scholarly journals Description and evaluation of the community aerosol dynamics model MAFOR v2.0

2021 ◽  
Author(s):  
Matthias Karl ◽  
Liisa Pirjola ◽  
Tiia Grönholm ◽  
Mona Kurppa ◽  
Srinivasan Anand ◽  
...  
Keyword(s):  
Street Canyon ◽  
Ultrafine Particles ◽  
Particle Number ◽  
Numerical Models ◽  
Operator Splitting ◽  
Aerosol Formation ◽  
Dynamics Model ◽  
Aerosol Dynamics ◽  
Model Version ◽  
Consistent Treatment

Abstract. Numerical models are needed for evaluating aerosol processes in the atmosphere in state-of-the-art chemical transport models, urban-scale dispersion models and climatic models. This article describes a publicly available aerosol dynamics model MAFOR (Multicomponent Aerosol FORmation model; version 2.0); we address the main structure of the model, including the types of operation and the treatments of the aerosol processes. The main advantage of MAFOR v2.0 is the consistent treatment of both the mass- and number-based concentrations of particulate matter. An evaluation of the model is also presented, against a high-resolution observational dataset in a street canyon located in the centre of Helsinki (Finland) during an afternoon traffic rush hour on 13 December 2010. The experimental data included measurements at different locations in the street canyon of ultrafine particles, black carbon, and fine particulate mass PM1. This evaluation has also included an intercomparison with the corresponding predictions of two other prominent aerosol dynamics models, AEROFOR and SALSA. All three models fairly well simulated the decrease of the measured total particle number concentrations with increasing distance from the vehicular emission source. The MAFOR model reproduced the evolution of the observed particle number size distributions more accurately than the other two models. The MAFOR model also predicted the variation of the concentration of PM1 better than the SALSA model. We also analysed the relative importance of various aerosol processes based on the predictions of the three models. As expected, atmospheric dilution dominated over other processes; dry deposition was the second most significant process. Numerical sensitivity tests with the MAFOR model revealed that the uncertainties associated with the properties of the condensing organic vapours affected only the size range of particles smaller than 10 nm in diameter. These uncertainties do not therefore affect significantly the predictions of the whole of the number size distribution and the total number concentration. The MAFOR model version 2 is well documented and versatile to use, providing a range of alternative parametrizations for various aerosol processes. The model includes an efficient numerical integration of particle number and mass concentrations, an operator-splitting of processes, and the use of a fixed sectional method. The model could be used as a module in various atmospheric and climatic models.

scholarly journals Aerosol ageing in an urban plume – implication for climate

2011 ◽  
Vol 11 (12) ◽  
pp. 5897-5915 ◽  
Author(s):  
P. Roldin ◽  
E. Swietlicki ◽  
A. Massling ◽  
A. Kristensson ◽  
J. Löndahl ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Particle Number ◽  
Particulate Emissions ◽  
Aerosol Formation ◽  
Aerosol Dynamics ◽  
Cloud Properties ◽  
Total Particle ◽  
Physical Particle ◽  
Urban Plume ◽  
Phase Chemistry

Abstract. The climate effects downwind of an urban area resulting from gaseous and particulate emissions within the city are as yet inadequately quantified. The aim of this work was to estimate these effects for Malmö city in southern Sweden (population 280 000). The chemical and physical particle properties were simulated with a model for Aerosol Dynamics, gas phase CHEMistry and radiative transfer calculations (ADCHEM) following the trajectory movement from upwind of Malmö, through the urban background environment and finally tens and hundreds of kilometers downwind of Malmö. The model results were evaluated using measurements of the particle number size distribution and chemical composition. The total particle number concentration 50 km (~ 3 h) downwind, in the center of the Malmö plume, is about 3700 cm−3 of which the Malmö contribution is roughly 30%. Condensation of nitric acid, ammonium and to a smaller extent oxidized organic compounds formed from the emissions in Malmö increases the secondary aerosol formation with a maximum of 0.7–0.8 μg m−3 6 to 18 h downwind of Malmö. The secondary mass contribution dominates over the primary soot contribution from Malmö already 3 to 4 h downwind of the emission sources and contributes to an enhanced total surface direct or indirect aerosol shortwave radiative forcing in the center of the urban plume ranging from −0.3 to −3.3 W m−2 depending on the distance from Malmö, and the specific cloud properties.

scholarly journals Aerosol ageing in an urban plume – implications for climate and health

2010 ◽  
Vol 10 (8) ◽  
pp. 18731-18780 ◽  
Author(s):  
P. Roldin ◽  
E. Swietlicki ◽  
A. Massling ◽  
A. Kristensson ◽  
J. Löndahl ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Particle Number ◽  
Particulate Emissions ◽  
Aerosol Formation ◽  
Aerosol Dynamics ◽  
Cloud Properties ◽  
Total Particle ◽  
Physical Particle ◽  
Climate And Health ◽  
Urban Plume

