scholarly journals Production, growth and properties of ultrafine atmospheric aerosol particles in an urban environment

2011 ◽  
Vol 11 (3) ◽  
pp. 1339-1353 ◽  
Author(s):  
I. Salma ◽  
T. Borsós ◽  
T. Weidinger ◽  
P. Aalto ◽  
T. Hussein ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Atmospheric Aerosol ◽  
Particle Number ◽  
Aerosol Particles ◽  
Formation Rate ◽  
Particle Formation ◽  
Number Concentration ◽  
New Particle Formation ◽  
Total Particle Number ◽  
Total Particle

Abstract. Number concentrations of atmospheric aerosol particles were measured by a flow-switching type differential mobility particle sizer in an electrical mobility diameter range of 6–1000 nm in 30 channels near central Budapest with a time resolution of 10 min continuously from 3 November 2008 to 2 November 2009. Daily median number concentrations of particles varied from 3.8 × 103 to 29 ×103 cm−3 with a yearly median of 11.8 × 103 cm−3. Contribution of ultrafine particles to the total particle number ranged from 58 to 92% with a mean ratio and standard deviation of (79 ± 6)%. Typical diurnal variation of the particle number concentration was related to the major emission patterns in cities, new particle formation, sinks of particles and meteorology. Shapes of the monthly mean number size distributions were similar to each other. Overall mean for the number median mobility diameter of the Aitken and accumulation modes were 26 and 93 nm, respectively, which are substantially smaller than for rural or background environments. The Aitken and accumulation modes contributed similarly to the total particle number concentrations at the actual measurement location. New particle formation and growth unambiguously occurred on 83 days, which represent 27% of all relevant days. Hence, new particle formation and growth are not rare phenomena in Budapest. Their frequency showed an apparent seasonal variation with a minimum of 7.3% in winter and a maximum of 44% in spring. New particle formation events were linked to increased gas-phase H2SO4 concentrations. In the studied area, new particle formation is mainly affected by condensation sink and solar radiation. The formation process seems to be not sensitive to SO2, which was present in a yearly median concentration of 6.7 μg m−3. This suggests that the precursor gas was always available in excess. Formation rate of particles with a diameter of 6 nm varied between 1.65 and 12.5 cm−3 s−1 with a mean and standard deviation of (4.2 ± 2.5) cm−3 s−1. Seasonal dependency for the formation rate could not be identified. Growth curves of nucleated particles were usually superimposed on the characteristic diurnal pattern of road traffic direct emissions. The growth rate of the nucleation mode with a median diameter of 6 nm varied from 2.0 to 13.3 nm h−1 with a mean and standard deviation of (7.7 ± 2.4) nm h−1. There was an indicative tendency for larger growth rates in summer and for smaller values in winter. New particle formation events increased the total number concentration by a mean factor and standard deviation of 2.3 ± 1.1 relative to the concentration that occurred immediately before the event. Several indirect evidences suggest that the new particle formation events occurred at least over the whole city, and were of regional type. The results and conclusions presented are the first information of this kind for the region over one-year long time period.

scholarly journals Production, growth and properties of ultrafine atmospheric aerosol particles in an urban environment

2010 ◽  
Vol 10 (6) ◽  
pp. 13689-13721
Author(s):  
I. Salma ◽  
T. Borsós ◽  
T. Weidinger ◽  
P. Aalto ◽  
T. Hussein ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Atmospheric Aerosol ◽  
Ultrafine Particles ◽  
Particle Number ◽  
Aerosol Particles ◽  
Formation Rate ◽  
Number Concentration ◽  
Nucleation Mode ◽  
Total Particle Number ◽  
Total Particle

