Trends of Temperature Regime Changes on the Territory of the Republic of Bashkortostan during the Cold Period

The results of the study of changes in the thermal regime in the cold period on the territory of the Republic of Bashkortostan are presented. The relevance of this study is due to the fact that the observed climatic changes may have different intensity within the Bashkir Pre-Urals, the Southern Urals and the Bashkir Trans-Urals. The assessment of regional changes in the thermal regime of the cold period was carried out on the basis of methods of statistical analysis of data from long-term observations, traditionally used in studies of this kind. The statistical significance of the values was estimated at a 95% confidence level. The data of observations at 30 meteorological stations of the republic in the period 1961-2020 were used for the analysis. It was found that the average monthly air temperatures tend to increase, statistically significant temperature increases are characterized by January (0.64°C/10 years), February (0.57°C/10 years) and March (0.47°C/10 years). The air temperature increases more significantly in the Pre-Urals (0.16-0.70°C/10 years), the smallest increase is observed in the Trans-Urals (0.13-0.40°C/10 years). In the considered 60-year period, more than half of the cases of temperature anomalies relate to the criteria of “warm season” (24 cases – 40.0%) and “very warm season” (7 cases – 11.7%). A reduction in the duration of the cold period in the republic was revealed due to the shift of its start date to a later date (1.8 days/10 years), and the end – to an earlier date (-1.0 days/10 years). During the correlation analysis, it was found out that the increase in air temperatures in the cold period is associated with a decrease in the blocking processes of the Scandinavian oscillation and an increase in zonal circulation created by the Arctic and North Atlantic oscillations.