scholarly journals Development of aerosol optical properties for improving the MESSy photolysis module in the GEM-MACH v2.4 air quality model and application for calculating photolysis rates in a biomass burning plume

2022 ◽  
Vol 15 (1) ◽  
pp. 219-249
Author(s):  
Mahtab Majdzadeh ◽  
Craig A. Stroud ◽  
Christopher Sioris ◽  
Paul A. Makar ◽  
Ayodeji Akingunola ◽  
...  
Keyword(s):  
Air Quality ◽  
Black Carbon ◽  
Optical Depth ◽  
Transport Model ◽  
Lookup Table ◽  
Asymmetry Factor ◽  
Fire Emissions ◽  
Previous Version ◽  
Photolysis Rates ◽  
Model Aerosol

Abstract. The photolysis module in Environment and Climate Change Canada's online chemical transport model GEM-MACH (GEM: Global Environmental Multi-scale – MACH: Modelling Air quality and Chemistry) was improved to make use of the online size and composition-resolved representation of atmospheric aerosols and relative humidity in GEM-MACH, to account for aerosol attenuation of radiation in the photolysis calculation. We coupled both the GEM-MACH aerosol module and the MESSy-JVAL (Modular Earth Submodel System) photolysis module, through the use of the online aerosol modeled data and a new Mie lookup table for the model-generated extinction efficiency, absorption and scattering cross sections of each aerosol type. The new algorithm applies a lensing correction factor to the black carbon absorption efficiency (core-shell parameterization) and calculates the scattering and absorption optical depth and asymmetry factor of black carbon, sea salt, dust and other internally mixed components. We carried out a series of simulations with the improved version of MESSy-JVAL and wildfire emission inputs from the Canadian Forest Fire Emissions Prediction System (CFFEPS) for 2 months, compared the model aerosol optical depth (AOD) output to the previous version of MESSy-JVAL, satellite data, ground-based measurements and reanalysis products, and evaluated the effects of AOD calculations and the interactive aerosol feedback on the performance of the GEM-MACH model. The comparison of the improved version of MESSy-JVAL with the previous version showed significant improvements in the model performance with the implementation of the new photolysis module and with adopting the online interactive aerosol concentrations in GEM-MACH. Incorporating these changes to the model resulted in an increase in the correlation coefficient from 0.17 to 0.37 between the GEM-MACH model AOD 1-month hourly output and AERONET (Aerosol Robotic Network) measurements across all the North American sites. Comparisons of the updated model AOD with AERONET measurements for selected Canadian urban and industrial sites, specifically, showed better correlation coefficients for urban AERONET sites and for stations located further south in the domain for both simulation periods (June and January 2018). The predicted monthly averaged AOD using the improved photolysis module followed the spatial patterns of MERRA-2 reanalysis (Modern-Era Retrospective analysis for Research and Applications – version 2), with an overall underprediction of AOD over the common domain for both seasons. Our study also suggests that the domain-wide impacts of direct and indirect effect aerosol feedbacks on the photolysis rates from meteorological changes are considerably greater (3 to 4 times) than the direct aerosol optical effect on the photolysis rate calculations.

scholarly journals Interactive Aerosol Feedbacks on Photolysis Rates in the GEM-MACH v2.4 Air Quality Model in Canadian Urban and Industrial Areas

2021 ◽  
Author(s):  
Mahtab Majdzadeh ◽  
Craig A. Stroud ◽  
Christopher Sioris ◽  
Paul A. Makar ◽  
Ayodeji Akingunola ◽  
...  
Keyword(s):  
Air Quality ◽  
Black Carbon ◽  
Optical Depth ◽  
Lookup Table ◽  
Asymmetry Factor ◽  
Fire Emissions ◽  
Previous Version ◽  
Photolysis Rates ◽  
Model Aerosol ◽  
On Line

