Figure 9 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Domain wide mean predicted vertical O 3 profile obtained with SAPRC07, RACM2 and CB05 chemical mechanisms during the modeling period.
Similar publications
The usefulness of radical reactions in alkaloid synthesis is reviewed from the perspective of the functional groups embedded in the molecular structure of synthetic intermediates, that act as precursors of carbon‐centered radicals in the construction of new C–C bonds. The functional groups featured are alkenes, alkynes, halides (alkyl, vinyl, aryl)...
Nine rivers (Etó, Kacumvi, Kimbi, Lubichako, Makungu, Kuwa, Mandje, Misisi and Kimuti) has been followed during a 16-month cycle (August and December 2016 to August and December 2017) to assess the level of mercury pollution and phy sicochemical quality of water during the dry and rainy season. Twenty-three parameters in general were measured (T °,...
Biodegradation has been proven as the most efficient, eco-friendly and cost-effective technique for
the treatment of wastewater. The present investigation was planned to identify the bacterial strains
which are effective for the biological degradation of dairy wastewater. Samples were collected from
Arab dairy factory located at Sendbes Al-Qanater...
We attempted to identify gene expression systems that dysregulate with age in human peripheral blood samples across five public datasets. Dysregulation of gene ontology (GO)-defined systems was measured using the Mahalanobis distance (D M ), a measure of multivariant aberrance. We expected many weak positive D M -age correlations, indicating loss o...
The increasing concentration of nitrogen compounds in the groundwater is of a growing concern in terms of human health and groundwater quality. Although an excess of nitrogen compounds in the groundwater of the Kathmandu Valley has been reported, the seasonal variations of the fate of the nitrogen compounds and their relationships to the subsurface...
Citations
... Therefore, accurate predictions of the mixing ratios and variations in the surface O 3 are essential. While operational models such as the Community Multiscale Air Quality (CMAQ) model have been widely used for this purpose, uncertainties still arise from poorly understood chemical mechanisms involving reactive nitrogen oxides (NO y ) and volatile organic compounds (VOCs), as well as the lack of their measurements Akimoto et al., 2019;Shareef et al., 2019;Canty et al., 2015;Mallet and Sportisse, 2006) In the urban atmosphere, NO y typically includes NO x (NO + NO 2 ), HONO, HNO 3 , organic nitrates (e.g., PAN), NO 3 , N 2 O 3 , and particulate NO − 3 . These species are produced and recycled through photochemical reactions until they are removed through wet or dry deposition Wang et al., 2020;Liebmann et al., 2018;Brown et al., 2017). ...
Nitrous acid (HONO) plays an important role in the formation of ozone and fine aerosols in the urban atmosphere. In this study, a new simulation approach is presented to calculate the HONO mixing ratios using a deep neural technique based on measured variables. The Reactive Nitrogen Species using a Deep Neural Network (RND) simulation is implemented in Python. The first version of RND (RNDv1.0) is trained, validated, and tested with HONO measurement data obtained in Seoul, South Korea, from 2016 to 2021. RNDv1.0 is constructed using k-fold cross validation and evaluated with index of agreement, correlation coefficient, root mean squared error, and mean absolute error. The results show that RNDv1.0 adequately represents the main characteristics of the measured HONO, and it is thus proposed as a supplementary model for calculating the HONO mixing ratio in a polluted urban environment.
... Furthermore, given the limited availability of suitable temporal and spatial measurements of pollutants, atmospheric chemical transport models (ACTMs) are essential for estimating secondary pollutant concentrations. However, ACTMs are typically developed to understand place-based (urban/rural, high elevation) problems using updated chemical kinetics and photolytic rates, additional chemical species, and/or additional chemical pathways [9]. Furthermore, adjustments to the mechanical component of an ACTM, e.g., the minimum eddy diffusivity coefficient as a function of land use [10], if any, must be considered when evaluating an ACTMs performance. ...
... The three chemical mechanisms discussed above all share the concept of reaction rates and products; however, as previously stated, they differ in terms of rate constants, photolysis (due to pressure and temperature changes), and the treatment of organic and inorganic chemistry. Several studies [9,[27][28][29][30][31][32][33] have compared these mechanisms and found considerable variations in the model predictions, particularly for O3. Kitayama et al. [34] investigated uncertainties in O3 formation caused by SAPRC07, CB05, RADM2, and SAPR99 and found that differences in reaction rate constants and lumped volatile organic compounds may be the cause of the differences in O3 production. ...
... Firstly, RACM2 produces more O3 and, subsequently, generates more O atoms under photolysis, with the O atoms reacting with H2O to produce OH radicals. Secondly, the lower reaction rate of NO2 + OH in RACM2 consumes fewer OH radicals from the atmosphere compared to CB6R3 and SAPRC07, as suggested by similar comparative studies between CB05TU and SAPRC07 [9,32]. Modelling studies comparing CB6R3 to CB05TU in the continental U.S. show an increase in the OH produced of ~25% for CB6R3 [23], which should reduce the OH deficit in the CB models; but, nevertheless, under the conditions considered (temperature, humidity), CB6R3 produced the least OH. ...
