Global uncertainty analysis of a regional-scale gas-phase chemical mechanism

1996 ◽  
Vol 101 (D4) ◽  
pp. 9107-9119 ◽  
Author(s):  
Dongfen Gao ◽  
William R. Stockwell ◽  
Jana B. Milford
Keyword(s):  
Uncertainty Analysis ◽  
Gas Phase ◽  
Regional Scale ◽  
Chemical Mechanism ◽  
Global Uncertainty ◽  
Phase Chemical

scholarly journals Gaseous chemistry and aerosol mechanism developments for version 3.5.1 of the online regional model, WRF-Chem

2014 ◽  
Vol 7 (6) ◽  
pp. 2557-2579 ◽  
Author(s):  
S. Archer-Nicholls ◽  
D. Lowe ◽  
S. Utembe ◽  
J. Allan ◽  
R. A. Zaveri ◽  
...  
Keyword(s):  
Gas Phase ◽  
Chemical Mechanism ◽  
Reduced Form ◽  
Sea Spray ◽  
Wind Fields ◽  
Aerosol Composition ◽  
Aerosol Emission ◽  
Sea Spray Aerosol ◽  
The Impact ◽  
Phase Chemical

Abstract. We have made a number of developments to the Weather, Research and Forecasting model coupled with Chemistry (WRF-Chem), with the aim of improving model prediction of trace atmospheric gas-phase chemical and aerosol composition, and of interactions between air quality and weather. A reduced form of the Common Reactive Intermediates gas-phase chemical mechanism (CRIv2-R5) has been added, using the Kinetic Pre-Processor (KPP) interface, to enable more explicit simulation of VOC degradation. N2O5 heterogeneous chemistry has been added to the existing sectional MOSAIC aerosol module, and coupled to both the CRIv2-R5 and existing CBM-Z gas-phase schemes. Modifications have also been made to the sea-spray aerosol emission representation, allowing the inclusion of primary organic material in sea-spray aerosol. We have worked on the European domain, with a particular focus on making the model suitable for the study of nighttime chemistry and oxidation by the nitrate radical in the UK atmosphere. Driven by appropriate emissions, wind fields and chemical boundary conditions, implementation of the different developments are illustrated, using a modified version of WRF-Chem 3.4.1, in order to demonstrate the impact that these changes have in the Northwest European domain. These developments are publicly available in WRF-Chem from version 3.5.1 onwards.

Gas-phase chemical mechanism compression strategies: Treatment of reactants

1996 ◽  
Vol 30 (6) ◽  
pp. 831-842 ◽  
Author(s):  
P.A. Makar ◽  
W.R. Stockwell ◽  
S.M. Li
Keyword(s):  
Gas Phase ◽  
Chemical Mechanism ◽  
Phase Chemical

Improvements of the RADM1 gas‐phase chemical mechanism

2000 ◽  
Vol 35 (10) ◽  
pp. 1931-1939 ◽  
Author(s):  
Jianzhong Ma ◽  
Weiliang Li ◽  
Xiuji Zhou
Keyword(s):  
Gas Phase ◽  
Chemical Mechanism ◽  
Phase Chemical

Impacts of monocyclic aromatics on regional and global tropospheric gas-phase chemistry

2020 ◽  
Author(s):  
Rolf Sander ◽  
David Cabrera-Perez ◽  
Sara Bacer ◽  
Sergey Gromov ◽  
Jos Lelieveld ◽  
...  
Keyword(s):  
East Asia ◽  
Gas Phase ◽  
Aromatic Compounds ◽  
General Circulation ◽  
Regional Scale ◽  
Circulation Model ◽  
Tropospheric Chemistry ◽  
Chemical Mechanism ◽  
Gas Phase Chemistry ◽  
Phase Chemistry

<p>Aromatic compounds in the troposphere are reactive towards ozone<br>(O<sub>3</sub>), hydroxyl (OH) and other radicals. Here we present an<br>assessment of their impacts on the gas-phase chemistry, using the<br>general circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry). The<br>monocyclic aromatics considered in this study comprise benzene, toluene,<br>xylenes, phenol, styrene, ethylbenzene, trimethylbenzenes, benzaldehyde<br>and lumped higher aromatics bearing more than 9 C atoms. On a global<br>scale, the estimated net changes are minor when aromatic compounds are<br>included in the chemical mechanism of our model. For instance, the<br>tropospheric burden of CO increases by about 6 %, and those of OH,<br>O<sub>3</sub>, and NO<sub>x</sub> (NO + NO<sub>2</sub>) decrease between<br>2 % and 14 %. The global mean changes are small partially because of<br>compensating effects between high- and low-NO<sub>x</sub> regions. The<br>largest change is predicted for glyoxal, which increases globally by 36<br>%. Significant regional changes are identified for several species. For<br>instance, glyoxal increases by 130 % in Europe and 260 % in East Asia,<br>respectively. Large increases in HCHO are also predicted in these<br>regions. In general, the influence of aromatics is particularly evident<br>in areas with high concentrations of NO<sub>x</sub>, with increases up<br>to 12 % in O<sub>3</sub> and 17 % in OH. Although the global impact of<br>aromatics is limited, our results indicate that aromatics can strongly<br>influence tropospheric chemistry on a regional scale, most significantly<br>in East Asia.</p>

scholarly journals Comparison of tropospheric gas-phase chemistry schemes for use within global models

2009 ◽  
Vol 9 (5) ◽  
pp. 1831-1845 ◽  
Author(s):  
K. M. Emmerson ◽  
M. J. Evans
Keyword(s):  
Gas Phase ◽  
Transport Model ◽  
Regional Scale ◽  
Tropospheric Chemistry ◽  
Chemical Mechanism ◽  
Model Framework ◽  
Transport Models ◽  
Global Models ◽  
Calculated Concentration ◽  
The Impact