Abstract. The photolysis module in Environment and Climate Change Canada’s on-line chemical transport model GEM-MACH (GEM: Global Environmental Multi-scale – MACH: Modelling Air quality and Chemistry) was improved, to make use of the on-line size and composition-resolved representation of atmospheric aerosols and relative humidity in GEM-MACH, to account for aerosol attenuation of radiation in the photolysis calculation. We coupled both the GEM-MACH aerosol module and the MESSy-JVAL (Modular Earth Sub-Model System) photolysis module, through the use of the on-line aerosol modeled data and a new Mie lookup table for the model-generated extinction efficiency, absorption and scattering cross sections of each aerosol type. The new algorithm applies a lensing correction factor to the black carbon absorption efficiency (core-shell parameterization) and calculates the scattering and absorption optical depth and asymmetry factor of black carbon, sea-salt, dust, and other internally mixed components. We carried out a series of simulations with the improved version of MESSy-JVAL and wildfire emission inputs from the Canadian Forest Fire Emissions Prediction System (CFFEPS) for two months, compared the model aerosol optical depth (AOD) output to the previous version of MESSy-JVAL, satellite data, ground-based measurements and re-analysis products, and evaluated the effects of AOD calculations and the interactive aerosol feedback on the performance of the GEM-MACH model. The comparison of the improved version of MESSy-JVAL with the previous version showed significant improvements in the model performance with the implementation of the new photolysis module, and with adopting the online interactive aerosol concentrations in GEM-MACH. Incorporating these changes to the model resulted in an increase in the correlation coefficient from 0.17 to 0.37 between the GEM-MACH model AOD one-month hourly output and AERONET (Aerosol Robotic Network) measurements across all the North American sites. Comparisons of the updated model AOD with AERONET measurements for selected Canadian urban and industrial sites specifically, showed better correlation coefficients for urban AERONET sites, and for stations located further south in the domain for both simulation periods (June and January 2018). The predicted monthly averaged AOD using the improved photolysis module followed the spatial patterns of MERRA-2 re-analysis (Modern-Era Retrospective analysis for Research and Applications – Version 2), with an overall under-prediction of AOD over the common domain for both seasons. Our study also suggests that the domain-wide impact of direct and indirect effect aerosol feedbacks on the photolysis rates from meteorological changes, are considerably greater (3 to 4 times) than the direct aerosol optical effect on the photolysis rate calculations.

Impact of Interactive Aerosol Feedbacks on Photolysis Rates and Air Quality for Urban and Industrial Areas in Canada using the GEM-MACH Air Quality Model

2021 ◽  
Author(s):  
Mahtab Majdzadeh ◽  
Craig Stroud ◽  
Christopher Sioris ◽  
Paul Makar ◽  
Ayodeji Akingunola ◽  
...  
Keyword(s):  
Air Quality ◽  
Black Carbon ◽  
Optical Depth ◽  
Transport Model ◽  
Lookup Table ◽  
Asymmetry Factor ◽  
Fire Emissions ◽  
Previous Version ◽  
Model Aerosol ◽  
On Line

<p>The photolysis module in Environment and Climate Change Canada’s on-line chemical transport model GEM-MACH (GEM: Global Environmental Multi-scale – MACH: Modelling Air quality and Chemistry) was improved by using the on-line chemical composition and size-resolved representation of atmospheric aerosols in GEM-MACH to calculate the attenuation of radiation in the photolysis module.</p><p>We coupled both the GEM-MACH aerosol module and the MESSy-JVAL (Modular Earth Sub-Model System) photolysis routine through the use of the on-line aerosol modeled data and a new Mie lookup table for the model-generated extinction efficiency, absorption and scattering cross sections of each aerosol. The new algorithm applies a lensing correction factor to the black carbon absorption efficiency (core-shell parametrization) and calculates the scattering and absorption optical depth and asymmetry factor of black carbon, sea-salt, dust and other internally mixed components.</p><p>In order to evaluate the effects of these modifications on the performance of the GEM-MACH model, a series of simulations with the updated version of MESSy-JVAL and wildfire emission inputs from the Canadian Forest Fire Emissions Prediction System (CFFEPS) were carried out, and the model aerosol optical depth (AOD) output was compared to the previous version of MESSy-JVAL, satellite data, ground-based measurements, and re-analysis products. The comparison of the updated version of MESSy-JVAL with the previous version showed significant improvements in the model performance with the implementation of the new photolysis module and adopting the online interactive aerosol concentrations in GEM-MACH.</p>

scholarly journals Estimation of black carbon emissions from Siberian fires using satellite observations of absorption and extinction optical depths

