scholarly journals GEM-AQ, an on-line global multiscale chemical weather modelling system: model description and evaluation of gas phase chemistry processes

2008 ◽  
Vol 8 (12) ◽  
pp. 3255-3281 ◽  
Author(s):  
J. W. Kaminski ◽  
L. Neary ◽  
J. Struzewska ◽  
J. C. McConnell ◽  
A. Lupu ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Nitrogen Dioxide ◽  
Gas Phase ◽  
Biomass Burning ◽  
Weather Prediction ◽  
Tropospheric Chemistry ◽  
Chemical Mechanism ◽  
Anthropogenic Sources ◽  
Model Description ◽  
On Line

Abstract. Tropospheric chemistry and air quality processes were implemented on-line in the Global Environmental Multiscale weather prediction model. The integrated model, GEM-AQ, was developed as a platform to investigate chemical weather at scales from global to urban. The current chemical mechanism is comprised of 50 gas-phase species, 116 chemical and 19 photolysis reactions, and is complemented by a sectional aerosol module with 5 aerosols types. All tracers are advected using the semi-Lagrangian scheme native to GEM. The vertical transport includes parameterized subgrid-scale turbulence and large scale deep convection. Dry deposition is included as a flux boundary condition in the vertical diffusion equation. Wet deposition of gas-phase species is treated in a simplified way, and only below-cloud scavenging is considered. The emissions used include yearly-averaged anthropogenic, and monthly-averaged biogenic, ocean, soil, and biomass burning emission fluxes, as well as NOx from lightning. In order to evaluate the ability to simulate seasonal variations and regional distributions of trace gases such as ozone, nitrogen dioxide and carbon monoxide, the model was run for a period of five years (2001–2005) on a global uniform 1.5°×1.5° horizontal resolution domain and 28 hybrid levels extending up to 10 hPa. Model results were compared with observations from satellites, aircraft measurement campaigns and balloon sondes. We find that GEM-AQ is able to capture the spatial details of the chemical fields in the middle and lower troposphere. The modelled ozone consistently shows good agreement with observations, except over tropical oceans. The comparison of carbon monoxide and nitrogen dioxide with satellite measurements emphasizes the need for more accurate, year-specific emissions fluxes for biomass burning and anthropogenic sources. Other species also compare well with available observations.

scholarly journals GEM-AQ/EC, an on-line global multi-scale chemical weather modelling system: model development and evaluation of global aerosol climatology

2012 ◽  
Vol 12 (17) ◽  
pp. 8237-8256 ◽  
Author(s):  
S. L. Gong ◽  
D. Lavoué ◽  
T. L. Zhao ◽  
P. Huang ◽  
J. W. Kaminski
Keyword(s):  
Organic Carbon ◽  
Black Carbon ◽  
Weather Prediction ◽  
Horizontal Resolution ◽  
Tropospheric Chemistry ◽  
Chemical Mechanism ◽  
Systematic Bias ◽  
Multi Scale ◽  
On Line ◽  
Aerosol Module

Abstract. A global air quality modeling system GEM-AQ/EC was developed by implementing tropospheric chemistry and aerosol processes on-line into the Global Environmental Multiscale weather prediction model – GEM. Due to the multi-scale features of the GEM, the integrated model, GEM-AQ/EC, is able to investigate chemical weather at scales from global to urban domains. The current chemical mechanism is comprised of 50 gas-phase species, 116 chemical and 19 photolysis reactions, and is complemented by a sectional aerosol module CAM (The Canadian Aerosol Module) with 5 aerosols types: sulphate, black carbon, organic carbon, sea-salt and soil dust. Monthly emission inventories of black carbon and organic carbon from boreal and temperate vegetation fires were assembled using the most reliable areas burned datasets by countries, from statistical databases and derived from remote sensing products of 1995–2004. The model was run for ten years from from 1995–2004 with re-analyzed meteorology on a global uniform 1° × 1° horizontal resolution domain and 28 hybrid levels extending up to 10 hPa. The simulating results were compared with various observations including surface network around the globe and satellite data. Regional features of global aerosols are reasonably captured including emission, surface concentrations and aerosol optical depth. For various types of aerosols, satisfactory correlations were achieved between modeled and observed with some degree of systematic bias possibly due to large uncertainties in the emissions used in this study. A global distribution of natural aerosol contributions to the total aerosols is obtained and compared with observations.

scholarly journals GEM-AQ/EC, an on-line global multiscale chemical weather modelling system: model development and evaluations of global aerosol climatology

2012 ◽  
Vol 12 (4) ◽  
pp. 9283-9330 ◽  
Author(s):  
S. L. Gong ◽  
D. Lavoue ◽  
T. L. Zhao ◽  
P. Huang ◽  
J. W. Kaminski
Keyword(s):  
Organic Carbon ◽  
Black Carbon ◽  
Weather Prediction ◽  
Model Development ◽  
Horizontal Resolution ◽  
Tropospheric Chemistry ◽  
Chemical Mechanism ◽  
Systematic Bias ◽  
On Line ◽  
Aerosol Module

