Eulerian-Lagrangian CFD-microphysics modeling of Aircraft-Emitted Aerosol Formation at Ground Level

2022 ◽  
Author(s):  
Sebastien S. Cantin ◽  
Mohamed Chouak ◽  
François Morency ◽  
François Garnier
Keyword(s):  
Ground Level ◽  
Aerosol Formation

scholarly journals Secondary organic aerosol formation from photooxidation of furan: effects of NOx and humidity

2019 ◽  
Author(s):  
Xiaotong Jiang ◽  
Narcisse T. Tsona ◽  
Long Jia ◽  
Shijie Liu ◽  
Hailiang Zhang ◽  
...  
Keyword(s):  
Ultrafine Particles ◽  
Mass Concentration ◽  
Secondary Organic Aerosol ◽  
Ground Level ◽  
Organic Aerosol ◽  
Liquid Water Content ◽  
Aerosol Formation ◽  
Scanning Mobility Particle Sizer ◽  
Experimental Conditions ◽  
Significant Difference

Abstract. Atmospheric furan is a primary and secondary pollutant in the atmosphere, and its emission contributes to the formation of ultrafine particles and ground-level ozone. We investigate the effects of NOx level and humidity on the formation of secondary organic aerosol (SOA) generated from the photooxidation of furan in the presence of NaCl seed particles. The particle mass concentration and size distribution were determined with a scanning mobility particle sizer (SMPS). SOA mass concentration and yield were determined under different NOx and humidity levels. A significant difference is observed both in the SOA mass concentration and SOA yield variation with the initial experimental conditions. Six organic products were identified in the collected SOA by electrospray ionization exactive orbitrap mass spectrometry (ESI-Exactive-Orbitrap MS). The –COOH, –OH, –C=O and NO2 functional groups were assigned in the FTIR spectra and used as the indicator for the mechanism inference. In addition, O3 formation was also observed during the furan-NOx-NaCl photooxidation. Based on the MS analysis, the reaction mechanism was proposed to follow the RO2+NO pathway. A significant amount of carbonyl-rich products was detected in the SOA products from the photooxidation of furan. The SOA mass concentration and yield increase with increasing humidity, because higher aerosol liquid water content brings more aqueous phase reactions. The present study demonstrates the effect of NOx and humidity on SOA formation during the furan-NOx-NaCl photooxidation. Furthermore, the results illustrate the importance of studying SOA formation over a comprehensive range of environmental conditions. Only such evaluations can induce meaningful SOA mechanisms to be implemented in air quality models.

Eddy covariance (EC) fluxes of monoterpene oxidation products from a boreal forest canopy

2020 ◽  
Author(s):  
Lejish Vettikkat ◽  
Arttu Ylisirniö ◽  
Iida Pullinen ◽  
Luís Miguel Feijó Barreira ◽  
Pasi Miettinen ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Eddy Covariance ◽  
Organic Compounds ◽  
Mass Spectrometer ◽  
Time Of Flight ◽  
Ground Level ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Aerosol Formation ◽  
Flux Measurements

<p>Oxidation of volatile organic compounds (VOC) by ozone (O<sub>3</sub>), hydroxyl radicals (OH) and nitrogen oxide radicals (NO<sub>3</sub>, NOx) reduces their volatility and leads to the formation of secondary organic aerosols (SOA) through gas-particle partitioning. Recent studies have shown that monoterpene (C<sub>10</sub>H<sub>16</sub>) oxidation products can participate in all stages of aerosol formation, especially in forested boreal environments. However, deposition of these semi-volatile and (extremely) low-volatility organic compounds (SVOC, LVOC, ELVOC) to surfaces in the canopy directly competes with the gas-particle partitioning and has a substantial effect (~50%) on organic aerosol loading. Hence understanding the fate of these oxidation products is crucial in determining the organic aerosol budget and thereby constraining their contribution to climate-relevant processes such as new-particle formation and cloud formation.</p><p>Oxidation products of monoterpenes were measured at the station for measuring ecosystem atmosphere relations (SMEAR II), a boreal forest research station in Hyytiälä, Finland, in spring/summer 2019. The forest is dominated by Scots pine (<em>Pinus sylvestris</em> L.) and Norway spruce (<em>Picea abies</em> (L.) H. Karst) which are well known high monoterpene emitters. Eddy covariance (EC) flux measurements of oxygenated organic compounds in the gas phase were performed using an iodide-adduct high-resolution time-of-flight chemical ionization mass spectrometer (I-CIMS) with high frequency (5 Hz) co-located with a sonic anemometer (METEK USA-1) on a tower, 35 m above the forest floor. The ion-molecule reaction (IMR) chamber of I-CIMS was actively humidified to mitigate the dependence of the sensitivity of the measurements on the ambient relative humidity. The EC data were analysed following standard correction procedures like lag correction, coordinate rotation and uncertainty analysis. VOCs and oxygenated VOCs were also measured at ground level using a Vocus proton-transfer-reaction time-of-flight mass spectrometer (Vocus PTR-MS), which is sensitive also to the majority of compounds measured by I-CIMS.</p><p>We present the first continuous I-CIMS dataset at high time resolution (5 Hz) from a tall tower and calculate the Eddy covariance fluxes of a wide range of monoterpene oxidation products during the primary plant-growth season in a boreal forest. Bidirectional fluxes for formic acid (HCOOH) were observed at a higher temporal resolution than reported in earlier studies. We found an increasing trend in the deposition velocity for heavier monoterpene oxidation products which enables us to constrain the net flow of organics between the atmosphere and the canopy layer using the continuity/mass balance equation. When coupled to ground-based measurements using Vocus-PTR, our EC flux measurements will give further insight about the abundance of organics above the canopy vs near ground-level. We also plan to integrate our observations with a chemical transport model containing details of monoterpene oxidation chemistry (ADCHEM) to simulate the sources and sinks and to derive parameterizations for representing the dry deposition rates of monoterpene oxidation products in the boreal forested environments.</p>

