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 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 Explaining global surface aerosol number concentrations in terms of primary emissions and particle formation

2010 ◽  
Vol 10 (10) ◽  
pp. 4775-4793 ◽  
Author(s):  
D. V. Spracklen ◽  
K. S. Carslaw ◽  
J. Merikanto ◽  
G. W. Mann ◽  
C. L. Reddington ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sulfuric Acid ◽  
Particle Number ◽  
Marine Boundary Layer ◽  
Sulfuric Acid Concentration ◽  
Particle Formation ◽  
Anthropogenic Sources ◽  
Secondary Source ◽  
Primary Particles ◽  
Activation Type

Abstract. We synthesised observations of total particle number (CN) concentration from 36 sites around the world. We found that annual mean CN concentrations are typically 300–2000 cm−3 in the marine boundary layer and free troposphere (FT) and 1000–10 000 cm−3 in the continental boundary layer (BL). Many sites exhibit pronounced seasonality with summer time concentrations a factor of 2–10 greater than wintertime concentrations. We used these CN observations to evaluate primary and secondary sources of particle number in a global aerosol microphysics model. We found that emissions of primary particles can reasonably reproduce the spatial pattern of observed CN concentration (R2=0.46) but fail to explain the observed seasonal cycle (R2=0.1). The modeled CN concentration in the FT was biased low (normalised mean bias, NMB=−88%) unless a secondary source of particles was included, for example from binary homogeneous nucleation of sulfuric acid and water (NMB=−25%). Simulated CN concentrations in the continental BL were also biased low (NMB=−74%) unless the number emission of anthropogenic primary particles was increased or a mechanism that results in particle formation in the BL was included. We ran a number of simulations where we included an empirical BL nucleation mechanism either using the activation-type mechanism (nucleation rate, J, proportional to gas-phase sulfuric acid concentration to the power one) or kinetic-type mechanism (J proportional to sulfuric acid to the power two) with a range of nucleation coefficients. We found that the seasonal CN cycle observed at continental BL sites was better simulated by BL particle formation (R2=0.3) than by increasing the number emission from primary anthropogenic sources (R2=0.18). The nucleation constants that resulted in best overall match between model and observed CN concentrations were consistent with values derived in previous studies from detailed case studies at individual sites. In our model, kinetic and activation-type nucleation parameterizations gave similar agreement with observed monthly mean CN concentrations.

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 Investigation of new particle formation at the summit of Mt. Tai, China

2016 ◽  
Author(s):  
Ganglin Lv ◽  
Xiao Sui ◽  
Jianmin Chen ◽  
Rohan Jayaratne ◽  
Abdelwahid Mellouki
Keyword(s):  
Growth Rate ◽  
Sulfuric Acid ◽  
Sulfur Dioxide ◽  
Growth Rates ◽  
Formation Rate ◽  
High Elevation ◽  
Particle Formation ◽  
Mean Value ◽  
New Particle Formation ◽  
Total Particle

Abstract. To date very few field observations of new particle formation (NPF) have been carried out at the high-elevation mountain sites in China. Simultaneously measurements of particle size distributions, gas species, meteorological conditions and PM2.5 were performed at the summit of Mt. Tai (1530 m ASL) from 25 July to 24 October 2014 (І), 21 September to 9 December 2014 (И) and 16 June to 7 August 2015 (Ш). The results showed that: (i) 66 NPF events were observed during 164 days, corresponding to an occurrence frequency of 40 %. Formation rates, growth rates and condensation sinks were in the range of 1.10–57.43 cm−3 s−1, 0.58–7.76 nm h−1 and 0.40 × 10−2–6.32 × 10−2 s−1, respectively, and Mt. Tai appeared to show the larger formation rate and smaller growth rate relative to other locations in China. The mean value of sulfur dioxide on NPF days was 46 % higher than that on non-NPF days, and a higher sulfur dioxide concentration could improve the possibility of rich precursors for NPF. (ii) Sulfuric acid condensation contributed to 16.20 % of growth rate, and sulfuric acid proxy showed an obvious correlation with total particle concentration of 3–6 nm (N3–6 nm). (iii) Low PM2.5 was favourable for nucleation, and NPF days with limited higher PM2.5 seemed to have larger growth rates which might be related to particles recombination in close sizes. Four NPF events were observed on haze episodes, which could be promoted by potential specific mechanisms or pollutants. (iv) Particles formed via NPF on both clean and polluted days mainly contributed to Aiken mode eventually, and PM2.5 variation was always in accordance with particle total volume concentration.

