scholarly journals Frontiers in air quality modelling

2014 ◽  
Vol 7 (1) ◽  
pp. 203-210 ◽  
Author(s):  
A. Colette ◽  
B. Bessagnet ◽  
F. Meleux ◽  
E. Terrenoire ◽  
L. Rouïl
Keyword(s):  
Air Pollution ◽  
Atmospheric Chemistry ◽  
Urban Areas ◽  
High Performance ◽  
Transport Model ◽  
Atomic Energy Commission ◽  
Computing System ◽  
Mitigation Strategies ◽  
Continental Scale ◽  
Computing Center

Abstract. The first pan-European kilometre-scale atmospheric chemistry simulation is introduced. The continental-scale air pollution episode of January 2009 is modelled with the CHIMERE offline chemistry transport model with a massive grid of 2 million horizontal points, performed on 2000 CPU of a high-performance computing system hosted by the Research and Technology Computing Center at the French Alternative Energies and Atomic Energy Commission (CCRT/CEA). Besides the technical challenge, we find that model biases are significantly reduced, especially over urban areas. The high-resolution grid also allows revisiting of the contribution of individual city plumes to the European burden of pollution, providing new insights to target the appropriate geographical level of action when designing air pollution mitigation strategies.

scholarly journals Frontiers in air quality modelling

2013 ◽  
Vol 6 (3) ◽  
pp. 4189-4205
Author(s):  
A. Colette ◽  
B. Bessagnet ◽  
F. Meleux ◽  
L. Rouïl
Keyword(s):  
Air Pollution ◽  
Atmospheric Chemistry ◽  
Urban Areas ◽  
High Performance ◽  
Transport Model ◽  
Control Strategies ◽  
Atomic Energy Commission ◽  
Computing System ◽  
Air Pollution Control ◽  
Continental Scale

Abstract. The first pan-European kilometre-scale atmospheric chemistry simulation is introduced. The continental-scale air pollution episode of January 2009 is modelled with the CHIMERE offline chemistry-transport model with a massive grid of 2 million horizontal points, performed on 2000 CPU of a high performance computing system hosted by the Research and Technology Computing Center at the French Alternative Energies and Atomic Energy Commission (CCRT/CEA). Besides the technical challenge, we find that model biases are significantly reduced, especially over urban areas. The high resolution grid also allows revisiting the contribution of individual city plumes to the European burden of pollution, providing new insights for designing air pollution control strategies.

scholarly journals Fostering a Collaborative Atmospheric Chemistry Research Community in the Latin America and Caribbean Region

2016 ◽  
Vol 97 (10) ◽  
pp. 1929-1939 ◽  
Author(s):  
Marcos Andrade-Flores ◽  
Nestor Rojas ◽  
Megan L. Melamed ◽  
Olga L. Mayol-Bracero ◽  
Michel Grutter ◽  
...  
Keyword(s):  
Air Pollution ◽  
Latin America ◽  
Atmospheric Chemistry ◽  
Rural Areas ◽  
Urban Areas ◽  
Caribbean Region ◽  
Rapid Urbanization ◽  
Chemistry Research ◽  
Latin America And Caribbean ◽  
Andean Glaciers

Abstract In 2013, the international Commission on Atmospheric Chemistry and Global Pollution (iCACGP) and the International Global Atmospheric Chemistry (IGAC) Project Americas Working Group (iCACGP/IGAC AWG) was formed to build a cohesive network and foster the next generation of atmospheric scientists with the goal of contributing to a scientific community focused on building collective knowledge for the Americas. The Latin America–Caribbean (LAC) region shares common history, culture, and socioeconomic issues but, at the same time, it is highly diverse in its physical and human geography. The LAC region is unique because approximately 80% of its population lives in urban areas, resulting in high-density hotspots of urbanization and vast unpopulated rural areas. In recent years, most countries of the region have experienced rapid growth in population and industrialization as their economies emerge. The rapid urbanization, the associated increases in mobile and industrial sources, and the growth of the agricultural activities related to biomass burning have degraded air quality in certain areas of the LAC region. Air pollution has negative implications for human health, ecosystems, and climate. In addition, air pollution and the warming caused by greenhouse gases could impact the melting of Andean glaciers, an important source of freshwater. To better understand the links between air pollution and climate, it is necessary to increase the number of atmospheric scientists and improve our observational, analytical, and modeling capacities. This requires sustained and prioritized funding as well as stronger collaboration within the LAC region.

scholarly journals Which processes drive observed variations of HCHO columns over India?

