Relationships Between the Wintertime Atmospheric Blocking and Cold Surges Over Eurasia Revealed by Clustering

A unified clustering framework based on pattern correlation is used to identify eight blocking regimes over Eurasia and surrounding oceans during the winter months (December–March) of 1948–2021. The regimes are labeled based on their centers of action, which are located over the West Atlantic, Greenland, the East Atlantic, Scandinavia, the Ural Mountains and Siberia, the Okhotsk Sea, the Bering Strait, and the North Pacific. It should be noted that the classification is almost insensitive to the time period but mainly depends on the percentage of different blocking events. The spatial distributions of cold surges differ substantially among these eight regimes. Due mainly to the cold advection downstream of the centers of blocking activities, cold surges can be observed over parts of the Eurasian continent. Possible relationships between the eight blocking regimes and large-scale modes of climate variability, including the Arctic Oscillation, the North Atlantic Oscillation, and the El Niño-Southern Oscillation, are explored. Not only contemporary connections but also the predictive value of large-scale modes is discussed.