Multiyear variability of atmospheric processes and ice cover in the Laptev Sea since 1942 to 2019

The Laptev Sea is influenced by synoptic regions of the Atlantic-Eurasian sector of the Northern Hemisphere. Types of large-scale processes are consider according to the G. J. Vangengeim typization: West (W) circulation form, with dominating zonal transport of air masses, East (E) and meridional (C) circulation forms with opposite phases of geographic orientation in the troposphere of the anticyclones ridges axes, blocking the Western transfer of air masses and developing the meridional circulation at high and middle latitudes. The Laptev Sea ice extent at the end of the melting season has a strong interannual variability, the oscillations amplitude reaches 86%.

The paper considers analysis of long-term trends of the large-scale atmosphere processes realignment and multiyear variability of the air temperature and ice cover anomalies in the Laptev Sea. According to multiyear course of integral anomalies values four steady periods of homogeneous  tendency of climatic processes revealed and described for data series from 1942 to 2019 (air reconnaissance and satellite data).

The types of ice conditions development (severe, medium, mild) at the end of the melting season were determined for the entire series of observations. More than half of cases during 78 years are distinguished as medium type of ice conditions. The repeatability of severe and mild types is almost the same numerically but varies in time according to revealed periods.

During 1942-1947 years in the Laptev Sea the “warming” period occurred (same for the whole polar region), known as the warming of the Arctic of 30th. At this period positive temperature anomalies and negative anomalies of sea ice extent (mean -2%) were dominated. During subsequent period 1948-1989 years the positive temperature trend has changed to the steady negative. The most dramatic temperature drops were observed in the 60-70^th. Positive ice anomalies increased (mean 9%), in August Laptev Sea remained mostly covered by ice. Of the 42 years 28 refer to the medium type of ice conditions, 11 to the severe. During the period 1990-2004 years frequent interannual rearrangements of the atmosphere circulation and multidirectional fluctuations of temperature and ice cover anomalies were observed. On average, the temperature and ice cover during the period are close to the long-term norm. After 2005 temperature regime in the polar climate system has changed. This period is the warmest for the whole observations series in the Laptev Sea. Ice extent at the end of the melting season steady decreases and shows dramatic growth of negative anomalies values and occur of extremely low anomaly for the entire observation period (up to -54-55%). The average negative ice anomaly for the period is -26.4 %. Of the 15 years 9 refer to the mild type of ice conditions.