scholarly journals Modelling and measurements of urban aerosol processes on the neighborhood scale in Rotterdam, Oslo and Helsinki

2015 ◽  
Vol 15 (23) ◽  
pp. 35157-35200
Author(s):  
M. Karl ◽  
J. Kukkonen ◽  
M. P. Keuken ◽  
S. Lützenkirchen ◽  
L. Pirjola ◽  
...  
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Dry Deposition ◽  
Particle Number ◽  
Measured Data ◽  
Sensitivity Analyses ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Coagulation Of Particles ◽  
Neighborhood Scale

Abstract. This study evaluates the influence of aerosol processes on the particle number (PN) concentrations in three major European cities on the temporal scale of one hour, i.e. on the neighborhood and city scales. We have used selected measured data of particle size distributions from previous campaigns in the cities of Helsinki, Oslo and Rotterdam. The aerosol transformation processes were evaluated using an aerosol dynamics model MAFOR, combined with a simplified treatment of roadside and urban atmospheric dispersion. We have compared the model predictions of particle number size distributions with the measured data, and conducted sensitivity analyses regarding the influence of various model input variables. We also present a simplified parameterization for aerosol processes, which is based on the more complex aerosol process computations; this simple model can easily be implemented to both Gaussian and Eulerian urban dispersion models. Aerosol processes considered in this study were (i) the coagulation of particles, (ii) the condensation and evaporation of n-alkanes, and (iii) dry deposition. The chemical transformation of gas-phase compounds was not taken into account. It was not necessary to model the nucleation of gas-phase vapors, as the computations were started with roadside conditions. Dry deposition and coagulation of particles were identified to be the most important aerosol dynamic processes that control the evolution and removal of particles. The effect of condensation and evaporation of organic vapors emitted by vehicles on particle numbers and on particle size distributions was examined. Under inefficient dispersion conditions, condensational growth contributed significantly to the evolution of PN from roadside to the neighborhood scale. The simplified parameterization of aerosol processes can predict particle number concentrations between roadside and the urban background with an inaccuracy of ∼ 10 %, compared to the fully size-resolved MAFOR model.

scholarly journals Modeling and measurements of urban aerosol processes on the neighborhood scale in Rotterdam, Oslo and Helsinki

2016 ◽  
Vol 16 (8) ◽  
pp. 4817-4835 ◽  
Author(s):  
Matthias Karl ◽  
Jaakko Kukkonen ◽  
Menno P. Keuken ◽  
Susanne Lützenkirchen ◽  
Liisa Pirjola ◽  
...  
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Dry Deposition ◽  
Particle Number ◽  
Measured Data ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Organic Vapors ◽  
Coagulation Of Particles ◽  
Neighborhood Scale

Abstract. This study evaluates the influence of aerosol processes on the particle number (PN) concentrations in three major European cities on the temporal scale of 1 h, i.e., on the neighborhood and city scales. We have used selected measured data of particle size distributions from previous campaigns in the cities of Helsinki, Oslo and Rotterdam. The aerosol transformation processes were evaluated using the aerosol dynamics model MAFOR, combined with a simplified treatment of roadside and urban atmospheric dispersion. We have compared the model predictions of particle number size distributions with the measured data, and conducted sensitivity analyses regarding the influence of various model input variables. We also present a simplified parameterization for aerosol processes, which is based on the more complex aerosol process computations; this simple model can easily be implemented to both Gaussian and Eulerian urban dispersion models. Aerosol processes considered in this study were (i) the coagulation of particles, (ii) the condensation and evaporation of two organic vapors, and (iii) dry deposition. The chemical transformation of gas-phase compounds was not taken into account. By choosing concentrations and particle size distributions at roadside as starting point of the computations, nucleation of gas-phase vapors from the exhaust has been regarded as post tail-pipe emission, avoiding the need to include nucleation in the process analysis. Dry deposition and coagulation of particles were identified to be the most important aerosol dynamic processes that control the evolution and removal of particles. The error of the contribution from dry deposition to PN losses due to the uncertainty of measured deposition velocities ranges from −76 to +64 %. The removal of nanoparticles by coagulation enhanced considerably when considering the fractal nature of soot aggregates and the combined effect of van der Waals and viscous interactions. The effect of condensation and evaporation of organic vapors emitted by vehicles on particle numbers and on particle size distributions was examined. Under inefficient dispersion conditions, the model predicts that condensational growth contributes to the evolution of PN from roadside to the neighborhood scale. The simplified parameterization of aerosol processes predicts the change in particle number concentrations between roadside and urban background within 10 % of that predicted by the fully size-resolved MAFOR model.

