Estimating Surface Attachment Kinetic and Growth Transition Influences on Vapor-Grown Ice Crystals

• Published in: Journal of the atmospheric sciences 2020-07, Vol.77 (7), p.2393-2410
• Main Authors: Pokrifka, Gwenore F., Moyle, Alfred M., Hanson, Lavender Elle, Harrington, Jerry Y.
• Format: Article
• Language: English
• Subjects: Crystal growth; Crystals; Deposition; Diffusion chambers; Growth rate; Ice; Ice crystals; Ice particles; Levitation; Vapors
• ISSN: 0022-4928; 1520-0469
• DOI: 10.1175/JAS-D-19-0303.1

There are few measurements of the vapor growth of small ice crystals at temperatures below −30°C. Presented here are mass-growth measurements of heterogeneously and homogeneously frozen ice particles grown within an electrodynamic levitation diffusion chamber at temperatures between −44° and −30°C and supersaturations s i between 3% and 29%. These growth data are analyzed with two methods devised to estimate the deposition coefficient α without the direct use of s i . Measurements of s i are typically uncertain, which has called past estimates of α into question. We find that the deposition coefficient ranges from 0.002 to unity and is scattered with temperature, as shown in prior measurements. The data collectively also show a relationship between α and s i , with α rising (falling) with increasing s i for homogeneously (heterogeneously) frozen ice. Analysis of the normalized mass growth rates reveals that heterogeneously frozen crystals grow near the maximum rate at low s i , but show increasingly inhibited (low α ) growth at high s i . Additionally, 7 of the 17 homogeneously frozen crystals cannot be modeled with faceted growth theory or constant α . These cases require the growth mode to transition from efficient to inefficient in time, leading to a large decline in α . Such transitions may be, in part, responsible for the inconsistency in prior measurements of α .