Photolysis controls the atmospheric burden of biogenic SOA
Abstract
Secondary organic aerosol (SOA) accounts for a large fraction of tropospheric particulate matter. Accurate modeling of the SOA life cycle is needed to quantify its effects on radiative forcing, cloud formation, and air quality. While SOA production rates and mechanisms have been extensively investigated, loss pathways remain uncertain. Most large-scale chemistry and transport models account for wet and dry removal of SOA, but not for chemical losses, such as photolysis. Here we show, through a combined experimental and modeling approach, that photolytic loss of SOA mass has the potential to significantly alter SOA predictions in models. Using environmental chamber experiments, we find photolysis mass loss rates between 0 and 2.2% ± 0.4% JNO2 from SOA produced from several representative biogenic hydrocarbons. Significant photolysis of biogenic SOA mass indicates that chamber yield measurements are often not static and thus have important implications for interpreting chamber results. We incorporate our photolysis rates into a high-resolution regional chemical transport model to test the sensitivity of biogenic SOA concentrations to photolytic losses. The addition of photolysis causes a 50% reduction in biogenic SOA loadings over the Amazon, indicating photolysis exerts a substantial control over the atmospheric SOA lifetime.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A43Q3130Z
- Keywords:
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- 0317 Chemical kinetic and photochemical properties;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0340 Middle atmosphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0394 Instruments and techniques;
- ATMOSPHERIC COMPOSITION AND STRUCTURE