scholarly journals Mechanism reduction for the formation of secondary organic aerosol for integration into a 3-dimensional regional Air Quality Model: <i>α</i>-pinene oxidation system

2008 ◽  
Vol 8 (4) ◽  
pp. 13301-13354
Author(s):  
A. G. Xia ◽  
D. V. Michelangeli ◽  
P. A. Makar
Keyword(s):  
Screening Method ◽  
Oxidation Mechanism ◽  
Principal Component ◽  
Organic Aerosol ◽  
General Mechanism ◽  
Air Quality Model ◽  
Quality Model ◽  
Sensitivity Matrix ◽  
Mechanism Reduction ◽  
Wide Range

Abstract. A detailed α-pinene oxidation mechanism was reduced systematically through the successive application of five mechanism reduction techniques. The resulting reduced mechanism preserves the ozone- and organic aerosol-forming properties of the original mechanism, while using less species. The methodologies employed included a directed relation graph method with error propagation (DRGEP, which removed a large number of redundant species and reactions), principal component analysis of the rate sensitivity matrix (PCA, used to remove unnecessary reactions), the quasi-steady-state approximation (QSSA, used to remove some QSS species), an iterative screening method (ISSA, which removes redundant species and reactions simultaneously), and a new lumping approach dependant on the hydrocarbon to NOx ratio (which reduced the number of species in mechanism subsets for specific hydrocarbon to NOx ranges). This multistage methodology results in a reduction ratio of 2.5 for the number of both species and reactions compared with the full mechanism. The simplified mechanism reproduces the important gas and aerosol phase species (the latter are examined in detail by individual condensing species as well as in classes according to four functional groups: PANs, nitrates, organic peroxides, and organic acids). The total SOA mass is also well represented in the condensed mechanism, to within 16% of the detailed mechanism under a wide range of conditions. The methodology described here is general, and may be used in general mechanism reduction problems.

scholarly journals Mechanism reduction for the formation of secondary organic aerosol for integration into a 3-dimensional regional air quality model: <i>α</i>-pinene oxidation system

2009 ◽  
Vol 9 (13) ◽  
pp. 4341-4362 ◽  
Author(s):  
A. G. Xia ◽  
D. V. Michelangeli ◽  
P. A. Makar
Keyword(s):  
Screening Method ◽  
Oxidation Mechanism ◽  
Principal Component ◽  
Organic Aerosol ◽  
General Mechanism ◽  
Air Quality Model ◽  
Quality Model ◽  
Sensitivity Matrix ◽  
Mechanism Reduction ◽  
Wide Range

Abstract. A detailed α-pinene oxidation mechanism was reduced systematically through the successive application of five mechanism reduction techniques. The resulting reduced mechanism preserves the ozone- and organic aerosol-forming properties of the original mechanism, while using less species. The methodologies employed included a directed relation graph method with error propagation (DRGEP, which removed a large number of redundant species and reactions), principal component analysis of the rate sensitivity matrix (PCA, used to remove unnecessary reactions), the quasi-steady-state approximation (QSSA, used to remove some QSS species), an iterative screening method (ISSA, which removes redundant species and reactions simultaneously), and a new lumping approach dependent on the hydrocarbon to NOx ratio (which reduced the number of species in mechanism subsets for specific hydrocarbon to NOx ranges). This multistage methodology results in a reduction ratio of 2.5 for the number of both species and reactions compared with the full mechanism. The simplified mechanism reproduces the important gas and aerosol phase species (the latter are examined in detail by individual condensing species as well as in classes according to four functional groups: PANs, nitrates, organic peroxides, and organic acids). The total SOA mass is also well represented in the condensed mechanism, to within 16% of the detailed mechanism under a wide range of conditions. The methodology described here is general, and may be used in general mechanism reduction problems.

scholarly journals Influence of biomass burning vapor wall loss correction on modeling organic aerosols in Europe by CAMx v6.50

