A Detailed Microphysical Model Within a Two-Dimensional Dynamic Framework: Model Description and Preliminary Results

Abstract

A two-dimensional anelastic cloud model which incorporates detailedtreatments of the water and ice phase is presented. The liquid phaseprocesses considered include condensation, quasi-stochastic coalescence,fallout and breakup, while the ice phase processes include diffusionaland accretional growth of ice particles. Results of two cloud simulationsare presented. The first case assumes an atmosphere with maritimecloud condensation nuclei (CCN) activation characteristics and considersthe warm rain processes only. It was found that with the appearanceof precipitation, the model-predicted supersaturations within updraftregions often reach values larger than 5% with respect to water.The second case assumes an atmosphere with continental CCN characteristicsand includes the ice phase processes leading to the formation ofgraupel. The results of the second case illustrate the importanceof cloud vertical motions in transporting ice particles from preferentialnucleation regions in the upper portions of the cloud to preferentialaccretional growth regions of larger liquid water content. Discrepanciesbetween model results and observations are discussed briefly andfuture research applications of this model are mentioned.