2018 ◽  
Author(s):  
Igor B. Konovalov ◽  
Daria A. Lvova ◽  
Matthias Beekmann ◽  
Hiren Jethva ◽  
Eugene F. Mikhailov ◽  
...  
Keyword(s):  
Black Carbon ◽  
Optical Depth ◽  
Transport Model ◽  
Measurement Data ◽  
Satellite Observations ◽  
The Arctic ◽  
Fire Season ◽  
Northern Eurasia ◽  
Top Down ◽  
Fire Emissions

Abstract. Black carbon (BC) emissions from open biomass burning (BB) are known to have a considerable impact on the radiative budget of the atmosphere on global and regional scales but are poorly constrained in models by atmospheric observations, especially in remote regions. Here, we investigate the feasibility of constraining BC emissions from BB with satellite observations of the aerosol absorption optical depth (AAOD) and the aerosol extinction optical depth (AOD) retrieved from OMI (Ozone monitoring instrument) and MODIS (Moderate Resolution Imaging Spectroradiometer) measurements, respectively. We consider the case of Siberian BB BC emissions, which have a strong potential to impact the Arctic climate system. Using aerosol remote sensing data collected at Siberian sites of the Aerosol Robotic Network (AERONET) along with the results of the Fourth Fire Lab at Missoula Experiment (FLAME-4), we establish an empirical parameterization relating the ratio of the elemental carbon (EC) and organic carbon (OC) contents in BB aerosol to the ratio of AAOD and AOD at the wavelengths of the satellite observations. Applying this parameterization to the BC and OC column amounts simulated with the CHIMERE chemistry transport model, we optimize the parameters of the BB emission model based on MODIS measurements of the fire radiative power (FRP) and obtain top-down optimized estimates of the total monthly BB BC amounts emitted from intense Siberian fires that occurred in May–September 2012. The top-down estimates are compared to the corresponding values obtained using the Global Fire Emissions Database (GFED4) and the Fire Emission Inventory–northern Eurasia (FEI-NE). Our simulations using the optimized BB aerosol emissions are verified against AAOD and AOD data that were withheld from the estimation procedure. The simulations are further evaluated against in situ EC and OC measurements at the Zotino Tall Tower Observatory (ZOTTO) and also against aerosol measurement data collected on board of an aircraft in the framework of the Airborne Extensive Regional Observations (YAK-AEROSIB) experiments. We conclude that our BC and OC emission estimates, considered with their confidence intervals, are consistent with the ensemble of the measurement data analyzed in this study. Siberian fires are found to emit 0.41 ± 0.14 Tg of BC over the whole period of the five months considered; this estimate is a factor of 2 larger and a factor of 1.5 smaller compared to that the corresponding estimates based on the GFED4 (0.20 Tg) and FEI-NE (0.61 Tg) data, respectively. Our estimates of monthly BC emissions are also found to be larger than the BC amounts calculated with the GFED4 data and smaller than those calculated with the FEI-NE data for any of the five months. Especially large positive differences of our estimates of monthly BC emissions with respect to the GFED4 data are found in May and September. This finding indicates that the GFED4 database is likely to strongly underestimate BC emissions from agricultural burns and grass fires in Siberia. All these differences have important implications for climate change in the Arctic, as it is found that about a quarter of the huge BB BC mass emitted in Siberia during the fire season of 2012 was transported across the polar circle into the Arctic. Overall, the results of our analysis indicate that a combination of the available satellite observations of AAOD and AOD can provide the necessary constraints on BB BC emissions.

scholarly journals Estimation of black carbon emissions from Siberian fires using satellite observations of absorption and extinction optical depths

2018 ◽  
Vol 18 (20) ◽  
pp. 14889-14924 ◽  
Author(s):  
Igor B. Konovalov ◽  
Daria A. Lvova ◽  
Matthias Beekmann ◽  
Hiren Jethva ◽  
Eugene F. Mikhailov ◽  
...  
Keyword(s):  
Black Carbon ◽  
Optical Depth ◽  
Transport Model ◽  
Measurement Data ◽  
Satellite Observations ◽  
The Arctic ◽  
Fire Season ◽  
Northern Eurasia ◽  
Top Down ◽  
Fire Emissions

