Determination of submicron atmospheric aerosol size distributions by use of continuous analog sensors

• Published in: Environmental science & technology 1977-12, Vol.11 (13), p.1171-1176
• Main Authors: Sverdrup, George M, Whitby, Kenneth T
• Format: Article
• Language: English
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es60136a007

A parametric aerosol size distribution measurement system was developed. By using this measurement method, the number, surface, and volume weightings of 15 submicron aerosol size distributions were determined from the output of three continuous, integral aerosol sensors and the relative humidity. The data inversion procedure involved calculating the theoretical sensor responses based upon a size distribution model. A composite distribution made up of two log-normal function components was selected because of its ability to model the three weightings of the size distribution. The parameters of the model distribution were then determined by adjusting them to minimize the sum of the relative differences between the experimental and theoretical sensor outputs. The results of the 15 measurements demonstrated that the parametric measurement gives as good results for total number concentration (NT), total surface (ST), and total volume (VT), and for the aerosol light-scattering coefficient (b sub(s) sub(p) ) in the submicron size range as does a direct size distribution measurement by using an Electrical Aerosol Analyzer and optical particle counters. The NT and b sub(s) sub(p) were identical for the two methods of measurement. ST and VT were 6.19 and 12% higher, respectively, for the parametric measurement, with relative standard deviations of 11.7 and 16%.