Effect of needle-like crystal shape on measured particle size distributions

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.

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Measured particle size distributions during winter time in Eastern Lappland

Journal of Aerosol Science ◽

10.1016/0021-8502(92)90580-o ◽

1992 ◽

Vol 23 ◽

pp. 995-998

Author(s):

Pasi Aalto ◽

Jyrki M. Mäkelä ◽

Markku Kulmala ◽

Pertti Hari

Keyword(s):

Particle Size ◽

Size Distributions ◽

Particle Size Distributions ◽

Winter Time ◽

Measured Particle

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Analysis of ice fragmentation process from measured particle size distributions of crushed ice

International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts ◽

10.1016/0148-9062(95)97273-l ◽

1995 ◽

Vol 32 (4) ◽

pp. A196

Keyword(s):

Particle Size ◽

Fragmentation Process ◽

Size Distributions ◽

Particle Size Distributions ◽

Crushed Ice ◽

Measured Particle

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

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-2-2413-2002 ◽

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.

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

10.5194/acp-2020-215 ◽

2020 ◽

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 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 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 size distributions of particle number emissions in urban environments.

Download Full-text