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 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 New Particle Formation and impact on CCN concentrations in the boundary layer and free troposphere at the high altitude station of Chacaltaya (5240 m a.s.l.), Bolivia

2016 ◽  
Author(s):  
C. Rose ◽  
K. Sellegri ◽  
I. Moreno ◽  
F. Velarde ◽  
M. Ramonet ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particle Number ◽  
Particle Growth ◽  
Particle Formation ◽  
Number Concentration ◽  
Particle Number Concentration ◽  
Free Troposphere ◽  
New Particle Formation ◽  
Radiative Processes ◽  
The Impact

Abstract. Global models predict that new particle formation (NPF) is, in some environments, responsible for a substantial fraction of the total atmospheric particle number concentration and subsequently contribute significantly to cloud condensation nuclei (CCN) concentrations. NPF events were frequently observed at the highest atmospheric observatory in the world, Chacaltaya (5240 m a.s.l.), Bolivia. The present study focuses on the impact of NPF on CCN population. Neutral cluster and Air Ion Spectrometer and mobility particle size spectrometer measurements were simultaneously used to follow the growth of particles from cluster sizes down to ~ 2 nm up to CCN threshold sizes set to 50, 80 and 100 nm. Using measurements performed between January 1 and December 31 2012, we found that 61% of the 94 analysed events showed a clear particle growth and significant enhancement of the CCN-relevant particle number concentration. We evaluated the contribution of NPF events relative to the transport of pre-existing particles to the site. The averaged production of 50 nm particles during those events was 5072 cm−3, and 1481 cm−3 for 100 nm particles, with a larger contribution of NPF compared to transport, especially during the wet season. The data set was further segregated into boundary layer (BL) and free troposphere (FT) conditions at the site. The NPF frequency of occurrence was higher in the BL (48 %) compared to the FT (39 %). Particle condensational growth was more frequently observed for events initiated in the FT, but on average faster for those initiated in the BL, when the amount of condensable species was most probably larger. As a result, the potential to form new CCN was higher for events initiated in the BL (67 % against 56 % in the FT). In contrast, higher CCN number concentration increases were found when the NPF process initially occurred in the FT, under less polluted conditions. This work highlights the competition between particle growth and the removal of freshly nucleated particles by coagulation processes. The results support model predictions which suggest that NPF is an effective source of CCN in some environments, and thus may influence regional climate through cloud related radiative processes.

scholarly journals Basic characteristics of atmospheric particles, trace gases and meteorology in a relatively clean Southern African Savannah environment

2008 ◽  
Vol 8 (2) ◽  
pp. 6313-6353 ◽  
Author(s):  
L. Laakso ◽  
H. Laakso ◽  
P. P. Aalto ◽  
P. Keronen ◽  
T. Petäjä ◽  
...  
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Regional Climate ◽  
Formation Rate ◽  
Measurement Data ◽  
Particle Growth ◽  
Particle Formation ◽  
New Particle Formation ◽  
Total Particle ◽  
Pm2.5 And Pm10

Abstract. We have analyzed one year (July 2006–July 2007) of measurement data from a relatively clean background site located in dry savannah in South Africa. The annual-median trace gas concentrations were equal to 0.7 ppb for SO2, 1.4 ppb for NOx, 36 ppb for O3 and 105 ppb for CO. The corresponding PM1, PM2.5 and PM10 concentrations were 9.0, 10.5 and 18.8 μg m−3, and the annual median total particle number concentration in the size range 10–840 nm was 2340 cm−3. Gases and particles had a clear seasonal and diurnal variation, which was associated with field fires and biological activity together with local meteorology. Atmospheric new-particle formation was observed to take place in more than 90% of the analyzed days. The days with no new particle formation were cloudy or rainy days. The formation rate of 10 nm particles varied in the range of 0.1–28 cm−3 s−1 (median 1.9 cm−3 s−1) and nucleation mode particle growth rates were in the range 3–21 nm h−1 (median 8.5 nm h−1). Due to high formation and growth rates, observed new particle formation gives a significant contribute to the number of cloud condensation nuclei budget, having a potential to affect the regional climate forcing patterns.

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 The roles of sulfuric acid in new particle formation and growth in the mega-city of Beijing

2010 ◽  
Vol 10 (10) ◽  
pp. 4953-4960 ◽  
Author(s):  
D. L. Yue ◽  
M. Hu ◽  
R. Y. Zhang ◽  
Z. B. Wang ◽  
J. Zheng ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Organic Compounds ◽  
Dominant Role ◽  
Formation Rate ◽  
Particle Growth ◽  
Particle Formation ◽  
New Particle Formation ◽  
Average Formation ◽  
Subsequent Neutralization

Abstract. Simultaneous measurements of gaseous sulfuric acid and particle number size distributions were performed to investigate aerosol nucleation and growth during CAREBeijing-2008. The analysis of the measured aerosols and sulfuric acid with an aerosol dynamic model shows the dominant role of sulfuric acid in new particle formation (NPF) process but also in the subsequent growth in Beijing. Based on the data of twelve NPF events, the average formation rates (2–13 cm−3 s−1) show a linear correlation with the sulfuric acid concentrations (R2=0.85). Coagulation seems to play a significant role in reducing the number concentration of nucleation mode particles with the ratio of the coagulation loss to formation rate being 0.41±0.16. The apparent growth rates vary from 3 to 11 nm h−1. Condensation of sulfuric acid and its subsequent neutralization by ammonia and coagulation contribute to the apparent particle growth on average 45±18% and 34±17%, respectively. The 30% higher concentration of sulfate than organic compounds in particles during the seven sulfur-rich NPF events but 20% lower concentration of sulfate during the five sulfur-poor type suggest that organic compounds are an important contributor to the growth of the freshly nucleated particles, especially during the sulfur-poor cases.

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