THE WINTER LAPTEV SEA POLYNYA AND ARCTIC OSCILLATION DURING THE LAST 300 YEARS: RECONSTRUCTIONS ON GEOCHEMICAL PROXY

It is shown that the area of winter Siberian polynya in the Laptev Sea has a negative correlation with the Arctic oscillation index (AO) for the winter period. Using this, a transfer function has been developed that connects the variations of winter polynya (the time series of the winter AO) and the geochemical time series of bottom sediments accumulated during the instrumental period (1898–2018) in the zone of distribution of the Lena polynya. The influence of winter polynya on sedimentation is determined by the formation of highly saline and cold waters entering to the bottom horizons. During the summer and in subsequent seasons, they determine the stratification of the water column of the shelf and make it difficult to convection. As a result, an oxygen deficit is formed in the bottom horizons, and the bottom sediments are enriched with redox-sensitive elements of anoxic environments and depleted of redox-sensitive elements of oxide environments. Reconstructions using the developed transfer function of the polynya during the last three centuries showed that its active development increases the average annual air temperature in the adjacent areas, but multidirectional affects the duration of the ice-free period.