We evaluated the uncertainty associated with secondary pollutants formation due to different chemical mechanisms in photochemical modelling. The CMAQ modelling system was utilized in conjunction with CB6R3, SAPRC07, and RACM2 chemical mechanisms and compared the concentrations of various chemical species, including ozone (O3) and particulate matter (PM2.5). Using datasets from ambient monitoring stations, we assessed the performance of each of the mechanism in summer and winter. The concentrations of various chemical species predicted by the three mechanisms varied significantly. The differences are more evident in summer than in winter for most of the species, except for hydrogen peroxide (H2O2), methyl hydroperoxide (MEPX), and Secondary Organic Aerosol—Anthropogenic. We observed that the summer daytime O3 predictions showed reasonable peaks at the three air quality monitoring sites, but the nighttime values under-predicted for all three mechanisms. In the winter, all three mechanisms tend to under-predict O3. Differences in the mean O3 values (bias) at the different sites, for the different seasons, are consistent with corrections made to previous modelling studies that modified KZMIN. PM2.5 predictions with RACM2 were slightly better. The dominant PM2.5 species in summer were sulfate and SOA-Bio, which may be attributed to non-mobile sources in the region, while NO3 became dominant in winter due to more favorable conditions for forming this species, including lower temperatures and an elevated NH4 to SO4 ratio. We concluded that the differences in O3 and PM2.5 predictions between the three mechanisms are significant, implying that when developing strategic and management actions are based on modelling, the most appropriate mechanism should be considered.
... SAPRC-11 was previously implemented in GEOS-Chem (v9-02) by Yan et al. (2019). Versions of SAPRC have also been implemented in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), the Community Multiscale Air Quality (CMAQ) model, and other regional 3-D models (Yu et al., 2010;Cai et al., 2011;Zhang et al., 2012;Kitayama et al., 2019;Shareef et al., 2019). ...
... It represents major first-generation products of BTX oxidation, including benzaldehyde, phenol, cresol, an epoxide, and photolabile dicarbonyls. RACM is implemented in both WRF-Chem and CMAQ (Sarwar et al., 2013;Kitayama et al., 2019;Shareef et al., 2019). ...
Aromatic hydrocarbons, including benzene, toluene, and xylenes, play an important role in atmospheric chemistry, but the associated chemical mechanisms are complex and uncertain. Sparing representation of this chemistry in models is needed for computational tractability. Here, we develop a new compact mechanism for aromatic chemistry (GC13) that captures current knowledge from laboratory and computational studies with only 17 unique species and 44 reactions. We compare GC13 to six other currently used mechanisms of varying complexity in box model simulations of environmental chamber data and diurnal boundary layer chemistry, and show that GC13 provides results consistent with or better than more complex mechanisms for oxygenated products (alcohols, carbonyls, dicarbonyls), ozone, and hydrogen oxide (HOx≡OH+HO2) radicals. Specifically, GC13 features increased radical recycling and increased ozone destruction from phenoxy–phenylperoxy radical cycling relative to other mechanisms. We implement GC13 into the GEOS-Chem global chemical transport model and find higher glyoxal yields and net ozone loss from aromatic chemistry compared with other mechanisms. Aromatic oxidation in the model contributes 23 %, 5 %, and 8 % of global glyoxal, methylglyoxal, and formic acid production, respectively, and has mixed effects on formaldehyde. It drives small decreases in global tropospheric OH (−2.2 %), NOx (≡NO+NO2; −3.7 %), and ozone (−0.8 %), but a large increase in NO3 (+22 %) from phenoxy–phenylperoxy radical cycling. Regional effects in polluted environments can be substantially larger, especially from the photolysis of carbonyls produced by aromatic oxidation, which drives large wintertime increases in OH and ozone concentrations.
... SAPRC-11 was previously implemented in GEOS-Chem (v9-02) by Yan et al. (2019). Versions of SAPRC have also been implemented in the Weather Research and Forecasting chemistry model (WRF-Chem), the 15 Community Multiscale Air Quality (CMAQ) model, and other regional 3D models (Yu et al., 2010;Cai et al., 2011;Zhang et al., 2012;Kitayama et al., 2019;Shareef et al., 2019). ...
... RACM2 is based on MCM for benzene and on Calvert (2002) for toluene and the individual xylene isomers, and represents major first-generation products of BTX oxidation, including benzaldehyde, phenol, cresol, an epoxide, and photolabile dicarbonyls. RACM is implemented in both WRF-Chem and CMAQ (Sarwar et al., 2013;Kitayama et al., 2019;Shareef et al., 2019). ...
Aromatic hydrocarbons (mainly benzene, toluene, and xylenes) play an important role in atmospheric chemistry but the associated chemical mechanisms are complex and uncertain. Spare representation of this chemistry in models is needed for computational tractability. Here we develop a new compact mechanism for aromatic chemistry (GC13) that captures current knowledge from laboratory and computational studies with only 17 unique species and 44 reactions. We compare GC13 to six 5 other currently used mechanisms of varying complexity in box model simulations of environmental chamber data and diurnal boundary layer chemistry, and show that GC13 provides results consistent with or better than more complex mechanisms for oxygenated products (alcohols, carbonyls, dicarbonyls), ozone, and hydrogen oxide (HO x ≡ OH + HO 2) radicals. GC13 features in particular increased radical recycling and increased ozone destruction from phenoxy-phenylperoxy radical cycling relative to other mechanisms. We implement GC13 into the GEOS-Chem global chemical transport model and find higher 10 glyoxal yields and net ozone loss from aromatic chemistry compared to other mechanisms. Aromatic oxidation in the model contributes 23%, 5%, and 8% of global glyoxal, methylglyoxal, and formic acid production respectively, and has mixed effects on formaldehyde. It drives small decreases in global tropospheric OH (-2.2%), NO x (≡ NO + NO 2 ;-3.7%) and ozone (-0.8%), but a large increase in NO 3 (+22%) from phenoxy-phenylperoxy radical cycling. Regional effects in polluted environments can be substantially larger, especially from photolysis of carbonyls produced by aromatic oxidation, which drives large wintertime 15 increases in OH and ozone concentrations.
