On the dynamical control of Northern Hemisphere polar stratospheric temperatures by planetary wave reflection

The impact of extreme negative heat flux events on the Northern Hemisphere residual circulation and Arctic lower-stratospheric temperatures is investigated. We show that extreme negative heat flux events lead to a transient reversal of the residual circulation and transient cooling of the lower stratosphere in high latitudes. The events act to weaken the seasonally averaged adiabatic warming. We subsequently highlight the role of extreme negative heat flux events during the winters of 1997 and 2011 and suggest that they likely contributed to the extreme nature of those winters.