A new 2-moment icemicrophysical scheme for large eddy simulations

With the increase of computing power, it now becomes feasible to perform large eddy simulations for atmospheric flows that go beyond classical boundary layer process studies, and move towards larger domains and deeper convection. In order to do so reliably, microphysical schemes need to incorporate solid phase water on a level of sophistication that is adjusted to the high resolution that is typical in LES. In this study, we present a model that is inspired by the work of Seifert and Beheng, as implemented in the COSMO-model, but adding more detail to it where appropriate.

The icemicrophysical model presented features prognostic equations for rain, cloud ice, snow and graupel; for rain and cloud ice we calculate two moments prognostically. The list of interactions between the various hydrometeors that is taken into account should ensure that at least the larger scale dynamics of the cloud system is modeled reliably. We will discuss the impact of the various processes on the outcome of the simulations, as well as the impact of the details of implementation.