Abstract. Methane and ozone are two important climate gases with significant tropospheric chemistry. Within chemistry-climate and transport models this chemistry is simplified for computational expediency. We compare the state of the art Master Chemical Mechanism (MCM) with six tropospheric chemistry schemes (CRI-reduced, GEOS-CHEM and a GEOS-CHEM adduct, MOZART-2, TOMCAT and CBM-IV) that could be used within composition transport models. We test the schemes within a box model framework under conditions derived from a composition transport model and from field observations from a regional scale pollution event. We find that CRI-reduced provides much skill in simulating the full chemistry, yet with greatly reduced complexity. We find significant variations between the other chemical schemes, and reach the following conclusions. 1) The inclusion of a gas phase N2O5+H2O reaction in one scheme and not others is a large source of uncertainty in the inorganic chemistry. 2) There are significant variations in the calculated concentration of PAN between the schemes, which will affect the long range transport of reactive nitrogen in global models. 3) The representation of isoprene chemistry differs hugely between the schemes, leading to significant uncertainties on the impact of isoprene on composition. 4) Differences are found in NO3 concentrations in the nighttime chemistry. Resolving these four issues through further investigative laboratory studies will reduce the uncertainties within the chemical schemes of global tropospheric models.

scholarly journals Formation of secondary aerosols: impact of the gas-phase chemical mechanism

2010 ◽  
Vol 10 (8) ◽  
pp. 20625-20672
Author(s):  
Y. Kim ◽  
K. Sartelet ◽  
C. Seigneur
Keyword(s):  
Gas Phase ◽  
Transport Model ◽  
Model Performance ◽  
Organic Aerosols ◽  
Chemical Kinetic ◽  
Chemical Mechanism ◽  
Chemical Components ◽  
The Impact ◽  
Phase Chemical ◽  
Inorganic And Organic

Abstract. The impact of two recent gas-phase chemical kinetic mechanisms (CB05 and RACM2) on the formation of secondary inorganic and organic aerosols is compared for simulations of PM2.5 over Europe between 15 July and 15 August 2001. The host chemistry transport model is Polair3D of the Polyphemus air-quality platform. Particulate matter is modeled with SIREAM, which is coupled to the thermodynamic model ISORROPIA and to the secondary organic aerosol module MAEC. Model performance is satisfactory with both mechanisms for speciated PM2.5. The monthly-mean difference of the concentration of PM2.5 is less than 1 μg/m3 (6%) over the entire domain. Secondary chemical components of PM2.5 include sulfate, nitrate, ammonium and organic aerosols, and the chemical composition of PM2.5 is not significantly different between the two mechanisms. Monthly-mean concentrations of inorganic aerosol are higher with RACM2 than with CB05 (+16% for sulfate, +11% for nitrate, and +12% for ammonium), whereas the concentrations of organic aerosols are slightly higher with CB05 than with RACM2 (+26% for anthropogenic SOA and +1% for biogenic SOA). Differences in the inorganic and organic aerosols result primarily from differences in oxidant concentrations (OH, O3 and NO3). Nitrate formation tends to be HNO3-limited over land and differences in the concentrations of nitrate are due to differences in concentration of HNO3. Differences in aerosols formed from aromatics SVOC are due to different aromatics oxidation between CB05 and RACM2. The aromatics oxidation in CB05 leads to more cresol formation, which then leads to more SOA. Differences in the aromatics aerosols would be significantly reduced with the recent CB05-TU mechanism for toluene oxidation. Differences in the biogenic aerosols are due to different oxidant concentrations (monoterpenes) and different particulate organic mass concentrations affecting the gas-particle partitioning of SOA (isoprene).

scholarly journals Chemistry of hydrogen oxide radicals (HO<sub>x</sub>) in the Arctic troposphere in spring

2010 ◽  
Vol 10 (13) ◽  
pp. 5823-5838 ◽  
Author(s):  
J. Mao ◽  
D. J. Jacob ◽  
M. J. Evans ◽  
J. R. Olson ◽  
X. Ren ◽  
...  
Keyword(s):  
Gas Phase ◽  
Transport Model ◽  
Chemical Mechanism ◽  
The Arctic ◽  
Peroxy Radicals ◽  
Chemical Transport Model ◽  
The North ◽  
Arctic Atmosphere ◽  
Hydrogen Oxide ◽  
Phase Chemical

Abstract. We use observations from the April 2008 NASA ARCTAS aircraft campaign to the North American Arctic, interpreted with a global 3-D chemical transport model (GEOS-Chem), to better understand the sources and cycling of hydrogen oxide radicals (HOx≡H+OH+peroxy radicals) and their reservoirs (HOy≡HOx+peroxides) in the springtime Arctic atmosphere. We find that a standard gas-phase chemical mechanism overestimates the observed HO2 and H2O2 concentrations. Computation of HOx and HOy gas-phase chemical budgets on the basis of the aircraft observations also indicates a large missing sink for both. We hypothesize that this could reflect HO2 uptake by aerosols, favored by low temperatures and relatively high aerosol loadings, through a mechanism that does not produce H2O2. We implemented such an uptake of HO2 by aerosol in the model using a standard reactive uptake coefficient parameterization with γ(HO2) values ranging from 0.02 at 275 K to 0.5 at 220 K. This successfully reproduces the concentrations and vertical distributions of the different HOx species and HOy reservoirs. HO2 uptake by aerosol is then a major HOx and HOy sink, decreasing mean OH and HO2 concentrations in the Arctic troposphere by 32% and 31% respectively. Better rate and product data for HO2 uptake by aerosol are needed to understand this role of aerosols in limiting the oxidizing power of the Arctic atmosphere.

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