scholarly journals Development and initial evaluation of a dynamic species-resolved model for gas phase chemistry and size-resolved gas/particle partitioning associated with secondary organic aerosol formation

2005 ◽  
Vol 110 (D5) ◽  
Author(s):  
Robert J. Griffin
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Initial Evaluation ◽  
Aerosol Formation ◽  
Gas Phase Chemistry ◽  
Secondary Organic Aerosol Formation ◽  
Phase Chemistry

scholarly journals Modeling organic aerosols in a megacity: comparison of simple and complex representations of the volatility basis set approach

2010 ◽  
Vol 10 (12) ◽  
pp. 30205-30277 ◽  
Author(s):  
M. Shrivastava ◽  
J. Fast ◽  
R. Easter ◽  
W. I. Gustafson ◽  
R. A. Zaveri ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Computational Cost ◽  
Organic Aerosols ◽  
Field Measurements ◽  
Organic Aerosol ◽  
Basis Set ◽  
Aerosol Formation ◽  
Secondary Organic Aerosol Formation ◽  
The City

Abstract. The Weather Research and Forecasting model coupled with chemistry (WRF-Chem) is modified to include a volatility basis set (VBS) treatment of secondary organic aerosol formation. The VBS approach, coupled with SAPRC-99 gas-phase chemistry mechanism, is used to model gas-particle partitioning and multiple generations of gas-phase oxidation of organic vapors. In addition to the detailed 9-species VBS, a simplified mechanism using 2 volatility species (2-species VBS) is developed and tested for similarity to the 9-species VBS in terms of both mass and oxygen-to-carbon ratios of organic aerosols in the atmosphere. WRF-Chem results are evaluated against field measurements of organic aerosols collected during the MILAGRO 2006 campaign in the vicinity of Mexico City. The simplified 2-species mechanism reduces the computational cost by a factor of 2 as compared to 9-species VBS. Both ground site and aircraft measurements suggest that the 9-species and 2-species VBS predictions of total organic aerosol mass as well as individual organic aerosol components including primary, secondary, and biomass burning are comparable in magnitude. In addition, oxygen-to-carbon ratio predictions from both approaches agree within 25%, providing evidence that the 2-species VBS is well suited to represent the complex evolution of organic aerosols. Model sensitivity to amount of anthropogenic semi-volatile and intermediate volatility (S/IVOC) precursor emissions is also examined by doubling the default emissions. Both the emission cases significantly under-predict primary organic aerosols in the city center and along aircraft flight transects. Secondary organic aerosols are predicted reasonably well along flight tracks surrounding the city, but are consistently over-predicted downwind of the city. Also, oxygen-to-carbon ratio predictions are significantly improved compared to prior studies by adding 15% oxygen mass per generation of oxidation; however, all modeling cases still under-predict these ratios downwind as compared to measurements, suggesting a need to further improve chemistry parameterizations of secondary organic aerosol formation.

scholarly journals Modeling organic aerosols in a megacity: comparison of simple and complex representations of the volatility basis set approach

2011 ◽  
Vol 11 (13) ◽  
pp. 6639-6662 ◽  
Author(s):  
M. Shrivastava ◽  
J. Fast ◽  
R. Easter ◽  
W. I. Gustafson ◽  
R. A. Zaveri ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Computational Cost ◽  
Organic Aerosols ◽  
Field Measurements ◽  
Organic Aerosol ◽  
Basis Set ◽  
Aerosol Formation ◽  
Secondary Organic Aerosol Formation ◽  
The City

Abstract. The Weather Research and Forecasting model coupled with chemistry (WRF-Chem) is modified to include a volatility basis set (VBS) treatment of secondary organic aerosol formation. The VBS approach, coupled with SAPRC-99 gas-phase chemistry mechanism, is used to model gas-particle partitioning and multiple generations of gas-phase oxidation of organic vapors. In addition to the detailed 9-species VBS, a simplified mechanism using 2 volatility species (2-species VBS) is developed and tested for similarity to the 9-species VBS in terms of both mass and oxygen-to-carbon ratios of organic aerosols in the atmosphere. WRF-Chem results are evaluated against field measurements of organic aerosols collected during the MILAGRO 2006 campaign in the vicinity of Mexico City. The simplified 2-species mechanism reduces the computational cost by a factor of 2 as compared to 9-species VBS. Both ground site and aircraft measurements suggest that the 9-species and 2-species VBS predictions of total organic aerosol mass as well as individual organic aerosol components including primary, secondary, and biomass burning are comparable in magnitude. In addition, oxygen-to-carbon ratio predictions from both approaches agree within 25 %, providing evidence that the 2-species VBS is well suited to represent the complex evolution of organic aerosols. Model sensitivity to amount of anthropogenic semi-volatile and intermediate volatility (S/IVOC) precursor emissions is also examined by doubling the default emissions. Both the emission cases significantly under-predict primary organic aerosols in the city center and along aircraft flight transects. Secondary organic aerosols are predicted reasonably well along flight tracks surrounding the city, but are consistently over-predicted downwind of the city. Also, oxygen-to-carbon ratio predictions are significantly improved compared to prior studies by adding 15 % oxygen mass per generation of oxidation; however, all modeling cases still under-predict these ratios downwind as compared to measurements, suggesting a need to further improve chemistry parameterizations of secondary organic aerosol formation.

