Browsing by Subject "AEROSOL FORMATION"

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  • Yli-Juuti, Taina; Tikkanen, Olli-Pekka; Manninen, Hanna E.; Nieminen, Tuomo; Kulmala, Markku (2016)
    We analyzed nanoparticle growth during new-particle-formation events based on ten years of measurements carried out at a boreal forest site in Hyytiala, Finland, concentrating on the sub-3 nm particles and the role of sulfuric acid in their growth. Growth rates of 1.5-3 nm diameter particles were determined from ion spectrometer measurements and compared with parameterized sulfuric acid concentration and other atmospheric parameters. The calculated growth rates from sulfuric acid condensation were on average 7.4% of the observed growth rates and the two did not correlate. These suggest that neither sulfuric acid monomer condensation nor coagulation of small sulfuric acid clusters was the primary growth mechanism in these atmospheric conditions. Also no clear sign of organic condensation being the single main growth mechanism was seen. These observations are consistent with the hypothesis that several factors have comparative roles in the sub-3 nm growth.
  • Kalivitis, Nikos; Kerminen, Veli-Matti; Kouvarakis, Giorgos; Stavroulas, Iasonas; Tzitzikalaki, Evaggelia; Kalkavouras, Panayiotis; Daskalakis, Nikos; Myriokefalitakis, Stelios; Bougiatioti, Aikaterini; Manninen, Hanna E.; Roldin, Pontus; Petäjä, Tuukka; Boy, Michael; Kulmala, Markku; Kanakidou, Maria; Mihalopoulos, Nikolaos (2019)
    Atmospheric new particle formation (NPF) is a common phenomenon all over the world. In this study we present the longest time series of NPF records in the eastern Mediterranean region by analyzing 10 years of aerosol number size distribution data obtained with a mobility particle sizer. The measurements were performed at the Finokalia environmental research station on Crete, Greece, during the period June 2008-June 2018. We found that NPF took place on 27% of the available days, undefined days were 23% and non-event days 50 %. NPF is more frequent in April and May probably due to the terrestrial biogenic activity and is less frequent in August. Throughout the period under study, nucleation was observed also during the night. Nucleation mode particles had the highest concentration in winter and early spring, mainly because of the minimum sinks, and their average contribution to the total particle number concentration was 8 %. Nucleation mode particle concentrations were low outside periods of active NPF and growth, so there are hardly any other local sources of sub-25 nm particles. Additional atmospheric ion size distribution data simultaneously collected for more than 2 years were also analyzed. Classification of NPF events based on ion spectrometer measurements differed from the corresponding classification based on a mobility spectrometer, possibly indicating a different representation of local and regional NPF events between these two measurement data sets. We used the MALTE-Box model for simulating a case study of NPF in the eastern Mediterranean region. Monoterpenes contributing to NPF can explain a large fraction of the observed NPF events according to our model simulations. However the adjusted parameterization resulting from our sensitivity tests was significantly different from the initial one that had been determined for the boreal environment.
