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Tuesday, June 14, 2011

Hygroscopic properties of volcanic ash

Hygroscopic properties of volcanic ash
GEOPHYSICAL RESEARCH LETTERS, VOL. 38, L11802, 4 PP., 2011
doi:10.1029/2011GL047298
by  P. Kumar T. L. Lathem A. Nenes J. Dufek I. N. Sokolik M. Trail A. Russell
Volcanic ash is hygroscopic
Water vapor adsorption is the main proceess controlling ash hygroscopicity
The results can be parameterized in a simple correlation for use in models
"Limited observational data exists on the physical interactions between volcanic ash particles and water vapor; yet it is thought that these interactions can strongly impact the microphysical evolution of ash, with implications for its atmospheric lifetime and transport, as well as formation of water and ice clouds. ...The hygroscopicity of the ash particles is quantified by their ability to uptake water and nucleate into cloud drops under controlled levels of water vapor supersaturation. Evidence presented strongly suggests that ash uptakes water efficiently via adsorption and a simple parameterization of ash hygroscopicity is developed for use in ash plume and atmospheric models."