scholarly journals A Spatial Analysis of Atmospheric Ammonia and Ammonium in the U.K.

2001 ◽  
Vol 1 ◽  
pp. 275-286 ◽  
Author(s):  
M.A. Sutton ◽  
Y.S. Tang ◽  
U. Dragosits ◽  
N. Fournier ◽  
A.J. Dore ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Low Cost ◽  
Monitoring Network ◽  
Ground Level ◽  
Aerosol Formation ◽  
National Network ◽  
Nh3 Emission ◽  
Annual Means

As measures are implemented internationally to reduce SO2 and NOx emissions, attention is falling on the contribution of NH3 emissions to acidification, nitrogen eutrophication, and aerosol formation. In the U.K., a monitoring network has been established to measure the spatial distribution and long-term trends in atmospheric gaseous NH3 and aerosol NH4+. At the same time, an atmospheric chemistry and transport model, FRAME, has been developed with a focus on reduced nitrogen (NHx). The monitoring data are important to evaluate the model, while the model is essential for a more detailed spatial assessment. The national network is established with over 80 sampling locations. Measurements of NH3 and NH4+ (at up to 50 sites) have been made using a new low-cost denuder-filterpack system. Additionally, improved passive sampling methods for NH3 have been applied to explore local variability. The measurements confirm the high spatial variability of NH3 (annual means 0.06 to 11 mg NH3 m�3), consistent with its nature as a primary pollutant emitted from ground-level sources, while NH4+, being a slowly formed secondary product, shows much less spatial variability (0.14 to 2.4 mg NH4+ m�3). These features are reproduced in the FRAME model, which provides estimates at a 5-km level. Analysis of the underlying NH3 emission inventory shows that sheep emissions may have been underestimated and nonagricultural sources overestimated relative to emissions from cattle. The combination of model and measurements is applied to estimate spatial patterns of dry deposition to different vegetation types. The combined approach provides the basis to assess NHx responses across the U.K. to international emission controls.

scholarly journals Urban Air Quality Modeling Using Low-Cost Sensor Network and Data Assimilation in the Aburrá Valley, Colombia

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 91
Author(s):  
Santiago Lopez-Restrepo ◽  
Andres Yarce ◽  
Nicolás Pinel ◽  
O.L. Quintero ◽  
Arjo Segers ◽  
...  
Keyword(s):  
Air Quality ◽  
Data Assimilation ◽  
Transport Model ◽  
Cost Model ◽  
Low Cost ◽  
Model Performance ◽  
Monitoring Network ◽  
Correlation Factor ◽  
Chemical Transport Model ◽  
High Quality

The use of low air quality networks has been increasing in recent years to study urban pollution dynamics. Here we show the evaluation of the operational Aburrá Valley’s low-cost network against the official monitoring network. The results show that the PM2.5 low-cost measurements are very close to those observed by the official network. Additionally, the low-cost allows a higher spatial representation of the concentrations across the valley. We integrate low-cost observations with the chemical transport model Long Term Ozone Simulation-European Operational Smog (LOTOS-EUROS) using data assimilation. Two different configurations of the low-cost network were assimilated: using the whole low-cost network (255 sensors), and a high-quality selection using just the sensors with a correlation factor greater than 0.8 with respect to the official network (115 sensors). The official stations were also assimilated to compare the more dense low-cost network’s impact on the model performance. Both simulations assimilating the low-cost model outperform the model without assimilation and assimilating the official network. The capability to issue warnings for pollution events is also improved by assimilating the low-cost network with respect to the other simulations. Finally, the simulation using the high-quality configuration has lower error values than using the complete low-cost network, showing that it is essential to consider the quality and location and not just the total number of sensors. Our results suggest that with the current advance in low-cost sensors, it is possible to improve model performance with low-cost network data assimilation.

scholarly journals Comparing three vegetation monoterpene emission models to measured gas concentrations with a model of meteorology, air chemistry and chemical transport

