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 hygroscopic growth. Annual average sub 10 um fRH values (the ratio of aerosol scattering at 85%/40% RH) were 1.75 and 1.87 for the gamma and kappa fit algorithms, respectively. The study found higher growth rates in the winter and spring seasons that correlated with 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 fraction had a strong influence, with fRH decreasing with increases in the organic mass fraction and absorption Ångström exponent and increasing with the aerosol single scatter albedo. Uncertainty analysis if the fit algorithms revealed high uncertainty at low scattering coefficients and slight increases in uncertainty at high RH and fit parameters values.
Revised: October 30, 2017 |
Published: September 16, 2017
Citation
Jefferson A., D. Hageman, H. Morrow, F. Mei, and T. Watson. 2017.Seven years of aerosol scattering hygroscopic growth measurements from SGP: factors influencing water uptake.Journal of Geophysical Research: Atmospheres 122, no. 17:9451-9466.PNNL-SA-124902.doi:10.1002/2017JD026804