Quasi-decadal oscillation of concurrent cold extremes and intense surface ultraviolet radiation events over the East European Plain

Abstract The East European Plain, a densely populated region and major contributor to global grain production, has emerged as a critical hotspot for climatic extremes. Using multiple sets of reanalysis data, this study identifies a systematic co-occurrence of cold extremes and intense surface ultraviolet (UV) radiation in winter over this region, forming compound cold-UV extreme events (cold-UV CEEs). The cold extremes are primarily driven by the East Atlantic blocking which disrupts the typical westerly flow, causing meridional transport of Arctic cold air masses into the East European Plain. Concurrently, the blocking high, which induces subsidence and stabilizes the atmosphere, suppresses cloud formation. The resultant cloud reduction elevates surface UV radiation intensity by about 20% relative to the climatology. In addition, our analysis identifies a significant 9 year cycle in the frequency of cold-UV CEEs, providing a critical foundation for predicting these cascading hazards.