2013 ◽  
Vol 10 (11) ◽  
pp. 18563-18611
Author(s):  
S. Smolander ◽  
Q. He ◽  
D. Mogensen ◽  
L. Zhou ◽  
J. Bäck ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Coniferous Forest ◽  
Chemical Species ◽  
Field Measurements ◽  
Global Scale ◽  
Aerosol Formation ◽  
Seasonal And Diurnal Variations ◽  
Air Chemistry ◽  
Emission Models

Abstract. Biogenic volatile organic compounds (BVOCs) are essential in atmospheric chemistry because of their chemical reactions that produce and destroy tropospheric ozone, their effects on aerosol formation and growth, and their potential influence on global warming. As one of the important BVOC groups, monoterpenes have been a focus of scientific attention in atmospheric research. Detailed regional measurements and model estimates are needed to study emission potential and the monoterpene budget on a global scale. Since the use of empirical measurements for upscaling is limited by many physical and biological factors such as genetic variation, temperature and light, water availability, seasonal changes, and environmental stresses, comprehensive inventories over larger areas are difficult to obtain. We applied the boundary layer-chemistry-transport model SOSA to investigate Scots pine (Pinus sylvestris) monoterpene emissions in a boreal coniferous forest at the SMEAR II site, Southern Finland. SOSA was applied to simulate monoterpene emissions with three different emission modules: the semi-empirical G95, MEGAN 2.04 with improved descriptions of temperature and light responses and including also carbonyl emissions, and a process-based model SIM-BIM. For the first time, the emission models included seasonal and diurnal variations in both quantity and chemical species of emitted monoterpenes, based on parameterizations obtained from field measurements. Results indicate that modelling and observations agreed reasonably well, and that the model can be used for investigating regional air chemistry questions related to monoterpenes. The predominant modelled monoterpene concentrations, α-pinene and Δ3-carene, are consistent with observations.

scholarly journals Simulating Lightning NO<sub>X</sub> Production in CMAQv5.2 Using mNLDN, hNLDN, and pNLDN Schemes: Performance Evaluation

2019 ◽  
Author(s):  
Daiwen Kang ◽  
Kristen Foley ◽  
Rohit Mathur ◽  
Shawn Roselle ◽  
Kenneth Pickering ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Wet Deposition ◽  
Monitoring Network ◽  
Ground Level ◽  
Daily Maximum ◽  
Lightning Flash ◽  
Vertical Profiles ◽  
Model Predictions ◽  
The Impact ◽  
Surface O3

Abstract. This study assesses the impact of the lightning NOX (LNOX) production schemes in the CMAQ model (Kang et al., 2019) on ground-level air quality as well as aloft atmospheric chemistry through detailed evaluation of model predictions of nitrogen oxides (NOx) and ozone (O3) with corresponding observations for the U.S. For ground-level evaluations, hourly O3 and NOx from the US EPA's AQS monitoring network are used to assess the impact of different LNOx schemes on model prediction of these species in time and space. Vertical evaluations are performed using ozonesonde and P-3B aircraft measurements during the DISCOVER-AQ campaign conducted in the Baltimore/Washington region during July 2011. The impact on wet deposition of nitrate is assessed using measurements from the National Atmospheric Deposition Program's National Trends Network (NADP/NTN). Compared with the base model (without LNOx), the impact of LNOx on surface O3 varies from region to region depending on the base model conditions. Overall statistics suggest that for regions where surface O3 mixing ratios are already overestimated, the incorporation of additional NOx from lightning generally increased model overestimation of mean daily maximum 8-hr (DM8HR) O3 by 1–2 ppb. In regions where surface O3 is underestimated by the base model, LNOx can significantly reduce the underestimation and bring model predictions close to observations. Analysis of vertical profiles reveals that LNOx can significantly improve the vertical structure of modeled O3 distributions by reducing underestimation aloft, and to a lesser degree decreasing overestimation near the surface. Since the base model underestimates the wet deposition of nitrate in most regions across the modeling domain except the Pacific Coast, the inclusion of LNOx leads to reduction in biases and errors and an increase in correlation coefficients at almost all the NADP/NTN sites. Among the three LNOx schemes described in Kang et al. (2019), the hNLDN scheme, which is implemented using hourly observed lightning flash data from National Lightning Detection Network (NLDN), performs best for the ground-level, vertical profiles, and wet deposition comparisons except that for the accumulated wet deposition of nitrate, the mNLDN scheme (the monthly NLDN-based scheme) performed slightly better. However, when observed lightning flash data are not available, the linear regression-based parameterization scheme, pNLDN, provides an improved estimate for LNOx compared to the base simulation that does not include LNOx.