Abstract. A global air quality modeling system GEM-AQ/EC was developed by implementing tropospheric chemistry and aerosol processes on-line into the Global Environmental Multiscale weather prediction model – GEM. Due to the multi-scale features of the GEM, the integrated model, GEM-AQ/EC, is able to investigate chemical weather at scales from global to urban domains. The current chemical mechanism is comprised of 50 gas-phase species, 116 chemical and 19 photolysis reactions, and is complemented by a sectional aerosol module CAM (The Canadian Aerosol Module) with 5 aerosols types: sulphate, black carbon, organic carbon, sea-salt and soil dust. Monthly emission inventories of black carbon and organic carbon from boreal and temperate vegetation fires were assembled using the most reliable areas burned datasets by countries, from statistical databases and derived from remote sensing products of 1995–2004. The model was run for ten years from from 1995–2004 with re-analyzed meteorology on a global uniform 1 × 1° horizontal resolution domain and 28 hybrid levels extending up to 10 hPa. The simulating results were compared with various observations including surface network around the globe and satellite data. Regional features of global aerosols are reasonably captured including emission, surface concentrations and aerosol optical depth. For various types of aerosols, satisfactory correlations were achieved between modeled and observed with some degree of systematic bias possibly due to large uncertainties in the emissions used in this study. A global distribution of natural aerosol contributions to the total aerosols is obtained and compared with observations.

scholarly journals Long-term measurements of aerosols and carbon monoxide at the ZOTTO tall tower to characterize polluted and pristine air in the Siberian Taiga

2013 ◽  
Vol 13 (7) ◽  
pp. 18345-18416
Author(s):  
X. Chi ◽  
J. Winderlich ◽  
J.-C. Mayer ◽  
A. V. Panov ◽  
M. Heimann ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Biomass Burning ◽  
Single Scattering ◽  
High Ratio ◽  
Dominant Mode ◽  
Anthropogenic Sources ◽  
Aerosol Size Distribution ◽  
Aerosol Formation ◽  
Mixing Ratios ◽  
Tall Tower

Abstract. Siberia is one of few background regions in the Northern Hemisphere where the atmosphere may sometimes approach pristine conditions. We present the time series of aerosol and carbon monoxide (CO) measurements between September~2006 and December 2010 at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia (61° N; 90° E). We investigate the seasonal, weekly and diurnal variations of aerosol properties (including absorption and scattering coefficients and derived parameters, like equivalent black carbon (BCe), Ångström exponent, single scattering albedo, and backscattering ratio) and the CO mixing ratios. Criteria were established to distinguish polluted and near-pristine air masses and characterize them separately. Depending on the season, 15–47% of the sampling time at ZOTTO was representative of a clean atmosphere. The summer pristine data indicates that primary biogenic and/or secondary organic aerosol formation are quite strong particle sources in the Siberian Taiga. The summer seasons 2007–2008 are dominated by an Aitken mode of 80 nm size, whereas the summer 2009 with prevailing easterly winds produced aerosols in the accumulation mode around 200 nm size. We found these differences mainly related to air temperature, in parallel with production rates of biogenic volatile organic compounds (VOC). In winter, the footprint and aerosol size distribution (with a peak at 160 nm) of the clean background air are characteristic for aged aerosols from anthropogenic sources at great distances from ZOTTO and diluted biofuel burning emissions from heating. The wintertime polluted air originates from the large cities to the south and southwest of the site; these aerosols have a dominant mode around 100 nm, and the Δ BCe/Δ CO ratio of 7–11 ng m−3 ppb−1 suggests dominant contributions from coal and biofuel burning for heating. During summer, anthropogenic emissions are the dominant contributor to the pollution aerosols at ZOTTO, while only 12% of the polluted events are classified as biomass burning dominated, but then often associated with extremely high CO concentrations and aerosol absorption coefficients. Two biomass-burning case studies revealed different Δ BCe/Δ CO ratios from different fire types, with the agricultural fires in April 2008 yielding a very high ratio of 21 ng m−3 ppb−1. Overall, we find that anthropogenic sources dominate the aerosol population at our site most of the time, even during nominally clean episodes in winter, and that near-pristine conditions are encountered only episodically in the growing season.

scholarly journals GEM-AQ, an on-line global multiscale chemical weather system: model description and evaluation of gas phase chemistry processes

2007 ◽  
Vol 7 (5) ◽  
pp. 14895-14937 ◽  
Author(s):  
J. W. Kaminski ◽  
L. Neary ◽  
J. Struzewska ◽  
J. C. McConnell ◽  
A. Lupu ◽  
...  
Keyword(s):  
Multiscale Model ◽  
Global Scale ◽  
Tropospheric Chemistry ◽  
Model Description ◽  
Weather System ◽  
Gas Phase Chemistry ◽  
Global Environmental ◽  
On Line ◽  
Phase Chemistry ◽  
Global Environmental Multiscale

Abstract. Tropospheric chemistry and air quality processes were implemented on-line in the Global Environmental Multiscale model. The integrated model, GEM-AQ, has been developed as a platform to investigate chemical weather at scales from global to urban. The model was exercised for five years (2001–2005) to evaluate its ability to simulate seasonal variations and regional distributions of trace gases such as ozone, nitrogen dioxide and carbon monoxide on the global scale. The model results presented are compared with observations from satellites, aircraft measurement campaigns and balloon sondes.

