Some Effects of Different Cloud Parameterizations in a Mesoscale Model and a Chemistry Transport Model

Abstract

Chemistry transport models often ignore the cloud parameters that can be provided by meteorological pre-processors like mesoscale meteorological models. They often recalculate these parameters with algorithms that differ from those used in the meteorological preprocessors. Hence, inconsistencies can occur between the treatment of clouds in the meteorological and chemical part of the model package. In this study the influence of five different cloud parameterization schemes used in a well-known mesoscale meteorological model on the results of a stand-alone version of a cloud and scavenging module is illustrated. The differences between the results provided by five model runs with different cloud modules and those recalculated by the stand-alone version are discussed. Such differences occur due to the inconsistencies between the different cloud parameterization schemes in the meteorological model and the cloud and scavenging module. The results of the cloud and scavenging module differ due to the different meteorological input data provided by the meteorological model. It is manifested both in recalculated cloud parameters and in predicted wet deposition rates. As illustrated in this study, the rate of wet deposition strongly depends on the cloud parameterization scheme used in the meteorological model and, hence, on the model architecture itself.