气候变化领域集成服务门户(CCPortal): Laboratory Investigation of Particle-Scale Factors Affecting the Settling Velocity of Volcaniclastic Dust

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DOI	10.1029/2020JD032660
	Laboratory Investigation of Particle-Scale Factors Affecting the Settling Velocity of Volcaniclastic Dust
	Richards-Thomas T.; McKenna-Neuman C.
发表日期	2020
ISSN	2169897X
卷号	125 期号:17
英文摘要	Iceland contains some of the largest and most active dust sources in the Arctic, with the frequency of major emission events increasing in the wake of catastrophic volcanic eruptions, such as the 2010 Eyjafjallajökull eruption. Relatively juvenile Icelandic volcaniclastic dust particles are porous and highly angular, and they frequently bear ultrafine nanoscale dustcoats. Their low density is speculated to affect deposition rates in the atmosphere, while substantial amounts of water adsorbed onto their expansive surface area may affect nucleation, aggregation, and settling. Using a 2-D laser Doppler anemometer, the present paper reports on a set of highly controlled fall column experiments designed to evaluate the dependency of the settling velocity upon particle morphology (e.g., size, shape, density, and surface area) and relative humidity (RH). Measurements for samples obtained from four Icelandic field sites are compared to those for solid glass spheres of similar diameter. The results confirm that the amount of adsorbed water increases with RH and the particle specific surface area. Higher dust concentrations are found to favor particle interaction and the formation of aggregates, especially at higher RH. Under dry conditions (20 % < RH < 30 %), the horizontal drift velocity measured for the angular, porous Icelandic particles exceeds that observed for solid glass spheres, although these measurements are an order of magnitude smaller than the vertical velocity. As compared to particle diameter, shape does not appear to influence either the settling rate or drag coefficient at Reynolds numbers ≤10−2, owing to the dominance of viscous effects over form drag. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	Fall column experiments; Iceland; Laser Doppler Anemometry; Particle characteristics; Settling velocity; volcaniclastic dust particles
语种	英语
来源期刊	Journal of Geophysical Research: Atmospheres
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/185805
作者单位	School of the Environment, Trent University, Peterborough, ON, Canada
推荐引用方式 GB/T 7714	Richards-Thomas T.,McKenna-Neuman C.. Laboratory Investigation of Particle-Scale Factors Affecting the Settling Velocity of Volcaniclastic Dust[J],2020,125(17).
APA	Richards-Thomas T.,&McKenna-Neuman C..(2020).Laboratory Investigation of Particle-Scale Factors Affecting the Settling Velocity of Volcaniclastic Dust.Journal of Geophysical Research: Atmospheres,125(17).
MLA	Richards-Thomas T.,et al."Laboratory Investigation of Particle-Scale Factors Affecting the Settling Velocity of Volcaniclastic Dust".Journal of Geophysical Research: Atmospheres 125.17(2020).