Particle number size distributions and new particle formation events over the northern Indian Ocean during continental outflow

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.

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Simultaneous measurements of particle number size distributions at ground level and 260 m on a meteorological tower in urban Beijing, China

10.5194/acp-2016-1064 ◽

2017 ◽

Cited By ~ 1

Author(s):

Wei Du ◽

Jian Zhao ◽

Yuying Wang ◽

Yingjie Zhang ◽

Qingqing Wang ◽

...

Keyword(s):

Particle Number ◽

Ground Level ◽

Particle Growth ◽

Particle Formation ◽

Size Distributions ◽

New Particle Formation ◽

Aerosol Composition ◽

Accumulation Mode ◽

Simultaneous Measurements ◽

Emission Controls

Abstract. Despite extensive studies into characterization of particle number size distributions at ground level, real-time measurements above the urban canopy in the megacity of Beijing has never been performed to date. Here we conducted the first simultaneous measurements of size-resolved particle number concentrations at ground level and 260 m in urban Beijing from 22 August to 30 September. Our results showed overall similar temporal variations in number size distributions between ground level and 260 m, yet periods with significant differences were also observed. Particularly, accumulation mode particles were highly correlated (r2 = 0.85) at the two heights while Aitken mode particles presented more differences. Detailed analysis suggests that the vertical differences in number concentrations strongly depended on particle size, and particles with mobility diameter between 100–200 nm generally showed higher concentrations at higher altitudes. Particle growth rates and condensation sinks were also calculated which were 3.2 and 3.6 nm h−1, and 2.8 × 10−2 and 2.9 × 10−2 s−1, at ground level and 260 m, respectively. By linking particle growth with aerosol composition, we found that organics appeared to play an important role in the early stage of the growth (9:00–12:00) while sulfate was also important during the later period. Positive matrix factorization of size-resolved number concentrations identified three common sources at ground level and 260 m including a factor associated with new particle formation and growth events (NPE), and two secondary factors that represent photochemical processing and regional transport, respectively. Cooking emission was found to have a large contribution to small particles, and showed much higher concentration at ground level than 260 m at dinner time. This result has significant implications that investigation of NPE at ground level in megacities needs to consider the influences of local cooking emissions. The impacts of regional emission controls on particle number concentrations were also illustrated. Our results showed that regional emission controls have a dominant impact on accumulation mode particles by decreasing gas precursors and particulate matter loadings, and hence suppressing particle growth. In contrast, the influences on Aitken particles were much smaller due to the enhanced new particle formation (NPF) events.

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Occurrence of new particle formation events in Siberian and Finnish boreal forest

10.5194/acp-2021-530 ◽

2021 ◽

Author(s):

Helmi Uusitalo ◽

Jenni Kontkanen ◽

Ilona Ylivinkka ◽

Ekaterina Ezhova ◽

Anastasiia Demakova ◽

...

Keyword(s):

Boreal Forest ◽

Particle Number ◽

Theoretical Calculations ◽

Particle Growth ◽

Particle Formation ◽

Size Distributions ◽

New Particle Formation ◽

Forest Environment ◽

Survival Probabilities ◽

Measured Particle

Abstract. The occurence of new particle formation (NPF) events was investigated at four sites in the boreal forest environment (Hyytiälä SMEAR II and Värriö SMEAR I in Finland; Tomsk-Fonovaya and ZOTTO in Siberia, Russia), by analyzing measured particle number size-distributions (PNSD) and theoretical calculations of particle survival probabilities. NPF events were less frequent at the Siberian sites than at the Finnish sites. This is likely linked to lower survival probabilities of the freshly-formed particles at the Siberian sites, due to higher coagulational losses and lower particle growth rates. Another factor affecting the frequency of observed NPF events is the minimum detectable particle size. When the NPF event classification was made for Hyytiälä, Värriö and Tomsk-Fonovaya sites based on PNSD starting from 15 nm instead of 3 nm, the observed NPF frequencies decreased. This result highlights the importance of measuring PNSD starting from sub-10 nm particles, in order to obtain reliable estimates of the NPF characteristics.

