Investigating the Sensitivity of Ice Crystal Habit and Nucleation on Hydrometeor Sedimentation Rates

Ice microphysics processes in clouds can control associated properties such as cloud lifetime, hydrometeor mixing ratios, and sedimentation rates. Ice crystal processes such as growth by vapor deposition are significantly affected by the habit of the ice crystal. While most bulk ice microphysics models disregard this shape effect and assume ice to grow spherically, a few models exist that assume ice crystals to grow non-spherically. This study focuses on how the (1) evolution of ice crystal shape and (2) choice of ice nucleation parameterization in the Adaptive Habit Model (AHM) influences process rates, such as aggregation, riming, and sedimentation. This is accomplished by focusing on a cold-season lake-effect storm (LeS) that occurred during the Ontario Winter Lake Effect Systems (OWLeS) Field Campaign. Emphasis is placed on LeS because these intense, localized snowstorms are capable of producing high snowfall amounts over a relatively short time period, providing an interesting natural laboratory to investigate many interacting microphysical processes. This lake-effect snow can have many negative impacts, including travel hazards and fatalities. Understanding the relationship, if any, among ice crystal habit, nucleation, and resultant cold-season mesoscale precipitation will help contribute to existing knowledge about the impact of these parameterizations within bulk microphysics models.