THE EFFECT OF RELATIVE HUMIDITY ON MARITIME POLLUTED AEROSOLS (Published)
In this paper, the author extracted and investigated the effect of relative humidity (RH) on some microphysical and optical properties of maritime polluted aerosols from OPAC at the spectral range of 0.25μm to 2.5μm and eight relative humidities (0, 50, 70, 80, 90, 95, 98, and 99%).The microphysical properties extracted were radii, volume mix ratio, number mix ratio and mass mix ratio as a function of RH while the optical properties were optical depth, extinction, scattering and absorption coefficients single scattering albedo, refractive indices and asymmetric parameters. Using the microphysical properties, hygroscopic growth factors and effective radii of the mixtures were determined while using optical properties we determined the enhancement parameters, effective refractive indices and Angstrom coefficients. The hygroscopic growth and enhancement parameters were then parameterized using some models to determine the hygroscopicity, bulk hygroscopicity, humidification factors and some other parameters that depend on RH and/or wavelengths. We observed that the data fitted the models very well. The effective radii increase with the increase in RH, while Angstrom coefficients decrease with the increase in RH and this signify the dominance of coarse mode particles. The angstrom coefficients show that the mixture has bimodal type of distribution and the mode size increases with the increase in RH.
Keywords: Angstrom Coefficients, Effective Refractive Indices., Enhancement Parameters, Hygroscopic Growth, Microphysical Properties, Optical Properties