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The main part of the annual primary production in the Arctic and Subarctic zones of the World Ocean is formed during the spring phytoplankton bloom. The timing of the bloom depends on combination of physical factors. Oscillating control hypothesis, proposed in [Hunt et al., 2002] for the Eastern Bering Sea, describes annual peculiarities of ecosystem development related to conditions of the spring phytoplankton bloom. We review propositions of this hypothesis on the reasons of phytoplankton bloom and its connection with physical processes for four local regions of the Bering Sea shelf. The regions include western, northern and south-eastern parts of the shelf. The analysis is based on ocean color and microwave remotely sensed data as well as on atmospheric reanalysis. The results allow for hypothesis improvement. An early phytoplankton bloom may be present in the surface layer in April or May along the eastern Bering Sea shelf even in situations of early sea ice retreat (e. g. February-March) or absence of ice during winter. However, such combinations were not observed in the western Bering Sea shelf region. In 1998–2018, early ice retreat in the western shelf region was always accompanied by relatively late phytoplankton bloom. The temporal lag between sea ice retreat and phytoplankton bloom may be substantial in some years along the southernmost position of the ice edge. On the other hand, the spring bloom in the northern part of the shelf usually follows the ice retreat. In case of early ice retreat, the timing of the bloom is determined not only by wind conditions, but also by heat balance at the surface of the sea. The results are proposed to be used in further analysis of ecosystem dynamics of the western Bering Sea shelf.

This paper provides the analysis of the role of the marginal ice zone into the air-sea interaction processes over the Arctic during the period 1979-2010 on the basis of NCEP CFSR reanalysis data. One of the major conclusion of this study is the fact that widely used boundary of the interacting with the ocean atmosphere and thermally isolated atmosphere from the ocean of 15% for the sea ice concentration is not optimal for studies of the air-sea interaction processes. We demonstrated that significant amount of the surface turbulent heat flux is transferred from the ocean to the atmosphere through the areas with sea ice concentrations higher than 15%, while this sea ice concentration criteria is widely used as a boundary of the ice-covered and ice-free ocean. We also show that the spatial pattern of the response of turbulent heat flux to sea ice variability is observed over the Barents and Bering Seas during a cold season and over the Chukchi and Beaufort Seas during a warm season.