2018 ◽  
Vol 18 (7) ◽  
pp. 4549-4566 ◽  
Author(s):  
Luke Surl ◽  
Paul I. Palmer ◽  
Gonzalo González Abad
Keyword(s):  
Atmospheric Chemistry ◽  
Seasonal Cycle ◽  
Transport Model ◽  
Monsoon Season ◽  
Gangetic Plain ◽  
Model Calculations ◽  
Propene Oxidation ◽  
Meridional Gradient ◽  
Northeastern India ◽  
Continental Scale

Abstract. We interpret HCHO column variations observed by the Ozone Monitoring Instrument (OMI), aboard the NASA Aura satellite, over India during 2014 using the GEOS-Chem atmospheric chemistry and transport model. We use a nested version of the model with a horizontal resolution of approximately 25 km. HCHO columns are related to local emissions of volatile organic compounds (VOCs) with a spatial smearing that increases with the VOC lifetime. Over India, HCHO has biogenic, pyrogenic, and anthropogenic VOC sources. Using a 0-D photochemistry model, we find that isoprene has the largest molar yield of HCHO which is typically realized within a few hours. We also find that forested regions that neighbour major urban conurbations are exposed to high levels of nitrogen oxides. This results in depleted hydroxyl radical concentrations and a delay in the production of HCHO from isoprene oxidation. We find that propene is the only anthropogenic VOC emitted in major Indian cities that produces HCHO at a comparable (but slower) rate to isoprene. The GEOS-Chem model reproduces the broad-scale annual mean HCHO column distribution observed by OMI (r = 0.6), which is dominated by a distinctive meridional gradient in the northern half of the country, and by localized regions of high columns that coincide with forests. Major discrepancies are noted over the Indo-Gangetic Plain (IGP) and Delhi. We find that the model has more skill at reproducing observations during winter (JF) and pre-monsoon (MAM) months with Pearson correlations r > 0.5 but with a positive model bias of  ≃ 1×1015 molec cm−2. During the monsoon season (JJAS) we reproduce only a diffuse version of the observed meridional gradient (r = 0.4). We find that on a continental scale most of the HCHO column seasonal cycle is explained by monthly variations in surface temperature (r = 0.9), suggesting a role for biogenic VOCs, in agreement with the 0-D and GEOS-Chem model calculations. We also find that the seasonal cycle during 2014 is not significantly different from the 2008 to 2015 mean seasonal variation. There are two main loci for biomass burning (the states of Punjab and Haryana, and northeastern India), which we find makes a significant contribution (up to 1×1015 molec cm−2) to observed HCHO columns only during March and April over northeastern India. The slow production of HCHO from propene oxidation results in a smeared hotspot over Delhi that we resolve only on an annual mean timescale by using a temporal oversampling method. Using a linear regression model to relate GEOS-Chem isoprene emissions to HCHO columns we infer seasonal isoprene emissions over two key forest regions from the OMI HCHO column data. We find that the a posteriori emissions are typically lower than the a priori emissions, with a much stronger reduction of emissions during the monsoon season. We find that this reduction in emissions during monsoon months coincides with a large drop in satellite observations of leaf phenology that recovers in post monsoon months. This may signal a forest-scale response to monsoon conditions.

scholarly journals Which processes drive observed variations of HCHO columns over India?

