Long‐Term Changes in Wintertime Temperature Extremes in Moscow and Their Relation to Regional Atmospheric Dynamics

Abstract

AbstractInterannual variability and long‐term changes in winter air temperature extremes in Moscow (1949–2017) are investigated using observational and reanalysis data. Significant interdecadal changes in principal characteristics of temperature extremes are revealed. Strong warming (0.50 °K per decade) is identified contrasting to the previously identified summer trend of 0.25 °K per decade. This is attributable to middle‐to‐late winter. Winter and summer daily air temperature variabilities are fundamentally different with wintertime anomalies strongly negatively skewed, while summer displays Gaussian variability. A reduction in the number of cold days and an increase in warm days in December and March are found. In January and February, the probability of warm extremes increases, while the probability of cold extremes remains constant. Intensification of January extremes (cold and warm) is revealed along with daily temperature variability reduction. In aggregate, potential shortening of Moscow's winter season, suppression of the previously strong seasonal cycle in daily temperature variability, and intensification of midwinter extremes are identified. Dynamical linkages are found to North Atlantic and Mediterranean storm track variability as well as synoptic activity over the Barents‐Kara Seas. Lagrangian analysis shows associations of wintertime extreme warm events to air masses originating over the North Atlantic and Mediterranean regions. Air masses implicated in cold extremes are mostly of Siberian and Arctic origin. On interannual time scales cold event frequency in Moscow is impacted by the negative phase of North Atlantic Oscillation, whereas frequency of warm events is influenced by the positive phase of North Atlantic Oscillation and the negative phase of Scandinavian teleconnection.