Portable cell for simultaneously measuring the coefficients of light scattering and extinction for ambient aerosols

A portable multipass cell is described in which optical transm ittance and scattering measurements are made simultaneously on the same volume of aerosol. The cell is filled with ambient aerosolin which the dispersed phase has been concentrated centrifugally by more than 1 order of magnitude. The cell was tested on board a ship for a wide variety of sea and atmospheric conditions. Measurement errors were identified and evaluated. The mean resolution of the transmittances was +/-0.16%, and the mean resolution of the scattering coefficients was +/-5 x 10(-6) m(-1) . Their combination gives the bulk single scattering albedo, which was resolved by +/-0.1 for atmospheres with a visual range of approximately 50 km and by rapidly increasing accuracy for shorter ranges. Concentrating the dispersed phase was not essential for the scattering measurements and, with achievable improvements in the cell, would not be necessary for the transmittance measurements.