Character of the summer meteorological regime on the Western plateau of Elbrus (the Caucasus)

Abstract

The results of meteorological observations, carried out in the framework of the international project Ice Memory on the Western plateau of the Elbrus Mountain during the Second drilling expedition (24.06–17.07.2018), are analyzed. The analysis of the field data made together with the assessment of the large-scale meteorological fields from the NCEP/NCAR reanalysis did show that, on the whole, the observed meteorological conditions corresponded to the background state of the atmosphere in the Greater Caucasus in the summer season (with the exception of the anomalous high moisture content). The Western plateau is characterized by a high frequency of storm winds ( > 20 m/s) with low drifting snow and intensive snowfalls: the precipitation sum for the expedition period is approximately estimated as 150 mm. Spectral analysis of time series allowed establishing the significant role of the mountain and valley circulation in the formation of the meteorological regime. It is shown that the melting of snow in high-mountain conditions is determined by the incoming short-wave radiation, while turbulent flows of heat and moisture mainly transport energy from the surface. For 20 days of the observations, approximately 49 mm of snow (in the water equivalent) melted, and about 25% of this volume evaporated. The rest of the moisture diffused into the snow cover, and thus, remained in the accumulation layer. During the expedition, deviations of meteorological values from the norm were relatively small, so it can be assumed that the obtained value of the evaporated liquid on the Western plateau during the ablation period was close to the climatic mean.