Abstract
Abstract. We present updated recommendations for the reactive uptake coefficients for glyoxal and methylglyoxal uptake to aqueous aerosol particles and cloud droplets. The particle and droplet types considered were based on definitions in GEOS-Chem v11, but the approach is general. Liquid maritime and continental cloud droplets were considered. Aerosol types include sea salt (fine and coarse), with varying relative humidity and particle size, and sulfate/nitrate/ammonium as a function of relative humidity and particle composition. We take into account salting effects, aerosol thermodynamics, mass transfer, and irreversible reaction of the organic species with OH in the aqueous phase. The new recommended values for the reactive uptake coefficients in most cases are lower than those currently used in large-scale models, such as GEOS-Chem. We expect application of these parameterizations will result in improved representation of aqueous secondary organic aerosol formation in atmospheric chemistry models.
Highlights
The uptake and reaction of water-soluble volatile organic compounds (VOCs) in cloud droplets and aerosol liquid water is likely a significant source of secondary organic aerosol (SOA) material (Carlton et al, 2008; Fu et al, 2008, 2009; McNeill, 2015; McNeill et al, 2012)
As α-dicarbonyl species, GLYX and MGLY exhibit similar aqueous-phase chemistry: they undergo reversible hydration and self-oligomerization (Ervens and Volkamer, 2010; Hastings et al, 2005; Sareen et al, 2010; Shapiro et al, 2009), they can be oxidized by aqueous-phase radicals to form organic acids or organosulfates (Carlton et al, 2007; Lim et al, 2013; Perri et al, 2010; Schaefer et al, 2012, 2015), and they can react with nitrogen-containing species to form brown carbon (De Haan et al, 2018; Lee et al, 2013; Maxut et al, 2015; Nozière et al, 2009; Powelson et al, 2014; Sareen et al, 2010; Schwier et al, 2010; Shapiro et al, 2009; Yu et al, 2011)
We base our calculations on the cloud and aerosol types used in GEOS-Chem v11, so these recommendations can be applied directly to that model, but the approach is general
Summary
The uptake and reaction of water-soluble volatile organic compounds (VOCs) in cloud droplets and aerosol liquid water is likely a significant source of secondary organic aerosol (SOA) material (Carlton et al, 2008; Fu et al, 2008, 2009; McNeill, 2015; McNeill et al, 2012) These processes may be referred to, collectively, as aqueous SOA (or aqSOA) formation. Glyoxal (CHOCHO, GLYX) and methylglyoxal (CH3C(O)CHO, MGLY) are both atmospherically abundant gas-phase oxidation products of multiple VOC precursors, including isoprene and toluene. Both GLYX and MGLY are water-soluble, GLYX more so than MGLY (Betterton and Hoffmann, 1988; Zhou and Mopper, 1990). We base our calculations on the cloud and aerosol types used in GEOS-Chem v11, so these recommendations can be applied directly to that model, but the approach is general
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