Abstract. Black carbon (BC) emissions from open biomass burning (BB) are known to have a considerable impact on the radiative budget of the atmosphere at both global and regional scales; however, these emissions are poorly constrained in models by atmospheric observations, especially in remote regions. Here, we investigate the feasibility of constraining BC emissions from BB using satellite observations of the aerosol absorption optical depth (AAOD) and the aerosol extinction optical depth (AOD) retrieved from OMI (Ozone Monitoring Instrument) and MODIS (Moderate Resolution Imaging Spectroradiometer) measurements, respectively. We consider the case of Siberian BB BC emissions, which have the strong potential to impact the Arctic climate system. Using aerosol remote sensing data collected at Siberian sites of the AErosol RObotic NETwork (AERONET) along with the results of the fourth Fire Lab at Missoula Experiment (FLAME-4), we establish an empirical parameterization relating the ratio of the elemental carbon (EC) and organic carbon (OC) contents in BB aerosol to the ratio of AAOD and AOD at the wavelengths of the satellite observations. Applying this parameterization to the BC and OC column amounts simulated using the CHIMERE chemistry transport model, we optimize the parameters of the BB emission model based on MODIS measurements of the fire radiative power (FRP); we then obtain top-down optimized estimates of the total monthly BB BC amounts emitted from intense Siberian fires that occurred from May to September 2012. The top-down estimates are compared to the corresponding values obtained using the Global Fire Emissions Database (GFED4) and the Fire Emission Inventory–northern Eurasia (FEI-NE). Our simulations using the optimized BB aerosol emissions are verified against AAOD and AOD data that were withheld from the estimation procedure. The simulations are further evaluated against in situ EC and OC measurements at the Zotino Tall Tower Observatory (ZOTTO) and also against aircraft aerosol measurement data collected in the framework of the Airborne Extensive Regional Observations in SIBeria (YAK-AEROSIB) experiments. We conclude that our BC and OC emission estimates, considered with their confidence intervals, are consistent with the ensemble of the measurement data analyzed in this study. Siberian fires are found to emit 0.41±0.14 Tg of BC over the whole 5-month period considered; this estimate is a factor of 2 larger and a factor of 1.5 smaller than the corresponding estimates based on the GFED4 (0.20 Tg) and FEI-NE (0.61 Tg) data, respectively. Our estimates of monthly BC emissions are also found to be larger than the BC amounts calculated using the GFED4 data and smaller than those calculated using the FEI-NE data for any of the 5 months. Particularly large positive differences of our monthly BC emission estimates with respect to the GFED4 data are found in May and September. This finding indicates that the GFED4 database is likely to strongly underestimate BC emissions from agricultural burns and grass fires in Siberia. All of these differences have important implications for climate change in the Arctic, as it is found that about a quarter of the huge BB BC mass emitted in Siberia during the fire season of 2012 was transported across the polar circle into the Arctic. Overall, the results of our analysis indicate that a combination of the available satellite observations of AAOD and AOD can provide the necessary constraints on BB BC emissions.

scholarly journals Modeling of photolysis rates over Europe: impact on chemical gaseous species and aerosols

2011 ◽  
Vol 11 (4) ◽  
pp. 1711-1727 ◽  
Author(s):  
E. Real ◽  
K. Sartelet
Keyword(s):  
Air Quality ◽  
Transport Model ◽  
Quantum Yields ◽  
Strong Impact ◽  
Peak Reduction ◽  
Gaseous Species ◽  
Clear Sky ◽  
Photolysis Rate ◽  
Photolysis Rates ◽  
The Impact