  • Berndt, T.; Stratmann, F.; Sipilä, Mikko; Vanhanen, Joonas; Petäjä, Tuukka; Mikkilä, Jyri; Gruener, A.; Spindler, G.; Mauldin, R. Lee; Curtius, J.; Kulmala, Markku; Heintzenberg, J. (2010)
  • Sarnela, Nina; Jokinen, Tuija; Duplissy, Jonathan; Yan, Chao; Nieminen, Tuomo; Ehn, Mikael; Schobesberger, Siegfried; Heinritzi, Martin; Ehrhart, Sebastian; Lehtipalo, Katrianne; Tröstl, Jasmin; Simon, Mario; Kürten, Andreas; Leiminger, Markus; Lawler, Michael J.; Rissanen, Matti P.; Bianchi, Federico; Praplan, Arnaud P.; Hakala, Jani; Amorim, Antonio; Gonin, Marc; Hansel, Armin; Kirkby, Jasper; Dommen, Josef; Curtius, Joachim; Smith, James N.; Petäjä, Tuukka; Worsnop, Douglas R.; Kulmala, Markku; Donahue, Neil M.; Sipilä, Mikko (2018)
    Atmospheric oxidation is an important phenomenon which produces large quantities of low-volatility compounds such as sulfuric acid and oxidized organic compounds. Such species may be involved in the nucleation of particles and enhance their subsequent growth to reach the size of cloud condensation nuclei (CCN). In this study, we investigate alpha-pinene, the most abundant monoterpene globally, and its oxidation products formed through ozonolysis in the Cosmic Leaving OUtdoor Droplets (CLOUD) chamber at CERN (the European Organization for Nuclear Research). By scavenging hydroxyl radicals (OH) with hydrogen (H-2), we were able to investigate the formation of highly oxygenated molecules (HOMs) purely driven by ozonolysis and study the oxidation of sulfur dioxide (SO2) driven by stabilized Criegee intermediates (sCIs). We measured the concentrations of HOM and sulfuric acid with a chemical ionization atmospheric-pressure interface time-of-flight (CI-APi-TOF) mass spectrometer and compared the measured concentrations with simulated concentrations calculated with a kinetic model. We found molar yields in the range of 3.5-6.5% for HOM formation and 22-32% for the formation of stabilized Criegee intermediates by fitting our model to the measured sulfuric acid concentrations. The simulated time evolution of the ozonolysis products was in good agreement with measured concentrations except that in some of the experiments sulfuric acid formation was faster than simulated. In those experiments the simulated and measured concentrations met when the concentration reached a plateau but the plateau was reached 20-50 min later in the simulations. The results shown here are consistent with the recently published yields for HOM formation from different laboratory experiments. Together with the sCI yields, these results help us to understand atmospheric oxidation processes better and make the reaction parameters more comprehensive for broader use.
  • Pirjola, L.; Karl, M.; Rönkkö, T.; Arnold, F. (2015)
    A high concentration of volatile nucleation mode particles (NUP) formed in the atmosphere when the exhaust cools and dilutes has hazardous health effects and it impairs the visibility in urban areas. Nucleation mechanisms in diesel exhaust are only poorly understood. We performed model studies using two sectional aerosol dynamics process models AEROFOR and MAFOR on the formation of particles in the exhaust of a diesel engine, equipped with an oxidative after-treatment system and running with low fuel sulfur content (FSC) fuel, under laboratory sampling conditions where the dilution system mimics real-world conditions. Different nucleation mechanisms were tested. Based on the measured gaseous sulfuric acid (GSA) and non-volatile core and soot particle number concentrations of the raw exhaust, the model simulations showed that the best agreement between model predictions and measurements in terms of particle number size distribution was obtained by barrier-free heteromolecular homogeneous nucleation between the GSA and a semi-volatile organic vapour combined with the homogeneous nucleation of GSA alone. Major growth of the particles was predicted to occur due to the similar organic vapour at concentrations of (1-2) x 10(12) cm(-3). The pre-existing core and soot mode concentrations had an opposite trend on the NUP formation, and the maximum NUP formation was predicted if a diesel particle filter (DPF) was used. On the other hand, the model predicted that the NUP formation ceased if the GSA concentration in the raw exhaust was less than 10(10) cm(-3), which was the case when biofuel was used.
