Multiyear variability of the fast ice thickness in the Laptev Sea according to the polar station data

Abstract

The series of data on the fast ice thickness and the surface air temperature at the Roshydromet land-based polar stations in the Laptev Sea are analyzed. Observations for the last 15-year period (2005-2020) are compared to observations prior to 2004, and the changes corresponding to the new climatic conditions are revealed. Over the past 15 years ice thicknesses during the period of maximum ice growth (maximum ice thickness) have decreased by 6% on average. The ice growth process has become much slower, transition between the sequentional stages of ice development is observed 1-2 ten-days periods later. The surface air temperature at the considered stations was on average 3°C higher than for the previous period. The most significant changes are observed in the autumn months (October, November) and in April. The cumulative sum of the degree-day of frost averaged for the Laptev Sea stations, decreased by 15%; all 15 recent winter seasons can be classified as mild. It was revealed that the decrease of the cumulative sum of degree-day of frost is in a good agreement with the decrease of the mean-seasonal ice thickness (averaged for November-May) at the stations. This indicator seems to be more informative than the maximum ice thickness for estimation of the changes. Averaging over all stations revealed a 10% decrease of the mean-seasonal ice thickness during the past 15 years.

Keywords

• ice thickness
• fast ice
• polar stations
• ice conditions
• laptev sea
• sum of frost degree-days