Abstract. The climate and health effects downwind of an urban area resulting from gaseous and particulate emissions within the city are as yet inadequately quantified. The aim of this work was to estimate these effects for Malmö city in Southern Sweden (population 280 000). The chemical and physical particle properties were simulated with a model for Aerosol Dynamics, gas phase CHEMistry and radiative transfer calculations (ADCHEM) following the trajectory movement from upwind Malmö, through the urban background environment and finally tens and hundreds of kilometers downwind Malmö. The model results were validated with measurements of the particle number size distribution and chemical composition. The total particle number concentration 50 km (~3 h) downwind in the center of the Malmö plume is about 3800 cm−3 and the Malmö contribution is roughly 35%. Condensation of nitric acid, ammonium and to a smaller extent oxidized organic compounds formed from the emissions in Malmö increases the secondary aerosol formation with a maximum of 0.6–0.7 μg/m3 6 to 18 h downwind of Malmö. The secondary mass contribution dominates over the primary soot contribution from Malmö already 2 to 3 h after the emissions and gives an enhanced total top of the atmosphere direct or indirect aerosol shortwave radiative forcing in the center of the urban plume ranging from −0.3 to −2.3 W m−2 depending on the distance from Malmö, and the cloud properties. It also gives an increased respiratory tract deposited mass dose, which increases with the distance downwind Malmö.

scholarly journals Sensitivity of Simulated PM2.5 Concentrations over Northeast Asia to Different Secondary Organic Aerosol Modules during the KORUS-AQ Campaign

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 1004
Author(s):  
Hyo-Jung Lee ◽  
Hyun-Young Jo ◽  
Chang-Keun Song ◽  
Yu-Jin Jo ◽  
Shin-Young Park ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Northeast Asia ◽  
Organic Aerosol ◽  
Model Verification ◽  
Basis Set ◽  
Aircraft Measurements ◽  
Aerosol Formation ◽  
Dynamics Model ◽  
Aerosol Dynamics ◽  
Secondary Organic Aerosol Formation

A numerical sensitivity study on secondary organic aerosol formation has been carried out by employing the WRF-Chem (Weather Research and Forecasting model coupled with Chemistry). Two secondary organic aerosol formation modules, the Modal Aerosol Dynamics model for Europe/Volatility Basis Set (MADE/VBS) and the Modal Aerosol Dynamics model for Europe/Secondary Organic Aerosol Model (MADE/SORGAM) were employed in the WRF-Chem model, and surface PM2.5 (particulate matter less than 2.5 μm in size) mass concentration and the composition of its relevant chemical sources, i.e., SO42−, NO3−, NH4+, and organic carbon (OC) were simulated during the Korea-United States Air Quality (KORUS-AQ) campaign period (1 May to 12 June 2016). We classified the KORUS-AQ period into two cases, the stagnant period (16–21 May) which was dominated by local emission and the long-range transport period (25–31 May) which was affected by transport from the leeward direction, and focused on the differences in OC secondary aerosol formation between two modules over Northeast Asia. The simulated surface PM2.5 chemical components via the two modules showed the largest systematic biases in surface OC, with a mean bias of 4.5 μg m−3, and the second largest in SO42− abundance of 2.2 μg m−3 over Seoul. Compared with surface observations at two ground sites located near the western coastal Korean Peninsula, MADE/VBS exhibited the overpredictions in OC by 170–180%, whereas MADE/SORGAM showed underpredictions by 49–65%. OC and sulfate via MADE/VBS were simulated to be much higher than that simulated by MADE/SORGAM by a factor of 2.8–3.5 and 1.5–1.9, respectively. Model verification against KORUS-AQ aircraft measurements also showed large discrepancies in simulated non-surface OC between the two modules by a factor of five, with higher OC by MADE/VBS and lower IC by MADE/SORGAM, whereas much closer MADE/VBS simulations to the KORUS-AQ aircraft measurements were found. On the basis of the aircraft measurements, the aggregated bias (sum of four components) for PM2.5 mass concentrations from the MADE/VBS module indicated that the simulation was much closer to the measurements, nevertheless more elaborate analysis on the surface OC simulation performance would be needed to improve the ground results. Our findings show that significant inconsistencies are present in the secondary organic aerosol formation simulations, suggesting that PM2.5 forecasts should be considered with great caution, as well as in the context of policymaking in the Northeast Asia region.

scholarly journals Impact on Ultrafine Particles Concentration and Turbulent Fluxes of SARS-CoV-2 Lockdown in a Suburban Area in Italy

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 407
Author(s):  
Antonio Donateo ◽  
Adelaide Dinoi ◽  
Gianluca Pappaccogli
Keyword(s):  
Ultrafine Particles ◽  
Particle Number ◽  
Ultrafine Particle ◽  
Turbulent Fluxes ◽  
Number Concentration ◽  
Suburban Area ◽  
Observation Site ◽  
Meteorological Forcing ◽  
Restrictive Measures ◽  
Measurement Area

