Attribution of Recovery in Lower-Stratospheric Ozone

摘要: [1] Multiple satellite and ground-based observations provide consistent evidence that the thickness of Earth's protective ozone layer has stopped declining since 1997, close to time peak stratospheric halogen loading. Regression analyses with Effective Equivalent Stratospheric Chlorine (EESC) in conjunction further using more sophisticated photochemical model calculations constrained by data demonstrate cessation depletion between 18 25 km altitude is a leveling off abundances chlorine bromine, due Montreal Protocol its amendments. However, increases lowest part stratosphere, from tropopause km, account for about half improvement total column during past 9 years at Northern Hemisphere midlatitudes. The increase altitudes below most likely driven changes transport, rather than bromine. Even this amendments are having desired, positive effect on above recovering faster expected because apparent transport lower altitudes. Accurate prediction future levels will require comprehensive understanding factors drive temporal various partitioning recent transport-driven natural variability atmospheric structure perhaps related anthropogenic climate change.