Home – Home – Jornals – Geography and Natural Resources 2023 number 4

Based on daily data on isobaric surface altitude 700 hPa (lower troposphere) of NCEP/NCAR reanalysis we made an objective classification of synoptic types over the Kodar Range (Transbaikalia) for the period 1970-2020 and investigated seasonal and interannual variability of cyclonic and anticyclonic weather types frequency. It was found that the advective atmospheric circulation regime dominates at the level of the lower troposphere over the Kodar, and cyclonic types prevail over anticyclonic types in all seasons except summer (June-August). It was further found that the frequency of occurrence of anticyclonic types has a tendency to increase in summer and decrease in autumn over the last 50 years, and the frequency of cyclonic types to decrease in spring and, on the contrary, to increase in autumn. It is concluded that the atmospheric circulation over the Kodar may influence changes in the mass balance of mountain glaciers. According to the ratio of cyclones and anticyclones in different seasons of the year, three main modes of atmospheric circulation, determining possible changes in the mass balance of glaciers, were established. Until the mid-1980s, the increased frequency of winter and spring cyclones contributed to a stabilization of the glacier mass balance. From the mid-1980s to the early 2000s, the frequency of winter, spring, and summer cyclones decreased and the number of summer anticyclones increased. It is concluded that such conditions contributed to a decrease in winter precipitation and summer cloudiness, an increase in the net radiation and accelerated ablation of glaciers in the 1990s. Since the early 2000s the atmospheric circulation has contributed to a partial restoring of the glacier mass balance.