Formation and growth of aerosol particles in boreal forest of Siberia

Author(s):  
Anastasiia Demakova ◽  
Olga Garmash ◽  
Ekaterina Ezhova ◽  
Mikhail Arshinov ◽  
Denis Davydov ◽  
...  

<p>New Particle Formation (NPF) is a process in which a large number of particles is formed in the atmosphere via gas-to-particle conversion. Previous research shows the important role of formation of new particles for atmosphere, clouds and climate (Kerminen, V.-M. et al. 2018).</p><p>              There exist measurements from different parts of the world which show that NPF is happening worldwide (Kerminen, V.-M. et al. 2018). Measurements at SMEAR II station in Hyytiälä, Finland (Hari P. and Kulmala M., 2005), show that NPF is a common process in Finland’s boreal forests. However, measurements at Zotto station in Siberia, Russia, show that NPF events are very rare in that area (Wiedensohler A. et al., 2018). Measurements in Siberian boreal forests are sparse. We have conducted new measurements at Fonovaya station near Tomsk (Siberia, Russia) using Neutral cluster Air Ion Spectrometer (NAIS), Particle Size Magnifier (PSM), Differential Mobility Particle Sizer (DMPS) and the Atmospheric Pressure interface Time-Of-Flight mass spectrometer (APi-TOF). Those instruments measure aerosol particle number size distribution (NAIS, DMPS), ion number size distribution (NAIS), size distribution of small particles (PSM) and chemical composition of aerosol particles (APi-TOF). The novelty of this work is that such complex measurements have not been done in Siberia before.</p><p>              Here we report the first results of our research on NPF phenomenon in Siberian boreal forest. We present detailed statistics of NPF events, as well as formation rates (J) and growth rates (GR) of aerosol particles. The results from Fonovaya station are compared with those from SMEAR II station and from SMEAR Estonia station in Järvselja, Estonia.</p><p>               </p><p> </p><p> </p><p>Literature</p><ul><li>[1] Kerminen V.-M. et al. “Atmospheric new particle formation and growth: review of field observations”. In: Environmental Research Letters 10 (2018), p. 103003.</li> <li>[2] Wiedensohler A. et al. “Infrequent new particle formation over the remote boreal forest of Siberia”. In: Atmospheric Environment 200 (2019), pp. 167–169.</li> <li>[3] Dada L. et al. “Long-term analysis of clear-sky new particle formation events and nonevents in Hyytiälä”. In: Atmospheric Chemistry and Physics 10 (2017), pp. 6227–6241.</li> </ul><p> </p>

2007 ◽  
Vol 7 (1) ◽  
pp. 211-222 ◽  
Author(s):  
M. Ehn ◽  
T. Petäjä ◽  
H. Aufmhoff ◽  
P. Aalto ◽  
K. Hämeri ◽  
...  

Abstract. The hygroscopic growth of aerosol particles present in a boreal forest was measured at a relative humidity of 88%. Simultaneously the gas phase concentration of sulfuric acid, a very hygroscopic compound, was monitored. The focus was mainly on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF) correlated positively with the gaseous phase sulfuric acid concentrations. The smaller the particles, the stronger the correlation, with r=0.20 for 50 nm and r=0.50 for 10 nm particles. The increase in GF due to condensing sulfuric acid is expected to be larger for particles with initially smaller masses. During new particle formation, the changes in solubility of the new particles were calculated during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that the initial particle growth was due to more hygroscopic compounds, whereas the later growth during the evening and night was mainly caused by less hygroscopic or even hydrophobic compounds. For all the measured sizes, a diurnal variation in GF was observed both during days with and without particle formation. The GF was lowest at around midnight, with a mean value of 1.12–1.24 depending on particle size and if new particle formation occurred during the day, and increased to 1.25–1.34 around noon. This can be tentatively explained by day- and nighttime gas-phase chemistry; different vapors will be present depending on the time of day, and through condensation these compounds will alter the hygroscopic properties of the particles in different ways.


2019 ◽  
Author(s):  
Sophia Brilke ◽  
Nikolaus Fölker ◽  
Thomas Müller ◽  
Konrad Kandler ◽  
Xianda Gong ◽  
...  

Abstract. Atmospheric particle size distributions were measured in Paphos, Cyprus, during the A-LIFE (Absorbing aerosol layers in a changing climate: aging, lifetime and dynamics) field experiment from April 3–30, 2017. The newly developed DMA-train is deployed for the first time in an atmospheric environment for the direct measurement of the nucleation mode size range between 1.8–10 nm diameter. The DMA-train setup consists of seven size channels, of which five are set to fixed particle mobility diameters and two additional diameters are obtained by alternating voltage settings in one DMA every 10 s. In combination with a conventional Mobility Particle Size Spectrometer (MPSS) and an Aerodynamic Particle Sizer (APS) the complete atmospheric aerosol size distribution from 1.8 nm–10 µm is covered. The focus of the A-LIFE study is to characterize new particle formation (NPF) in the Eastern Mediterranean region at a measurement site with strong local pollution sources. The nearby Paphos airport was found to be a large emission source for nucleation mode particles and we analysed the size distribution of the airport emission plumes at approximately 500 m from the main runway. The analysis yielded 9 NPF events in 27 measurement days from the combined analysis of the DMA-train, MPSS and trace gas monitors. Growth rate calculations were performed and a size-dependency of the initial growth rate (


2020 ◽  
Author(s):  
Nikolay Romanov ◽  
Alexey Paley ◽  
Yuri Andreev ◽  
Sergey Dubtsov ◽  
Oleg Ozols ◽  
...  

