Intraseasonal temperature variability features in Northern Eurasia regions under changing climate

The estimations of various factors influence on weather regimes formation in Russian regions in transitional (spring, fall) seasons are presented. Changes in those regimes comparing to the middle of 20th century are analyzed, considering atmospheric circulation features under the changes in meridional heat transfer and Rossby waves stationary modes. Using long-term observations of surface air temperature from several locations across Russia, the multimodal features of the probability density functions (PDF) in several decades of 20th and 21st centuries are identified. Focusing on surface temperature anomalies in transitional seasons, we examine the connection between the multimodal features of their PDFs and the nonlinear dependence of surface albedo on temperature during the formation and melting of snow cover. We investigate the impacts of other mechanisms that can facilitate these features, including blocking of zonal atmospheric transport in middle latitudes and formation of blocking anticyclones (blockings) and stationary Rossby waves.