Abstract. This paper evaluates the impact of photolysis rate calculation on simulated European air composition and air quality. In particular, the impact of the cloud parametrisation and the impact of aerosols on photolysis rates are analysed. Photolysis rates are simulated using the Fast-JX photolysis scheme and gas and aerosol concentrations over Europe are simulated with the regional chemistry-transport model Polair3D of the Polyphemus platform. The photolysis scheme is first used to update the clear-sky tabulation of photolysis rates used in the previous Polair3D version. Important differences in photolysis rates are simulated, mainly due to updated cross-sections and quantum yields in the Fast-JX scheme. In the previous Polair3D version, clouds were taken into account by multiplying the clear-sky photolysis rates by a correction factor. In the new version, clouds are taken into account more accurately by simulating them directly in the photolysis scheme. Differences in photolysis rates inside clouds can be large but outside clouds, and especially at the ground, differences are small. To take into account the impact of aerosols on photolysis rates, Polair3D and Fast-JX are coupled. Photolysis rates are updated every hour. Large impact on photolysis rates is observed at the ground, decreasing with altitude. The aerosol specie that impact the most photolysis rates is dust especially in south Europe. Strong impact is also observed over anthropogenic emission regions (Paris, The Po and the Ruhr Valley) where mainly nitrate and sulphate reduce the incoming radiation. Differences in photolysis rates lead to changes in gas concentrations, with the largest impact simulated on OH and NO concentrations. At the ground, monthly mean concentrations of both species are reduced over Europe by around 10 to 14% and their tropospheric burden by around 10%. The decrease in OH leads to an increase of the life-time of several species such as VOC. NO2 concentrations are not strongly impacted and O3 concentrations are mostly reduced at the ground (−3%). O3 peaks are systematically decreased because of the NO2 photolysis rate coefficient decrease. Not only gas are impacted but also secondary aerosols, due to changes in gas precursors concentrations. However changes in aerosol species concentrations often compensate each other resulting in a low impact on PM10 and PM2.5 concentrations (lower than 2%). The changes in gas concentrations at the ground induced by the modification of photolysis rates (by aerosols and clouds) are compared to changes induced by 29 different model parametrisations in Roustan et al. (2010). Among the 31 model parametrisations, "including aerosols on photolysis rates calculation" has the strongest impact on OH concentrations and on O3 bias in July. In terms of air quality, ground concentrations (NO2, O3, PM10) are compared with measurements. Changes arising from cloud parametrisation are small. Simulation performances are often slightly better when including aerosol in photolysis rates calculation. The systematic O3 peak reduction leads to large differences in the exceedances of the European O3 standard as calculated by the model, in better agreement with measurements. The number of exceedances of the information and the alert threshold is divided by 2 when the aerosol impact on photochemistry is simulated. This shows the importance of taking into account aerosols impact on photolysis rates in air quality studies.

scholarly journals Assessment of co-benefits of black carbon emission reduction measures in Southeast Asia: Part 1 emission inventory and simulation for the base year 2007

2017 ◽  
Author(s):  
Didin Agustian Permadi ◽  
Nguyen Thi Kim Oanh ◽  
Robert Vautard
Keyword(s):  
Air Quality ◽  
Southeast Asia ◽  
Black Carbon ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Model Evaluation ◽  
Emission Reduction ◽  
Emission Inventory ◽  
Climate Forcing ◽  
Urban Site

