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Seven years of aerosol scattering hygroscopic growth measurements from SGP: Factors influencing water uptake
Author(s) -
Jefferson A.,
Hageman D.,
Morrow H.,
Mei F.,
Watson T.
Publication year - 2017
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2017jd026804
Subject(s) - aerosol , single scattering albedo , angstrom exponent , relative humidity , albedo (alchemy) , atmospheric sciences , scattering , mass fraction , environmental science , angstrom , absorption (acoustics) , chemistry , nitrate , analytical chemistry (journal) , meteorology , environmental chemistry , physics , optics , art , performance art , crystallography , art history , organic chemistry
Abstract Long‐term measurements of changes in the aerosol scattering coefficient hygroscopic growth at the U.S. Department of Energy Southern Great Plains site provide information on the seasonal as well as size and chemical dependence of aerosol water uptake. Annual average sub‐10 μm fRH values (the ratio of aerosol scattering at 85%/40% relative humidity (RH)) were 1.78 and 1.99 for the gamma and kappa fit algorithms, respectively. The study found higher growth rates in the winter and spring seasons that correlated with a high aerosol nitrate mass fraction. fRH exhibited strong, but differing, correlations with the scattering Ångström exponent and backscatter fraction, two optical size‐dependent parameters. The aerosol organic mass fraction had a strong influence on fRH. Increases in the organic mass fraction and absorption Ångström exponent coincided with a decrease in fRH. Similarly, fRH declined with decreases in the aerosol single scatter albedo. Uncertainty analysis of the fit algorithms revealed high uncertainty at low scattering coefficients and increased uncertainty at high RH and fit parameters values.