Toward a better quantitative understanding of polar stratospheric ozone loss

Abstract

Previous studies have shown that observed large O 3 loss rates in cold Arctic Januaries cannot be explained with current understanding of the loss processes, recommended reaction kinetics, and standard assumptions about total stratospheric chlorine and bromine. Studies based on data collected during recent field campaigns suggest faster rates of photolysis and thermal decomposition of ClOOCl and higher stratospheric bromine concentrations than previously assumed. We show that a model accounting for these kinetic changes and higher levels of BrO can largely resolve the January Arctic O 3 loss problem and closely reproduces observed Arctic O 3 loss while being consistent with observed levels of ClO and ClOOCl. The model also suggests that bromine catalysed O 3 loss is more important relative to chlorine catalysed loss than previously thought.