I think you will find some answers in other articles from the series (especially Q8 and Q9), all of which are available at https://www.esrl.noaa.gov/csd/assessm

I think you will find some answers in other articles from the series (especially Q8 and Q9), all of which are available at https://www.esrl.noaa.gov/csd/assessments/ozone/2014/twentyquestions/ https://www.esrl.noaa.gov/csd/assessments/ozone/2014/twentyq... I will just point out about the gas diffusion that up to ~100km or so above ground turbulent mixing is the prevalent force. You can look at concentration of argon gas (Ar2 ~80g/mol) which also does not change in that altitude. About the PSC particles 'falling from gravity' keep in mind these are no longer gases (the operative word is 'particles') so you want to look at their density not molecular weight. (Simplistically, one mol of any gas is 22.4 L while one mol of water/ice is ~0.018 L.)