2021 ◽  
Vol 14 (3) ◽  
pp. 1681-1697
Author(s):  
Jianhui Jiang ◽  
Imad El Haddad ◽  
Sebnem Aksoyoglu ◽  
Giulia Stefenelli ◽  
Amelie Bertrand ◽  
...  
Keyword(s):  
Air Quality ◽  
Biomass Burning ◽  
Experimental Studies ◽  
Organic Aerosol ◽  
Basis Set ◽  
Reference Scenario ◽  
Air Quality Model ◽  
Quality Model ◽  
The Balkans ◽  
Wall Loss

Abstract. Increasing evidence from experimental studies suggests that the losses of semi-volatile vapors to chamber walls could be responsible for the underestimation of organic aerosol (OA) in air quality models that use parameters obtained from chamber experiments. In this study, a box model with a volatility basis set (VBS) scheme was developed, and the secondary organic aerosol (SOA) yields with vapor wall loss correction were optimized by a genetic algorithm based on advanced chamber experimental data for biomass burning. The vapor wall loss correction increases the SOA yields by a factor of 1.9–4.9 and leads to better agreement with measured OA for 14 chamber experiments under different temperatures and emission loads. To investigate the influence of vapor wall loss correction on regional OA simulations, the optimized parameterizations (SOA yields, emissions of intermediate-volatility organic compounds from biomass burning, and enthalpy of vaporization) were implemented in the regional air quality model CAMx (Comprehensive Air Quality Model with extensions). The model results from the VBS schemes with standard (VBS_BASE) and vapor-wall-loss-corrected parameters (VBS_WLS), as well as the traditional two-product approach, were compared and evaluated by OA measurements from five Aerodyne aerosol chemical speciation monitor (ACSM) or aerosol mass spectrometer (AMS) stations in the winter of 2011. An additional reference scenario, VBS_noWLS, was also developed using the same parameterization as VBS_WLS except for the SOA yields, which were optimized by assuming there is no vapor wall loss. The VBS_WLS generally shows the best performance for predicting OA among all OA schemes and reduces the mean fractional bias from −72.9 % (VBS_BASE) to −1.6 % for the winter OA. In Europe, the VBS_WLS produces the highest domain average OA in winter (2.3 µg m−3), which is 106.6 % and 26.2 % higher than VBS_BASE and VBS_noWLS, respectively. Compared to VBS_noWLS, VBS_WLS leads to an increase in SOA by up to ∼80 % (in the Balkans). VBS_WLS also leads to better agreement between the modeled SOA fraction in OA (fSOA) and the estimated values in the literature. The substantial influence of vapor wall loss correction on modeled OA in Europe highlights the importance of further improvements in parameterizations based on laboratory studies for a wider range of chamber conditions and field observations with higher spatial and temporal coverage.

scholarly journals Aircraft study of the impact of lake-breeze circulations on trace gases and particles during BAQS-Met 2007

2011 ◽  
Vol 11 (4) ◽  
pp. 11497-11546 ◽  
Author(s):  
K. L. Hayden ◽  
D. M. L. Sills ◽  
J. R. Brook ◽  
S.-M. Li ◽  
P. A. Makar ◽  
...  
Keyword(s):  
Formation Rate ◽  
Organic Aerosol ◽  
Lake Breeze ◽  
Air Quality Model ◽  
Breeze Circulation ◽  
Quality Model ◽  
Cumulus Clouds ◽  
Time Resolved ◽  
Air Mass ◽  
The Impact

Abstract. High time-resolved aircraft data, concurrent surface measurements and air quality model simulations were explored to diagnose the processes influencing aerosol chemistry under the influence of lake-breeze circulations in a polluted region of southwestern Ontario, Canada. The analysis was based upon horizontal aircraft transects at multiple altitudes across an entire lake-breeze circulation. Air mass boundaries due to lake-breeze fronts were identified in the aircraft meteorological and chemical data, which were consistent with the frontal locations determined from surface analyses. Observations and modelling support the interpretation of a lake-breeze circulation where pollutants were lofted at a lake-breeze front, transported in the synoptic flow, caught in a downdraft over the lake, and then confined by onshore flow. The detailed analysis led to the development of conceptual models that summarize the complex 3-D circulation patterns and their interaction with the synoptic flow. The identified air mass boundaries, the interpretation of the lake-breeze circulation, and best estimates for air parcel circulation times in the lake-breeze circulation (1.2 to 3.0 h) enabled formation rates of oxygenated organic aerosol (OOA/ΔCO) and SO42− to be determined. The formation rate for OOA, relative to excess CO, was found to be 2.5–6.2 μg m−3 ppmv−1 h−1 and the SO42− formation rate was 1.8–4.6% h−1. The formation rates are enhanced relative to regional background rates implying that lake-breeze circulations are an important dynamic in the formation of SO42− and secondary organic aerosol. The presence of cumulus clouds associated with the lake-breeze fronts suggests that these enhancements could be due to cloud processes. Additionally, the effective confinement of pollutants along the shoreline may have limited pollutant dilution leading to elevated oxidant concentrations.