Abstract. This research assessed the potential co-benefits associated with selected black carbon (BC) emission reduction measures on mitigation of air pollution and climate forcing in Southeast Asia (SEA). This paper presents Part 1 of the research with details on the emission inventory (EI) results and the WRF/CHIMERE model performance evaluation. The SEA regional emissions for 2007 were updated with our EI results for Indonesia, Thailand and Cambodia and used for the model input. WRF/CHIMERE simulated PM10, PM2.5 and BC over the SEA domain (0.25º x 0.25º) of the year 2007 and the results were evaluated against the available monitoring data in the domain. WRF hourly simulation results were evaluated using the observed data at 8 international airport stations in 5 SEA countries and showed a satisfactory performance. WRF/CHIMERE results for PM10 and PM2.5 showed strong seasonal influence of biomass open burning while BC distribution showed the influence of urban activities in big SEA cities. Daily average PM10 constructed from the hourly concentrations were obtained from the automatic monitoring stations in three SEA large cities, i.e. Bangkok, Kuala Lumpur and Surabaya for model evaluation. The daily observed PM2.5 and BC concentrations obtained from the Improving Air Quality in the Asian Developing Countries (AIRPET) project for 4 cities (i.e. Bangkok, Hanoi, Bandung, and Manila) were also used for model evaluation. In addition, hourly BC concentrations were taken from the measurement results of the Asian Pacific Network (APN) project at a sub-urban site in Bangkok. The modeled PM10 and BC satisfactorily met all suggested statistical criteria for PM evaluation. The modeled PM2.5/PM10 ratios estimated for four AIRPET sites ranged between 0.47–0.59, lower than observed values of 0.6–0.83. Better agreement was found for BC/PM2.5 ratios with the modeled values of 0.05–0.33 as compared to the observation values of 0.05–0.28. AODEM (extended aerosol optical depth module) was used to calculate the total columnar aerosol optical depth (AOD) and BC AOD using the internal mixing assumption. The model AOD results were evaluated against the observed AOD by both AERONET and MODIS satellite in 10 countries in the domain. Our model results showed that the BC AOD contributed 7.5–12 % of the total AOD, which was in the same ranges reported by other studies for places with intensive emissions. The Part 1 results (this study) is used in Part 2 (Permadi et al., 2017a) which calculates the regional aerosol direct radiative forcing under different emission reduction scenarios to explore potential co-benefits for air quality improvement, reduction in number of premature deaths and climate forcing mitigation in SEA in 2030.

Interactive Aerosol Feedbacks on Photolysis Rates in the GEM-MACH Air Quality Model for an Athabasca Oil-Sands Modelling Study

2020 ◽  
Author(s):  
Mahtab Majdzadeh ◽  
Craig Stroud ◽  
Ayodeji Akingunola ◽  
Paul Makar ◽  
Christopher Sioris ◽  
...  
Keyword(s):  
Optical Properties ◽  
Air Quality ◽  
Radiative Transfer ◽  
Forest Fire ◽  
Lookup Table ◽  
Aerosol Optical Properties ◽  
Extinction Efficiency ◽  
Scattering Cross ◽  
Photolysis Rates ◽  
On Line

<p>The radiative transfer module of an on-line chemical transport models requires input data from aerosol extinction efficiency, single scatter albedo and asymmetry factor, in order to predict the radiative state of the atmosphere. These aerosol optical properties (aerosol optical depth, AOD), may be integrated vertically for comparison to satellite observations. These optical effects may also influence the shorter wavelengths associated with atmospheric gas photolysis, influencing atmospheric reactivity. These processes may be harmonized in an on-line reaction transport model, such as Environment and Climate Change Canada’s GEM-MACH (GEM: Global Environmental Multi-scale – MACH: Modelling Air quality and Chemistry). Previous photolysis routine in the radiative transfer module, MESSY-JVAL (Modular Earth Sub-Model System), in GEM-MACH, made use of a climatology of aerosol optical properties, and the previous on-line version made use of a homogeneous mixture Mie code for meteorological radiative transfer calculations.</p><p>We calculated a new lookup table for the extinction efficiency, absorption and scattering cross sections of each aerosol type. The new version of MESSY-JVAL uses GEM-MACH predicted aerosol size distributions, chemical composition and relative humidity in each vertical column at each time step as input, reads aerosol absorption and scattering cross section data from the new lookup table and calculates aerosol optical properties, that are then used to modify both photolysis and meteorological radiative transfer calculations.</p><p>In order to evaluate these modifications to the model, we performed a series of simulations with GEM-MACH with wildfire emissions inputs from the Canadian Forest Fire Emissions Prediction System (CFFEPS) and compared the model AOD output with satellite and AERONET (Aerosol Robotic Network) measurement data. Comparison of the hourly AERONET and monthly-averaged satellite AOD demonstrates major improvements in the revised model AOD predictions. The impact of the updated photolysis rates and meteorological radiative transfer calculations on predictions of oxidant mixing ratios and rates of pollutant oxidation (nitrogen dioxide conversion to nitric acid) will be assessed both within and below the forest fire plume.</p>

scholarly journals Impact of Mexico City emissions on regional air quality from MOZART-4 simulations

