New Pathway of Tropical Influences on Arctic Subseasonal Warming Events in the Troposphere

Midlatitdue weather extremes are highly correlative to the variations of Arctic and midlatidue circulations. High-amplitude fluctuations of the jet stream result in heat exchange between the Arctic and midlatitude regions, creating a feedback mechanism between subseasonal Arctic warming and stagnation of midlatitude atmospheric waves. The documented increase in the frequency of rapid Arctic warming within the troposphere, as oppose to stratospheric warming, has been linked to increased weather extremes. Previous research links the subseasonalArctic warming events with tropical convective activities in the Pacific region; this link may have strengthened in the recent decades. This study investigates the changing tropical convection linkage with the increased subseasonal Arctic warming. We found that the subseasonal Arctic warming events during the recent decade exhibit a stronger poleward wave activity flux in the North Atlantic and this is traced to the pronounced change in the convection of tropical Eastern Pacific. Given that the global warming has enhanced convection in the Maritime Continent and Eastern Pacific, our results suggest an increasingly important role of the tropical East Pacific in affecting the subseasonal Arctic warming events that occur within the troposphere.