Technical Note: Particle Extinction Coefficient for Polydispersed Aerosol Using a Harmonic Mean Type General Approximated Solution

Theoretical study on the change of the particle extinction coefficient during the aerosol dynamic processes

“…Jung and Kim (2007) introduced a harmonic mean expression to estimate the extinction coefficient for an intermediate range:…”

“…This study assumed b ext exists between the two limits of b ext_Geo and b ext_Ray for an intermediate region, b ext was approximated using the harmonic mean type approximation. The harmonic mean type approximation has computational advantage in integrating the polydispersed aerosol distribution (Jung & Kim, 2007). From the overall extinction coefficient, the visibility can be estimated using the following formula suggested by Koschmieder (1925):…”

“…Later, Jung and Kim (2007) developed general expressions for the single particle extinction efficiency and an overall extinction coefficient without the limitations of specific refractive indices or an applicable particle size range, based on the harmonic mean between the Rayleigh scattering and geometric scattering regions.…”

“…In this study, the changes to the overall extinction coefficient and visibility during coagulation and condensation were obtained analytically using the harmonic mean approximation developed by Jung and Kim (2007) to evaluate the influence of aerosol dynamics on the optical properties. The derived analytical expressions obtained for the extinction coefficient for the continuum region were compared with the numerical or exact solutions for the coagulation and condensation processes.…”

Sensitivity and Contribution of Organic Aerosols to Aerosol Optical Properties Based on Their Refractive Index and Hygroscopicity

“…Theoretically, the overall extinction coefficient can be calculated using Mie's theory [15]. Further, the Lorenz-Mie theory reasonably estimates the variation in ambient aerosol properties and optical characteristics [2,[19][20][21].…”