Recent modelling and measurement studies have shown that convective transport in the Asian monsoon region can provide a significant source of CO to the lower stratosphere. Correlations between species such as CO and O3 are useful diagnostics of stratosphere-troposphere exchange in the extratropical UTLS. We are using correlations between satellite observations of CO and O3 and assimilated data products to quantify stratosphere-troposphere exchange in the UTLS and to better constrain the influence of pollution from convective regions such as Asia on the composition of the UTLS region.