Gas-phase products and secondary organic aerosol formation from the ozonolysis and photooxidation of myrcene

2013 ◽  
Vol 79 ◽  
pp. 553-560 ◽  
Author(s):  
Olaf Böge ◽  
Anke Mutzel ◽  
Yoshiteru Iinuma ◽  
Pasi Yli-Pirilä ◽  
Ariane Kahnt ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Aerosol Formation ◽  
Secondary Organic Aerosol Formation

The Gas-phase Ozonolysis of 1-Penten-3-ol, (Z)-2-Penten-1-ol and 1-Penten-3-one: Kinetics, Products and Secondary Organic Aerosol Formation

2010 ◽  
Vol 224 (7-8) ◽  
pp. 1059-1080 ◽  
Author(s):  
M. A. O Dwyer ◽  
T. J. Carey ◽  
R. M. Healy ◽  
J. C. Wenger ◽  
B. Picquet-Varrault ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Aerosol Formation ◽  
Secondary Organic Aerosol Formation

scholarly journals Kinetic modeling of formation and evaporation of secondary organic aerosol from NO<sub>3</sub> oxidation of pure and mixed monoterpenes

2020 ◽  
Vol 20 (24) ◽  
pp. 15513-15535
Author(s):  
Thomas Berkemeier ◽  
Masayuki Takeuchi ◽  
Gamze Eris ◽  
Nga L. Ng
Keyword(s):  
Kinetic Model ◽  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Phase Reaction ◽  
Particle Phase ◽  
Environmental Chamber ◽  
Gas Phase Chemistry ◽  
Phase Chemistry

Abstract. Organic aerosol constitutes a major fraction of the global aerosol burden and is predominantly formed as secondary organic aerosol (SOA). Environmental chambers have been used extensively to study aerosol formation and evolution under controlled conditions similar to the atmosphere, but quantitative prediction of the outcome of these experiments is generally not achieved, which signifies our lack in understanding of these results and limits their portability to large-scale models. In general, kinetic models employing state-of-the-art explicit chemical mechanisms fail to describe the mass concentration and composition of SOA obtained from chamber experiments. Specifically, chemical reactions including the nitrate radical (NO3) are a source of major uncertainty for assessing the chemical and physical properties of oxidation products. Here, we introduce a kinetic model that treats gas-phase chemistry, gas–particle partitioning, particle-phase oligomerization, and chamber vapor wall loss and use it to describe the oxidation of the monoterpenes α-pinene and limonene with NO3. The model can reproduce aerosol mass and nitration degrees in experiments using either pure precursors or their mixtures and infers volatility distributions of products, branching ratios of reactive intermediates and particle-phase reaction rates. The gas-phase chemistry in the model is based on the Master Chemical Mechanism (MCM) but trades speciation of single compounds for the overall ability of quantitatively describing SOA formation by using a lumped chemical mechanism. The complex branching into a multitude of individual products in MCM is replaced in this model with product volatility distributions and detailed peroxy (RO2) and alkoxy (RO) radical chemistry as well as amended by a particle-phase oligomerization scheme. The kinetic parameters obtained in this study are constrained by a set of SOA formation and evaporation experiments conducted in the Georgia Tech Environmental Chamber (GTEC) facility. For both precursors, we present volatility distributions of nitrated and non-nitrated reaction products that are obtained by fitting the kinetic model systematically to the experimental data using a global optimization method, the Monte Carlo genetic algorithm (MCGA). The results presented here provide new mechanistic insight into the processes leading to formation and evaporation of SOA. Most notably, the model suggests that the observed slow evaporation of SOA could be due to reversible oligomerization reactions in the particle phase. However, the observed non-linear behavior of precursor mixtures points towards a complex interplay of reversible oligomerization and kinetic limitations of mass transport in the particle phase, which is explored in a model sensitivity study. The methodologies described in this work provide a basis for quantitative analysis of multi-source data from environmental chamber experiments but also show that a large data pool is needed to fully resolve uncertainties in model parameters.

Secondary organic aerosol formation from the gas-phase reaction of guaiacol (2-methoxyphenol) with NO3 radicals

2020 ◽  
Vol 240 ◽  
pp. 117740
Author(s):  
Lingshuo Meng ◽  
Cécile Coeur ◽  
Layal Fayad ◽  
Nicolas Houzel ◽  
Paul Genevray ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Phase Reaction ◽  
Aerosol Formation ◽  
Gas Phase Reaction ◽  
Secondary Organic Aerosol Formation

scholarly journals Mechanism of the hydroxyl radical oxidation of methacryloyl peroxynitrate (MPAN) and its pathway toward secondary organic aerosol formation in the atmosphere

2015 ◽  
Vol 17 (27) ◽  
pp. 17914-17926 ◽  
Author(s):  
Tran B. Nguyen ◽  
Kelvin H. Bates ◽  
John D. Crounse ◽  
Rebecca H. Schwantes ◽  
Xuan Zhang ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Alkyl Radical ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Particle Phase ◽  
Aerosol Formation ◽  
Radical Oxidation ◽  
Secondary Organic Aerosol Formation ◽  
Phase Chemistry

The photooxidation of MPAN forms an energetic alkyl radical that promptly cyclizes, producing an α-lactone that participates in particle-phase chemistry.

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