Injection of iodine to the stratosphere

ALFONSO SAIZ-LOPEZ; BAIDAR, S.; CARLOS A CUEVAS; KOENING, T.K.; RAFAEL PEDRO FERNÁNDEZ; DIX, BARBARA; DOUGLAS E. KINNISON; JEAN-FRANCOISE LAMARQUE; XAVIER RODRIGUEZ-LLOEVERAS; TERESA CAMPOS; RAINER VOLKAMER

Viena

Conferencia; European Geosciences Union General Assembly (EGU-2016); 2016

European Geosciences Union

There are still many uncertainties about the influence of iodine chemistry in the stratosphere, as the real amount of reactive iodine injected to this layer the troposphere and the partitioning of iodine species are still unknown. In this work we report a new estimation of the injection of iodine into the stratosphere based on novel daytime (SZA < 45o) aircraft observations in the tropical tropopause layer (TORERO campaign) and a 3D global chemistry-climate model (CAM-Chem) with the most recent knowledge about iodine photochemistry. The results indicate that significant levels of total reactive iodine (0.25-0.7 pptv), between 2 and 5 times larger than the accepted upper limits, could be injected into the stratosphere via tropical convective outflow. At these iodine levels, modelled iodine catalytic cycles account for up to 30% of the contemporary ozone loss in the tropical lower stratosphere and can exert a stratospheric ozone depletion potential equivalent or even larger than that of very short-lived bromocarbons. Therefore, we suggest that iodine sources and chemistry need to be considered in assessments of the historical and future evolution of the stratospheric ozone layer.