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First long-term study of particle number size distributions and new particle formation events of regional aerosol in the North China Plain

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-25205-2010 ◽

2010 ◽

Vol 10 (10) ◽

pp. 25205-25242 ◽

Cited By ~ 2

Author(s):

X. J. Shen ◽

J. Y. Sun ◽

Y. M. Zhang ◽

B. Wehner ◽

A. Nowak ◽

...

Keyword(s):

North China Plain ◽

North China ◽

Particle Number ◽

Particle Formation ◽

Mean Value ◽

Size Distributions ◽

New Particle Formation ◽

Air Masses ◽

Nucleation Mode ◽

The North

Abstract. Atmospheric particle number size distributions (size range 0.003–10 μm) were measured between March 2008 and August 2009 at Shangdianzi (SDZ), a rural research station in the North China Plain. These measurements were made in an attempt to better characterize the tropospheric background aerosol in Northern China, one of the currently more polluted regions of the globe. The mean particle number concentrations of the total aerosol, as well as the nucleation, Aitken and accumulation modes were determined to 1.2±0.9×104, 3.6±7.9×103, 4.4±3.4×103 and 3.5±2.8×103 cm−3, respectively. A general finding is that the particle number concentrations were higher during spring compared to the other seasons. The air mass origin had an important effect on the particle number concentration and new particle formation events. Air masses from northwest (i.e. inner Asia) showed the highest concentrations of nucleation mode particles, while southeasterly air masses showed the highest concentrations of accumulation mode particles. Significant diurnal variations in particle number were observed, which could be linked to new particle formation events, i.e. gas-to-particle conversion. During particle formation events, the number concentration of the nucleation mode rose up to maximum values of 104 cm−3. New particle formation events were observed on 36% of the measurement days. The formation rate ranged between 0.7 and 72.7 cm−3 s−1, with a mean value of 8.0 cm−3 s−1. The values of the nucleation mode growth rate ranged between 0.3 and 14.5 nm h−1, with a mean value of 4.3 nm h−1. It is an essential observation that on many occasions, the nucleation mode was able to grow into the size of cloud condensation nuclei (CCN) within a matter of several hours. Furthermore, the new particle formation were usually followed by a measurable increase in total particle mass concentration and extinction coefficient, indicative of a high abundance of condensable vapors in the atmosphere under study.

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On the annual variability of Antarctic aerosol size distributions at Halley Research Station

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-4461-2020 ◽

2020 ◽

Vol 20 (7) ◽

pp. 4461-4476 ◽

Cited By ~ 1

Author(s):

Thomas Lachlan-Cope ◽

David C. S. Beddows ◽

Neil Brough ◽

Anna E. Jones ◽

Roy M. Harrison ◽

...

Keyword(s):

