Anti-aging scheme

Atmospheric Mixing The air of the lower stratosphere in the Southern Hemisphere has been getting younger since 1994. Strahan et al. report measurements of atmospheric HNO3 and HCl showing that changes in the transport circulation between the troposphere and stratosphere in the Southern Hemisphere are decreasing the age of its stratospheric air, whereas the age of its Northern Hemisphere counterpart is not declining. Understanding and quantifying the processes behind this differential aging is important for modeling how the protective stratospheric ozone layer will evolve in the future. Geophys. Res. Lett. 47 , e2020GL088567 (2020).