Pan-Atlantic North American cold spells and European wind extremes in CMIP6 historical simulations

not-yet-known not-yet-known not-yet-known unknown This study investigates the representation of near-simultaneous cold and windy extremes in North America and Europe in an ensemble of historical climate model simulations as compared to reanalysis. By leveraging a weather regime perspective, we identify five dynamical pathways for cold spells in three regions of North America. Three of the pathways also engender European wind extremes. The pathways are: (i) A wave train producing central and eastern Canada cold spells, culminating in Scandinavian blocking. (ii) A persistent Atlantic low producing eastern Canada cold spells and wind extremes in the British Isles. (iii) A quasi-stationary wave-2 pattern producing central Canada cold spells and Scandinavian blocking. (iv) An Arctic high producing eastern United States cold spells and wind extremes in Iberia. (v) A wave train producing eastern United States cold spells, culminating in an Atlantic low and wind extremes in Iberia. Models represent well both the frequency and evolution of the pathways compared to reanalysis. However, they under-represent the frequency of pathways (i) and (iii) associated with Scandinavian blocking. The models perform very well in replicating mean surface temperature anomalies during cold spells, though they perform less well on European wind extremes. Typically, the models capture the region and timing of wind extremes associated with Atlantic lows, albeit with some under-representation of occurrence frequency, but fail to adequately capture the wind extremes associated with Arctic highs. This is linked to deficits in how the models reproduce the evolution of the dynamical pathways in the East Atlantic.