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Comparing total inorganic chlorine climatologies from ACE-FTS and CMAM39

Inorganic chlorine radicals are major catalysts for ozone depletion. Industrial chlorine sources have been phased out since the 1987 Montreal Protocol and its subsequent amendments, allowing ozone recovery to begin, but a significant amount of inorganic chlorine remains in the atmosphere in the form of inert reservoir species (e.g. HCl, ClONO2, and HOCl) and active radical species (e.g. ClO and Cl). These gases make up the total inorganic chlorine chemical family, Cly. The extent of Cly’s impact on ozone in a given year is heavily determined by the partitioning between radical and reservoir species. Therefore, climate models must be able to accurately simulate chlorine partitioning in order to predict ozone recovery. To this end, we use a combination of satellite measurements to investigate a chemistry climate model’s ability to capture chlorine partitioning. The specified dynamics version of the Canadian Middle Atmosphere Model (CMAM39) now provides the 6-hourly fields for the four most abundant Cly gases (HCl, ClONO2, ClO, and HOCl) up to the end of 2018. In this study, model-based global upper tropospheric and stratospheric climatologies for these gases are compared with climatologies based on satellite measurements taken from 2004-2018. These climatologies are based on measurements from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer, which are supplemented with collocated measurements from the Aura Microwave Limb Sounder and climatologies from the Michelson Interferometer for Passive Atmospheric Sounding and the Superconducting Submillimeter Wave Limb-Emission Sounder.

Event series  Brewer-Wilson Seminar Series