Particle Number ◽

Particle Formation ◽

Sea Salt ◽

Sea Spray ◽

Substantial Part ◽

Research Station ◽

Size Distributions ◽

Blowing Snow ◽

New Particle Formation ◽

The Antarctic

Abstract. The Southern Ocean and Antarctic region currently best represent one of the few places left on our planet with conditions similar to the preindustrial age. Currently, climate models have a low ability to simulate conditions forming the aerosol baseline; a major uncertainty comes from the lack of understanding of aerosol size distributions and their dynamics. Contrasting studies stress that primary sea salt aerosol can contribute significantly to the aerosol population, challenging the concept of climate biogenic regulation by new particle formation (NPF) from dimethyl sulfide marine emissions. We present a statistical cluster analysis of the physical characteristics of particle size distributions (PSDs) collected at Halley (Antarctica) for the year 2015 (89 % data coverage; 6–209 nm size range; daily size resolution). By applying the Hartigan–Wong k-mean method we find eight clusters describing the entire aerosol population. Three clusters show pristine average low particle number concentrations (< 121–179 cm−3) with three main modes (30, 75–95 and 135–160 nm) and represent 57 % of the annual PSD (up to 89 %–100 % during winter and 34 %–65 % during summer based on monthly averages). Nucleation and Aitken mode PSD clusters dominate summer months (September–January, 59 %–90 %), whereas a clear bimodal distribution (43 and 134 nm, respectively; Hoppel minimum at mode 75 nm) is seen only during the December–April period (6 %–21 %). Major findings of the current work include: (1) NPF and growth events originate from both the sea ice marginal zone and the Antarctic plateau, strongly suggesting multiple vertical origins, including the marine boundary layer and free troposphere; (2) very low particle number concentrations are detected for a substantial part of the year (57 %), including summer (34 %–65 %), suggesting that the strong annual aerosol concentration cycle is driven by a short temporal interval of strong NPF events; (3) a unique pristine aerosol cluster is seen with a bimodal size distribution (75 and 160 nm, respectively), strongly associated with high wind speed and possibly associated with blowing snow and sea spray sea salt, dominating the winter aerosol population (34 %–54 %). A brief comparison with two other stations (Dome C – Concordia – and King Sejong Station) during the year 2015 (240 d overlap) shows that the dynamics of aerosol number concentrations and distributions are more complex than the simple sulfate–sea-spray binary combination, and it is likely that an array of additional chemical components and processes drive the aerosol population. A conceptual illustration is proposed indicating the various atmospheric processes related to the Antarctic aerosols, with particular emphasis on the origin of new particle formation and growth.

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Simultaneous measurements of particle number size distributions at ground level and 260 m on a meteorological tower in urban Beijing, China

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-6797-2017 ◽

2017 ◽

Vol 17 (11) ◽

pp. 6797-6811 ◽

Cited By ~ 20

Author(s):

Wei Du ◽

Jian Zhao ◽

Yuying Wang ◽

Yingjie Zhang ◽

Qingqing Wang ◽

...

Keyword(s):

Particle Number ◽

Ground Level ◽

Particle Growth ◽

Particle Formation ◽

Size Distributions ◽

New Particle Formation ◽

Aerosol Composition ◽

Accumulation Mode ◽

Simultaneous Measurements ◽

Emission Controls

Abstract. Despite extensive studies into the characterization of particle number size distributions at ground level, real-time measurements above the urban canopy in the megacity of Beijing have never been performed to date. Here we conducted the first simultaneous measurements of size-resolved particle number concentrations at ground level and 260 m in urban Beijing from 22 August to 30 September. Our results showed overall similar temporal variations in number size distributions between ground level and 260 m, yet periods with significant differences were also observed. Particularly, accumulation-mode particles were highly correlated (r2 = 0. 85) at the two heights, while Aitken-mode particles presented more differences. Detailed analysis suggests that the vertical differences in number concentrations strongly depended on particle size, and particles with a mobility diameter between 100 and 200 nm generally showed higher concentrations at higher altitudes. Particle growth rates and condensation sinks were also calculated, which were 3.2 and 3.6 nm h−1, and 2.8  ×  10−2 and 2.9  ×  10−2 s−1, at ground level and 260 m, respectively. By linking particle growth with aerosol composition, we found that organics appeared to play an important role in the early stage of the growth (09:00–12:00 LT) while sulfate was also important during the later period. Positive matrix factorization of size-resolved number concentrations identified three common sources at ground level and 260 m, including a factor associated with new particle formation and growth events (NPEs), and two secondary factors that represent photochemical processing and regional transport. Cooking emission was found to have a large contribution to small particles and showed much higher concentration at ground level than 260 m in the evening. These results imply that investigation of NPEs at ground level in megacities needs to consider the influences of local cooking emissions. The impacts of regional emission controls on particle number concentrations were also illustrated. Our results showed that regional emission controls have a dominant impact on accumulation-mode particles by decreasing gas precursors and particulate matter loadings, and hence suppressing particle growth. In contrast, the influences on Aitken particles were much smaller due to the enhanced new particle formation (NPF) events.