scholarly journals Development of an inorganic and organic aerosol model (Chimere2017<i>β</i> v1.0): seasonal and spatial evaluation over Europe

2017 ◽  
Author(s):  
Florian Couvidat ◽  
Bertrand Bessagnet ◽  
Marta Garcia-Vivanco ◽  
Elsa Real ◽  
Laurent Menut ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Thermodynamic Model ◽  
Regional Analysis ◽  
Organic Aerosol ◽  
Air Quality Model ◽  
Quality Model ◽  
Sea Salts ◽  
Aerosol Model ◽  
Seasonal Evolution ◽  
Deposition Processes

Abstract. A new aerosol module was developed and integrated in the air quality model CHIMERE. Developments include an update of biogenic emissions and of the inorganic thermodynamic model ISORROPIA, revision of wet deposition processes and of the algorithms of condensation/evaporation and coagulation and the implementation of the SOA mechanism H2O and the thermodynamic model SOAP. Concentrations of particles over Europe were simulated by the model for the year 2013. Model concentrations were compared to the EMEP program observations and other observations available in the EBAS database to evaluate the performances of the model. Performances were determined for several components of particles (sea salts, sulfate, ammonium, nitrate, organic aerosol) with a seasonal and regional analysis of results. The model gives good performances in general. For sea salts, the model succeeds in reproducing the seasonal evolution of concentrations for Western and Central Europe. For sulfate, except for an overestimation of sulfate in Northern Europe, modeled concentrations are close to observations with a good seasonal evolution of concentrations. For organic aerosol, the model performs well for stations with strong modeled biogenic SOA concentrations. However, the model strongly overestimates ammonium nitrate concentrations during late autumn (possibly due to problems in the temporal evolution of emissions) and strongly underestimates SOA concentrations over most of stations (especially in the Northern half of Europe). This underestimation could be due to a lack of anthropogenic SOA in the model. A list of recommended tests and developments to improve the model is also given.

scholarly journals Simulating secondary organic aerosol in a regional air quality model using the statistical oxidation model – Part 2: Assessing the influence of vapor wall losses

2015 ◽  
Vol 15 (21) ◽  
pp. 30081-30126 ◽  
Author(s):  
C. D. Cappa ◽  
S. H. Jathar ◽  
M. J. Kleeman ◽  
K. S. Docherty ◽  
J. L. Jimenez ◽  
...  
Keyword(s):  
Air Quality ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Air Quality Model ◽  
Quality Model ◽  
Wall Losses ◽  
Regional Air Quality ◽  
High Vapor ◽  
Wall Loss ◽  
Oxidation Model

