Nucleation mode particles in upslope valley winds at Mount Norikura, Japan: Implications for the vertical extent of new particle formation events in the lower troposphere

Abstract. During the monsoon season of the year 2017 the airborne StratoClim mission took place in Kathmandu, Nepal, with eight mission flights of the M-55 Geophysica in the upper troposphere–lower stratosphere (UTLS) of the Asian monsoon anticyclone (AMA) over northern India, Nepal, and Bangladesh. More than 100 events of new particle formation (NPF) were observed. In total, more than 2 h of flight time was spent under NPF conditions as indicated by the abundant presence of nucleation-mode aerosols, i.e. with particle diameters dp smaller than 15 nm, which were detected in situ by means of condensation nuclei counting techniques. Mixing ratios of nucleation-mode particles (nnm) of up to ∼ 50 000 mg−1 were measured at heights of 15–16 km (θ ≈ 370 K). NPF was most frequently observed at ∼ 12–16 km altitude (θ ≈ 355–380 K) and mainly below the tropopause. Resulting nnm remained elevated (∼ 300–2000 mg−1) up to altitudes of ∼ 17.5 km (θ ≈ 400 K), while under NPF conditions the fraction (f) of sub-micrometre-sized non-volatile residues (dp > 10 nm) remained below 50 %. At ∼ 12–14 km (θ ≈ 355–365 K) the minimum of f (< 15 %) was found, and underneath, the median f generally remains below 25 %. The persistence of particles at nucleation-mode sizes is limited to a few hours, mainly due to coagulation, as demonstrated by a numerical simulation. The frequency of NPF events observed during StratoClim 2017 underlines the importance of the AMA as a source region for UTLS aerosols and for the formation and maintenance of the Asian tropopause aerosol layer (ATAL). The observed abundance of NPF-produced nucleation-mode particles within the AMA is not unambiguously attributable to (a) specific source regions in the boundary layer (according to backward trajectory analyses), or (b) the direct supply with precursor material by convective updraught (from correlations of NPF with carbon monoxide), or (c) the recent release of NPF-capable material from the convective outflow (according to air mass transport times in the tropical tropopause layer, TTL). Temperature anomalies with ΔT of 2 K (peak-to-peak amplitude), as observed at a horizontal wavelength of ∼ 70–100 km during a level flight of several hours, match with NPF detections and represent an additional mechanism for local increases in supersaturation of the NPF precursors. Effective precursor supply and widely distributed temperature anomalies within the AMA can explain the higher frequency of intense NPF observed during StratoClim 2017 than all previous NPF detections with COPAS (COndensation PArticle counting System) at TTL levels over Brazil, northern Australia, or West Africa.

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Iodine speciation and size distribution in ambient aerosols at a coastal new particle formation hotspot in China

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-4025-2019 ◽

2019 ◽

Vol 19 (6) ◽

pp. 4025-4039 ◽

Cited By ~ 11

Author(s):

Huan Yu ◽

Lili Ren ◽

Xiangpeng Huang ◽

Mingjie Xie ◽

Jun He ◽

...

Keyword(s):

Particle Formation ◽

Coastal Areas ◽

Aerosol Sample ◽

Size Distributions ◽

New Particle Formation ◽

Nucleation Mode ◽

Iodine Species ◽

Organic Iodine ◽

Iodine Compounds ◽

Iodine Speciation

Abstract. Intense new particle formation (NPF) events were observed in the coastal atmosphere during algae growth and farming season at Xiangshan gulf of the east China coast. High nucleation-mode iodine concentrations measured by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) confirmed that the NPF events were induced by iodine species. Our study provides important information on iodine speciation, size distributions, and its role in NPF in the context of heavy air pollution in China's coastal areas. For the first time, we identified 5 inorganic iodine species, 45 organic iodine compounds (35 molecular formulas), and a group of iodide–organic adducts in aerosols. The concentrations and size distributions of iodine species down to 10 nm were measured during the iodine-induced NPF, continental NPF, and non-NPF days at the coastal site and compared to those at an inland site. The iodine in the above four aerosol sample types were characterized by iodate, aromatic iodine compounds, iodoacetic acid or iodopropenoic acid, and iodide–organic adducts, respectively. Iodide and organic iodine compounds were found in the nucleation-mode particles; however, it is still not clear whether they contributed to nucleation or just new particle growth. Wild algae, as well as farmed algae, could be an important NPF source in China's coastal areas.