  • Ostrom, Emilie; Putian, Zhou; Schurgers, Guy; Mishurov, Mikhail; Kivekas, Niku; Lihavainen, Heikki; Ehn, Mikael; Rissanen, Matti P.; Kurten, Theo; Boy, Michael; Swietlicki, Erik; Roldin, Pontus (2017)
    In this study, the processes behind observed new particle formation (NPF) events and subsequent organicdominated particle growth at the Pallas AtmosphereEcosystem Supersite in Northern Finland are explored with the one-dimensional column trajectory model ADCHEM. The modeled sub-micron particle mass is up to similar to 75% composed of SOA formed from highly oxidized multifunctional organic molecules (HOMs) with low or extremely low volatility. In the model the newly formed particles with an initial diameter of 1.5 nm reach a diameter of 7 nm about 2 h earlier than what is typically observed at the station. This is an indication that the model tends to overestimate the initial particle growth. In contrast, the modeled particle growth to CCN size ranges (> 50 nm in diameter) seems to be underestimated because the increase in the concentration of particles above 50 nm in diameter typically occurs several hours later compared to the observations. Due to the high fraction of HOMs in the modeled particles, the oxygen-to-carbon (O V C) atomic ratio of the SOA is nearly 1. This unusually high O V C and the discrepancy between the modeled and observed particle growth might be explained by the fact that the model does not consider any particle-phase reactions involving semi-volatile organic compounds with relatively low O V C. In the model simulations where condensation of low-volatility and extremely low-volatility HOMs explain most of the SOA formation, the phase state of the SOA (assumed either liquid or amorphous solid) has an insignificant impact on the evolution of the particle number size distributions. However, the modeled particle growth rates are sensitive to the method used to estimate the vapor pressures of the HOMs. Future studies should evaluate how heterogeneous reactions involving semi-volatility HOMs and other less-oxidized organic compounds can influence the SOA composition-and size-dependent particle growth.
  • Lehtipalo, Katrianne; Yan, Chao; Dada, Lubna; Bianchi, Federico; Xiao, Mao; Wagner, Robert; Stolzenburg, Dominik; Ahonen, Lauri R.; Amorim, Antonio; Baccarini, Andrea; Bauer, Paulus S.; Baumgartner, Bernhard; Bergen, Anton; Bernhammer, Anne-Kathrin; Breitenlechner, Martin; Brilke, Sophia; Buchholz, Angela; Mazon, Stephany Buenrostro; Chen, Dexian; Chen, Xuemeng; Dias, Antonio; Dommen, Josef; Draper, Danielle C.; Duplissy, Jonathan; Ehn, Mikael; Finkenzeller, Henning; Fischer, Lukas; Frege, Carla; Fuchs, Claudia; Garmash, Olga; Gordon, Hamish; Hakala, Jani; He, Xucheng; Heikkinen, Liine; Heinritzi, Martin; Helm, Johanna C.; Hofbauer, Victoria; Hoyle, Christopher R.; Jokinen, Tuija; Kangasluoma, Juha; Kerminen, Veli-Matti; Kim, Changhyuk; Kirkby, Jasper; Kontkanen, Jenni; Kuerten, Andreas; Lawler, Michael J.; Mai, Huajun; Mathot, Serge; Mauldin, Roy L.; Molteni, Ugo; Nichman, Leonid; Nie, Wei; Nieminen, Tuomo; Ojdanic, Andrea; Onnela, Antti; Passananti, Monica; Petäjä, Tuukka; Piel, Felix; Pospisilova, Veronika; Quelever, Lauriane L. J.; Rissanen, Matti P.; Rose, Clémence; Sarnela, Nina; Schallhart, Simon; Schuchmann, Simone; Sengupta, Kamalika; Simon, Mario; Sipilä, Mikko; Tauber, Christian; Tome, Antonio; Trostl, Jasmin; Väisänen, Olli; Vogel, Alexander L.; Volkamer, Rainer; Wagner, Andrea C.; Wang, Mingyi; Weitz, Lena; Wimmer, Daniela; Ye, Penglin; Ylisirniö, Arttu; Zha, Qiaozhi; Carslaw, Kenneth S.; Curtius, Joachim; Donahue, Neil M.; Flagan, Richard C.; Hansel, Armin; Riipinen, Ilona; Virtanen, Annele; Winkler, Paul M.; Baltensperger, Urs; Kulmala, Markku; Worsnop, Douglas R. (2018)
    A major fraction of atmospheric aerosol particles, which affect both air quality and climate, form from gaseous precursors in the atmosphere. Highly oxygenated organic molecules (HOMs), formed by oxidation of biogenic volatile organic compounds, are known to participate in particle formation and growth. However, it is not well understood how they interact with atmospheric pollutants, such as nitrogen oxides (NOx) and sulfur oxides (SOx) from fossil fuel combustion, as well as ammonia (NH3) from livestock and fertilizers. Here, we show how NOx suppresses particle formation, while HOMs, sulfuric acid, and NH3 have a synergistic enhancing effect on particle formation. We postulate a novel mechanism, involving HOMs, sulfuric acid, and ammonia, which is able to closely reproduce observations of particle formation and growth in daytime boreal forest and similar environments. The findings elucidate the complex interactions between biogenic and anthropogenic vapors in the atmospheric aerosol system.
