![]() ![]() However, the overall simulated impacts of Br chemistry globally are overestimated and thus caution is warranted in their interpretation. In regions where simulated mixing ratios of reactive Br and Cl fell within observed ranges, though, halogen chemistry drove large changes in oxidant fields and associated chemical processes relative to simulations with no halogens. In the modern IUPAC nomenclature, this group is known as group 17. The artificially created element 117, tennessine (Ts), may also be a halogen. Although variable geographically, much of this sensitivity is attributable to either over-vigorous activation of Br (primarily BrCl) via the chemical mechanism or overproduction of sea-salt aerosol simulated under higher-wind regimes. The halogens are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Globally, halogen chemistry had relatively less impact on SO 2 and non-sea-salt (nss) SO 4 2− although significant regional differences were evident. Comparing simulations using chemical mechanisms with and without reactive Cl and Br species demonstrates a significant temporal and spatial sensitivity of primary atmospheric oxidants (O 3, HO x, NO x), CH 4, non-methane hydrocarbons (NMHCs), and dimethyl sulfide (DMS) to halogen cycling. Br in the stratosphere was lower than observed due to the lack of long-lived precursor organobromine species in the simulation. In addition, the emission scheme for marine aerosol and associated Br −, which is the only source for Br in the model, overestimates emission fluxes from the high-latitude Southern Ocean. However, simulated total volatile inorganic Br mixing ratios in the troposphere were generally higher than observed, due in part to the overly efficient net production of BrCl. They also point to possible physicochemical mechanisms that may account for several previously unexplained phenomena, including the enrichment of Br - in submicron aerosol and the presence of a BrO maximum in the polar free troposphere. Simulated results revealed strong meridional and vertical gradients in Cl and Br species. The sensitivity of global atmospheric chemistry to the production of marine aerosol and the associated activation and cycling of inorganic Cl and Br was investigated using a size-resolved multiphase coupled chemistry–global climate model (National Center for Atmospheric Research's Community Atmosphere Model (CAM) v3.6.33). Observations and model calculations indicate that highly non-linear multiphase atmospheric processes involving inorganic Cl and Br significantly impact tropospheric chemistry and composition, aerosol evolution, and radiative transfer. ![]()
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