Abstract. Number concentrations of atmospheric aerosol particles were measured by a flow-switching type differential mobility particle sizer in an electrical mobility diameter range of 6–1000 nm in 30 channels near central Budapest with a time resolution of 10 min continuously from 3 November 2008 to 2 November 2009. Daily median number concentrations of particles varied from 3.8×103 to 29×103 cm−3 with a yearly median of 11.8×103 cm−3. Contribution of ultrafine particles to the total particle number ranged from 58 to 92% with a mean ratio and standard deviation of (79±6)%. Daily average number concentrations in various size fractions and contribution of ultrafine particles to the total particle number showed no seasonal dependency. Monthly mean number size distributions were similar to each other. Overall mean for the number median mobility diameter of the Aitken and accumulation modes were 26 and 93 nm, respectively, which are substantially smaller than for rural or background environments. The Aitken and accumulation modes contributed similarly to the total particle number concentrations at the actual measurement location. Median diameters of the Aitken and accumulation modes were shifted to larger values before nucleation started and over the growth process, which can be related to the presence of aged aerosol under the conditions that favour nucleation and growth. Particle concentrations were usually increased substantially after nucleations. Overall mean and standard deviation of the nucleation mode number concentrations were (10.4±2.8)×103 cm−3. Mean ratio and standard deviation of the nucleation mode number concentration to the total particle number concentration that was averaged for two hours just before the formation was detected was 2.3±1.1. Nucleation unambiguously occurred on 83 days, which represent 27% of all relevant days. Its frequency showed a remarkable seasonal variation with a minimum of 7.3% in winter and a maximum of 44% in spring. Formation rate of particles with a diameter of 6 nm varied between 1.65 and 12.5 cm−3 s−1 with a mean and standard deviation of (4.2±2.5) cm−3 s−1. Seasonal dependency for the formation rate could not be identified. Growth curves of nucleated particles were usually superimposed on the characteristic diurnal pattern of road traffic direct emissions. The growth rate of the nucleation mode with a median diameter of 6 nm varied from 2.0 to 13.3 nm h−1 with a mean and standard deviation of (7.7±2.4) nm h−1. There was an indicative tendency for larger growth rates in summer and for smaller values in winter. Several indirect evidences suggest that the nucleation events occurred at least over the whole city, and were of regional type.

scholarly journals Seasonal cycle and modal structure of particle number size distribution at Dome C, Antarctica

2013 ◽  
Vol 13 (15) ◽  
pp. 7473-7487 ◽  
Author(s):  
E. Järvinen ◽  
A. Virkkula ◽  
T. Nieminen ◽  
P. P. Aalto ◽  
E. Asmi ◽  
...  
Keyword(s):  
Size Distribution ◽  
Seasonal Cycle ◽  
Particle Number ◽  
Formation Rate ◽  
Particle Growth ◽  
Particle Formation ◽  
Distribution Data ◽  
New Particle Formation ◽  
Total Particle Number ◽  
Total Particle

Abstract. We studied new particle formation and modal behavior of ultrafine aerosol particles on the high East Antarctic plateau at the Concordia station, Dome C (75°06' S, 123°23' E). Aerosol particle number size distributions were measured in the size range 10–600 nm from 14 December 2007 to 7 November 2009. We used an automatic algorithm for fitting up to three modes to the size distribution data. The total particle number concentration was low with the median of 109 cm−3. There was a clear seasonal cycle in the total particle number and the volume concentrations. The concentrations were at their highest during the austral summer with the median values of 260 cm−3 and 0.086 μm3 cm−3, and at their lowest during the austral winter with corresponding values of 15 cm−3 and 0.009 μm3 cm−3. New particle formation events were determined from the size distribution data. During the measurement period, natural new particle formation was observed on 60 days and for 15 of these days the particle growth rates from 10 to 25 nm in size could be determined. The median particle growth rate during all these events was 2.5 nm h−1 and the median formation rate of 10 nm particles was 0.023 cm−3 s−1. Most of the events were similar to those observed at other continental locations, yet also some variability in event types was observed. Exceptional features in Dome C were the winter events that occurred during dark periods, as well as the events for which the growth could be followed during several consecutive days. We called these latter events slowly growing events. This paper is the first one to analyze long-term size distribution data from Dome C, and also the first paper to show that new particle formation events occur in central Antarctica.

scholarly journals Seasonal cycle and modal structure of particle number size distribution at Dome C, Antarctica

2013 ◽  
Vol 13 (3) ◽  
pp. 5729-5768
Author(s):  
E. Järvinen ◽  
A. Virkkula ◽  
T. Nieminen ◽  
P. P. Aalto ◽  
E. Asmi ◽  
...  
Keyword(s):  
Size Distribution ◽  
Seasonal Cycle ◽  
Particle Number ◽  
Formation Rate ◽  
Particle Growth ◽  
Particle Formation ◽  
Distribution Data ◽  
New Particle Formation ◽  
Total Particle Number ◽  
Total Particle

