The Ice Particle and Aggregate Simulator (IPAS): Investigating Aggregate Properties Using a Multifaceted Modeling Approach

Aggregation, the process by which two or more ice particles attach to each other, is investigated to determine frequently occurring characteristics with the intent of improving ice-microphysical aggregation parameterizations via statistical analysis. A novel ice particle and aggregate simulator (IPAS) is employed as a statistical tool to simulate theoretical aggregates. Both monomer and aggregate physical characteristics such as aspect ratio and axis lengths can be determined and evolved offline using the simulator to reduce computational expense in bulk ice microphysical models. To emulate laboratory data, IPAS acts as a `theoretical laboratory' and provides likely aggregate properties given an input monomer shape and size to be collected.

A new aggregation scheme is to be implemented into a bulk microphysical scheme in WRF, namely the Adaptive Habit Model (AHM). Model output that uses IPAS-derived quantities will then be validated through radar and aircraft observations for idealized and real case studies to examine the influence of aggregation on the dynamic and thermodynamic properties of the environment. Precise aggregate characteristics calculated in IPAS should better predict aggregation rate and snow development in the newly implemented aggregation scheme in the AHM.