Dry deposition and particle size distributions measured during the Lake Michigan Urban Air Toxics Study

1993 ◽  
Vol 27 (7) ◽  
pp. 1327-1333 ◽  
Author(s):  
Thomas M. Holsen ◽  
Kenneth E. Noll ◽  
Guor Cheng Fang ◽  
Wen Jhy Lee ◽  
Jui Min Lin ◽  
...  
Keyword(s):  
Particle Size ◽  
Dry Deposition ◽  
Lake Michigan ◽  
Urban Air ◽  
Air Toxics ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Urban Air Toxics

scholarly journals Size-resolved particle number emissions in Beijing determined from measured particle size distributions

2020 ◽  
Vol 20 (19) ◽  
pp. 11329-11348 ◽  
Author(s):  
Jenni Kontkanen ◽  
Chenjuan Deng ◽  
Yueyun Fu ◽  
Lubna Dada ◽  
Ying Zhou ◽  
...  
Keyword(s):  
Particle Size ◽  
Air Quality ◽  
Particle Number ◽  
Aerosol Particles ◽  
Urban Environments ◽  
Integrated Assessment Model ◽  
Assessment Model ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Measured Particle

Abstract. The climate and air quality effects of aerosol particles depend on the number and size of the particles. In urban environments, a large fraction of aerosol particles originates from anthropogenic emissions. To evaluate the effects of different pollution sources on air quality, knowledge of size distributions of particle number emissions is needed. Here we introduce a novel method for determining size-resolved particle number emissions, based on measured particle size distributions. We apply our method to data measured in Beijing, China, to determine the number size distribution of emitted particles in a diameter range from 2 to 1000 nm. The observed particle number emissions are dominated by emissions of particles smaller than 30 nm. Our results suggest that traffic is the major source of particle number emissions with the highest emissions observed for particles around 10 nm during rush hours. At sizes below 6 nm, clustering of atmospheric vapors contributes to calculated emissions. The comparison between our calculated emissions and those estimated with an integrated assessment model GAINS (Greenhouse Gas and Air Pollution Interactions and Synergies) shows that our method yields clearly higher particle emissions at sizes below 60 nm, but at sizes above that the two methods agree well. Overall, our method is proven to be a useful tool for gaining new knowledge of the size distributions of particle number emissions in urban environments and for validating emission inventories and models. In the future, the method will be developed by modeling the transport of particles from different sources to obtain more accurate estimates of particle number emissions.

scholarly journals Mass-particle size distributions of atmospheric dust and the dry deposition of dust to the remote ocean

1997 ◽  
Vol 102 (D13) ◽  
pp. 15867-15874 ◽  
Author(s):  
R. Arimoto ◽  
B. J. Ray ◽  
N. F. Lewis ◽  
U. Tomza ◽  
R. A. Duce
Keyword(s):  
Particle Size ◽  
Dry Deposition ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Atmospheric Dust ◽  
Mass Particle

Gas-phase particle size distributions and lead loss during spray pyrolysis of (Bi,Pb)–Sr–Ca–Cu–O

1995 ◽  
Vol 10 (7) ◽  
pp. 1644-1652 ◽  
Author(s):  
Abhijit S. Gurav ◽  
Toivo T. Kodas ◽  
Jorma Joutsensaari ◽  
Esko I. Kauppincn ◽  
Riitta Zilliacus
Keyword(s):  
Particle Size ◽  
Spray Pyrolysis ◽  
Gas Phase ◽  
Phase Particle ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Processing Temperature ◽  
Average Particle ◽  
Size Distributions ◽  
Particle Size Distributions

Gas-phase particle size distributions and lead loss were measured during formation of (Bi,Pb)-Sr-Ca-Cu-O and pure PbO particles by spray pyrolysis at different temperatures. A differential mobility analyzer (DMA) in conjunction with a condensation particle counter (CPC) was used to monitor the gas-phase particle size distributions, and a Berner-type low-pressure impactor was used to obtain mass size distributions and size-classified samples for chemical analysis. For (Bi,Pb)-Sr-Ca-Cu-O, as the processing temperature was raised from 200 to 700 °C, the number average particle size decreased due to metal nitrate decomposition, intraparticle reactions forming mixed-metal oxides and particle densification. The geometric number mean particle diameter was 0.12 μm at 200 °C and reduced to 0.08 and 0.07 μm, respectively, at 700 and 900 °C. When the reactor temperature was raised from 700 and 800 °C to 900 °C, a large number (∼107 no./cm3) of new ultrafine particles were formed from PbO vapor released from the particles and the reactor walls. Particles made at temperatures up to 700 °C maintained their initial stoichiometry over the whole range of particle sizes monitorcd; however, those made at 800 °C and above were heavily depleted in lead in the size range 0.5–5.0 μm. The evaporative losses of lead oxide from (Bi,Pb)-Sr-Ca-Cu-O particles were compared with the losses from PbO particles to gain insight into the pathways involved in lead loss and the role of intraparticle processes in controlling it.

