Large-scale Transport within the Upper Troposphere and Lower Stratosphere: Representation in Climate Models and Projected Response to Future Climate Change (Invited Presentation)

Earth's upper troposphere/lower stratosphere (UTLS) and surface climate are coupled through direct chemically-driven radiative impacts on Earth's energy budget and through the stratosphere-troposphere exchange of ozone and aerosols. Trace gas and ozone distributions within the UTLS are in turn largely shaped by large-scale transport processes connecting surface emission regions to the lower stratosphere and to dynamical processes within the lower stratosphere. Here I present a review of work over the past decade focused on quantifying different components of this effective transport circulation, both in chemistry climate models and in observations, with a focus on interhemispheric transport associated with the Asian monsoon anticyclone. I then discuss how UTLS transport is projected to respond to future climate change, highlighting changes in both stratosphere-troposphere exchange in the (sub)tropics and in high-latitude coupling with the Atlantic Meridional Overturning Circulation.