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Direct observation of molecular clusters and nucleation mode particles in the Amazon

10.5194/acp-2017-782 ◽

2017 ◽

Cited By ~ 2

Author(s):

Daniela Wimmer ◽

Stephany Buenrostro Mazon ◽

Hanna Elina Manninen ◽

Juha Kangasluoma ◽

Alessandro Franchin ◽

...

Keyword(s):

Growth Rates ◽

Ground Level ◽

Particle Formation ◽

New Particle Formation ◽

Wet Season ◽

Ion Concentrations ◽

Nucleation Mode ◽

Rain Events ◽

20 Nm ◽

Spectrometer Data

Abstract. We investigated atmospheric new particle formation (NPF) in the Amazon rainforest using direct measurement methods. The occurrence of NPF on ground level in the Amazon region has not been observed previously in pristine conditions. Our measurements extended to two field sites and two tropical seasons (wet and dry). We measured the variability of air ion concentrations (0.8–20 nm) with an ion spectrometer between 2011 and 2014 at the T0t site and between February and October 2014 at the GoAmazon 2014/5 T3 site. The main difference between the two sites is their geographical location. Both sites are influenced by the Manaus pollution plume yet with different frequencies. T0t is reached by the pollution about 1 day in 7, where the T3 site is about 15 % of the time affected by Manaus. The sampling was performed at ground level at both sites. At T0t the instrumentation was located inside the rainforest, whereas the T3 site was an open pasture site. T0t site is mostly parallel wind to Manaus, whereas T3 site is downwind of Manaus. No NPF events were observed inside the rainforest canopy (site T0t) at ground level during the period Sep 2011–Jan 2014. However, rain-induced ion and particle bursts (hereafter, “rain events”) occurred frequently (306/529 days) at T0t throughout the year but most frequently between January and April (wet season). Rain events increased nucleation mode (2–20 nm) particle and ion concentrations on the order of 104 cm−3. We observed 8 NPF events at the pasture site during the wet season. We calculated the growth rates (GR) and formation rates of neutral particles and ions for the size ranges 2–3 nm, 3–7 nm and 7–20 nm using the ion spectrometer data. One explanation for the absence of new particle formation events at the T0t site could be a combination of cleaner airmasses and the rainforest canopy acting as an ‘umbrella’, hindering the mixing of the airmasses down to the measurement height. Neutral particle growth rates in the 3–7 nm regime showed two phenomena. Growth rates were either about 2 nm h−1 or about 14 nm h−1. There was no clear difference in the sulfuric acid concentrations for NPF days vs days without NPF. Back trajectory calculations show different airmass origin for the NPF days compared to non NPF days.

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Horizontal homogeneity and vertical extent of new particle formation events

Tellus B ◽

10.1111/j.1600-0889.2007.00260.x ◽

2007 ◽

Vol 59 (3) ◽

pp. 362-371 ◽

Cited By ~ 51

Author(s):

Birgit Wehner ◽

Holger Siebert ◽

Frank Stratmann ◽

Thomas Tuch ◽

Alfred Wiedensohler ◽

...

Keyword(s):

Particle Formation ◽

New Particle Formation ◽

Vertical Extent

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Characterization of satellite based proxies for estimating nucleation mode particles over South Africa

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-25825-2014 ◽

2014 ◽

Vol 14 (18) ◽

pp. 25825-25867

Author(s):

A.-M. Sundström ◽

A. Nikandrova ◽

K. Atlaskina ◽

T. Nieminen ◽

V. Vakkari ◽

...

Keyword(s):

