Investigation of potential sources of widespread high ice water content in deep convection anvil outflow, Part 2: Simulated updraft microphysical pathways associated with observed ice size distribution properties

In part one of this two-part work, we establish that observed ice size distribution features from Airbus airborne measurements in stratiform outflow with substantial ice water content and modest radar reflectivity are generally consistent with a range of ground-based remote sensing observations of quasi-steady, heavy stratiform rain regions in the tropics. Here we consider the convective updraft microphysical pathways that may lead to the observed stratiform ice size distribution features. We use simulations with size-resolved microphysics, including heterogeneous and homogeneous ice nucleation. Assumed aerosol and ice microphysical properties and microphysical processes in updrafts are informed by various relevant measurements. We find that the observed size distribution features associated with substantial ice water content outflow can be linked to reduced precipitation efficiency in deep convection updrafts via particular microphysical pathways, which therefore appear as likely candidates to explain the conditions affecting jet engines.