Abstract. We studied new particle formation and modal behavior of ultrafine aerosol particles on the high Antarctic East-Plateau at the Concordia station, Dome C (75°06' S, 123°23' E). Aerosol particle number size distributions were measured in the size range 10–600 nm from 14 December 2007 to 7 November 2009. We used an automatic algorithm for fitting up to three modes to the size distribution data. The total particle number concentration was low with the median of 109 cm−3. There was a clear seasonal cycle in the total particle number and the volume concentrations. The concentrations were at their highest during the austral summer with the median values of 260 cm−3 and 0.086 μm3 cm−3, and at their lowest during the austral winter with corresponding values of 15 cm−3 and 0.009 μm3 cm−3. New particle formation events were determined from the size distribution data. During the measurement period, new particle formation was seen on 80 days and for 15 of these days the particle growth rates from 10 to 25 nm size could be determined. The median particle growth rate during all these events was 2.5 nm h−1 and the median formation rate of 10 nm particles was 0.023 cm−3 s−1. Most of the events were similar to those observed in other continental locations, yet also some variability in event types was observed. Exceptional features in Dome C were the winter events that occurred during dark periods, as well as the events for which the growth could be followed during several consecutive days. We called these latter events as slowly-growing events. This paper is the first one to analyze long-term size distribution data from Dome C, and also the first paper to show that new particle formation events occur in the central Antarctica.

scholarly journals Particle number concentrations over Europe in 2030: the role of emissions and new particle formation

2013 ◽  
Vol 13 (20) ◽  
pp. 10271-10283 ◽  
Author(s):  
L. Ahlm ◽  
J. Julin ◽  
C. Fountoukis ◽  
S. N. Pandis ◽  
I. Riipinen
Keyword(s):  
Human Health ◽  
Particle Number ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Number Concentration ◽  
Anthropogenic Emissions ◽  
Particle Number Concentration ◽  
New Particle Formation ◽  
So2 Emissions ◽  
Emission Reductions

Abstract. The aerosol particle number concentration is a key parameter when estimating impacts of aerosol particles on climate and human health. We use a three-dimensional chemical transport model with detailed microphysics, PMCAMx-UF, to simulate particle number concentrations over Europe in the year 2030, by applying emission scenarios for trace gases and primary aerosols. The scenarios are based on expected changes in anthropogenic emissions of sulfur dioxide, ammonia, nitrogen oxides, and primary aerosol particles with a diameter less than 2.5 μm (PM2.5) focusing on a photochemically active period, and the implications for other seasons are discussed. For the baseline scenario, which represents a best estimate of the evolution of anthropogenic emissions in Europe, PMCAMx-UF predicts that the total particle number concentration (Ntot) will decrease by 30–70% between 2008 and 2030. The number concentration of particles larger than 100 nm (N100), a proxy for cloud condensation nuclei (CCN) concentration, is predicted to decrease by 40–70% during the same period. The predicted decrease in Ntot is mainly a result of reduced new particle formation due to the expected reduction in SO2 emissions, whereas the predicted decrease in N100 is a result of both decreasing condensational growth and reduced primary aerosol emissions. For larger emission reductions, PMCAMx-UF predicts reductions of 60–80% in both Ntot and N100 over Europe. Sensitivity tests reveal that a reduction in SO2 emissions is far more efficient than any other emission reduction investigated, in reducing Ntot. For N100, emission reductions of both SO2 and PM2.5 contribute significantly to the reduced concentration, even though SO2 plays the dominant role once more. The impact of SO2 for both new particle formation and growth over Europe may be expected to be somewhat higher during the simulated period with high photochemical activity than during times of the year with less incoming solar radiation. The predicted reductions in both Ntot and N100 between 2008 and 2030 in this study will likely reduce both the aerosol direct and indirect effects, and limit the damaging effects of aerosol particles on human health in Europe.

scholarly journals The contribution of boundary layer nucleation events to total particle concentrations on regional and global scales

2006 ◽  
Vol 6 (12) ◽  
pp. 5631-5648 ◽  
Author(s):  
D. V. Spracklen ◽  
K. S. Carslaw ◽  
M. Kulmala ◽  
V.-M. Kerminen ◽  
G. W. Mann ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sulfuric Acid ◽  
Particle Number ◽  
Formation Rate ◽  
Particle Surface ◽  
Particle Formation ◽  
New Particle Formation ◽  
Particle Surface Area ◽  
Primary Particles ◽  
Total Particle

