A note on subgrid-scale processes in photochemical modelling

Abstract

The effects of including a parameterization of subgrid-scale dispersion and chemical processes in the Eulerian-Lagrangian transport model of Hess are investigated. A case chosen to maximize the subgrid-scale effects is studied, and it is found that the predicted change in maximum O₃ when subgrid-scale processes are included is small (∼5%) compared with predictions based on direct injection of point emissions. It is also found for this model that the parameterization of subgrid-scale processes is not necessary to provide numerical stability in calculating the chemical kinetics.