Sensitivity of the Reaction Mechanism for the Ozone Depletion Events during the Arctic Spring on the Initial Atmospheric Composition of the Troposphere

The ozone depletion events (ODEs) in the spring of Arctic has been investigated since the 1980s. It is found that the depletion of ozone is highly associated with the release of halogens especially bromine containing compounds from various substrates such as the ice/snow-covered surfaces in Arctic. In the present study, the dependence of the mixing ratios of ozone and principal bromine species during ODEs on the initial composition of the atmosphere in the boundary layer of Arctic is investigated by using a concentration sensitivity analysis, which is performed by implementing a reaction mechanism representing the ozone depletion and halogen release in a box model KINAL. The ratio between the relative change of the mixing ratios of particular species such as ozone and the variation in the initial concentration of each  atmospheric component is calculated, which reveals the relative importance of each initial species in the chemical kinetic system. The simulation results show that the impacts of various chemical species are different for ozone and bromine containing compounds during the depletion of ozone. It is found the species CH₃CHO is the most influential species which critically controls the time scale of the complete removal of ozone. However, the rate of ozone depletion and the maximum values of bromine species are only slightly influenced by the presence of CH₃CHO. Besides, according to the concentration sensitivity analysis, the reduction of initial Br₂ is found to cause a significant retardant of the ODE while the initial mixing ratio of HBr exerts minor influence on both ozone and bromine species. In addition, it is also interesting to note that the increase of C₂H₂ would significantly raise the amount of HOBr and Br in the atmosphere while the ozone depletion is hardly changed.