Distinct Regional Impacts of Oceanic Variability on Eurasian Winter Decadal Surface Temperature and Predictability

Abstract Eurasian surface air temperature (SAT) exhibits pronounced decadal variability with socio‐economic, ecological, and environmental impacts. However, it remains unclear whether slowly varying oceanic modes exert a persistent influence on continent‐scale Eurasian SAT anomalies, the extent to which this influence operates through dynamic or thermodynamic processes, and whether it offers a source of decadal predictability. Here we identify two leading decadal modes of Eurasian winter SAT from observations. The first, a meridional tripole with mid‐latitude cooling flanked by warming to the north and south, is driven by a positive‐phased Atlantic Multidecadal Variability (AMV). AMV‐related Rossby waves, amplified by Arctic sea‐ice loss, induce a northwestern Eurasian high that drives mid‐latitude cooling, while mean westerly advection warms the northern Eurasia and enhanced downward radiation warms southern Eurasia. The second mode features pan‐continental warming associated with a positive‐phased Pacific Decadal Variability (PDV). A deepened Aleutian Low and strengthened westerlies enhance Rossby wave propagation into Eurasia, favoring warm‐air advection across central and northern Eurasia, while radiative feedbacks reinforce warming over East Asia. Large‐ensemble simulations reproduce these mechanisms in a subset of realizations, supporting their physical plausibility. Incorporating AMV and PDV indices into a linear inverse model improves decadal prediction skill relative to persistence and SAT‐only forecasts. These results reveal physically interpretable oceanic influences on Eurasian winter SAT and demonstrate their potential for decadal prediction.