Global modeling of secondary organic aerosol with organic nucleation
Abstract
Organic nucleation has been identified as an important way to form secondary organic aerosol (SOA) and change the number concentration of aerosol and thus its climate effect. A global atmospheric chemistry model is developed to include a comprehensive organic nucleation scheme that includes heteromolecular nucleation of sulfuric acid and organics, neutral pure organic nucleation, and ion-induced pure organic nucleation. Ion-induced pure organic nucleation contributes the most to the total organic nucleation rate, which peaks around 400 hPa in the tropics. Heteromolecular nucleation of sulfuric acid and organics dominates the total organic nucleation rate in the summer and mostly occurs in the lower troposphere. Including organic nucleation decreases the bias of the annual average particle number concentration at 54% of the available observation sites and increases the temporal correlation coefficients at 58% of the sites. In our base case, we treat 4 compounds from the oxidation of a-pinene as capable of nucleation. When the low-volatility products formed from IEPOX, glyoxal and methylglyoxal take part in the growth of new SOA particles, the temporal correlation between simulated and observed number concentration of aerosol increases from 0.12 to 0.35, but the mean number concentration is overestimated by 48% while that is overestimated by 19% in our base case. If more compounds, for example the oxidation products from limonene, are able to nucleate new particles, the number concentration of new SOA particles can increase by a further 5.2% but decrease the number concentration of newly nucleated sulfate particles due to the condensation of sulfuric acid on new SOA particles. Observations of the chemical compounds that are able to nucleate are needed to evaluate the simulation of nucleation processes. Newly formed SOA particles could have radiative effect of 0.35 W/m2on cirrus clouds.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A31W2716Z
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0368 Troposphere: constituent transport and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE