Estimates of ice crystal terminal velocity using IPAS

 
Poster PDF

Authors

Carl G. Schmitt — National Center for Atmospheric Research
Kara Jo Sulia — University of Albany

Category

Microphysics (cloud, aerosol and/or precipitation)

Description

The terminal velocity of hydrometeors is of high importance to atmospheric modeling. For liquid hydrometeors, terminal velocity estimation is simple given their spherical or near-spherical shape. For ice hydrometeors, the story is more complicated due to the variety of ice shapes possible in the atmosphere. Because the aggregation of ice crystals relies on the relative terminal velocities of the colliding particles, understanding the particle characteristics that contribute to the distribution of ice particle terminal velocities is crucial. For one particle "size", a variety of terminal velocities are possible. The Ice Particle Aggregate Simulator (IPAS) model is used to create realistic ice particles and ice particle aggregates in order to explore the variability of terminal velocities possible for a given particle maximum dimension. IPAS employs detailed information on ice crystal characteristics to approximate the various aspects of ice particle sedimentation and produces a statistical outline of terminal velocity. Future studies will extend these results to investigate aggregation through the differential sedimentation of ice particles.