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 Impacts of 2006 Indonesian fires and dynamics on tropical upper tropospheric carbon monoxide and ozone

2011 ◽  
Vol 11 (21) ◽  
pp. 10929-10946 ◽  
Author(s):  
L. Zhang ◽  
Q. B. Li ◽  
J. Jin ◽  
H. Liu ◽  
N. Livesey ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Biomass Burning ◽  
Model Comparison ◽  
Model Simulation ◽  
Deep Convection ◽  
Tropospheric Chemistry ◽  
Three Dimensional Model ◽  
Dynamic Impact ◽  
Fire Emissions ◽  
Dynamic Impacts

Abstract. We investigate the relative impacts of biomass burning emissions and dynamics on tropical upper tropospheric carbon monoxide (CO) and ozone (O3) over western and central Indonesia during the August–November 2006 fires in equatorial Asia by using a global three-dimensional model of tropospheric chemistry (GEOS-Chem) and by comparing model results with Microwave Limb Sounder (MLS) observations of upper tropospheric CO and O3. GEOS-Chem CO and O3 show similarities with MLS observed enhancements from convective lifting of fire emissions. In the tropical upper troposphere (UT), fire effluents from equatorial Asia are primarily transported southwestward to the eastern tropical Indian Ocean, driven by the high-pressure systems along 10° N–15° N and 10° S–15° S latitudes, and northeastward to southeast Asia and beyond, driven by the western North Pacific subtropical high. A characteristic feature of these CO enhancements is that they lag behind biomass burning emissions (by 2–3 weeks) at the three pressure levels 215, 147 and 100 hPa, resulting from the decreasing influence of deep convective lifting with altitude in the tropical UT. Inclusion of biomass burning injection height significantly improves model comparison with observations. We estimate the fire influences by contrasting one model simulation with year-specific and another with climatological biomass burning emissions. Biomass burning accounts for about 50–150 ppbv of CO and 5–15 ppbv of O3 in the tropical UT below 100 hPa during October and November, with temporal variations driven by biomass burning and deep convection. We estimate the dynamic impacts by examining the difference between a model simulation for 2006 (El Niño) and another for 2005 (neutral). The dynamic impacts are far more complex and account for up to 100 ppbv of CO and 30 ppbv of O3 in the tropical UT below 100 hPa. The temporal variation of the dynamic impact on CO is driven by deep convection. The variation of the dynamic impact on O3 depends on deep convection as well as the associated lightning NOx emissions and also reflects non-linearity of O3 chemistry.

scholarly journals Impacts of 2006 Indonesian fires on tropical upper tropospheric carbon monoxide and ozone

2011 ◽  
Vol 11 (7) ◽  
pp. 19357-19393
Author(s):  
L. Zhang ◽  
Q. Li ◽  
J. Jin ◽  
H. Liu ◽  
N. Livesey ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Biomass Burning ◽  
Model Simulation ◽  
Deep Convection ◽  
Temporal Variations ◽  
Tropospheric Chemistry ◽  
Three Dimensional Model ◽  
Dynamic Impact ◽  
Fire Emissions ◽  
Dynamic Impacts

Abstract. We investigate the relative impacts of biomass burning emissions and dynamics on tropical upper tropospheric carbon monoxide (CO) and ozone (O3) over western and central Indonesia during the August-November 2006 fires in equatorial Asia by using a global three-dimensional model of tropospheric chemistry (GEOS-Chem) and by comparing model results with Microwave Limb Sounder (MLS) observations of upper tropospheric CO and O3. GEOS-Chem CO and O3 reproduce MLS observed enhancements from convective lifting of fire emissions. In the tropical upper troposphere (UT), fire effluents from equatorial Asia are primarily transported southwestward to the eastern tropical Indian Ocean, driven by the high-pressure systems along 10° N–15° N and 10° S–15° S latitudes, and northeastward to southeast Asia and beyond, driven by the western North Pacific subtropical high. A characteristic feature of these CO enhancements is that they lag behind biomass burning emissions (by 2–3 weeks) at the three pressure levels from 215 hPa to 100 hPa, resulting form the decreasing influence of deep convective lifting with altitude in the UT. We estimate the fire influences by contrasting one model simulation with year-specific and another with climatological biomass burning emissions. Biomass burning accounts for about 50–150 ppbv of CO and 5–20 ppbv of O3 in the tropical UT below 100 hPa during October and November, with temporal variations driven by biomass burning and deep convection. We estimate the dynamic impacts by examining the difference between a model simulation for 2006 (El Niño) and another for 2005 (neutral). The dynamic impacts are far more complex and account for up to 100 ppb of CO and 30 ppb of O3 in the tropical UT below 100 hPa. The temporal variation of the dynamic impact on CO is driven by deep convection. The variation of the dynamic impact on O3 not only depends on deep convection but also reflects the non-linearity of O3 chemistry.

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