheric circulation [12,13], cyclonic activity [14, 15], heat fluxes from the ocean to the atmosphere [16,17] and wind, in particular. For example, proceeding from the results of the 465-year numerical experiment, the authors of [18] concluded that the inter-annual variability of the ice area in the Barents Sea is conditioned mainly by the ice import or export occurring due to the local wind forcing; whereas heat transfer by currents is of noticeably less importance. It was also pointed out in [14, 19 and 20] that intensive north or south winds play an important role in displacement of the ice boundary in the Barents Sea.