In order to slow the spread of SARS-CoV-2, governments have implemented several restrictive measures (lockdown, stay-in-place, and quarantine policies). These provisions have drastically changed the routines of residents, altering environmental conditions in the affected areas. In this context, our work analyzes the effects of the reduced emissions during the COVID-19 period on the ultrafine particles number concentration and their turbulent fluxes in a suburban area. COVID-19 restrictions did not significantly reduce anthropogenic related PM10 and PM2.5 levels, with an equal decrement of about 14%. The ultrafine particle number concentration during the lockdown period decreased by 64% in our measurement area, essentially due to the lower traffic activity. The effect of the restriction measures and the reduction of vehicles traffic was predominant in reducing concentration rather than meteorological forcing. During the lockdown in 2020, a decrease of 61% in ultrafine particle positive fluxes can be observed. At the same time, negative fluxes decreased by 59% and our observation site behaved, essentially, as a sink of ultrafine particles. Due to this behavior, we can conclude that the principal particle sources during the lockdown were far away from the measurement site.

scholarly journals Laboratory and field evaluation of the Aerosol Dynamics Inc. concentrator (ADIc) for aerosol mass spectrometry

2019 ◽  
Author(s):  
Sanna Saarikoski ◽  
Leah R. Williams ◽  
Steven R. Spielman ◽  
Gregory S. Lewis ◽  
Arantzazu Eiguren-Fernandez ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Concentration Factor ◽  
Ultrafine Particles ◽  
Ultrafine Particle ◽  
Chemical Characterization ◽  
Field Evaluation ◽  
Aerosol Dynamics ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Road Paving

Abstract. An air-to-air ultrafine particle concentrator (Aerosol Dynamics Inc. concentrator; ADIc) has been designed to enhance on-line chemical characterization of ambient aerosols by aerosol mass spectrometry. The ADIc employs a three-stage, moderated water-based condensation growth tube coupled to an aerodynamic focusing nozzle to concentrate ultrafine particles into a portion of the flow. The system can be configured to sample between 1.0–1.7 L min−1 with an output concentrated flow between 0.08–0.12 L min−1, resulting in a theoretical concentration factor (sample flow/output flow) ranging from 8 to 21. Laboratory tests with monodisperse particles show that the ADIc is effective for particles as small as 10 nm. Laboratory experiments conducted with the Aerosol Mass Spectrometer (AMS) showed no shift in the particle size after the ADIc, as measured by the AMS particle time-of-flight. The ADIc-AMS system was operated unattended over a one-month period near Boston, Massachusetts. Comparison to a parallel AMS without the concentrator showed concentration factors of 9.7 ± 0.15 and 9.1 ± 0.1 for sulfate and nitrate, respectively, when operated with a theoretical concentration factor of 10.5 ± 0.3. Concentration factor of organics was lower, possibly due to the presence of large particles from nearby road-paving operations, and a difference in aerodynamic lens cutoff between the two AMS instruments. Another field deployment was carried out in Helsinki, Finland. Two ~ 10-day measurement periods showed good correlation for the concentrations of organics, sulfate, nitrate and ammonium measured with an Aerosol Chemical Speciation Monitor (ACSM) after the ADIc, and a parallel AMS without the concentrator. Additional experiments with an AMS alternating between the ADIc and a bypass line demonstrated that the concentrator did not change the size distribution or the chemistry of the ambient aerosol particles.

scholarly journals Enhancement of secondary aerosol formation by reduced anthropogenic emissions during Spring Festival 2019 and enlightenment for regional PM<sub>2.5</sub> control in Beijing

2020 ◽  
Author(s):  
Yuying Wang ◽  
Zhanqing Li ◽  
Qiuyan Wang ◽  
Xiaoai Jin ◽  
Peng Yan ◽  
...  
Keyword(s):  
Particle Number ◽  
Surface Ozone ◽  
Sulfur Oxidation ◽  
Anthropogenic Emissions ◽  
Aerosol Formation ◽  
Spring Festival ◽  
Sulfate Formation ◽  
Oxidation Ratio ◽  
The Impact ◽  
Mass Concentrations

Abstract. A comprehensive field experiment measuring aerosol chemical and physical properties at a suburban site in Beijing around the 2019 Spring Festival was carried out to investigate the impact of reduced anthropogenic emissions on aerosol formation. Sharply reduced sulfur dioxide (SO2) and nitrogen dioxide (NO2) concentrations during the festival holiday resulted in an unexpected increase in the surface ozone (O3) concentration, leading to enhancement of the atmospheric oxidation capacity. Simultaneously, the reduced anthropogenic emissions resulted in massive decreases in particle number concentration at all sizes and the mass concentrations of organics and black carbon. However, the mass concentrations of inorganics (especially sulfate) decreased weakly. Detailed analyses of the sulfur oxidation ratio and the nitrogen oxidation ratio suggest that sulfate formation during the holiday could be promoted by enhanced nocturnal aqueous-phase chemical reactions between SO2 and O3 under moderate relative humidity (RH) conditions (40 % 

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.

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