ABSORPTION-MEASUREMENTS WITH AN INTEGRATING PLATE PHOTOMETER CALIBRATION AND ERROR ANALYSIS

In this study, the integrating plate photometer (Lin et al., 1973), used at the University of Vienna, was calibrated with nonabsorbing and absorbing test aerosols to determine the systematical errors of the technique, which can be interpreted as apparent absorption coefficients sigma(a)a. A nonlinear calibration curve was obtained from measurements with polystyrene latex particles of various sizes, which includes the scattering properties (expressed in terms or the scattering coefficient cr, of the particles) and the area coverage f of the filter. Application of this curve sigma(a)a/sigma(s) = 0.0398f-0.441 to polydisperse paraffin aerosols gave satisfactory results. For the soot aerosol, sigma(a)a is < 10% of the calculated ''true'' absorption coefficient.