scholarly journals Atmospheric sub-3 nm particles at high altitudes

2009 ◽  
Vol 9 (5) ◽  
pp. 19435-19470 ◽  
Author(s):  
S. Mirme ◽  
A. Mirme ◽  
A. Minikin ◽  
A. Petzold ◽  
U. Hõrrak ◽  
...  
Keyword(s):  
Atmospheric Aerosol ◽  
Aerosol Particles ◽  
Particle Diameter ◽  
Ground Level ◽  
Atmospheric Particles ◽  
Aerosol Formation ◽  
Upper Troposphere ◽  
Ion Clusters ◽  
Almost All ◽  
Atmospheric Clusters

Abstract. Formation of new atmospheric aerosol particles is known to occur almost all over the world and the importance of these particles to climate and air quality has been recognized. Recently, it was found that atmospheric aerosol formation begins at particle diameter of around 1.5–2.0 nm and a pool of sub-3 nm atmospheric particles – consisting of both charged and uncharged ones – was observed at the ground level. Here, we report on the first airborne observations of the pool of sub-3 nm neutral atmospheric particles. Between 2 and 3 nm, their concentration is roughly two orders of magnitude larger than that of the ion clusters, depending slightly on the altitude. Our findings indicate that new particle formation takes place actively throughout the tropospheric column up to the tropopause. Particles were found to be formed via neutral pathways in the boundary layer, and there was no sign of an increasing role by ion-induced nucleation toward the upper troposphere. Clouds, while acting as a source of sub-10 nm ions, did not perturb the overall budget of atmospheric clusters or particles.

scholarly journals Secondary organic aerosol formation from photooxidation of furan: effects of NO<sub>x</sub> level and humidity

2018 ◽  
Author(s):  
Xiaotong Jiang ◽  
Narcisse T. Tsona ◽  
Long Jia ◽  
Shijie Liu ◽  
Yongfu Xu ◽  
...  
Keyword(s):  
Ultrafine Particles ◽  
Mass Concentration ◽  
Secondary Organic Aerosol ◽  
Ground Level ◽  
Organic Aerosol ◽  
Organic Nitrate ◽  
Aerosol Formation ◽  
Scanning Mobility Particle Sizer ◽  
Seed Particles ◽  
Significant Difference

Abstract. Atmospheric furan is both primary and secondary pollutants in the atmosphere, and their emission contributes to the formation of ultrafine particles and ground-level ozone. We investigate the effects of NOx level and humidity on the formation of secondary organic aerosol (SOA) generated from the photooxidation of furan in the presence of NaCl seed particles. The particle mass concentration and size distribution were determined with a scanning mobility particle sizer (SMPS). SOA mass concentration and yield were determined under different NOx and humidity levels. Owing to condensation and coagulation, the particle number concentration decreases with increasing particle size. A significant difference is observed both in the SOA mass concentration and SOA yield variation with the initial experiment conditions. A relatively high NOx level, ranging from 16.8 to 97.5 ppb, contributes to effective formation of SOA in the presence of NaCl seed particles, with the mass concentration of SOA and SOA yield ranging from 0.96 μg m−3 to 23.46 μg m−3 and from 0.04 % to 1.01 %, respectively. Likewise, the SOA mass concentration and yield increase with increasing humidity, because the increasing RH increases the aerosol liquid water content, which contributes to the liquid phase reactions. Nine organic nitrate species were detected by electrospray ionization exactive orbitrap mass spectrometry (ESI-Exactive-Orbitrap MS). The -COOH，-OH，-C = O and NO2 functional groups were assigned in the FTIR spectra and used as the indicator for the mechanism inference. The present study directly addresses NOx effects and reinforces the implication of humidity on SOA formation during the furan-NOx-NaCl photooxidation. Furthermore, the results illustrate the importance of studying SOA formation over a comprehensive range of environmental conditions. Only such evaluations can induce meaningful SOA mechanisms to be implemented in air quality models.

