| Summary: | Here, we present the first implementation of an interactive polar module into the halogen version of the CAM-Chem model with the intention of expanding the model applicability to the polar regions, besides its widely usage for atmospheric studies throughout the tropics and mid-latitudes. The state-of-the-art polar module considers full gas-phase and heterogeneous inorganic chlorine, bromine and iodine chemistry and sources, which adds up to the organic halogen emissions from the ocean surface (the so-called very short-lived (VSL) substances). The online sea-ice halogen sources depend on the seasonal variation of different types of icy surfaces and the intensity of radiation reaching the polar surface. Our results indicate that the contribution of polar halogen sources represents between 45 and 80% of the global biogenic VSL bromine and chlorine emissions, respectively; and that the Antarctic iodine sea-ice annual flux is ~10 times larger than the total iodine source arising from the Southern Ocean. This work provides, for the first time, quantitative estimates of the annual and seasonal flux strength of each halogen family from the Arctic and Antarctic, as well as their contribution to the global tropospheric halogen budget, highlighting the importance of including the contribution of polar tropospheric halogens in global chemistry-climate models.
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