2017 ◽  
Author(s):  
Luke Surl ◽  
Paul I. Palmer ◽  
Gonzalo González Abad
Keyword(s):  
Atmospheric Chemistry ◽  
Seasonal Cycle ◽  
Transport Model ◽  
Monsoon Season ◽  
Gangetic Plain ◽  
Model Calculations ◽  
Propene Oxidation ◽  
Meridional Gradient ◽  
Northeastern India ◽  
Continental Scale

Abstract. We interpret HCHO column variations observed by the Ozone Monitoring Instrument (OMI), aboard the NASA Aura satellite, over India during 2014 using the GEOS-Chem atmospheric chemistry and transport model. We use a nested version of the model with a spatial resolution of approximately 25 km. HCHO columns are related to local emissions of volatile organic compounds (VOCs) with a spatial smearing that increases with the VOC lifetime. Over India, HCHO has biogenic, pyrogenic, and anthropogenic VOC sources. Using a 0-D photochemistry model, we find that isoprene has the largest molar yield of HCHO that is typically realized within a few hours. We find that forested regions that neighbours major urban conurbations are exposed to high levels of nitrogen oxides. This results in depleted hydroxyl radical concentrations and a delay in the production of HCHO from isoprene oxidation. We find that propene is the only anthropogenic VOC emitted in major Indian cities that produces HCHO at a comparable (slower) rate to isoprene. The GEOS-Chem model reproduces the broadscale annual mean HCHO column distribution observed by OMI (r = 0.6), which is dominated by a distinctive meridional gradient in the northern half of the country, and by localized regions of high columns that coincide with forests. Major discrepancies are over the Indo-Gangetic Plain and Delhi. We find that the model has more skill at reproducing observations during winter (JF) and pre-monsoon (MAM) months with Pearson correlations r > 0.5 but with a positive model bias of 1 × 1015 molec/cm2. During the monsoon season (JJAS) we reproduce only a diffuse version of the observed meridional gradient (r = 0.4). Generally, we find that on a continental scale most of the seasonal cycle is explained by monthly variations in surface temperature (r = 0.9), suggesting a strong role for biogenic VOCs, in agreement with the 0-D and GEOS-Chem model calculations. We also find that the seasonal cycle during 2014 is not significantly different from the 2008–2015 mean seasonal variation but there are large year to year variations. There are two main loci for biomass burning (states of Punjab and Haryana, and northeastern India), which we find only contributes a significant contribution (up to 1 × 1015 molec/cm2) to observed HCHO columns during March to April over northeastern India. The slow production of HCHO from propene oxidation results in a smeared hotspot over Delhi that we resolve only on an annual mean timescale by using a temporal oversampling method. Using a linear regression model to relate GEOS-Chem isoprene emissions to HCHO columns we infer seasonal isoprene emissions over two key forest regions from the OMI HCHO column data. We find that the a posteriori emissions are typically lower than the a priori emissions, with a much stronger reduction of emissions during the monsoon season. We find that this reduction in emissions during monsoon months coincides with a large drop in satellite observations of leaf phenology that recovers in post monsoon months. This may signal a forest-scale response to monsoon conditions.

scholarly journals Nature-Based Solutions for Co-mitigation of Air Pollution and Urban Heat in Indian Cities

2021 ◽  
Vol 3 ◽  
Author(s):  
Jyothi S. Menon ◽  
Richa Sharma
Keyword(s):  
Air Pollution ◽  
Urban Areas ◽  
Well Being ◽  
Mitigation Strategies ◽  
Multiple Exposures ◽  
Premature Deaths ◽  
Wide Range ◽  
Urban Heat ◽  
Pollution Exposure ◽  
Indian Cities

