Contrasting Influence of Nitrogen Oxides on the Cloud Condensation Nuclei Activity of Monoterpene‐Derived Secondary Organic Aerosol in Daytime and Nighttime Oxidation

Abstract

Organic matters are important components of aerosols in the atmosphere making up a large fraction (20%-90%) of the submicron particulate mass (Jimenez et al., 2009;Zhang et al., 2007). Organic aerosols influence the climate (Kanakidou et al., 2005) by contributing to aerosol-radiation interactions and aerosol-cloud interaction (Kuniyal & Guleria, 2019). According to the 6th assessment report by IPCC (IPCC, 2021), the latter still has large uncertainties, which are related to uncertainties in the challenging prediction of concentration of cloud condensation nuclei (CCN). Organic aerosols are often of secondary nature (secondary organic aerosols, SOA) (Zhang et al., 2007). On global scale, the production rate of biogenic SOA (BSOA) is much higher than anthro-

Effect of relative humidity on the molecular composition of secondary organic aerosols from α-pinene ozonolysis

“…The decrease of the average molecular weight with increasing RH may enhance the hygroscopic parameter k, which is inversely proportional to the molar volume of solute, and thus to the molecular weight (provided that the density of different organics is largely similar). [66][67][68] Moreover, the RH-dependent SOA composition reported here highlights the necessity to consider the inuence of RH on the SOA formation in atmospheric numerical models. 69,70 Additionally, this work emphasizes the necessity to characterize the composition at the molecular level, as the RH-dependent composition is not manifested in the elemental composition (O/C, H/C), which remains largely unchanged with increasing RH.…”

Effect of Relative Humidity on the Rate of New Particle Formation for Different VOCs

“…In this work, each VOC was subjected independently to dark ozonolysis under dry and humid conditions, from which ∆N max was determined using Equation (2). For a typical experiment, the UVMEC was sealed while slightly over pressure (+2 mbar) to maintain a consistent initial chamber volume.…”

“…Understanding the chemical and physical properties of atmospheric aerosols is critical to interpreting their direct and indirect impacts on climate change, such as by scattering and absorbing solar radiation and impacting cloud formation [1][2][3][4][5]. Organic aerosol (OA) accounts for up to 90% of Earth's total aerosol mass budget [6][7][8], with secondary organic aerosol (SOA) making up 70-90% of OA fine particle mass [9,10].…”

Secondary organic aerosol from biomass burning phenolic compounds and nitrate radicals can be highly viscous over a wide relative humidity range

“…[81][82][83][84] In addition, there have been some studies on the hygroscopicity of phenolic SOA and proxies for phenolic SOA. [85][86][87][88] In comparison, there have been fewer studies on the hygroscopicity of SOA generated by NO 3 , [89][90][91] and we are not aware of any research that has quantified the hygroscopicity of phenolic SOA generated with NO 3 as the oxidant.…”