Interdecadal Modulation of the Warm Arctic-Cold Eurasia Reversal by the North Atlantic Sea Surface Temperature Tripole

The reversal of the warm Arctic-cold Eurasia (WACE) pattern significantly influences weather and climate extremes across Eurasia. Based on previous studies, the WACE reversal is defined as the third season-reliant empirical orthogonal function of surface air temperature (SAT) variability over the Arctic-Eurasian continent in Northern Hemisphere winter. This study investigates the interdecadal changes in the interannual variability of WACE reversal, revealing that its dominant periodicities have shifted across different decades. Observational analyses identify three characteristic Ural blocking (UB) patterns, each associated with shifts in the Arctic-Eurasian SAT dipole during reversal events. Furthermore, the results indicate that the interdecadal transitions of WACE reversal are largely attributable to the North Atlantic tripole sea surface temperature anomalies (SSTAs). Meanwhile, cold SSTAs over the North Pacific induced by these tripole patterns, may suppress the North Atlantic’s influence by reducing downstream wave activity to the reversal region. Our results demonstrate that North Atlantic SSTAs play an important role in modulating WACE reversal on interannual timescales, with their impact further shaped by coupled Atlantic-Pacific interactions.