The urban population is subjected to multiple exposures of air pollution and heat stress and bear severe impacts on their health and well-being in terms of premature deaths and morbidity. India tops the list of countries with the highest air pollution exposure and hosts some of the most polluted cities in the world. Similarly, Indian cities are highly vulnerable to extreme heat with the frequency of heatwaves expected to increase several-fold in urban areas in India. It is reported that mitigating air pollution could reduce the rural-urban difference of the incoming radiation thus resulting in mitigation of the urban heat island effect. Since the interaction between urban heat and air pollution is dynamic and complex, both these factors should be considered by the urban authorities in designing mitigation strategies. Given the multi-functional nature and cost-effectiveness of Nature-Based Solutions (NbS), they appear to be the most appropriate remedy for environmental issues of urban areas, particularly in developing countries. In addition to improving public health (through the reduction in air pollution and urban heat), NbS also provides a wide range of co-benefits such as reducing energy cost and health costs as well as conservation of biodiversity. This review is an attempt to understand the potentials of NbS in co-mitigating air pollution and urban heat in Indian cities. A framework for the planning and design of NbS in Indian cities is also proposed based on the review that could help city planners and decision-makers in addressing these two issues in an integrated manner.

scholarly journals Modeling organic aerosol over Europe in summer conditions with the VBS-GECKO parameterization: sensitivity to secondary organic compound properties and IVOC (intermediate-volatility organic compound) emissions

2020 ◽  
Vol 20 (8) ◽  
pp. 4905-4931 ◽  
Author(s):  
Victor Lannuque ◽  
Florian Couvidat ◽  
Marie Camredon ◽  
Bernard Aumont ◽  
Bertrand Bessagnet
Keyword(s):  
Organic Compound ◽  
Urban Areas ◽  
Transport Model ◽  
Organic Aerosol ◽  
Basis Set ◽  
Anthropogenic Sources ◽  
Continental Scale ◽  
Model Configuration ◽  
Aging Rates ◽  
Terpene Oxidation

Abstract. The VBS-GECKO (volatility basis set – Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) parameterization for secondary organic aerosol (SOA) formation was integrated into the chemistry-transport model CHIMERE. Concentrations of organic aerosol (OA) and SOA were simulated over Europe for the July–August 2013 period. Simulated concentrations with VBS-GECKO were compared to results obtained with the former H2O parameterization implemented in CHIMERE and to observations from EMEP, ACTRIS and other observations available in the EBAS database. The model configuration using the VBS-GECKO parameterization slightly improves the performances compared to the model configuration using the former H2O parameterization. The VBS-GECKO model configuration performs well for stations showing a large SOA concentration from biogenic sources, especially in northern Europe, but underestimates OA concentrations over stations close to urban areas. Simulated OA was found to be mainly secondary (∼85 %) and from terpene oxidation. Simulations show negligible contribution of the oxidation of mono-aromatic compounds to SOA production. Tests performed to examine the sensitivity of simulated OA concentrations to hydro-solubility, volatility, aging rates and NOx regime have shown that the VBS-GECKO parameterization provides consistent results, with a weak sensitivity to changes in the parameters provided by the gas-phase mechanism included in CHIMERE (e.g., HOx or NOx concentrations). Different scenarios considering intermediate-volatility organic compound (IVOC) emissions were tested to examine the contribution of IVOC oxidation to SOA production. At the continental scale, these simulations show a weak sensitivity of OA concentrations to IVOC emission variations. At the local scale, accounting for IVOC emissions was found to lead to a substantial increase in OA concentrations in the plume from urban areas. This additional OA source remains too small to explain the gap between simulated and measured values at stations where anthropogenic sources are dominant.

scholarly journals Temporal variations in CO<sub>2</sub> and CO at Ahmedabad in western India

2015 ◽  
Vol 15 (22) ◽  
pp. 32185-32238 ◽  
Author(s):  
N. Chandra ◽  
S. Lal ◽  
S. Venkataramani ◽  
P. K. Patra ◽  
V. Sheel
Keyword(s):  
Atmospheric Chemistry ◽  
Urban Areas ◽  
Fossil Fuel ◽  
Transport Model ◽  
Urban Site ◽  
Urban Region ◽  
Western India ◽  
Study Region ◽  
Late Night ◽  
South West Monsoon

