Parameterization of polydisperse aerosol optical properties during hygroscopic growth

Abstract

Aerosol water uptake and the related influence on its optical properties owing to the hygroscopic growth of polydisperse aerosols have a significant effect on air quality and climate. This study develops an analytical parameterization for a single hygroscopic optical parameter and the scattering enhancement factor for polydisperse aerosol sizes. Polydisperse lognormal size distributions for geometric mean diameters of 0.05–1 µm and geometric standard deviations of 1.3–2.5 are considered with real refractive indices between 1.35 and 1.6. The analytical expression obtained for the optical parameter is compared to Mie theory and reasonable agreements within the size range investigated in this study are observed. Further, our results show that the analytical expression could express polydispersed aerosol optical properties as a function of geometric mean diameter and geometric standard deviation of a lognormal distribution and the refractive index. The obtained analytical expression can be efficiently used for 3D models with a reduced computational burden.

Copyright © 2023 American Association for Aerosol Research

Editor:

• Hans Moosmüller

Additional information

Funding

This study was supported by the FRIEND (Fine Particle Research Initiative in East Asia Considering National Differences) Project through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (grant number 2020M3G1A1114617); the National Research Foundation of Korea Grant from the Korean Government (MSIT) (grant number NRF2021M1A5A1065672/KOPRI-PN23011, NRF2021R1F1A1046878, NRF2020R1A2C1003215, and NRF2023R1A2C1002367). This research was also supported by Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (no. 2020R1A6A1A03044834).