scholarly journals Simultaneous measurements of new particle formation at 1 s time resolution at a street site and a rooftop site

2017 ◽  
Vol 17 (15) ◽  
pp. 9469-9484 ◽  
Author(s):  
Yujiao Zhu ◽  
Caiqing Yan ◽  
Renyi Zhang ◽  
Zifa Wang ◽  
Mei Zheng ◽  
...  
Keyword(s):  
Time Resolution ◽  
Particle Number ◽  
Formation Rate ◽  
Particle Formation ◽  
Photochemical Reactions ◽  
Urban Atmosphere ◽  
New Particle Formation ◽  
Gaseous Species ◽  
A Site ◽  
New Particles

Abstract. This study is the first to use two identical Fast Mobility Particle Sizers for simultaneous measurement of particle number size distributions (PNSDs) at a street site and a rooftop site within 500 m distance in wintertime and springtime to investigate new particle formation (NPF) in Beijing. The collected datasets at 1 s time resolution allow deduction of the freshly emitted traffic particle signal from the measurements at the street site and thereby enable the evaluation of the effects on NPF in an urban atmosphere through a site-by-site comparison. The number concentrations of 8 to 20 nm newly formed particles and the apparent formation rate (FR) in the springtime were smaller at the street site than at the rooftop site. In contrast, NPF was enhanced in the wintertime at the street site with FR increased by a factor of 3 to 5, characterized by a shorter NPF time and higher new particle yields than at the rooftop site. Our results imply that the street canyon likely exerts distinct effects on NPF under warm or cold ambient temperature conditions because of on-road vehicle emissions, i.e., stronger condensation sinks that may be responsible for the reduced NPF in the springtime but efficient nucleation and partitioning of gaseous species that contribute to the enhanced NPF in the wintertime. The occurrence or absence of apparent growth for new particles with mobility diameters larger than 10 nm was also analyzed. The oxidization of biogenic organics in the presence of strong photochemical reactions is suggested to play an important role in growing new particles with diameters larger than 10 nm, but sulfuric acid is unlikely to be the main species for the apparent growth. However, the number of datasets used in this study is relatively small, and larger datasets are essential to draw a general conclusion.

scholarly journals Simultaneous measurements of new particle formation in 1-second time resolution at a street site and a rooftop site

2017 ◽  
Author(s):  
Yujiao Zhu ◽  
Caiqing Yan ◽  
Renyi Zhang ◽  
Zifa Wang ◽  
Mei Zheng ◽  
...  
Keyword(s):  
Time Resolution ◽  
Particle Number ◽  
Particle Formation ◽  
Photochemical Reactions ◽  
Seasonal Effects ◽  
New Particle Formation ◽  
Gaseous Species ◽  
20 Nm ◽  
First Time ◽  
New Particles

Abstract. This study is the first time to use two identical Fast Mobility Particle Sizers for simultaneously measuring particle number size distributions (PNSD) at a street site and a rooftop site within 500 m distance in winter and spring times in Beijing. The obtained datasets in 1-second time resolution allow reasonably deducting the freshly emitted traffic particle signal from the measurements at the street site and thereby pave the way to study reduced or enhanced effects on new particle formation (NPF) in urban atmospheres through the site-by-site comparison. The number concentration of newly formed particles, i.e., smaller than 20 nm, and the NPF rate in the springtime were smaller at the street site than at the rooftop site. In contrast, NPF was enhanced in the wintertime at the street site with NPF rates increased by 3–5 times, characterized by a shorter NPF time and higher new particle yields than those at the rooftop site. Our results imply that the street canyon likely exerts distinct seasonal effects on NPF because of on-road vehicle emissions, i.e., stronger condensation sinks that may be responsible for reduced NPF in the springtime but efficient nucleation and partitioning of gaseous species that contribute to the enhanced NPF in the wintertime. We also analyzed the occurrence or absence of apparent growth for > 10 nm new particles. The oxidization of biogenic organics in the presence of strong photochemical reactions was argued to play an important role in growing > 10 nm new particles, but sulfuric acid was unlikely the crucial specie for the apparent growth.

scholarly journals Frequency of new particle formation events in the urban Mediterranean climate

2014 ◽  
Vol 14 (19) ◽  
pp. 26463-26494 ◽  
Author(s):  
M. Brines ◽  
M. Dall'Osto ◽  
D. C. S. Beddows ◽  
R. M. Harrison ◽  
F. Gómez-Moreno ◽  
...  
Keyword(s):  
Los Angeles ◽  
Ultrafine Particles ◽  
Mediterranean Climate ◽  
Particle Number ◽  
Road Traffic ◽  
Particle Formation ◽  
Urban Environments ◽  
Urban Atmosphere ◽  
Size Distributions ◽  
New Particle Formation