South Africa ◽

Industrial Area ◽

Particle Formation ◽

Point Sources ◽

New Particle Formation ◽

Factors Affecting ◽

Nucleation Mode ◽

Sink Term ◽

Major Factors

Abstract. In this work satellite observations from the NASA's A-Train constellation were used to derive the values of primary emission and regional nucleation proxies over South Africa to estimate the potential for new particle formation. As derived in Kulmala et al. (2011), the satellite based proxies consist of source terms (NO2, SO2 and UV-B radiation), and a sink term describing the pre-existing aerosols. The first goal of this work was to study in detail the use of satellite aerosol optical depth (AOD) as a substitute to the in situ based condensation sink (CS). One of the major factors affecting the agreement of CS and AOD was the elevated aerosol layers that increased the value of column integrated AOD but not affected the in situ CS. However, when the AOD in the proxy sink was replaced by an estimate from linear bivariate fit between AOD and CS, the agreement with the actual nucleation mode number concentration improved somewhat. The second goal of the work was to estimate how well the satellite based proxies can predict the potential for new particle formation. For each proxy the highest potential for new particle formation were observed over the Highveld industrial area, where the emissions were high but the sink due to pre-existing aerosols was relatively low. Best agreement between the satellite and in situ based proxies were obtained for NO2/AOD and UV-B/AOD2, whereas proxies including SO2 in the source term had lower correlation. Even though the OMI SO2 boundary layer product showed reasonable spatial pattern and detected the major sources over the study area, some of the known minor point sources were not detected. When defining the satellite proxies only for days when new particle formation event was observed, it was seen that for all the satellite based proxies the event day medians were higher than the entire measurement period median.

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Submicron aerosols at thirteen diversified sites in China: size distribution, new particle formation and corresponding contribution to cloud condensation nuclei production

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-15149-2014 ◽

2014 ◽

Vol 14 (10) ◽

pp. 15149-15189 ◽

Cited By ~ 2

Author(s):

J. F. Peng ◽

M. Hu ◽

Z. B. Wang ◽

X. F. Huang ◽

P. Kumar ◽

...

Keyword(s):

Size Distribution ◽

Particle Number ◽

Cloud Condensation Nuclei ◽

Particle Formation ◽

New Particle Formation ◽

Condensation Nuclei ◽

Accumulation Mode ◽

Nucleation Mode ◽

Secondary Formation ◽

Urban Sites

Abstract. Understanding the particle number size distributions in diversified atmospheric environments is important in order to design mitigation strategies related to submicron particles and their effect on regional air quality, haze and human health. In this study, we conducted 15 different field measurement campaigns, each one-month long, between 2007 and 2011 at 13 individual sites in China. These were 5 urban sites, 4 regional sites, 3 coastal/background sites and one ship cruise measurement along eastern coastline of China. Size resolved particles were measured in the 15–600 nm size range. The median particle number concentrations (PNC) were found to vary in the range of 1.1–2.2 × 104 cm−3 at urban sites, 0.8–1.5 × 104 cm−3 at regional sites, 0.4–0.6 × 104 cm−3 at coastal/background sites, and 0.5 × 104 cm−3 during cruise measurements. Peak diameters at each of these sites varied greatly from 24 nm to 115 nm. Particles in the 15–25 nm (nucleation mode), 25–100 nm (Aitken mode) and 100–600 nm (accumulation mode) range showed different characteristics at each of the studied sites, indicating the features of primary emissions and secondary formation in these diversified atmospheric environments. Diurnal variations show a build-up of accumulation mode particles belt at regional sites, suggesting the contribution of regional secondary aerosol pollution. Frequencies of new particle formation (NPF) events were much higher at urban and regional sites than at coastal sites and cruise measurement. The average growth rates (GRs) of nucleation mode particles were 8.0–10.9 nm h−1 at urban sites, 7.4–13.6 nm h−1 at regional sites and 2.8–7.5 nm h−1 at both coastal and cruise measurement sites. The high gaseous precursors and strong oxidation at urban and regional sites not only favored the formation of particles, but also accelerated the growth rate of the nucleation mode particles. No significant difference in condensation sink (CS) during NPF days were observed among different site types, suggesting that the NPF events in background area were more influenced by the pollutant transport. In addition, average contributions of NPF events to potential cloud condensation nuclei (CCN) at 0.2% super-saturation in the afternoon of all sampling days were calculated as 11% and 6% at urban sites and regional sites, respectively. On the other hand, NPF events at coastal and cruise measurement sites had little impact on potential production of CCN. This study provides a large dataset of aerosol size distribution in diversified atmosphere of China, improving our general understanding of emission, secondary formation, new particles formation and corresponding CCN activity of submicron aerosols in Chinese environments.