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

Environmental Science & Technology ◽

10.1021/acs.est.0c07465 ◽

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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Modeling particle nucleation and growth over northern California during the 2010 CARES campaign

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-12283-2015 ◽

2015 ◽

Vol 15 (21) ◽

pp. 12283-12313 ◽

Cited By ~ 11

Author(s):

A. Lupascu ◽

R. Easter ◽

R. Zaveri ◽

M. Shrivastava ◽

M. Pekour ◽

...

Keyword(s):

Size Distribution ◽

Particle Number ◽

Particle Formation ◽

Number Concentration ◽

Aerosol Size Distribution ◽

Particle Nucleation ◽

Particle Number Concentration ◽

New Particle Formation ◽

Organic Vapors ◽

Diurnal Variability

Abstract. Accurate representation of the aerosol lifecycle requires adequate modeling of the particle number concentration and size distribution in addition to their mass, which is often the focus of aerosol modeling studies. This paper compares particle number concentrations and size distributions as predicted by three empirical nucleation parameterizations in the Weather Research and Forecast coupled with chemistry (WRF-Chem) regional model using 20 discrete size bins ranging from 1 nm to 10 μm. Two of the parameterizations are based on H2SO4, while one is based on both H2SO4 and organic vapors. Budget diagnostic terms for transport, dry deposition, emissions, condensational growth, nucleation, and coagulation of aerosol particles have been added to the model and are used to analyze the differences in how the new particle formation parameterizations influence the evolving aerosol size distribution. The simulations are evaluated using measurements collected at surface sites and from a research aircraft during the Carbonaceous Aerosol and Radiative Effects Study (CARES) conducted in the vicinity of Sacramento, California. While all three parameterizations captured the temporal variation of the size distribution during observed nucleation events as well as the spatial variability in aerosol number, all overestimated by up to a factor of 2.5 the total particle number concentration for particle diameters greater than 10 nm. Using the budget diagnostic terms, we demonstrate that the combined H2SO4 and low-volatility organic vapor parameterization leads to a different diurnal variability of new particle formation and growth to larger sizes compared to the parameterizations based on only H2SO4. At the CARES urban ground site, peak nucleation rates are predicted to occur around 12:00 Pacific (local) standard time (PST) for the H2SO4 parameterizations, whereas the highest rates were predicted at 08:00 and 16:00 PST when low-volatility organic gases are included in the parameterization. This can be explained by higher anthropogenic emissions of organic vapors at these times as well as lower boundary-layer heights that reduce vertical mixing. The higher nucleation rates in the H2SO4-organic parameterization at these times were largely offset by losses due to coagulation. Despite the different budget terms for ultrafine particles, the 10–40 nm diameter particle number concentrations from all three parameterizations increased from 10:00 to 14:00 PST and then decreased later in the afternoon, consistent with changes in the observed size and number distribution. We found that newly formed particles could explain up to 20–30 % of predicted cloud condensation nuclei at 0.5 % supersaturation, depending on location and the specific nucleation parameterization. A sensitivity simulation using 12 discrete size bins ranging from 1 nm to 10 μm diameter gave a reasonable estimate of particle number and size distribution compared to the 20 size bin simulation, while reducing the associated computational cost by ~ 36 %.

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CCN production by new particle formation in the free troposphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-1529-2017 ◽

2017 ◽

Vol 17 (2) ◽

pp. 1529-1541 ◽

Cited By ~ 17

Author(s):

Clémence Rose ◽

Karine Sellegri ◽

Isabel Moreno ◽

Fernando Velarde ◽

Michel Ramonet ◽

...

Keyword(s):

Particle Number ◽

Particle Growth ◽

Particle Formation ◽

Number Concentration ◽

Particle Number Concentration ◽

Free Troposphere ◽

New Particle Formation ◽

Data Set ◽

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 contributes significantly to cloud condensation nuclei (CCN) concentrations. NPF events were frequently observed at the highest atmospheric observatory in the world, on 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 1 January and 31 December 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, relative to the transport and growth of pre-existing particles, to CCN size. The averaged production of 50 nm particles during those events was 5072, 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 53 % 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.

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