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1995
Conference Paper
Titel
On the role of parameterized ice microphysics on cloud structures, dynamics and sulfate distributions
Abstract
A mesoscale alpha chemical transport model and its meteoroloolcal preprocessor were used to investigate the influence of parameterized ice microphysics on cloud structure, dynamics and sulfate distributions. The results of simulations with and without ice and with and without riming were compared with those obtained with the original model packages using a cumulus parameterization. These numerical experiments substantiated that the relative humidity, water substance mixing ratio fields. and, hence, cloud structures were strongly altered by turning off the ice phase or the riming process. The differences in dynamics may be mainly attributed to the different assumptions made upon cloud and precipitation formation, and, hence, to the treatment of the consumption and release of latent heat and the sedimentation of hydrometeors. The differences in predicted cloud amount, cloud distribution, cloud structure and cloud type cause large differences in the calculated sulfate and SO2 concentratio n distributions. The cloud lifetime and the treatment of aqueous chemistry (cloud mean values versus heightdependent values) strongly, influence sulfate and SO2 concentrations in the gasphase and wet deposition rates. All results indicate that the predicted concentration distributions and the wet and dry deposition fluxes of the atmospheric trace constituents are strongly sensitive to the model assumptions and the model architecture itself.