Size-resolved hygroscopic behavior of atmospheric aerosols during heavy aerosol pollution episodes in Beijing in December 2016

Abstract The size-resolved hygroscopic properties of submicron particles were observed by a Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) at an urban site in Beijing in December 2016. HTDMA was operated at the relative humidity (RH) of 30–90% with the particle size range of 30–200 nm. The probability distribution of the hygroscopic growth factor (HGF-PDF) during the measurement usually showed a bimodal pattern, namely, hydrophobic mode (HGF