Abstract. The influence of losses of organic vapors to chamber walls during secondary organic aerosol (SOA) formation experiments has recently been established. Here, the influence of such losses on simulated ambient SOA concentrations and properties is assessed in the UCD/CIT regional air quality model using the statistical oxidation model (SOM) for SOA. The SOM was fit to laboratory chamber data both with and without accounting for vapor wall losses following the approach of Zhang et al. (2014). Two vapor wall loss scenarios are considered when fitting of SOM to chamber data to determine best-fit SOM parameters, one with "low" and one with "high" vapor wall-loss rates to approximately account for the current range of uncertainty in this process. Simulations were run using these different parameterizations (scenarios) for both the southern California/South Coast Air Basin (SoCAB) and the eastern United States (US). Accounting for vapor wall losses leads to substantial increases in the simulated SOA concentrations from VOCs in both domains, by factors of ~ 2–5 for the low and ~ 5–10 for the high scenario. The magnitude of the increase scales approximately inversely with the absolute SOA concentration of the no loss scenario. In SoCAB, the predicted SOA fraction of total OA increases from ~ 0.2 (no) to ~ 0.5 (low) and to ~ 0.7 (high), with the high vapor wall loss simulations providing best general agreement with observations. In the eastern US, the SOA fraction is large in all cases but increases further when vapor wall losses are accounted for. The total OA/ΔCO ratio represents dilution-corrected SOA concentrations. The simulated OA/ΔCO in SoCAB (specifically, at Riverside, CA) is found to increase substantially during the day only for the high vapor wall loss scenario, which is consistent with observations and indicative of photochemical production of SOA. Simulated O : C atomic ratios for both SOA and for total OA increase when vapor wall losses are accounted for, while simulated H : C atomic ratios decrease. The agreement between simulations and observations of both the absolute values and the diurnal profile of the O : C and H : C atomic ratios for total OA was greatly improved when vapor wall-losses were accounted for. Similar improvements would likely not be possible solely through the inclusion of semi/intermediate volatility organic compounds in the simulations. These results overall demonstrate that vapor wall losses in chambers have the potential to exert a large influence on simulated ambient SOA concentrations, and further suggest that accounting for such effects in models can explain a number of different observations and model/measurement discrepancies.

scholarly journals Development of an inorganic and organic aerosol model (CHIMERE 2017<i>β</i> v1.0): seasonal and spatial evaluation over Europe

2018 ◽  
Vol 11 (1) ◽  
pp. 165-194 ◽  
Author(s):  
Florian Couvidat ◽  
Bertrand Bessagnet ◽  
Marta Garcia-Vivanco ◽  
Elsa Real ◽  
Laurent Menut ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Thermodynamic Model ◽  
Regional Analysis ◽  
Organic Aerosol ◽  
Sea Salt ◽  
Northern Europe ◽  
Biogenic Emissions ◽  
Air Quality Model ◽  
Quality Model ◽  
Seasonal Evolution

Abstract. A new aerosol module was developed and integrated in the air quality model CHIMERE. Developments include the use of the Model of Emissions and Gases and Aerosols from Nature (MEGAN) 2.1 for biogenic emissions, the implementation of the inorganic thermodynamic model ISORROPIA 2.1, revision of wet deposition processes and of the algorithms of condensation/evaporation and coagulation and the implementation of the secondary organic aerosol (SOA) mechanism H2O and the thermodynamic model SOAP. Concentrations of particles over Europe were simulated by the model for the year 2013. Model concentrations were compared to the European Monitoring and Evaluation Programme (EMEP) observations and other observations available in the EBAS database to evaluate the performance of the model. Performances were determined for several components of particles (sea salt, sulfate, ammonium, nitrate, organic aerosol) with a seasonal and regional analysis of results. The model gives satisfactory performance in general. For sea salt, the model succeeds in reproducing the seasonal evolution of concentrations for western and central Europe. For sulfate, except for an overestimation of sulfate in northern Europe, modeled concentrations are close to observations and the model succeeds in reproducing the seasonal evolution of concentrations. For organic aerosol, the model reproduces with satisfactory results concentrations for stations with strong modeled biogenic SOA concentrations. However, the model strongly overestimates ammonium nitrate concentrations during late autumn (possibly due to problems in the temporal evolution of emissions) and strongly underestimates summer organic aerosol concentrations over most of the stations (especially in the northern half of Europe). This underestimation could be due to a lack of anthropogenic SOA or biogenic emissions in northern Europe. A list of recommended tests and developments to improve the model is also given.

scholarly journals Modelling organic aerosol concentrations and properties during ChArMEx summer campaigns of 2012 and 2013 in the western Mediterranean region

