Water Vapor at the Tropical Tropopause and Arctic Ozone Loss

Stratospheric water vapor influences the chemical ozone losses, e.g. via controlling the PSC formation in the polar stratosphere. The amount of water entering the stratosphere through the tropical tropopause differs substantially between CCMs because the present-day models have difficulties in capturing the whole complexity of processes that control the water transport across the tropopause. As a result there are large differences in the stratospheric water vapor between the models. In this study we investigate the sensitivity of simulated Arctic ozone loss to the amount of water which enters the stratosphere through the tropical tropopause. We employ a comprehensive stratospheric chemistry-transport model driven by ECMWF meteorological fields and prescribed tropospheric abundances of the chemicals. Several simulations of the Arctic winter 2010/2011 are performed which differ from each other by the water vapor concentration at the tropical tropopause. The results indicate a sensitivity of the Arctic ozone loss to the tropical water vapor.