A parameterization of warm cloud microphysical conversion processes

A parameterization scheme is presented by which coagulation growth of drops is simulated. It is oriented at the common parameterization idea of partitioning the total water substance in a cloud water and a rainwater portion. This concept is accordingly applied to the stochastic collection equation by which the time evolution of a drop spectrum is described. Thus, the distinct conversion rates selfcollection, autoconversion and accretion can mathematically be formulated for number and mass densities of cloud water and rainwater which can then be numerically evaluated. With these results as standards a new parameter scheme is developed whose constituting equations consist in rates combining number and mass densities as well as a width parameter. The range of variables for which this parameterization is valid covers a wide range of relevant cloudphysical variables. Comparisons with other parameterizations are presented.