A Review on Laboratory Studies and Field Measurements of Atmospheric Organic Aerosol Hygroscopicity and Its Parameterization Based on Oxidation Levels

Size-resolved characterization of organic aerosol in the North China Plain: new insights from high resolution spectral analysis

“…Both L chem and L org during three campaigns showed increasing trends as the increases of particle size mainly due to the elevated contributions of SIA and SOA, consistent with the results from previous studies. 2 The L org varied from 0.03 to 0.18 at Gucheng in winter, which was comparable to that (0.08) observed in winter of 2018 at the same site. 57 Note that the L org at Gucheng was lower than that in Beijing during wintertime at the same size, which was attributed to the higher contributions of POA.…”

“…The water uptake capacity of aerosol as indicated by hygroscopicity parameter ALD affects atmospheric radiative forcing, aerosol-cloud interactions and atmospheric multiphase chemistry. 2 The L was widely characterized by using Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA, denoted as L HTDMA ), and can also be 5 estimated by the Zdanovskii-Stokes-Robinson (ZSR) mixing rule (denoted as L chem ).…”

Contrasting effects of secondary organic aerosol formations on organic aerosol hygroscopicity

“…(1) We might relate κ OA to VOC precursors in laboratory studies, but the laboratoryderived empirical relationship will likely fail in the application of ambient aerosols due to the formation pathway, or the existence of other VOC precursors might result in different chemical properties of ambiently formed SOA, such as functional groups, from the laboratory case. (2) It seems more plausible to find parameters other than O/C ratio to parameterize κ OA , which should be independent of sources and associated with the physical properties of OA, such as volatility (Kuwata et al, 2007;Asa-Awuku et al, 2009;Frosch et al, 2013;Kostenidou et al, 2018). Overall, these results further highlighted that κ OA parameterizations can be quite difficult and require a lot of future efforts.…”

Aging of atmospheric aerosols and the role of iron in catalyzing brown carbon formation

“…In the case of hydrophobic organics, their hygroscopicity is related to surface tension, which isaffected by carbon chain length, functional groups, presence of surfactants, and oxygen to carbon (O:C) ratio, and can lead to liquid-liquid phase separation. 44 Water uptake by pure salts, highly soluble organics and mixtures of soluble salts and organics proceeds via different mechanisms than on surfaces of insoluble materials. [45][46][47] While adsorption still occurs on dry salt particles at low RH, phase transitions, namely deliquescence and efflorescence are observed at room temperature as a function of increasing and decreasing RH, respectively.…”