Oxidation of volcanic SO 2 : A sink for stratospheric OH and H 2 O

The oxidation of volcanic SO 2 to sulphate in the stratosphere is investigated for an anomalously large volcanic sulphur loading (∼200 Mt) similar to that generated by the Tambora eruption in 1815. Model calculations suggest that stratospheric OH levels can be severely reduced by the gas‐phase oxidation of SO 2 . One implication of this is that dense volcanic SO 2 clouds may last substantially longer than previously thought. SO 2 oxidation is also found to lead to significant stratospheric dehydration because approximatively three molecules of H 2 O are consumed for each molecule of SO 2 converted to sulphate. Therefore it is possible to view major volcanic eruptions as a potential sink for stratospheric H 2 O.