EFFECTS OF VARIATION IN WATER INSOLUBLE AEROSOL CONCENTRATIONS AND RELATIVE HUMIDITY IMPACT ON THE POLARIZABILITY AND PHASE FUNCTION OF URBAN ATMOSPHERE

Abstract: This study utilizes Optical Properties of Aerosols and Clouds software (OPAC 4.0) to simulate urban aerosol optical properties, varying the concentration of Water-Insoluble (INSO) aerosol components were simulated across eight relative humidities (0%,50%,70%,80%,90%,95%,98%,99%), and visible wavelengths (0.4-0.8 µm). The Stokes parameters are used to obtain polarizability and phase function data for non-spherical urban aerosols. The study computes effective polarizabilities for non-spherical urban atmospheric aerosol components using Claussi Massoti, Maxwell relations, and Lorentz-Lorentz relation were used for computation of effective polarizabilities. The resulting data, including effective polarizabilities, polarization, and phase function, are extracted from OPAC 4.0. The mean exponent of aerosol size growth curve is determined from the effective hygroscopic growth. Phase function decreases with the increase in wavelength and also, decreases with the increase in scattering angle, satisfies power law. When all the plots were compared, phase function increase with the increase in relative humidity. The phase function increases with the increase in the concentration of water-insoluble aerosols. Effective polarizability exhibits a decrease with increasing wavelength and water-insoluble aerosols concentration, whereas it increases with increasing relative humidity.