Sensitivity of tropospheric ozone to halogen chemistry in the chemistry–climate model LMDZ-INCA vNMHC

Abstract. The atmospheric chemistry of halogenated species (Cl, Br, I) participates in the global chemical sink tropospheric ozone and perturbs oxidising capacity troposphere, notably by influencing lifetime methane. Global chemistry–climate models are commonly used to assess budget its sensitivity emissions precursors, as well project long-term evolution. Here, we report on implementation sources halogens model LMDZ-INCA (Laboratoire de Météorologie Dynamique general circulation model, LMDZ, Interactions with Chemistry Aerosols, INCA, version Non-Methane HydroCarbon chemistry, vNMHC) evaluate halogen effects budget. Overall, results show that simulates satisfactorily impact photo-oxidising system particular marine boundary layer. To quantify LMDZ-INCA, standard metrics representative behaviour (Ox, HOx, NOx, CH4 non-methane volatile organic compounds – NMVOCs) computed without halogens. addition leads a decrease 22 % burden, 8 OH 33 NOx. Sensitivity simulations for first time inclusion makes more sensitive perturbations CH4, NOx NMVOCs. Consistent other studies, burden changes from pre-industrial present-day is found be ∼20 lower when taken into account.