Snow cover stratigraphy in the northeast of Moscow region

Abstract

Snow stratigraphy can be considered as an integral characteristic of weather conditions of the corresponding winter season. The stratigraphic approach is convenient for a comparative analysis of the snow stratigraphy at different spatial-temporal scales, including the variability of the snow cover due to climate change. The snow stratigraphy can be sufficiently modeled on the basis of three meteorological characteristics: air temperature, wind speed and precipitation. Consequently, significant differences in the winter meteorological conditions should produce different stratigraphy.In the Moscow region winter temperatures are almost three degrees higher in the 21‑st century compared to the middle of the 20th century, though precipitation and wind speed are similar. Thus, changes in the snow stratigraphy can be expected. Comparative analysis of the results of stratigraphic studies carried out in the mid‑1950s to 1960s and 2010s indicates a slight decrease in the proportion of faceted crystal and depth hoar layers and increase in melt-freeze layers during the last decade, while the proportion of settled layers composed by rounded grains remains relatively invariable. However, the interannual variability of the winter weather produces higher variability in the snow structure compared to the expected effect of the long-term climate trends. The spatial distribution of the melt-freeze layers in the 2014–2019 was different compared to 1957/58 and 1961/62 due to the increase in the number and intensity of thaws in the winter seasons. In the 2010s, the number and thickness of ice crusts and melt-freeze layers increased in the middle part of the strata, which usually forms in January–February. Such layers composed 5 to 31% (17% in average) in 2014–2019 winters, while in 1957/58 and 1961/62 it was 7 and 10% respectively. A further increase in winter temperatures can enhance changes in snow stratigraphy and properties. It may result in thicker melt-freeze layers, weaker kinetic growth and shorter winter seasons.