The Effects of variation of water soluble aerosols concentration, relative humidity, effective polarizability with wavelength, phase functions and scattering angles of desert aerosols

Abstract: This paper investigates the effects of variation of Water soluble concentrations (WASO), relative humidity, phase functions and scattering angles with wavelength, effective polarizability of desert aerosols. OPAC 4.0 (Optical Properties of Aerosols and Clouds) software package using FORTRAN program to model the effect of Water soluble concentrations at the visible spectral range of (0.4-0.80µm) and at eight relative humidities (0%,50%,70%,80%,90%,95%,98% & 99%) was used. Water soluble concentrations (WASO) were varied while that of Mineral accumulation, Mineral nucleation and Mineral coarse was kept constant. From the results obtained it was observed that the phase functions decreases as the scattering angle increased. Comparing phase functions at 0%RH to 99%RH, at each model there is more scattering at shorter wavelength due to smaller particles it signifies more absorption at larger scattering angle. The results have shown the clear increase in concentration and decrease in volume mix ratio as the relative humidity (RH) increases. The concentrations were varied to obtain five different models. Stokes parameter was use to obtain the phase functions and Lorentz- Lorentz relation for refractive index to determine the polarizability for single and effective polarizability aerosol, present in the desert atmosphere.