2017 ◽  
Author(s):  
Mounir Chrit ◽  
Karine Sartelet ◽  
Jean Sciare ◽  
Jorge Pey ◽  
Nicolas Marchand ◽  
...  
Keyword(s):  
Oxidation State ◽  
Organic Aerosols ◽  
Organic Aerosol ◽  
Western Mediterranean ◽  
Water Soluble ◽  
Oxidation Products ◽  
Organic Nitrate ◽  
Air Quality Model ◽  
Remote Site ◽  
Quality Model

Abstract. In the framework of the Chemistry-Aerosol Mediterranean Experiment, a measurement site was set up at a remote site (Ersa) on Corsica Island in the northwestern Mediterranean Sea. Measurement campaigns performed during the summers of 2012 and 2013 showed high organic aerosol concentrations, mostly from biogenic origin. This work aims at representing the organic aerosol concentrations and properties (oxidation state and hydrophilic) using the air-quality model Polyphemus with a surrogate approach for secondary organic aerosol (SOA) formation. Biogenic precursors are isoprene, monoterpenes (with α-pinene and limonene as surrogate species) and sesquiterpenes. In this work, the following model oxidation products of monoterpenes are added: (i) a carboxylic acid (MBTCA) to represent multi-generation oxidation products in the low-NOx regime, (ii) organic nitrate chemistry, (iii) extremely low volatility organic compounds (ELVOCs) formed by ozonolysis. The model shows good agreement to measurements of organic concentrations for both 2012 and 2013 summer campaigns. The modeled oxidation state and hydrophilic properties of the organic aerosols also agree reasonably well with the measurements. The influence of the different chemical processes added to the model on the oxidation level of organics is studied. Measured and simulated water-soluble organic concentrations (WSOC) show that even at a remote site next to the sea, about 64 % of the organic carbon is soluble. The concentrations of WSOC vary with the origins of the air masses and the composition of organic aerosols. The marine organic emissions only contribute to a few percents of the organic mass in PM1, with maxima above the sea.

scholarly journals Aircraft study of the impact of lake-breeze circulations on trace gases and particles during BAQS-Met 2007

2011 ◽  
Vol 11 (19) ◽  
pp. 10173-10192 ◽  
Author(s):  
K. L. Hayden ◽  
D. M. L. Sills ◽  
J. R. Brook ◽  
S.-M. Li ◽  
P. A. Makar ◽  
...  
Keyword(s):  
Formation Rate ◽  
Organic Aerosol ◽  
Lake Breeze ◽  
Air Quality Model ◽  
Breeze Circulation ◽  
Quality Model ◽  
Cumulus Clouds ◽  
Time Resolved ◽  
Air Mass ◽  
The Impact

Abstract. High time-resolved aircraft data, concurrent surface measurements and air quality model simulations were explored to diagnose the processes influencing aerosol chemistry under the influence of lake-breeze circulations in a polluted region of southwestern Ontario, Canada. The analysis was based upon horizontal aircraft transects conducted at multiple altitudes across an entire lake-breeze circulation. Air mass boundaries due to lake-breeze fronts were identified in the aircraft meteorological and chemical data, which were consistent with the frontal locations determined from surface analyses. Observations and modelling support the interpretation of a lake-breeze circulation where pollutants were lofted at a lake-breeze front, transported in the synoptic flow, caught in a downdraft over the lake, and then confined by onshore flow. The detailed analysis led to the development of conceptual models that summarize the complex 3-D circulation patterns and their interaction with the synoptic flow. The identified air mass boundaries, the interpretation of the lake-breeze circulation, and the air parcel circulation time in the lake-breeze circulation (3.0 to 5.0 h) enabled formation rates of organic aerosol (OA/ΔCO) and SO42− to be determined. The formation rate for OA (relative to excess CO in ppmv) was found to be 11.6–19.4 μg m−3 ppmv−1 h−1 and the SO42− formation rate was 5.0–8.8% h−1. The formation rates are enhanced relative to regional background rates implying that lake-breeze circulations are an important dynamic in the formation of SO42− and secondary organic aerosol. The presence of cumulus clouds associated with the lake-breeze fronts suggests that these enhancements could be due to cloud processes. Additionally, the effective confinement of pollutants along the shoreline may have limited pollutant dilution leading to elevated oxidant concentrations.

Sign in / Sign up

Export Citation Format

Share Document