Relationship between aerosol oxidation level and hygroscopic properties of laboratory generated secondary organic aerosol (SOA) particles

[1] Laboratory experiments investigated the relationship between oxidation level and hygroscopic properties of secondary organic aerosol (SOA) particles generated via OH radical oxidation in an aerosol flow reactor. The hygroscopic growth factor at 90% RH (HGF90%), the CCN activity ( ORG,CCN) and the level of oxidation (atomic O:C ratio) of the SOA particles were measured. Both HGF90% and ORG,CCN increased with O:C; the HGF90% varied linearly with O:C, while ORG,CCN mostly followed a nonlinear trend. An average HGF90% of 1.25 and ORG,CCN of 0.19 were measured for O:C of 0.65, in agreement with results reported for ambient data. The ORG values estimated from the HGF90% ( ORG,HGF) were 20 to 50% lower than paired ORG,CCN values for all SOA particles except 1 ,3 ,5‐ t r imethylbenzene (TMB), the leas t hygroscopic of the SOA systems. Within the limitations of instrumental capabilities, we show that differences in hygroscopic behavior among the investigated SOA systems may correspond to differences in elemental composition. Citation: Massoli, P., et al. (2010), Relationship between aerosol oxidation level and hygroscopic properties of laboratory generated secondary organic aerosol (SOA) particles, Geophys. Res. Lett., 37, L24801, doi:10.1029/2010GL045258.