Road tunnel measurements of submicrometer particle size distributions, elemental composition and gas phase components

1999 ◽  
Vol 30 ◽  
pp. S49-S50 ◽  
Author(s):  
E. Swietlicki ◽  
J. Zhou ◽  
C. Johansson ◽  
R. Westerholm ◽  
G. Papaspiropoulos
Keyword(s):  
Particle Size ◽  
Elemental Composition ◽  
Gas Phase ◽  
Size Distributions ◽  
Road Tunnel ◽  
Particle Size Distributions

scholarly journals Particle formation at a continental background site: comparison of modelresults with observations

2002 ◽  
Vol 2 (6) ◽  
pp. 2413-2448
Author(s):  
U. Uhrner ◽  
W. Birmili ◽  
F. Stratmann ◽  
M. Wilck ◽  
I. J. Ackermann ◽  
...  
Keyword(s):  
Particle Size ◽  
Sulphuric Acid ◽  
Particle Number ◽  
Particle Formation ◽  
Rural Site ◽  
Size Distributions ◽  
Correction Factors ◽  
Convective Conditions ◽  
Particle Size Distributions ◽  
Measured Particle

Abstract. At Hohenpeissenberg (47°48'N, 11°07'E, 988 m asl), a rural site 200-300 m higher than the surrounding terrain, sulphuric acid concentrations, particle size distributions, and other trace gas concentrations were measured over a two and a half year period. Measured particle number concentrations and inferred particle surface area-concentrations were compared with box-model simulations based on a multimodal lognormal aerosol module that included a binary sulphuric acid water nucleation scheme. The calculated nucleation rates were corrected with a factor to match measured particle number concentrations. These corrections varied over a range of 10-3 - 1017. The correction factors were close to 1 for the measurements made in the winter, which represented stable thermal stratification and low wind conditions. In contrast, the correction factors were the largest for measurements made under strong convective conditions. Our comparison of measured and simulated particle size distributions suggest a distant particle-formation process under convective conditions near the interface of the mixed layer and the entrainment zone, followed by downward transport and particle growth. For stable stratification and low winds, our comparisons suggest that particles formed close to the measurement site.

scholarly journals Remarkable dynamics of nanoparticles in the urban atmosphere

2011 ◽  
Vol 11 (13) ◽  
pp. 6623-6637 ◽  
Author(s):  
M. Dall'Osto ◽  
A. Thorpe ◽  
D. C. S. Beddows ◽  
R. M. Harrison ◽  
J. F. Barlow ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Urban Areas ◽  
Particle Number ◽  
Road Traffic ◽  
Urban Atmosphere ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Number Count ◽  
Adverse Health Effects

Abstract. Nanoparticles emitted from road traffic are the largest source of respiratory exposure for the general public living in urban areas. It has been suggested that adverse health effects of airborne particles may scale with airborne particle number, which if correct, focuses attention on the nanoparticle (less than 100 nm) size range which dominates the number count in urban areas. Urban measurements of particle size distributions have tended to show a broadly similar pattern dominated by a mode centred on 20–30 nm diameter emitted by diesel engine exhaust. In this paper we report the results of measurements of particle number concentration and size distribution made in a major London park as well as on the BT Tower, 160 m aloft. These measurements taken during the REPARTEE project (Regents Park and BT Tower experiment) show a remarkable shift in particle size distributions with major losses of the smallest particle class as particles are advected away from the traffic source. In the Park, the traffic related mode at 20–30 nm diameter is much reduced with a new mode at <10 nm. Size distribution measurements also revealed higher number concentrations of sub-50 nm particles at the BT Tower during days affected by higher turbulence as determined by Doppler Lidar measurements and are indicative of loss of nanoparticles from air aged during less turbulent conditions. These results are suggestive of nanoparticle loss by evaporation, rather than coagulation processes. The results have major implications for understanding the impacts of traffic-generated particulate matter on human health.

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