Long-term variability of the spring taryn-aufeises

Abstract

Long-term variability of large taryn-aufeises was studied for several decades in different regions of the USA (Alaska) and Russia (Chukotka, Kolyma, Southern Yakutia, Transbaikalia, and Eastern Sayan). Differences between volumes of individual ice massifs and the recorded maximal values change from 2–3 to 95–100%, and they do not depend on sizes of ice fields and their geographical locations. No statistically significant dependence of the aufeis volumes on the atmospheric precipitation amount and the air temperature was revealed in the most of the above areas. However, a general tendency for decreasing of the annual maxima of the ice reserves due to the climate warming was noticed. The long-term variations of the aufeises show existence of cycles of increase and decrease in their maximum sizes with their durations of 3, 7 and 11 years with the 25–30% amplitude of variations relative to the mean long-term values. In the Arctic areas, some of the giant aufeises do not melt completely during the summer and remain for a next winter. The volume of pereletoks (shortterm permafrost) varies within the range of 5–25%, averaging 16% of the spring ice reserves. In the southern geocryological zone, a clearly pronounced dependence of activity of the aufeis processes on the snow thickness was found: when the snow depth increased from 70 to 100 cm, volumes of aufeises decreased by a factor of three, and the aufeises disappeared completely under the thickness larger 120 cm. It should be noted that the processes producing the aufeis-forming sources of subsurface water, and the factors of their layered-ice accumulation remain almost unexplored.

Keywords

• вечная мерзлота, криогенные процессы, наледи-тарыны, родники, сезонное оледенение