In situ photometric observations of angular scattering from atmospheric aerosols

Variability in atmospheric light-scattering properties with altitude

The altitudinal variability in angular scattering properties of the troposphere and stratosphere was measured with a balloonborne polar nephelometer. An analysis of interdependent experimental parameters provides information on the scattering phase function and inferred size distribution of aerosol particles as a function of altitude. These aerosol characteristics are extractable from the scattering dissymmetry index and its relationship to spectral dispersion in turbidity and the aerosol phase function. The problem of the correlation between backscatter and extinction is addressed from the perspectives of in situ observations.

Radiative transfer in two dimensions through fog

The 3-D time-independent unpolarized radiative transfer equation is developed into a form amenable to numerical solution by expansion of the total intensity in orders of scattering. A 2-D numerical algorithm is formulated using an eight-direction quadrature approximation to the source function and an optimized path-by-path intensity integration scheme. Computer code generated from the algorithm is used to examine the multiple scattering effects at 1.06 microm, 3.0 microm, and 10.6 microm in Deirmendjian C3 fog on a finite uniform intensity profile beam and an infinite Gaussian intensity profile beam. Transmission and backscatter for both beams are examined as well as contrast degradation of the uniform beam and spread of the Gaussian beam.