Abstract. The contribution of boundary layer (BL) nucleation events to total particle concentrations on the global scale has been studied by including a new particle formation mechanism in a global aerosol microphysics model. The mechanism is based on an analysis of extensive observations of particle formation in the BL at a continental surface site. It assumes that molecular clusters form at a rate proportional to the gaseous sulfuric acid concentration to the power of 1. The formation rate of 3 nm diameter observable particles is controlled by the cluster formation rate and the existing particle surface area, which acts to scavenge condensable gases and clusters during growth. Modelled sulfuric acid vapour concentrations, particle formation rates, growth rates, coagulation loss rates, peak particle concentrations, and the daily timing of events in the global model agree well with observations made during a 22-day period of March 2003 at the SMEAR II station in Hyytiälä, Finland. The nucleation bursts produce total particle concentrations (>3 nm diameter) often exceeding 104 cm−3, which are sustained for a period of several hours around local midday. The predicted global distribution of particle formation events broadly agrees with what is expected from available observations. Over relatively clean remote continental locations formation events can sustain mean total particle concentrations up to a factor of 8 greater than those resulting from anthropogenic sources of primary organic and black carbon particles. However, in polluted continental regions anthropogenic primary particles dominate particle number and formation events lead to smaller enhancements of up to a factor of 2. Our results therefore suggest that particle concentrations in remote continental regions are dominated by nucleated particles while concentrations in polluted continental regions are dominated by primary particles. The effect of BL particle formation over tropical regions and the Amazon is negligible. These first global particle formation simulations reveal some interesting sensitivities. We show, for example, that significant reductions in primary particle emissions may lead to an increase in total particle concentration because of the coupling between particle surface area and the rate of new particle formation. This result suggests that changes in emissions may have a complicated effect on global and regional aerosol properties. Overall, our results show that new particle formation is a significant component of the aerosol particle number budget.

scholarly journals Modelling the contribution of biogenic VOCs to new particle formation in the Jülich plant atmosphere chamber

2014 ◽  
Vol 14 (20) ◽  
pp. 27973-28018 ◽  
Author(s):  
L. Liao ◽  
M. Dal Maso ◽  
D. Mogensen ◽  
P. Roldin ◽  
A. Rusanen ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Particle Number ◽  
Particle Formation ◽  
Oxidation Products ◽  
New Particle Formation ◽  
Particle Volume ◽  
Aerosol Dynamics ◽  
Total Particle Number ◽  
Total Particle ◽  
Air Chemistry

Abstract. We used the MALTE-BOX model including near-explicit air chemistry and detailed aerosol dynamics to study the mechanisms of observed new particle formation events in the Jülich Plant Atmosphere Chamber. The modelled and measured H2SO4 (sulfuric acid) concentrations agreed within a factor of two. The modelled total monoterpene concentration was in line with PTR-MS observations, and we provided the distributions of individual isomers of terpenes, when no measurements were available. The aerosol dynamic results supported the hypothesis that H2SO4 is one of the critical compounds in the nucleation process. However, compared to kinetic H2SO4 nucleation, nucleation involving OH oxidation products of monoterpenes showed a better agreement with the measurements, with R2 up to 0.97 between modelled and measured total particle number concentrations. The nucleation coefficient for kinetic H2SO4 nucleation was 2.1 × 10−11 cm3 s−1, while the organic nucleation coefficient was 9.0 × 10−14 cm3 s−1. We classified the VOC oxidation products into two sub-groups including extremely low-volatility organic compounds (ELVOCs) and semi-volatile organic compounds (SVOCs). These ELVOCs and SVOCs contributed approximately equally to the particle volume production, whereas only ELVOCs made the smallest particles to grow in size. The model simulations revealed that the chamber walls constitute a major net sink of SVOCs on the first experiment day. However, the net wall SVOC uptake was gradually reduced because of SVOC desorption during the following days. Thus, in order to capture the observed temporal evolution of the particle number size distribution, the model needs to consider reversible gas-wall partitioning.

scholarly journals The contribution of boundary layer nucleation events to total particle concentrations on regional and global scales

