Wavelength effects of soil-derived aerosols on atmospheric scattering coefficient

Relative scattering coefficients have been measured over the 400900 nm wavelength range under various weather conditions in the northern Negev desert. Wavelength dependence is seen to be quite variable, befitting bimodal aerosol conditions as predicted by Patterson. However, wavelength dependence in the near-infrared region is observed to be much sharper than the negligible dependence predicted in the literature for this spectral range under conditions where dust is noticeably present in the atmosphere. The sharp degree of dependence is attributed to an additive effect of the separate scattering coefficients of each of the two aerosol modes, both of which decrease with wavelength in the near-infrared region.