scholarly journals Detecting changes in Arctic methane emissions: limitations of the inter-polar difference of atmospheric mole fractions

2018 ◽  
Author(s):  
Oscar B. Dimdore-Miles ◽  
Paul I. Palmer ◽  
Lori P. Bruhwiler
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Random Noise ◽  
Monitoring Network ◽  
The Arctic ◽  
Polar Regions ◽  
Annual Growth Rate ◽  
The Difference ◽  
The Antarctic

Abstract. We consider the utility of the annual inter-polar difference (IPD) as a metric for changes in Arctic emission of methane (CH4). The IPD has been previously defined as the difference between weighted annual means of CH4 mole fraction data collected at polar stations (−53° > latitude > 53°). This subtraction approach (IPDΔ) implicitly assumes that extra-polar CH4 emissions arrive within the same calendar year at both poles. Using an analytic approach we show that a comprehensive description of the IPD includes terms corresponding to the atmospheric transport of air masses from lower latitudes to the polar regions. We show the importance of these transport flux terms in understanding the IPD using idealized numerical experiments with the TM5 global 3-D atmospheric chemistry transport model run from 1980 to 2010. A northern mid-latitude pulse in January 1990, which increases prior emission distributions, arrives at the Arctic with a higher mixing ratio and ≃ 12 months earlier than at the Antarctic. The perturbation at the poles subsequently decays with an e-folding lifetime of ≃ 4 years. A similarly timed pulse emitted from the tropics arrives with a higher value at the Antarctic ≃ 11 months earlier than at the Arctic. This perturbation decays with an e-folding lifetime of ≃ 7 years. These simulations demonstrate that the assumption of symmetric transport of extra-polar emissions to the poles is not realistic, resulting in considerable IPDΔ variations due to variations in emissions and atmospheric transport. We assess how well the annual IPD can detect a constant annual growth rate of Arctic emissions for three scenarios, 0.5 %, 1 %, and 2 %, superimposed on signals from lower latitudes, including random noise. We find that it can take up to 16 years to detect the smallest prescribed trend in Arctic emissions at the 95 % confidence level. Scenarios with higher, but likely unrealistic, growth in Arctic emissions are detected in less than a decade. We argue that a more reliable measurement-driven IPD metric would include data collected from all latitudes, emphasizing the importance of maintaining a global monitoring network to observe decadal changes in atmospheric greenhouse gases.

scholarly journals Comparing three vegetation monoterpene emission models to measured gas concentrations with a model of meteorology, air chemistry and chemical transport

2014 ◽  
Vol 11 (19) ◽  
pp. 5425-5443 ◽  
Author(s):  
S. Smolander ◽  
Q. He ◽  
D. Mogensen ◽  
L. Zhou ◽  
J. Bäck ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Coniferous Forest ◽  
Chemical Species ◽  
Field Measurements ◽  
Global Scale ◽  
Aerosol Formation ◽  
Seasonal And Diurnal Variations ◽  
Air Chemistry ◽  
Emission Models