2006 ◽  
Vol 6 (4) ◽  
pp. 7323-7368 ◽  
Author(s):  
D. V. Spracklen ◽  
K. S. Carslaw ◽  
M. Kulmala ◽  
V.-M. Kerminen ◽  
G. W. Mann ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particle Number ◽  
Marine Boundary Layer ◽  
Formation Rate ◽  
Particle Surface ◽  
Particle Formation ◽  
New Particle Formation ◽  
Particle Surface Area ◽  
Primary Particles ◽  
Total Particle

Abstract. The contribution of boundary layer nucleation events to total particle concentrations on the global scale has been studied by including a new particle formation mechanism in a global aerosol microphysics model. The mechanism is based on an analysis of extensive observations of particle formation in the boundary layer at a continental surface site. It assumes that molecular clusters form at a rate proportional to the gaseous sulfuric acid concentration to the power of 1. The formation rate of 3 nm diameter observable particles is controlled by the cluster formation rate and the existing particle surface area, which acts to scavenge condensable gases and clusters during growth. Modelled sulfuric acid vapour concentrations, particle formation rates, growth rates, coagulation loss rates, peak particle concentrations, and the daily timing of events in the global model agree well with observations made during a 22-day period of March 2003 at the SMEAR II station in Hyytiälä, Finland. The nucleation bursts produce total particle concentrations (>3 nm diameter) often exceeding 104 cm−3, which are sustained for a period of several hours around local midday. The predicted global distribution of particle formation events broadly agrees with what is expected from available observations. Over relatively clean remote continental locations formation events can sustain mean total particle concentrations up to a factor of 8 greater than those resulting from anthropogenic sources of primary organic and black carbon particles. However, in polluted continental regions anthropogenic primary particles dominate particle number and formation events lead to smaller enhancements of up to a factor of 2. Our results therefore suggest that particle concentrations in remote continental are dominated by nucleated particles while concentrations in polluted continental regions are dominated by primary particles. The effect of boundary layer particle formation over tropical regions and the Amazon is negligible. Particle concentrations are enhanced by a factor 3–10 over the remote Southern Ocean (30–70° S), resulting in total concentrations of ~250–1000 cm−3, in good agreement with observations. Particle formation tends to peak towards the top of the marine boundary layer and there is a lack of obvious burst-like behaviour at the sea surface. This result suggests that new particle formation in the marine boundary layer could be confused with entrainment from the free troposphere. These first global particle formation simulations reveal some interesting sensitivities. We show, for example, that significant reductions in primary particle emissions may lead to an increase in total particle concentration because of the coupling between particle surface area and the rate of new particle formation. This result suggests that changes in emissions may have a complicated effect on global and regional aerosol properties. Overall, our results show that new particle formation is a significant component of the aerosol particle number budget.

scholarly journals On the diurnal cycle of urban aerosols, black carbon and the occurrence of new particle formation events in springtime São Paulo, Brazil

2012 ◽  
Vol 12 (23) ◽  
pp. 11733-11751 ◽  
Author(s):  
J. Backman ◽  
L. V. Rizzo ◽  
J. Hakala ◽  
T. Nieminen ◽  
H. E. Manninen ◽  
...  
Keyword(s):  
Light Scattering ◽  
Black Carbon ◽  
Diurnal Cycle ◽  
Light Absorption ◽  
Particle Number ◽  
Particle Formation ◽  
Number Concentration ◽  
Particle Number Concentration ◽  
Total Particle Number ◽  
Total Particle