  • Lee, Ben H.; Lopez-Hilfiker, Felipe D.; D'Ambro, Emma L.; Zhou, Putian; Boy, Michael; Petäjä, Tuukka; Hao, Liqing; Virtanen, Annele; Thornton, Joel A. (2018)
    We present hourly online observations of molecular compositions (CxHyOzN0-1) and abundances of oxygenated organic species in gas and submicron particle phases from April to June of 2014 as part of the Biogenic Aerosols-Effects on Cloud and Climate (BAECC) campaign. Measurements were made using the Filter Inlet for Gases and AEROsols coupled to a high-resolution time-of-flight iodide-adduct ionization mass spectrometer (FIGAERO-CIMS) located atop a 35m tall tower, about 10m above a boreal forest canopy at the SMEAR II research station in Hyytiala, Finland. Semi-volatile and highly oxygenated multifunctional (HOM) organic species possessing from 1 up to 20 carbon atoms, and with as few as 2 and as many as 16 oxygen atoms, were routinely observed. Utilizing non-negative matrix factorization, we determined that > 90 and > 99% of the organic mass in the gas and particle phases, respectively, exhibited one of three distinct diel trends: one in which abundances were enhanced at daytime, another in the early morning hours, and thirdly during nighttime. Particulate organic nitrates contributed similar to 35% to the total organic aerosol mass loading at night during BAECC, much higher than observed by the same instrument package at a mixed-deciduous forest site in the southeastern US that experienced higher nighttime concentrations of nitrogen oxides. Unique HOM monomers (defined here as those with 10 carbon and 7 or more oxygen atoms) and dimers (at least 16 carbon atoms), with and without a nitrogen atom, were found in most of the three subgroups of both phases. We show the potential to connect these groupings of compounds based on their distinct behavior in time to the expected chemical conditions (biogenic VOC precursor, oxidant type, etc.) responsible for their production. A suite of nitrated dimer-like compounds was detected in both the gas and particle phases, suggesting a potential role for the formation of low-volatility organics from NO3-radical-driven, as well as daytime NO-influenced, monoterpene chemistry.
