The chemical fractionation of atmospheric aerosol as a result of snow crystal formation and growth |
| |
Authors: | Randolph D. Borys Edward E. Hindman Paul J. DeMott |
| |
Affiliation: | (1) Department of Atmospheric Science, Colorado State University, 80523 Fort Collins, CO, U.S.A.;(2) Present address: Atmospheric Sciences Center, Desert Research Institute, University of Nevada System, P.O. Box 60220, 89506 Reno, NV, U.S.A.;(3) Present address: Earth and Planetary Sciences Department, The City College of CUNY, 10031 New York, NY, U.S.A. |
| |
Abstract: | The relationships between the physical and chemical properties of mixed-phase clouds were investigated at Storm Peak Laboratory (3220m MSL) located near the continental divide in northwestern Colorado. Interstitial aerosol particles, cloud droplets and snow crystals were concurrently collected when the laboratory was enveloped by a precipitating cloud. All samples were analyzed for trace elements, soluble anions, electrical conductivity and acidity.The results show average trace constituent concentration ratios of cloud water to snow water range from 0.4 to 26. All but six of the 32 elements and ions measured had ratios greater than one. This result suggests a chemical species dependency of in-cloud aerosol particle scavenging processes. Evidence of a decrease of in-cloud aerosol particle scavenging efficiency by snow due to increases in aerosol concentration is also presented.Differences between the chemical composition of cloud water and snow water are manifested most strongly when snow crystals grow by vapor deposition. In-cloud scavenging efficiencies by snow crystals for most aerosol particle chemical species are dependent on the growth of the snow crystals by accretion of cloud droplets. This chemical fractionation of the atmospheric aerosol by snow crystal formation and growth should be most active where narrow, continental cloud droplet size distributions and low liquid water contents are prevalent, enhancing the probability of snow crystal growth by diffusion. |
| |
Keywords: | Snow aerosol scavenging cloud and precipitation chemistry |
本文献已被 SpringerLink 等数据库收录! |
|