Features of Formation of the Lena Polynya on the Estuarine Coast of the Bykovsky Arm in the Summer

Based on the results of the global oceanic reanalysis (GLORYS12.v.1), materials of hydrometeorological observations of the Roshydromet network in the Laptev Sea and the mouth of the Lena River, reviews of the ice processes in the Arctic Ocean by the Arctic and Antarctic Research Institute, this paper considers the features of the evolution of the Lena Polynya on the estuarine coast of the Bykovsky Arm in the warm period 1993–2019. The relationship between the timing of the formation of a polynya on the seashore of this arm with the dates of the beginning of the flood at the top of the Lena River delta has been revealed. The assumption is confirmed that the average growth rate of the Lena polynya in summer is determined by the timing of its formation – the earlier the flood begins, the earlier the polynya forms on the coast of the Bykovsky arm and the smaller the average rate its growth. It has been established that the process of warming in the mouth area of the Lena in 2008–2019 stabilized, as there are no significant trends in the characteristics of water and ice regimes. These regularities may be invariant for other mouths of the rivers of the Laptev Sea basin, and the obtained dependences can be used to improve the forecast of the dates of cleansing of the water area at the estuary seashore of the Lena from ice and planning icebreaking navigation along the route Tiksi port–Lena River.