A comparison of two schemes for the convective transport of chemical species in a Lagrangian global chemistry model

We have developed a detailed parametrization scheme to represent the effects of subgrid-scale convective transport in a three-dimensional chemistry-tran sport model (CTM). The CTM utilize.,, the meteorological fields generated by a general-circulation model (GCM) to redistribute over 70 chemical species. The convective transport is implemented using the convective mass fluxes. entrainment rates and detrainment rates from the GCM. We compare the modelled distributions of Rn-222 with observations. This shows that the vertical profile of this species is affected by the choice of convective-transport parametrization, The neck parametrization is found to improve significantly the simulation of Rn-222 over the summertime continents.