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Impact of temperature dependence on the possible contribution of organics to new particle formation in the atmosphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-4997-2017 ◽

2017 ◽

Vol 17 (8) ◽

pp. 4997-5005 ◽

Cited By ~ 11

Author(s):

Fangqun Yu ◽

Gan Luo ◽

Alexey B. Nadykto ◽

Jason Herb

Keyword(s):

North America ◽

Temperature Dependence ◽

Radiative Forcing ◽

Particle Number ◽

Cloud Condensation Nuclei ◽

Lower Troposphere ◽

Particle Formation ◽

Strong Impact ◽

New Particle Formation ◽

Aerosol Model

Abstract. Secondary particles formed via new particle formation (NPF) dominate cloud condensation nuclei (CCN) abundance in most parts of the troposphere and are important for aerosol indirect radiative forcing (IRF). Laboratory measurements have shown that certain organic compounds can significantly enhance the binary nucleation of sulfuric acid and H2O. According to our recent study comparing particle size distributions measured in nine forest areas in North America with those predicted by a global size-resolved aerosol model, current H2SO4–organics nucleation parameterizations appear to significantly overpredict NPF and particle number concentrations in summer. The lack of temperature dependence in the current H2SO4–organics nucleation parameterization has been suggested to be a possible reason for the observed overprediction. In this work, H2SO4–organics clustering thermodynamics from quantum chemical studies has been employed to develop a scheme to incorporate temperature dependence into H2SO4–organics nucleation parameterization. We show that temperature has a strong impact on H2SO4–organics nucleation rates and may reduce the nucleation rate by ∼  1 order of magnitude per 10 K of temperature increase. The particle number concentrations in summer over North America based on the revised scheme is a factor of more than 2 lower, which is in much better agreement with the observations. With the temperature-dependent H2SO4–organics nucleation parameterization, the summer CCN concentrations in the lower troposphere in the Northern Hemisphere are about 10–30 % lower compared to the temperature-independent parameterization. This study highlights the importance of the temperature effect and its impacts on NPF in the global modeling of aerosol number abundance.

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Characterization of ultrafine particle number concentration and new particle formation in an urban environment of Taipei, Taiwan

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-8935-2013 ◽

2013 ◽

Vol 13 (17) ◽

pp. 8935-8946 ◽

Cited By ~ 29

Author(s):

H. C. Cheung ◽

C. C.-K. Chou ◽

W.-R. Huang ◽

C.-Y. Tsai

Keyword(s):

Growth Rate ◽

Urban Areas ◽

Particle Formation ◽

Number Concentration ◽

Submicron Particles ◽

Radiation Budget ◽

New Particle Formation ◽

Urban Background ◽

Nucleation Mode ◽

Quadratic Relationship

Abstract. An intensive aerosol characterization experiment was performed at the Taipei Aerosol and Radiation Observatory (TARO, 25.02° N, 121.53° E) in the urban area of Taipei, Taiwan, during July 2012. Number concentration and size distribution of aerosol particles were measured continuously, which were accompanied by concurrent measurements of mass concentration of submicron particles, PM1 (d ≤ 1 μm), and photolysis rate of ozone, J(O1D). The averaged number concentrations of total (Ntotal), accumulation mode (Nacu), Aitken mode (NAitken), and nucleation mode (Nnuc) particles were 13.9 × 103 cm−3, 1.2 × 103 cm−3, 6.1 × 103 cm−3, and 6.6 × 103 cm−3, respectively. Accordingly, the ultrafine particles (UFPs, d ≤ 100 nm) accounted for 91% of the total number concentration of particles measured in this study (10 ≤ d ≤ 429 nm), indicating the importance of UFPs to the air quality and radiation budget in Taipei and its surrounding areas. An averaged Nnuc / NOx ratio of 192.4 cm−3 ppbv−1 was derived from nighttime measurements, which was suggested to be the characteristic of vehicle emissions that contributed to the "urban background" of nucleation mode particles throughout a day. On the contrary, it was found that the number concentration of nucleation mode particles was independent of NOx and could be elevated up to 10 times of the "urban background" levels during daytime, suggesting a substantial amount of nucleation mode particles produced from photochemical processes. Averages (± 1σ) of the diameter growth rate (GR) and formation rate of nucleation mode particles, J10, were 11.9 ± 10.6 nm h−1 and 6.9 ± 3.0 cm−3 s−1, respectively. Consistency in the time series of the nucleation mode particle concentration and the proxy of H2SO4 production, UVB · SO2/CS, for new particle formation (NPF) events suggested that photooxidation of SO2 was likely one of the major mechanisms for the formation of new particles in our study area. Moreover, it was revealed that the particle growth rate correlated exponentially with the photolysis of ozone, implying that the condensable vapors were produced mostly from photooxidation reactions. In addition, this study also revealed that Nnuc exhibited a quadratic relationship with J10. The quadratic relationship was inferred as a result of aerosol dynamics and featured NPF processes in urban areas.

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