  • Yang, Yuan; Wang, Yonghong; Yao, Dan; Zhao, Shuman; Yang, Shuanghong; Ji, Dongsheng; Sun, Jie; Wang, Yinghong; Liu, Zirui; Hu, Bo; Zhang, Renjian; Wang, Yuesi (2020)
    To what extent anthropogenic emissions could influence volatile organic compound (VOCs) concentrations and related atmospheric reactivity is still poorly understood. China's 70th National Day holidays, during which anthropogenic emissions were significantly reduced to ensure good air quality on Anniversary Day, provides a unique opportunity to investigate these processes. Atmospheric oxidation capacity (AOC), OH reactivity, secondary transformation, O-3 formation and VOCs-PM2.5 sensitivity are evaluated based on parameterization methods and simultaneous measurements of VOCs, O-3, NOx, CO, SO2, PM2.5, JO(1)D, JNO(2), JNO(3) carried out at a suburban site between Beijing and Tianjin before, during, and after the National Day holiday 2019. During the National Day holidays, the AOC, OH reactivity, O-3 formation potential (OFP) and secondary organic aerosol formation potential (SOAP) were 1.6 x 10(7) molecules cm(-3) s(-1), 41.8 s(-1), 299.2 mg cm(-3) and 1471.8 mg cm(-3), respectively, which were 42%, 29%, 47% and 42% lower than pre-National Day values and -12%, 42%, 36% and 42% lower than post-National Day values, respectively. Reactions involving OH radicals dominated the AOC during the day, but OH radicals and O-3 reactions at night. Alkanes (the degree of unsaturation = 0, (D, Equation (1)) accounted for the largest contributions to the total VOCs concentration, oxygenated VOCs (OVOCs; D
  • Zhou, Luxi; Nieminen, Tuomo; Mogensen, Ditte; Smolander, Sampo; Rusanen, Anton; Kulmala, Markku; Boy, Michael (2014)
    Natural and anthropogenic aerosols may have a great impact on climate as they directly interact with solar radiation and indirectly affect the Earth’s radiation balance and precipitation by modifying clouds. In order to quantify the direct and indirect effects, it is essential to understand the complex processes that connect aerosol particles to cloud droplets. Modern measurement techniques are able to detect particle sizes down to 1 nm in diameter, from ground to the stratosphere. However, the data are not sufficient in order to fully understand the processes. Here we demonstrate how the newly developed one-dimensional column model SOSAA was used to investigate the complex processes of aerosols at a boreal forest site for a six-month period during the spring and summer of 2010. Two nucleation mechanisms (kinetic and organic) were tested in this study, and both mechanisms produced a good prediction of the particle number concentrations in spring. However, overestimation of the particle number concentration in summer by the organic mechanism suggests that the OH oxidation products from monoterpenes may not be the essential compounds in atmospheric nucleation. In general, SOSAA was correct in predicting new particle formation events for 35% of the time and partly correct for 45% of the time.
  • Baranizadeh, Elham; Arola, Antti; Hamed, Amar; Nieminen, Tuomo; Mikkonen, Santtu; Virtanen, Annele; Kulmala, Markku; Lehtinen, Kari; Laaksonen, Ari (2014)
  • Leino, Katri; Lampilahti, Janne; Poutanen, Pyry; Väänänen, Riikka; Manninen, Antti; Mazon, Stephany Buenrostro; Dada, Lubna; Franck, Anna; Wimmer, Daniela; Aalto, Pasi P.; Ahonen, Lauri R.; Enroth, Joonas; Kangasluoma, Juha; Keronen, Petri; Korhonen, Frans; Laakso, Heikki; Matilainen, Teemu; Siivola, Erkki; Manninen, Hanna E.; Lehtipalo, Katrianne; Kerminen, Veli-Matti; Petäjä, Tuukka; Kulmala, Markku (2019)
    This work presents airborne observations of sub-3 nm particles in the lower troposphere and investigates new particle formation (NPF) within an evolving boundary layer (BL). We studied particle concentrations together with supporting gas and meteorological data inside the planetary BL over a boreal forest site in Hyytiala, southern Finland. The analysed data were collected during three flight measurement campaigns: May-June 2015, August 2015 and April-May 2017, including 27 morning and 26 afternoon vertical profiles. As a platform for the instrumentation, we used a Cessna 172 aircraft. The analysed flight data were collected horizontally within a 30 km distance from SMEAR II in Hyytiala and vertically from 100 m above ground level up to 2700 m. The number concentration of 1.5-3 nm particles was observed to be, on average, the highest near the forest canopy top and to decrease with increasing altitude during the mornings of NPF event days. This indicates that the precursor vapours emitted by the forest play a key role in NPF in Hyytiala. During daytime, newly formed particles were observed to grow in size and the particle population became more homogenous within the well-mixed BL in the afternoon. During undefined days with respect to NPF, we also detected an increase in concentration of 1.5-3 nm particles in the morning but not their growth in size, which indicates an interrupted NPF process during these undefined days. Vertical mixing was typically stronger during the NPF event days than during the undefined or non-event days. The results shed light on the connection between boundary layer dynamics and NPF.