2010 ◽  
Vol 10 (2) ◽  
pp. 3457-3498 ◽  
Author(s):  
L. K. Emmons ◽  
E. C. Apel ◽  
J.-F. Lamarque ◽  
P. G. Hess ◽  
M. Avery ◽  
...  
Keyword(s):  
Air Quality ◽  
Mexico City ◽  
Production Efficiency ◽  
Transport Model ◽  
Ozone Production ◽  
Atmospheric Composition ◽  
Chemical Transport Model ◽  
Model Calculations ◽  
Fire Emissions ◽  
Regional Air Quality

Abstract. An extensive set of measurements was made in and around Mexico City as part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) experiments in March 2006. Simulations with the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4), a global chemical transport model, have been used to provide a regional context for these observations and assist in their interpretation. These MOZART-4 simulations reproduce the aircraft observations generally well, but some differences in the modeled volatile organic compounds (VOCs) from the observations result from incorrect VOC speciation assumed for the emission inventories. The different types of CO sources represented in the model have been "tagged" to quantify the contributions of regions outside Mexico, as well as the various emissions sectors within Mexico, to the regional air quality of Mexico. This analysis indicates open fires have some, but not a dominant, impact on the atmospheric composition in the region around Mexico City, when averaged over the month. However, considerable variation in the fire contribution (2–15% of total CO) is seen during the month. The transport and photochemical aging of Mexico City emissions were studied using tags of CO emissions for each day, showing that typically the air near Mexico City was a combination of many ages. Ozone production in MOZART-4 is shown to agree well with the net production rates from box model calculations constrained by the MILAGRO aircraft measurements. Ozone production efficiency derived from the ratio of Ox to NOz is higher in MOZART-4 than in the observations for moderately polluted air. OH reactivity determined from the MOZART-4 results shows the same increase in relative importance of oxygenated VOCs downwind of Mexico City as the reactivity inferred from the observations. The amount of ozone produced by emissions from Mexico City and surrounding areas has been quantified in the model by tracking NO emissions, showing little influence beyond Mexico's borders, and also relatively minor influence from fire emissions on the monthly average tropospheric ozone column.

scholarly journals How emissions uncertainty influences the distribution and radiative impacts of smoke from fires in North America

2020 ◽  
Vol 20 (4) ◽  
pp. 2073-2097 ◽  
Author(s):  
Therese S. Carter ◽  
Colette L. Heald ◽  
Jose L. Jimenez ◽  
Pedro Campuzano-Jost ◽  
Yutaka Kondo ◽  
...  
Keyword(s):  
Air Quality ◽  
North America ◽  
Black Carbon ◽  
Dry Matter ◽  
Organic Aerosol ◽  
Carbonaceous Aerosol ◽  
Burned Area ◽  
Emission Inventories ◽  
Fire Emissions ◽  
Radiative Impacts

