Keywords: model boundaries and initialisation, model domain size, photochemical modelling
The influence of the lateral boundaries and background concentrations on limited area photochemical model simulations
In this study, an attempt was made to investigate the influence of the lateral boundaries and the background concentrations on the predicted air pollutants' concentrations, as calculated by limited area, grid-based photochemical models. This influence is more pronounced in the case of mesoscale applications because of the limited domain. The lateral boundaries should be defined in such a way as to take into account the recirculation phenomena that occur as a result of the interaction of different scale atmospheric circulations. In addition, the influence of air pollutant sources located near the domain boundaries (inside or outside), on the concentrations of the photochemical pollutants inside the domain have to be considered. In this study, the UAM-IV photochemical model has been implemented and simulations have been performed over the Athens Basin. It was found that the concentrations of the photochemical oxidants are mainly affected by the lateral boundary conditions, while the influence of the background is evident in the first hours of the simulation.