The absence of an Atlantic imprint on the multidecadal variability of wintertime European temperature

Multi-decadal variability in North Atlantic sea surface temperatures (SST) is a prominent component of Northern Hemisphere climate: Sahel drought, Atlantic hurricanes, large-scale atmospheric circulation, and summertime European temperature and precipitation all respond sensitively to low-frequency variability in North Atlantic SST. It is therefore surprising that an imprint of North Atlantic multidecadal variability is conspicuously absent in western European temperature in wintertime, despite the fact that Europe's maritime climate is strongly influenced by its neighbouring ocean, where multidecadal variability in basin-average SST persists in all seasons. Here, we trace the cause of the missing imprint of North Atlantic SST multidecadal variability on European wintertime temperature to a dynamic response of the atmospheric circulation that masks its thermodynamic response to SST anomalies. Specifically, the pathways Lagrangian particles take to Europe are sufficiently different during anomalous SST winters to suppress the expected fluctuations in turbulent air-sea heat exchange accumulated along those trajectories. Because decadal variability in North Atlantic-average SST is thought to be driven largely by variability in the Atlantic Meridional Overturning Circulation (AMOC), the atmosphere's dynamical adjustment to this mode of variability may have important implications for the European wintertime temperature response to a projected 21st century AMOC decline.