Microphysical Modeling of Ground-Level Aircraft-Emitted Aerosol Formation: Roles of Sulfur-Containing Species

2008 ◽  
Vol 24 (3) ◽  
pp. 590-602 ◽  
Author(s):  
Hsi-Wu Wong ◽  
Paul E. Yelvington ◽  
Michael T. Timko ◽  
Timothy B. Onasch ◽  
Richard C. Miake-Lye ◽  
...  
Keyword(s):  
Ground Level ◽  
Aerosol Formation ◽  
Sulfur Containing

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 Impacts of the COVID-19 lockdown on air pollution at regional and urban background sites in northern Italy

2021 ◽  
Vol 21 (10) ◽  
pp. 7597-7609
Author(s):  
Jean-Philippe Putaud ◽  
Luca Pozzoli ◽  
Enrico Pisoni ◽  
Sebastiao Martins Dos Santos ◽  
Friedrich Lagler ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Environmental Protection Agency ◽  
Ground Level ◽  
Northern Italy ◽  
Atmospheric Pollutants ◽  
Aerosol Formation ◽  
Economic Sectors ◽  
Urban Background ◽  
Regional Background

Abstract. The COVID-19 lockdown measures gradually implemented in Lombardy (northern Italy) from 23 February 2020 led to a downturn in several economic sectors with possible impacts on air quality. Several communications claimed in the first weeks of March 2020 that the mitigation in air pollution observed at that time was actually related to these lockdown measures without considering that seasonal variations in emissions and meteorology also influence air quality. To determine the specific impact of lockdown measures on air quality in northern Italy, we compared observations from the European Commission Atmospheric Observatory of Ispra (regional background) and from the regional environmental protection agency (ARPA) air monitoring stations in the Milan conurbation (urban background) with expected values for these observations using two different approaches. On the one hand, intensive aerosol variables determined from specific aerosol characterisation observations performed in Ispra were compared to their 3-year averages. On the other hand, ground-level measured concentrations of atmospheric pollutants (NO2, PM10, O3, NO, SO2) were compared to expected concentrations derived from the Copernicus Atmosphere Monitoring Service Regional (CAMS) ensemble model forecasts, which did not account for lockdown measures. From these comparisons, we show that NO2 concentrations decreased as a consequence of the lockdown by −30 % and −40 % on average at the urban and regional background sites, respectively. Unlike NO2, PM10 concentrations were not significantly affected by lockdown measures. This could be due to any decreases in PM10 (and PM10 precursors) emissions from traffic being compensated for by increases in emissions from domestic heating and/or from changes in the secondary aerosol formation regime resulting from the lockdown measures. The implementation of the lockdown measures also led to an increase in the highest O3 concentrations at both the urban and regional background sites resulting from reduced titration of O3 by NO. The relaxation of the lockdown measures beginning in May resulted in close-to-expected NO2 concentrations in the urban background and to significant increases in PM10 in comparison to expected concentrations at both regional and urban background sites.

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 Cosmic ray-induced stratospheric aerosols: A possible connection to polar ozone depletions

2005 ◽  
Vol 23 (3) ◽  
pp. 675-679 ◽  
Author(s):  
E. A. Kasatkina ◽  
O. I. Shumilov
Keyword(s):  
Total Content ◽  
Cosmic Ray ◽  
Ground Level ◽  
Aerosol Formation ◽  
Neutron Monitors ◽  
Model Calculations ◽  
Altitude Distribution ◽  
Concentration Enhancement ◽  
Moderate Magnitude ◽  
Polar Ozone

Abstract. The model calculations of altitude distribution of CN (condensation nuclei), plausible centers of sulfate aerosol formation after the occurrence of GLE, are presented. Events with relativistic solar protons (i.e. protons with energies >450MeV) are observed at ground level by neutron monitors and called ground-level events (GLEs) (Shea and Smart, 2001). Analysis of experimental data and model calculations permits us to explain some distinctions observed in ozone total content (OTC) variations during several GLEs. For example, model simulations show a significant CN concentration enhancement during the May 1990 GLEs of relatively "moderate" magnitude, when polar ozone "mini-holes" (OTC depletions up to 20%) have been observed, while no OTC variations and considerable aerosol enhancements were seen during more powerful GLEs (4 August 1972, 2 May 1998, 14 July 2000) (Reagan et al., 1981; Shumilov et al., 1995, 2003). Our results demonstrate that "moderate" GLEs may increase aerosol content significantly and cause ozone "mini-hole" creation.

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