SIMULATION OF THE OPTICAL-PARTICLE COUNTER FORWARD SCATTERING SPECTROMETER PROBE-100 (FSSP-100) - CONSEQUENCES FOR SIZE DISTRIBUTION MEASUREMENTS

The physical properties of an optical aerosol particle counter are simulated with a numerical algorithm showing the influence of monochromatic light scattering on the results of size distribution measurements. By using model size distribution as an input to the simulation, the oscillations of the theoretical light-scattering curve are seen to cause unrealistic maxima and minima. This indicates that the structures in a number of published size distribution measurements might be artefacts and are possibly discussed incorrectly. The simulation shows that the counter under investigation is useful for measurements of cloud/fog droplet size distributions and for calculating the liquid water content. In addition, some published size distributions using the investigated optical laser particle counter are examined. By using model size distributions and published refractive indices; the resulting simulated size distributions are made to agree closely with those published. Artificial minima show up at nearly the same particle sizes as those published. Consequently, such published distributions have to be discussed with reservation and only if additional-information is available.