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| Titel |
Consideration of HOMs in α- and β-pinene SOA model |
| VerfasserIn |
Kathrin Gatzsche, Yoshiteru Iinuma, Anke Mutzel, Torsten Berndt, Ralf Wolke |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250133519
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| Publikation (Nr.) |
 EGU/EGU2016-14139.pdf |
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| Zusammenfassung |
| Secondary organic aerosol (SOA) is the major burden of the atmospheric organic particulate
matter with 140 – 910 TgC yr−1 (Hallquist et al., 2009). SOA particles are formed via the
oxidation of volatile organic carbons (VOCs), where the volatility of the VOCs is lowered
due to the increase in their functionalization as well as their binding ability. Therefore,
gaseous compounds can either nucleate to form new particles or condense on existing
particles. The framework of SOA formation under natural conditions is very complex,
because there are a multitude of gas-phase precursors, atmospheric degradation
processes and products after oxidation. A lacking understanding about chemical
and physical processes associated with SOA formation makes modeling of SOA
processes difficult, leading to discrepancy between measured and modeled global SOA
burdens.
The present study utilizes a parcel model SPACCIM (SPectral Aerosol Cloud Chemistry
Interaction Model, Wolke et al., 2005) that couples a multiphase chemical model with a
microphysical model. For SOA modeling a further development of SPACCIM was necessary.
Therefore, two components are added (i) a gas-phase chemistry mechanism for the VOC
oxidation and (ii) a partitioning approach for the gas-to-particle phase transfer.
An aggregated gas-phase chemistry mechanism for α- and β-pinene was adapted
from Chen and Griffin (2005). For the phase transfer an absorptive partitioning
approach (Pankow, 1994) and a kinetic approach (Zaveri et al., 2014) are implemented.
Whereby the kinetic approach serves some advantages. The organic aerosol can be
resolved in different size sections, whereby the particle radius is involved in the
partitioning equations. The phase state of the organic material and the reactivity of
the organic compounds in the particle-phase directly influence the modeled SOA
yields.
Recently, highly oxidized multifunctional organic compounds (HOMs) were found in the
gas phase from lab and field studies. They are also known as extremely low-volatile organic
compounds (ELVOCs) (Ehn et al. 2014). The importance of HOMs for the early aerosol
growth makes them indispensable in SOA modeling. Thus, we included HOMs in our model
framework. The measurements from the institute’s own smog chamber LEAK are used as a
base for model evaluation and process analysis, especially since HOMs were lately identified
from LEAK data (Mutzel et al., 2015). The presentation will provide a sensitivity study
for the kinetic approach as well as a comparison of measured and modeled SOA
yields.
References:
Ehn, M., Thornton, J. A., Kleist, E. et al. (2014) Nature, 506, 476 – 479
Hallquist, M., Wenger, J. C., Baltensperger, U., et al. (2009) Atmos. Chem. Phys., 9,
5155 – 5236
Mutzel, A., Poulain, L., Berndt, T. et al. (2015) Environ. Sci. Technol., 49,
7754 – 7761
Pankow, J. F. (1994) Atmos. Environ., 28, 2, 189 – 193
Wolke, R., Sehili, A. M., Simmel, M., Knoth, O., Tilgner, A. and Herrmann, H. (2005)
Atmos. Environ., 39, 4375 – 4388
Zaveri, R. A., Easter, R. C., Shilling J. E. and Seinfeld, J. H. (2014) Atmos. Chem. Phys.,
14, 5153 – 5181 |
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