Abstract. Road traffic emissions are often considered the main source of ultrafine particles (UFP, diameter smaller than 100 nm) in urban environments. However, recent studies have shown that – in southern European urban regions at least – new particle formation events can also contribute to UFP. In order to quantify such events we systematically studied four cities with a Mediterranean climate: Barcelona, Madrid, Rome and Los Angeles. The city of Brisbane is also included in our study due to its similar climate. Five long term datasets (from 3 months to 2 years) of fine and ultrafine particle number size distributions (measured by SMPS, Scanning Mobility Particle Sizer) were analysed. By applying k-Means clustering analysis, we categorized the collected aerosol size distributions in four main classes: "Traffic" (prevailing 41–63% of the time), "Background Pollution" (6–53%), "Nucleation" (6–33%) and "Specific case" (7–20%) the latter being site specific. The daily variation of the average UFP concentrations for a typical nucleation day at each site revealed a similar pattern for all cities, with three distinct particle bursts. A morning and an evening spike reflected traffic rush hours, whereas a third one at midday showed new particle formation events. This work shows that the average occurrence of particle size spectra dominated by new particle formation events was 18% of the time, showing the importance of this process as a source of UFP in the Mediterranean urban atmosphere. Furthermore, in a number of the studied cities, particle number concentration averaged daily profiles for the whole study periods clearly showed the same three particle bursts. This reveals nucleation events as a relevant contributor to the average daily urban exposure to UFP in Mediterranean urban environments.

scholarly journals Evaluation on the role of sulfuric acid in the mechanisms of new particle formation for Beijing case

2011 ◽  
Vol 11 (8) ◽  
pp. 24165-24189 ◽  
Author(s):  
Z. B. Wang ◽  
M. Hu ◽  
D. L. Yue ◽  
J. Zheng ◽  
R. Y. Zhang ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Particle Number ◽  
Particle Formation ◽  
Urban Atmosphere ◽  
Limiting Factors ◽  
New Particle Formation ◽  
H2so4 Concentration ◽  
Nucleation Mechanisms ◽  
Better Than

Abstract. New particle formation (NPF) is considered as an important mechanism for gas-to-particle transformation, and gaseous sulfuric acid is believed as a curcial precursor. Up to now few field-based studies on nucleation mechanisms and the role of sulfuric acid were conducted in China. In this study, simultaneously measurements of particle number size distributions and gaseous sulfuric acid concentrations were performed from July to September in 2008. Totally, 22 new particle formation events were observed during the entire 85 campaign days. The results show that the condensation sink of pre-existing particles is one of the limiting factors to determine the occurrence of nucleation events in Beijing. The concentrations of gaseous sulfuric acid show good correlations with freshly nucleated particles (N3–6) and formation rates (J3 and J1.5). The power-law relationship between H2SO4 concentration and N3–6 or J was adopted to explore the nucleation mechanism. The exponents range from 1 to 5. More than half of the NPF events exhibit an exponent larger than 2.5. For these cases, the thermodynamic process works better than the activation or kinetic nucleation theories to explain the nucleation events in urban atmosphere of Beijing.

scholarly journals Spring and summer contrast in new particle formation over nine forest areas in North America

2015 ◽  
Vol 15 (24) ◽  
pp. 13993-14003 ◽  
Author(s):  
F. Yu ◽  
G. Luo ◽  
S. C. Pryor ◽  
P. R. Pillai ◽  
S. H. Lee ◽  
...  
Keyword(s):  
North America ◽  
Radiative Forcing ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Formation Rate ◽  
Ultrafine Particle ◽  
Particle Formation ◽  
New Particle Formation ◽  
Forest Sites ◽  
Chamber Studies

Abstract. Recent laboratory chamber studies indicate a significant role for highly oxidized low-volatility organics in new particle formation (NPF), but the actual role of these highly oxidized low-volatility organics in atmospheric NPF remains uncertain. Here, particle size distributions (PSDs) measured in nine forest areas in North America are used to characterize the occurrence and intensity of NPF and to evaluate model simulations using an empirical formulation in which formation rate is a function of the concentrations of sulfuric acid and low-volatility organics from alpha-pinene oxidation (Nucl-Org), and using an ion-mediated nucleation mechanism (excluding organics) (Nucl-IMN). On average, NPF occurred on ~ 70 % of days during March for the four forest sites with springtime PSD measurements, while NPF occurred on only ~ 10 % of days in July for all nine forest sites. Both Nucl-Org and Nucl-IMN schemes capture the observed high frequency of NPF in spring, but the Nucl-Org scheme significantly overpredicts while the Nucl-IMN scheme slightly underpredicts NPF and particle number concentrations in summer. Statistical analyses of observed and simulated ultrafine particle number concentrations and frequency of NPF events indicate that the scheme without organics agrees better overall with observations. The two schemes predict quite different nucleation rates (including their spatial patterns), concentrations of cloud condensation nuclei, and aerosol first indirect radiative forcing in North America, highlighting the need to reduce NPF uncertainties in regional and global earth system models.

scholarly journals Spring and summer contrast in new particle formation over nine forest areas in North America

