![]() The size distributions of cloud droplets, drizzle/rain drops, and ice particles are represented using gamma distributions. In this paper, the new approach is implemented in a bulk two-moment microphysical scheme representing both warm-rain and ice processes and it is applied to an idealized 2D kinematic framework mimicking a shallow mixed-phase cumulus. With some modifications, the new approach can be employed in either bin or bulk microphysical models. In traditional approaches, these processes are treated by separating ice particles into predefined categories (such as cloud ice, snow, and graupel) using fairly arbitrary thresholds and conversion rates. This approach allows representing in a natural way the gradual transition from small to large ice particles due to growth by water vapor deposition and aggregation and from unrimed crystals to graupel due to riming. ![]() The third predicted variable is the number concentration of ice particles. The rimed mass fraction is predicted locally by separately predicting the ice mixing ratios acquired through water vapor deposition and through riming. ![]() ![]() All ice microphysical processes and parameters are calculated in a self-consistent manner in terms of these mass–dimension and area–dimension relationships. In this approach, the ice particle mass–dimension and projected-area–dimension relationships vary as a function of particle size and rimed mass fraction. ![]() This paper documents the development of a novel approach for representing ice microphysics in numerical models. ![]()
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