Abstract. Large conurbations are a significant source of the anthropogenic pollution and demographic differences between cities that result in a different pollution burden. The metropolitan area of São Paulo (MASP, population 20 million) accounts for one fifth of the Brazilian vehicular fleet. A feature of MASP is the amount of ethanol used by the vehicular fleet, known to exacerbate air quality. The study describes the diurnal behaviour of the submicron aerosol and relies on total particle number concentration, particle number size distribution, light scattering and light absorption measurements. Modelled planetary boundary layer (PBL) depth and air mass movement data were used to aid the interpretation. During morning rush-hour, stagnant air and a shallow PBL height favour the accumulation of aerosol pollution. During clear-sky conditions, there was a wind shift towards the edge of the city indicating a heat island effect with implications on particulate pollution levels at the site. The median total particle number concentration for the submicron aerosol typically varied in the range 1.6 × 104–3.2 × 104 cm−3 frequently exceeding 4 × 104 cm−3 during the day. During weekdays, nucleation-mode particles are responsible for most of the particles by numbers. The highest concentrations of total particle number concentrations and black carbon (BC) were observed on Fridays. Median diurnal values for light absorption and light scattering (at 637 nm wavelength) varied in the range 12–33 Mm−1 and 21–64 Mm−1, respectively. The former one is equal to 1.8–5.0 μg m−3 of BC. The growth of the PBL, from the morning rush-hour until noon, is consistent with the diurnal cycle of BC mass concentrations. Weekday hourly median single-scattering albedo (ω0) varied in the range 0.59–0.76. Overall, this suggests a top of atmosphere (TOA) warming effect. However, considering the low surface reflectance of urban areas, for the given range of ω0, the TOA radiative forcing can be either positive or negative for the sources within the MASP. On the average, weekend ω0 values were 0.074 higher than during weekdays. During 11% of the days, new particle formation (NPF) events occurred. The analysed events growth rates ranged between 9 and 25 nm h−1. Sulphuric acid proxy concentrations calculated for the site were less than 5% of the concentration needed to explain the observed growth. Thus, other vapours are likely contributors to the observed growth.

scholarly journals Particle number concentrations over Europe in 2030: the role of emissions and new particle formation

2013 ◽  
Vol 13 (4) ◽  
pp. 8769-8803
Author(s):  
L. Ahlm ◽  
J. Julin ◽  
C. Fountoukis ◽  
S. N. Pandis ◽  
I. Riipinen
Keyword(s):  
Human Health ◽  
Particle Number ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Number Concentration ◽  
Anthropogenic Emissions ◽  
Particle Number Concentration ◽  
New Particle Formation ◽  
So2 Emissions ◽  
Emission Reductions

Abstract. The aerosol particle number concentration is a key parameter when estimating impacts of aerosol particles on climate and human health. We use a three-dimensional chemical transport model with detailed microphysics, PMCAMx-UF, to simulate particle number concentrations over Europe in the year 2030, by applying emission scenarios for trace gases and primary aerosols. The scenarios are based on expected changes in anthropogenic emissions of sulphur dioxide, ammonia, nitrogen oxides, and primary aerosol particles with a diameter less than 2.5 μm (PM2.5) focusing on a photochemically active period. For the baseline scenario, which represents a best estimate of the evolution of anthropogenic emissions in Europe, PMCAMx-UF predicts that the total particle number concentration (Ntot) will decrease by 30–70% between 2008 and 2030. The number concentration of particles larger than 100 nm (N100), a proxy for cloud condensation nuclei (CCN) concentration, is predicted to decrease by 40–70% during the same period. The predicted decrease in Ntot is mainly a result of reduced new particle formation due to the expected reduction in SO2 emissions, whereas the predicted decrease in N100 is a result of both decreasing condensational growth and reduced primary aerosol emissions. For larger emission reductions, PMCAMx-UF predicts reductions of 60–80% in both Ntot and N100 over Europe. Sensitivity tests reveal that a reduction in SO2 emissions is far more efficient than any other emission reduction investigated, in reducing Ntot. For N100, emission reductions of both SO2 and PM2.5 contribute significantly to the reduced concentration, even though SO2 plays the dominant role once more. The impact of SO2 for both new particle formation and growth over Europe may be expected to be somewhat higher during the simulated period with high photochemical activity than during times of the year with less incoming solar radiation. The predicted reductions in both Ntot and N100 between 2008 and 2030 in this study will likely reduce both the aerosol direct and indirect effects, and limit the damaging effects of aerosol particles on human health in Europe.

Impact of Urban Pollution on Organic-Mediated New-Particle Formation and Particle Number Concentration in the Amazon Rainforest

2021 ◽  
Vol 55 (8) ◽  
pp. 4357-4367
Author(s):  
Bin Zhao ◽  
Jerome D. Fast ◽  
Neil M. Donahue ◽  
Manish Shrivastava ◽  
Meredith Schervish ◽  
...  
Keyword(s):  
Particle Number ◽  
Urban Pollution ◽  
Particle Formation ◽  
Number Concentration ◽  
Amazon Rainforest ◽  
Particle Number Concentration ◽  
New Particle Formation
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