Northern Hemisphere Winter Blocking: Differing Onset Mechanisms across Regions

Abstract Atmospheric blocking is a prolific producer of extreme weather with significant socioeconomic impacts. Different physical mechanisms for onset have been proposed and are generally focused on two sectors: the Eurasian North Pacific. Here, we objectively separate into four regions investigate how vary from one region to another, focusing three factors: scale interactions between frequency bands, Rossby wave breaking (RWB), diabatic heating. Atlantic blocks dominated by low-frequency flow evolution that resembles negative phase Oscillation influenced cyclonic RWB toward western edge anticyclone. Europe high-frequency, traveling waves across Ocean develop rapidly, mainly attributed strong anticyclonic interaction high- intermediate-frequency components. Asian fixated within stationary train spans upstream do not potential vorticity or features. The Pacific an retrograding train, while component resembling Pacific–North American pattern evident. also contain precursor signals in stratosphere. Backward trajectory analysis revealed 35%–45% parcels initialized Atlantic, Europe, anticyclones experience heating ascent, adiabatic processes dominate blocking. Overall, our demonstrates importance decomposing bands illustrates different over sectors.