Abstract. Biogenic volatile organic compounds (BVOCs) are essential in atmospheric chemistry because of their chemical reactions that produce and destroy tropospheric ozone, their effects on aerosol formation and growth, and their potential influence on global warming. As one of the important BVOC groups, monoterpenes have been a focus of scientific attention in atmospheric research. Detailed regional measurements and model estimates are needed to study emission potential and the monoterpene budget on a global scale. Since the use of empirical measurements for upscaling is limited by many physical and biological factors, such as genetic variation, temperature and light, water availability, seasonal changes, and environmental stresses, comprehensive inventories over larger areas are difficult to obtain. We applied the boundary-layer–chemistry-transport model SOSA (model to Simulate the concentrations of Organic vapours and Sulphuric Acid) to investigate Scots pine (Pinus sylvestris) monoterpene emissions in a boreal coniferous forest at the SMEAR (Station for Measuring forest Ecosystem–Atmosphere Relations) II site, southern Finland. SOSA was applied to simulate monoterpene emissions with three different emission modules: the semiempirical G95, MEGAN (Model of Emissions of Gases and Aerosols from Nature) 2.04 with improved descriptions of temperature and light responses and including also carbonyl emissions, and a process-based model SIM–BIM (Seasonal Isoprenoid synthase Model – Biochemical Isoprenoid biosynthesis Model). For the first time, the emission models included seasonal and diurnal variations in both quantity and chemical species of emitted monoterpenes, based on parameterizations obtained from field measurements. Results indicate that modelling and observations agreed reasonably well and that the model can be used for investigating regional air chemistry questions related to monoterpenes. The predominant modelled monoterpene concentrations, α-pinene and Δ3-carene, are consistent with observations.

scholarly journals Impact of primary formaldehyde on air pollution in the Mexico City Metropolitan Area

2008 ◽  
Vol 8 (6) ◽  
pp. 19605-19635 ◽  
Author(s):  
W. Lei ◽  
M. Zavala ◽  
B. de Foy ◽  
R. Volkamer ◽  
M. J. Molina ◽  
...  
Keyword(s):  
Mexico City ◽  
Metropolitan Area ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Monitoring Network ◽  
Ambient Air ◽  
Urban Atmosphere ◽  
Chemical Transport Model ◽  
Early Afternoon ◽  
The Impact

Abstract. Formaldehyde (HCHO) is a radical source that plays an important role in urban atmospheric chemistry and ozone formation. The Mexico City Metropolitan Area (MCMA) is characterized by high anthropogenic emissions of HCHO (primary HCHO), which together with photochemical production of HCHO from hydrocarbon oxidation (secondary HCHO), lead to high ambient HCHO levels. The CAMx chemical transport model was employed to evaluate the impact of primary HCHO on its ambient concentration, on the ROx radical budget, and on ozone (O3) formation in the MCMA. Important radical sources, including HCHO, HONO, and O3-olefin reactions, were constrained by measurements from routine observations of the local ambient air monitoring network and the MCMA-2003 field campaign. Primary HCHO was found not only contributing significantly to the ambient HCHO concentration, but also enhancing the radical budget and O3 production in the urban atmosphere of the MCMA. Overall in the urban area, total daytime radical production is enhanced by up to 10% and peak O3 concentration by up to 8%. While primary HCHO contributes predominantly to the ambient HCHO concentration between nighttime and morning rush hours, significant influence on the radical budget and O3 production starts early morning, culminates at mid-morning and is sustained until early afternoon.

scholarly journals Significant contrasts in aerosol acidity between China and the Unites States

2020 ◽  
Author(s):  
Bingqing Zhang ◽  
Huizhong Shen ◽  
Pengfei Liu ◽  
Hongyu Guo ◽  
Yongtao Hu ◽  
...  
Keyword(s):  
United States ◽  
Transport Model ◽  
Ground Level ◽  
The United States ◽  
Formation Mechanisms ◽  
Aerosol Formation ◽  
Chemical Transport Model ◽  
Aerosol Composition ◽  
Aerosol Acidity ◽  
Acidic Component

