Index Geophysics

An alternative method for estimating hygroscopic growth factor of aerosol light-scattering coefficient: a case study in an urban area of Guangzhou, South China

A method was developed to estimate hygroscopic growth factor (<i>f</i>(RH)) of aerosol light-scattering coefficient (<i>b</i>_sp), making use of the measured size- and chemically resolved aerosol samples. In this method, chemical composition of the measured aerosol samples were first reconstructed using the equilibrium model ISORROPIA II. The reconstructed chemical composition, which varies with relative humidity (RH), was then employed to calculate <i>b</i>_sp and hygroscopic growth factor of <i>b</i>_sp (<i>f</i>_sp(RH)) using the Mie model. Furthermore, the calculated <i>f</i>_sp(RH) was fitted with an empirical curve. To evaluate the applicability of <i>f</i>_sp(RH), the curve of <i>f</i>_sp(RH) was used to correct the long-term records of the measured <i>b</i>_sp from the values under comparative dry conditions to the ones under ambient RH conditions. Compared with the original <i>b</i>_sp data, the <i>f</i>_sp(RH)-corrected <i>b</i>_sp had a higher linear correlation with, and a smaller discrepancy from, the <i>b</i>_sp derived directly from visibility and absorption measurements. The <i>f</i>_sp(RH) determined here was further compared with that reported in previous studies. The method described in this manuscript provides an alternative approach to derive credible <i>f</i>_sp(RH) with high accuracy and has many potential applications in aerosol-related research.

Lin, Z. J.

Zhang, Z. S.

Zhang, L.

Tao, J.

Zhang, R. J.

Cao, J. J.

Fan, S. J.

Zhang, Y. H.

2018-09-06

Text

application/pdf

10.5194/acp-14-7631-2014

https://acp.copernicus.org/articles/14/7631/2014/

eISSN: 1680-7324

eng