Abstract. About 70 % of the anthropogenic CO2 is emitted from the megacities and urban areas of the world. In-situ simultaneous measurements of carbon dioxide (CO2) and carbon monoxide (CO) have been made using a state-of-the-art laser based cavity ring down spectroscopy technique at Ahmedabad, an urban site in western India, from November 2013 to May 2015 with a break during March to June 2014. Annual average concentrations of CO2 and CO have been found to be 413.0 ± 13.7 ppm and 0.50 ± 0.37 ppm respectively. Both the species show strong seasonality, with lower concentrations of 400.3 ± 6.8 ppm and 0.19 ± 0.13 ppm, respectively during the south-west monsoon, and higher values of 419.6 ± 22.8 ppm and 0.72 ± 0.68 ppm, respectively in autumn (SON). Strong diurnal variations are also observed for both the species. The common factors for diurnal cycles of CO2 and CO are the vertical mixing and rush hour traffic, while the influence of biospheric fluxes is also seen in CO2 diurnal cycle. Using CO and CO2 covariation, we differentiate the anthropogenic and biospheric components of CO2 and found that significant contributions of biospheric respiration and anthropogenic emission in the late night (00:00–05:00 IST) and evening rush hours (18:00–22:00 IST) respectively. We compute total yearly emission of CO to be 69.2 ± 0.07 Gg for the study region using the observed CO : CO2 correlation slope and bottom-up CO2 emission inventory. This calculated emission of CO is 52 % larger than the estimated emission of CO by the EDGAR inventory. The observations of CO2 have been compared with an atmospheric chemistry transport model (i.e., ACTM), which incorporates various components of CO2 fluxes. ACTM is able to capture the basic variabilities, but both diurnal and seasonal amplitudes are largely underestimated compared to the observations. We attribute this underestimation by model to uncertainties in terrestrial biosphere fluxes and coarse model resolution. The fossil fuel signal from the model shows fairly good correlation with observed CO2 variations, which supports the overall dominance of fossil fuel emissions over the biospheric fluxes in this urban region.

scholarly journals The influence of megacities on global atmospheric chemistry: a modelling study

2009 ◽  
Vol 6 (3) ◽  
pp. 219 ◽  
Author(s):  
Timothy M. Butler ◽  
Mark G. Lawrence
Keyword(s):  
Atmospheric Chemistry ◽  
Urban Areas ◽  
Radiative Forcing ◽  
Transport Model ◽  
Spatial Scales ◽  
Global Scale ◽  
Reactive Nitrogen ◽  
Grid Cells ◽  
Chemical Transport Model ◽  
Future Scenario

Environmental context. Over half of the population of the world now live in urban areas, and the number of so-called ‘megacities’, with populations of ~10 million or more, is growing at a tremendous rate. We show how these patterns of urbanisation have the potential to influence the atmospheric chemical environment on a global scale, particularly through the effects of emissions from megacities on the reactive nitrogen cycle. With the growing worldwide interest in the study of the effects of megacities at all spatial scales, such as current European Union projects MEGAPOLI and CityZen, our study represents the first of many future studies that examine the effects of megacities on atmospheric chemistry on the global scale. Abstract. We present the first study of the effects of megacities on global atmospheric chemistry using a global three-dimensional chemical transport model. The effects on air quality, radiative forcing and atmospheric oxidation capacity are disproportionately smaller than the proportion of anthropogenic emissions due to megacities. Disproportionately large effects of megacities are modelled for reactive nitrogen compounds, in particular PAN (peroxy acetyl nitrate), which has increased in abundance globally by 9% due to megacities under year 2000 conditions, with 23% of the Earth experiencing an increase of 10% or more. These influences decrease under two very different future emission scenarios. Under a low-emission future scenario, the influence of megacities is generally reduced, and under a high-emission future scenario, although the local influence of megacities is increased, the geographical extent of the influence becomes smaller. In our model, the individual grid cells that contain megacities respond to the megacity emissions differently depending on their latitude. Tropical megacity grid cells generally show increased ozone year-round, while northern extratropical megacities generally show reduced ozone year-round. Better parameterisation of the sub-grid effects of megacities is an important issue for future work.

scholarly journals Clean air for some: Unintended spillover effects of regional air pollution policies

