Determination of aerosol size distribution from observation of the aureole around a point source 2: Experimental

In Part 1 of this study1 it was shown theoretically that the aerosol size distribution may be derived from the single scattering radiance around a point source. In this paper preliminary results of aerosol size distribution derived by this method are presented. A solar blind radiometer designed and constructed for aureole measurements is described. It is shown that, if the light source is unobscured, a large systematic error may result, especially at small angles. This suggests the use of an obscured source. A comparison with the aerosol size distribution derived from transmittance measurements gives good agreement. A correlation is found between estimated visibility and aureole measurements.