Abstract. Fires and the aerosols that they emit impact air quality, health, and climate, but the abundance and properties of carbonaceous aerosol (both black carbon and organic carbon) from biomass burning (BB) remain uncertain and poorly constrained. We aim to explore the uncertainties associated with fire emissions and their air quality and radiative impacts from underlying dry matter consumed and emissions factors. To investigate this, we compare model simulations from a global chemical transport model, GEOS-Chem, driven by a variety of fire emission inventories with surface and airborne observations of black carbon (BC) and organic aerosol (OA) concentrations and satellite-derived aerosol optical depth (AOD). We focus on two fire-detection-based and/or burned-area-based (FD-BA) inventories using burned area and active fire counts, respectively, i.e., the Global Fire Emissions Database version 4 (GFED4s) with small fires and the Fire INventory from NCAR version 1.5 (FINN1.5), and two fire radiative power (FRP)-based approaches, i.e., the Quick Fire Emission Dataset version 2.4 (QFED2.4) and the Global Fire Assimilation System version 1.2 (GFAS1.2). We show that, across the inventories, emissions of BB aerosol (BBA) differ by a factor of 4 to 7 over North America and that dry matter differences, not emissions factors, drive this spread. We find that simulations driven by QFED2.4 generally overestimate BC and, to a lesser extent, OA concentrations observations from two fire-influenced aircraft campaigns in North America (ARCTAS and DC3) and from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network, while simulations driven by FINN1.5 substantially underestimate concentrations. The GFED4s and GFAS1.2-driven simulations provide the best agreement with OA and BC mass concentrations at the surface (IMPROVE), BC observed aloft (DC3 and ARCTAS), and AOD observed by MODIS over North America. We also show that a sensitivity simulation including an enhanced source of secondary organic aerosol (SOA) from fires, based on the NOAA Fire Lab 2016 experiments, produces substantial additional OA; however, the spread in the primary emissions estimates implies that this magnitude of SOA can be neither confirmed nor ruled out when comparing the simulations against the observations explored here. Given the substantial uncertainty in fire emissions, as represented by these four emission inventories, we find a sizeable range in 2012 annual BBA PM2.5 population-weighted exposure over Canada and the contiguous US (0.5 to 1.6 µg m−3). We also show that the range in the estimated global direct radiative effect of carbonaceous aerosol from fires (−0.11 to −0.048 W m−2) is large and comparable to the direct radiative forcing of OA (−0.09 W m−2) estimated in the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). Our analysis suggests that fire emissions uncertainty challenges our ability to accurately characterize the impact of smoke on air quality and climate.

scholarly journals Modelling and assimilation of lidar signals over Greater Paris during the MEGAPOLI summer campaign

2014 ◽  
Vol 14 (7) ◽  
pp. 3511-3532 ◽  
Author(s):  
Y. Wang ◽  
K. N. Sartelet ◽  
M. Bocquet ◽  
P. Chazette
Keyword(s):  
Particulate Matter ◽  
Air Quality ◽  
Data Assimilation ◽  
Transport Model ◽  
Interpolation Method ◽  
Optimal Interpolation ◽  
Atmospheric Conditions ◽  
Model Aerosol ◽  
Paris Area ◽  
Lidar Observations

Abstract. In this study, we investigate the ability of the chemistry transport model (CTM) Polair3D of the air quality modelling platform Polyphemus to simulate lidar backscattered profiles from model aerosol concentration outputs. This investigation is an important preprocessing stage of data assimilation (validation of the observation operator). To do so, simulated lidar signals are compared to hourly lidar observations performed during the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) summer experiment in July 2009, when a ground-based mobile lidar was deployed around Paris on-board a van. The comparison is performed for six different measurement days, 1, 4, 16, 21, 26 and 29 July 2009, corresponding to different levels of pollution and different atmospheric conditions. Overall, Polyphemus well reproduces the vertical distribution of lidar signals and their temporal variability, especially for 1, 16, 26 and 29 July 2009. Discrepancies on 4 and 21 July 2009 are due to high-altitude aerosol layers, which are not well modelled. In the second part of this study, two new algorithms for assimilating lidar observations based on the optimal interpolation method are presented. One algorithm analyses PM10 (particulate matter with diameter less than 10 μm) concentrations. Another analyses PM2.5 (particulate matter with diameter less than 2.5 μm) and PM2.5–10 (particulate matter with a diameter higher than 2.5 μm and lower than 10 μm) concentrations separately. The aerosol simulations without and with lidar data assimilation (DA) are evaluated using the Airparif (a regional operational network in charge of air quality survey around the Paris area) database to demonstrate the feasibility and usefulness of assimilating lidar profiles for aerosol forecasts. The evaluation shows that lidar DA is more efficient at correcting PM10 than PM2.5, probably because PM2.5 is better modelled than PM10. Furthermore, the algorithm which analyses both PM2.5and PM2.5–10 provides the best scores for PM10. The averaged root-mean-square error (RMSE) of PM10 is 11.63 μg m−3 with DA (PM2.5 and PM2.5–10), compared to 13.69 μg m−3 with DA (PM10) and 17.74 μg m−3 without DA on 1 July 2009. The averaged RMSE of PM10 is 4.73 μg m−3 with DA (PM2.5 and PM2.5–10), against 6.08 μg m−3 with DA (PM10) and 6.67 μg m−3 without DA on 26 July 2009.

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