Impact of secondary and primary particulate matter (PM) sources on the enhanced light absorption by brown carbon (BrC) particles in central Los Angeles

Aging of Atmospheric Brown Carbon Aerosol

“…The chemical generation of absorbing molecules in the gas phase, which condense to form SOA can contribute to the formation one form of secondary BrC. There are indications that this can occur with primary emitted precursors, both in polluted settings 97 and within biomass burning plumes. 98 However, the extent of secondary BrC influence is still poorly defined with one study 97 reporting up to 30 % of total BrC formation in the Los Angeles area, whereas another 99 showing minor impacts.…”

The Roles of N, S, and O in Molecular Absorption Features of Brown Carbon in PM2.5 in a Typical Semi‐Arid Megacity in Northwestern China

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Brown carbon (BrC) is a nonnegligible chemical component of organic aerosols and has great influences on radiative forcing, regional and global climates, and even human health (Lin et al, 2018). BrC can be released from a variety of emission sources such as traffic, biomass burning, and coal combustion, and formed from secondary transformation (Fleming et al, 2020;Soleimanian et al, 2020). BrC formed through different mechanisms could have unique light absorption capacities (Lei et al, 2019;Lukacs et al, 2007).

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Author Response to RC2

“…Second, since the paper was first submitted, we have obtained levoglucosan data from November 2018 (3 rd campaign) that were collected by colleagues at USC who were conducting an independent air quality study in the LA Basin (Soleimanian et al 2020).…”