2019 ◽  
Vol 5 (4) ◽  
pp. eaav4707 ◽  
Author(s):  
Delin Fang ◽  
Bin Chen ◽  
Klaus Hubacek ◽  
Ruijing Ni ◽  
Lulu Chen ◽  
...  
Keyword(s):  
Air Pollution ◽  
Water Consumption ◽  
Urban Areas ◽  
Transport Model ◽  
Spillover Effects ◽  
Chemical Transport Model ◽  
Target Region ◽  
Clean Air ◽  
The Cost ◽  
Reduced Water

China has enacted a number of ambitious pollution control policies to mitigate air pollution in urban areas. Unintended side effects of these policies to other environmental policy arenas and regions have largely been ignored. To bridge this gap, we use a multiregional input-output model in combination with an atmospheric chemical transport model to simulate clean air policy scenarios and evaluate their environmental impacts on primary PM2.5and secondary precursor emissions, as well as CO2emissions and water consumption, in the target region and spillover effects to other regions. Our results show that the reduction in primary PM2.5and secondary precursor emissions in the target regions comes at the cost of increasing emissions especially in neighboring provinces. Similarly, co-benefits of lower CO2emissions and reduced water consumption in the target region are achieved at the expense of higher impacts elsewhere, through outsourcing production to less developed regions in China.

scholarly journals Delivery of anthropogenic bioavailable iron from mineral dust and combustion aerosols to the ocean

2015 ◽  
Vol 15 (16) ◽  
pp. 23051-23088 ◽  
Author(s):  
A. Ito ◽  
Z. Shi
Keyword(s):  
Air Pollution ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Mineral Dust ◽  
Water Soluble ◽  
Anthropogenic Sources ◽  
Molar Ratio ◽  
Deposition Flux ◽  
Atmospheric Concentration ◽  
Mineral Aerosols

Abstract. Atmospheric deposition of anthropogenic soluble iron (Fe) to the ocean has been suggested to modulate primary ocean productivity and thus indirectly affect the climate. A key process contributing to anthropogenic sources of soluble Fe is associated with air pollution, which acidifies Fe-containing mineral aerosols during their transport and leads to Fe transformation from insoluble to soluble forms. However, there is large uncertainty in our estimate of this anthropogenic soluble Fe. Here, we, for the first time, interactively combined laboratory kinetic experiments with global aerosol modeling to more accurately quantify anthropogenic soluble Fe due to air pollution. We firstly examined Fe dissolution kinetics of African dust samples at acidic pH values with and without ionic species commonly found in aerosol water (i.e., sulfate and oxalate). We then constructed a new empirical scheme for Fe release from mineral dust due to inorganic and organic anions in aerosol water, by using acidity as a master variable. We implemented this new scheme and applied an updated mineralogical emission database in a global atmospheric chemistry transport model to estimate the atmospheric concentration and deposition flux of soluble Fe under preindustrial and modern conditions. Our improved model successfully captured the inverse relationship of Fe solubility and total Fe loading measured over the North Atlantic Ocean (i.e., 1–2 orders of magnitude lower Fe solubility in North African- than combustion-influenced aerosols). The model results show a positive relationship between Fe solubility and water soluble organic carbon (WSOC)/Fe molar ratio, which is consistent with previous field measurements. We estimated that deposition of soluble Fe to the ocean increased from 0.05–0.07 Tg Fe yr−1 in preindustrial era to 0.11–0.12 Tg Fe yr−1 in present days, due to air pollution. Over the High Nitrate Low Chlorophyll (HNLC) regions of the ocean, the modeled Fe solubility remains low for mineral dust (< 1 %) in a base simulation but is substantially enhanced in a sensitivity simulation, which permits the Fe dissolution for mineral aerosols in the presence of excess oxalate under low acidity during daytime. Our model results suggest that human activities contribute to about half of the soluble Fe supply to a significant portion of the oceans in the Northern Hemisphere, while their contribution to oceans in high latitudes remains uncertain due to limited understanding of dust Fe dissolution under pristine conditions.

Sign in / Sign up

Export Citation Format

Share Document