SOME EFFECTS OF DIFFERENT CLOUD PARAMETERIZATIONS IN A MESOSCALE MODEL AND A CHEMISTRY TRANSPORT MODEL

Chemistry transport models often ignore the cloud parameters that can be provided by meteorological preprocessors like mesoscale meteorologi cal models. They often recalculate these parameters with algorithms th at differ from those used in the meteorological preprocessors. Hence, inconsistencies can occur between the treatment of clouds in the meteo rological and chemical part of the model package. In this study the in fluence of five different cloud parameterization schemes used in a wel l-known mesoscale meteorological model on the results of a stand-alone version of a cloud and scavenging module is illustrated. The differen ces between the results provided by five model runs with different clo ud modules and those recalculated by the stand-alone version are discu ssed. Such differences occur due to the inconsistencies between the di fferent cloud parameterization schemes in the meteorological model and the cloud and scavenging module. The results of the cloud and scaveng ing module differ due to the different meteorological input data provi ded by the meteorological model. It is manifested both in recalculated cloud parameters and in predicted wet deposition rates. As illustrate d in this study, the rate of wet deposition strongly depends on the cl oud parameterization scheme used in the meteorological model and, henc e, on the model architecture itself.