Abstract. The paper reports on an investigation of nanometre-sized new particles formation (NPF) in aerosol-free outdoor air. This phenomenon was observed after filling of Large Aerosol Chamber (LAC) RPA Typhoon with the volume of 3200 m3 with outdoor air, passed through HEPA 13 class filter (H13). During the summer-autumn period of 2018, even in the full darkness and in presence ionizing radiation only in the shape of secondary galactic cosmic rays, new particle formation with the particle size greater than 15 nm starts 0.5–1 hour after the end of LAC filling. During the 2018–2019 winter periods the NPF event was not observed once only. Approximately one day after NPF narrow bell-shaped spectra with number concentration up to 104 cm−3 and mass concentration up to 0.6 µg per m3 are formed. During the next five or more days, these size distributions evolve due to coagulation, while their asymptotic shape remains constant with relative breadth σc ≈ 0.28, and relative asymmetry ras ≈ 2 (ras = skewness/σc). The value ras ≈ 2 defines the analytical description of the size distribution as the gamma-distribution. During additional purification of newly formed particles with the inner H13 filter, aerosol particles concentration in LAC decreases down to a few particles per cm3. This concentration remained constant for more than a week. This demonstrates that new aerosol particles are formed by homogeneous gas-to-particle conversion of gaseous precursors, which passed through the external H13 filter. The mass concentration of newly formed particles depends on the concentration of precursors. It was found that after filling LAC with outdoor unfiltered air, approximately after 10 hours the left-hand side of aerosol particle size distribution below 15 nm disappears, and after several days there forms an asymptotic bell-shaped size spectrum with σc ≈ 0.4–0.5 and ras = 2–3. The modal diameter becomes about 150 nm after five days, while the size distribution greater than 200 nm remains unchanged. This allows concluding that aerosol particles greater than 200 nm have a life-time of more than five days, while particles smaller than 15 nm, not more than five hours. The observed regularities of NPF and pre-existing aerosol spectra evolution may contribute significantly to understanding the processes of the formation of atmospheric aerosols, which are responsible for cloud and precipitation formation. They also should be considered during the design of purification methods for facilities and living spaces. During the investigation of size distribution evolution of aerosol particles generated by the spraying of tap water, it was found that this aerosol particles size distribution transforms from a power law to a bell-shaped distribution in five days with σc ≈ 0.4 and ras ≈ 2. These results may be used for the development of aerosol evolution models.


2020 ◽  
Vol 20 (9) ◽  
pp. 5645-5656 ◽  
Author(s):  
Sophia Brilke ◽  
Nikolaus Fölker ◽  
Thomas Müller ◽  
Konrad Kandler ◽  
Xianda Gong ◽  
...  

Abstract. Atmospheric particle size distributions were measured in Paphos, Cyprus, during the A-LIFE (absorbing aerosol layers in a changing climate: ageing, lifetime and dynamics) field experiment from 3 to 30 April 2017. The newly developed differential mobility analyser train (DMA-train) was deployed for the first time in an atmospheric environment for the direct measurement of the nucleation mode size range between 1.8 and 10 nm diameter. The DMA-train set-up consists of seven size channels, of which five are set to fixed particle mobility diameters and two additional diameters are obtained by alternating voltage settings in one DMA every 10 s. In combination with a conventional mobility particle size spectrometer (MPSS) and an aerodynamic particle sizer (APS) the complete atmospheric aerosol size distribution from 1.8 nm to 10 µm was covered. The focus of the A-LIFE study was to characterize new particle formation (NPF) in the eastern Mediterranean region at a measurement site with strong local pollution sources. The nearby Paphos airport was found to be a large emission source for nucleation mode particles, and we analysed the size distribution of the airport emission plumes at approximately 500 m from the main runway. The analysis yielded nine NPF events in 27 measurement days from the combined analysis of the DMA-train, MPSS and trace gas monitors. Growth rate calculations were performed, and a size dependency of the initial growth rate (<10 nm) was observed for one event case. Fast changes of the sub-10 nm size distribution on a timescale of a few minutes were captured by the DMA-train measurement during early particle growth and are discussed in a second event case. In two cases, particle formation and growth were detected in the nucleation mode size range which did not exceed the 10 nm threshold. This finding implies that NPF likely occurs more frequently than estimated from studies where the lower nanometre size regime is not covered by the size distribution measurements.


2013 ◽  
Vol 13 (4) ◽  
pp. 1751-1770 ◽  
Author(s):  
V. Vakkari ◽  
J. P. Beukes ◽  
H. Laakso ◽  
D. Mabaso ◽  
J. J. Pienaar ◽  
...  

Abstract. This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the southern African savannah, an environment with few previous observations covering a full seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006–January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008–May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano), which is a more polluted location with both pyrometallurgical industries and informal settlements nearby. The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12–840 nm, 50–840 nm and 100–840 nm the median concentrations were 1856, 1278 and 698 particles cm−3 at Botsalano and 7805, 3843 and 1634 particles cm−3 at Marikana, respectively. The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous. Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season, the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry season. However, the sources of burning differ: at Botsalano the rise in concentration originates from regional wild fires, while at Marikana domestic heating in the informal settlements is the main source. Air mass history analysis for Botsalano identified four regional scale source areas in southern Africa and enabled the differentiation between fresh and aged rural background aerosol originating from the clean sector, i.e., western sector with very few large anthropogenic sources. Comparison to size distributions published for other comparable environments in Northern Hemisphere shows southern African savannah to have a unique combination of sources and meteorological parameters. The observed strong link between combustion and seasonal variation is comparable only to the Amazon basin; however, the lack of long-term observations in the Amazonas does not allow a quantitative comparison. All the data presented in the figures, as well as the time series of monthly mean and median size distributions are included in numeric form as a Supplement to provide a reference point for the aerosol modelling community.


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