2015 ◽  
Vol 15 (15) ◽  
pp. 21271-21298 ◽  
Author(s):  
F. Yu ◽  
G. Luo ◽  
S. C. Pryor ◽  
P. R. Pillai ◽  
S. H. Lee ◽  
...  
Keyword(s):  
North America ◽  
Radiative Forcing ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Formation Rate ◽  
Ultrafine Particle ◽  
Particle Formation ◽  
New Particle Formation ◽  
Forest Sites ◽  
Chamber Studies

Abstract. Recent laboratory chamber studies indicate a significant role for highly oxidized low volatility organics in new particle formation (NPF) but the actual role of these highly oxidized low volatility organics in atmospheric NPF remains uncertain. Here, particle size distributions (PSDs) measured in nine forest areas in North America are used to characterize the occurrence and intensity of NPF and to evaluate model simulations using an empirical formulation in which formation rate is a function of the concentrations of sulfuric acid and low volatility organics from alpha-pinene oxidation (Nucl-Org), and using an ion-mediated nucleation mechanism (excluding organics; Nucl-IMN). On average, NPF occurred on ~ 70 % of days during March for the four forest sites with springtime PSD measurements, while NPF occurred on only ~ 10 % of days in July for all nine forest sites. Both Nucl-Org and Nucl-IMN schemes capture the observed high frequency of NPF in spring, but the Nucl-Org scheme significantly over-predicts while the Nucl-IMN scheme slightly under-predicts NPF and particle number concentrations in summer. Statistical analyses of observed and simulated ultrafine particle number concentrations and frequency of NPF events indicate that the scheme without organics agrees better overall with observations. The two schemes predict quite different nucleation rates (including their spatial patterns), concentrations of cloud condensation nuclei, and aerosol first indirect radiative forcing in North America, highlighting the need to reduce NPF uncertainties in regional and global earth system models.

scholarly journals Investigating three patterns of new particles growing to cloud condensation nuclei size in Beijing's urban atmosphere

2020 ◽  
Author(s):  
Liya Ma ◽  
Yujiao Zhu ◽  
Mei Zheng ◽  
Yele Sun ◽  
Lei Huang ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Particle Formation ◽  
Urban Atmosphere ◽  
New Particle Formation ◽  
Condensation Nuclei ◽  
Median Diameter ◽  
New Particles

Abstract. The growth of newly formed particles with diameters from ~ 10 nm to a larger size was investigated in Beijing's urban atmosphere on 10–23 December 2011, 12–27 April 2012 and through June–August 2014. The maximum geometric median diameter (Dpgmax) of newly formed particles in 11/27 new particle formation (NPF) events through June–August exceeded 75 nm, and the grown new particles may contribute to the population of cloud condensation nuclei. In contrast, no apparent growth in new particles with Dpgmax 

scholarly journals Changes in the production rate of secondary aerosol particles in Central Europe in view of decreasing SO<sub>2</sub> emissions between 1996 and 2006

2010 ◽  
Vol 10 (3) ◽  
pp. 1071-1091 ◽  
Author(s):  
A. Hamed ◽  
W. Birmili ◽  
J. Joutsensaari ◽  
S. Mikkonen ◽  
A. Asmi ◽  
...  
Keyword(s):  
Growth Rate ◽  
Cloud Condensation Nuclei ◽  
Formation Rate ◽  
Global Radiation ◽  
Particle Diameter ◽  
Particle Formation ◽  
Research Station ◽  
Particle Nucleation ◽  
New Particle Formation ◽  
New Particles

Abstract. In anthropogenically influenced atmospheres, sulphur dioxide (SO2) is the main precursor of gaseous sulphuric acid (H2SO4), which in turn is a main precursor for atmospheric particle nucleation. As a result of socio-economic changes, East Germany has seen a dramatic decrease in anthropogenic SO2 emissions between 1989 and present, as documented by routine air quality measurements in many locations. We have attempted to evaluate the influence of changing SO2 concentrations on the frequency and intensity of new particle formation (NPF) using two different data sets (1996–1997; 2003–2006) of experimental particle number size distributions (diameter range 3–750 nm) from the atmospheric research station Melpitz near Leipzig, Germany. Between the two periods SO2 concentrations decreased by 65% on average, while the frequency of NPF events dropped by 45%. Meanwhile, the average formation rate of 3 nm particles decreased by 68% on average. The trends were statistically significant and therefore suggest a connection between the availability of anthropogenic SO2 and freshly formed new particles. In contrast to the decrease in new particle formation, we found an increase in the mean growth rate of freshly nucleated particles (+22%), suggesting that particle nucleation and subsequent growth into larger sizes are delineated with respect to their precursor species. Using three basic parameters, the condensation sink for H2SO4, the SO2 concentration, and the global radiation intensity, we were able to define the characteristic range of atmospheric conditions under which particle formation events take place at the Melpitz site. While the decrease in the concentrations and formation rates of the new particles was rather evident, no similar decrease was found with respect to the generation of cloud condensation nuclei (CCN; particle diameter >100 nm) as a result of atmospheric nucleation events. On the contrary, the production of CCN following nucleation events appears to have increased by tens of percents. Our aerosol dynamics model simulations suggest that such an increase can be caused by the increased particle growth rate.

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 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.

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