Abstract. Aerosol acidity governs several key processes in aerosol physics and chemistry, thus affecting aerosol mass and composition, and ultimately the climate and human health. Previous studies have reported the aerosol pH separately in China and the United States, implying a different aerosol acidity between these two countries. However, underlying mechanisms responsible for the pH difference are not fully understood, limited by the scarcity of simultaneous measurements of aerosol composition and gas species, especially in China. Here we conduct a comprehensive assessment of the aerosol acidity in China and the United States, using extended ground-level measurements and regional chemical transport model simulations. We show aerosol in China is significantly less acidic than that in the United States, with pH values 1–2 units higher. Based on a multivariable Taylor Series method and a series of sensitivity tests, we identify several major factors leading to the pH difference. Compared to the United States, aerosols in China are generally in total ammonia (TNH3 = NH4+ + NH3) rich conditions where particle phase ammonium (NH4+) concentrations are adequate enough to nearly neutralize major acidic inorganic anions such as sulfate, nitrate, and chloride, leading to a higher aerosol pH. Higher relative availability of the stronger acidic component, sulfate, compared with the weaker acidic component, total nitrate (TNO3 = NO3− + HNO3), also contributes to the lower aerosol pH in the United States. As a response to higher aerosol pH, the higher nitrate to sulfate molar ratios in China indicates a nitrate-rich condition, further leading to higher aerosol water uptake which will continually promote nitrate aerosol formation. Considering the historical emissions trends, the difference in aerosol acidity between these two countries is expected to continue as SO2 and NOx emissions are further controlled. The differences in aerosol acidity highlight in the present study imply potential differences in formation mechanisms, physicochemical properties, and toxicity of aerosol particles between China and the United States.

scholarly journals H2020 project CAPTOR dataset: raw data collected by low-cost MOX ozone sensors in a real air pollution monitoring network.

Data in Brief ◽  
2021 ◽  
pp. 107127
Author(s):  
Jose M. Barcelo-Ordinas ◽  
Pau Ferrer-Cid ◽  
Jorge Garcia-Vidal ◽  
Mar Viana ◽  
Ana Ripoll
Keyword(s):  
Air Pollution ◽  
Low Cost ◽  
Monitoring Network ◽  
Pollution Monitoring ◽  
Raw Data ◽  
Air Pollution Monitoring

scholarly journals Oceanic phytoplankton are a potentially important source of benzenoids to the remote marine atmosphere

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Manon Rocco ◽  
Erin Dunne ◽  
Maija Peltola ◽  
Neill Barr ◽  
Jonathan Williams ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Dimethyl Sulfide ◽  
Laboratory Culture ◽  
Marine Phytoplankton ◽  
Marine Atmosphere ◽  
Aerosol Formation ◽  
Incubation Experiments ◽  
Phytoplankton Communities ◽  
Anthropogenic Air Pollutants ◽  
Benzene Toluene

AbstractBenzene, toluene, ethylbenzene and xylenes can contribute to hydroxyl reactivity and secondary aerosol formation in the atmosphere. These aromatic hydrocarbons are typically classified as anthropogenic air pollutants, but there is growing evidence of biogenic sources, such as emissions from plants and phytoplankton. Here we use a series of shipborne measurements of the remote marine atmosphere, seawater mesocosm incubation experiments and phytoplankton laboratory cultures to investigate potential marine biogenic sources of these compounds in the oceanic atmosphere. Laboratory culture experiments confirmed marine phytoplankton are a source of benzene, toluene, ethylbenzene, xylenes and in mesocosm experiments their sea-air fluxes varied between seawater samples containing differing phytoplankton communities. These fluxes were of a similar magnitude or greater than the fluxes of dimethyl sulfide, which is considered to be the key reactive organic species in the marine atmosphere. Benzene, toluene, ethylbenzene, xylenes fluxes were observed to increase under elevated headspace ozone concentration in the mesocosm incubation experiments, indicating that phytoplankton produce these compounds in response to oxidative stress. Our findings suggest that biogenic sources of these gases may be sufficiently strong to influence atmospheric chemistry in some remote ocean regions.

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