Author
Stephanie Gagne
Other affiliations: Helsinki Institute of Physics
Bio: Stephanie Gagne is an academic researcher from University of Helsinki. The author has contributed to research in topics: Nucleation & Particle. The author has an hindex of 12, co-authored 17 publications receiving 2078 citations. Previous affiliations of Stephanie Gagne include Helsinki Institute of Physics.
Topics: Nucleation, Particle, Ion, Charged particle, Carbon neutrality
Papers
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CERN1, Goethe University Frankfurt2, University of Beira Interior3, University of Leeds4, University of Helsinki5, Helsinki Institute of Physics6, University of Vienna7, University of Innsbruck8, Paul Scherrer Institute9, Leibniz Association10, University of Milan11, California Institute of Technology12, Lebedev Physical Institute13, University of Eastern Finland14, Earth System Research Laboratory15, Finnish Meteorological Institute16
TL;DR: First results from the CLOUD experiment at CERN are presented, finding that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100–1,000-fold and ion-induced binary nucleation of H2SO4–H2O can occur in the mid-troposphere but is negligible in the boundary layer.
Abstract: Atmospheric aerosols exert an important influence on climate through their effects on stratiform cloud albedo and lifetime and the invigoration of convective storms. Model calculations suggest that almost half of the global cloud condensation nuclei in the atmospheric boundary layer may originate from the nucleation of aerosols from trace condensable vapours, although the sensitivity of the number of cloud condensation nuclei to changes of nucleation rate may be small. Despite extensive research, fundamental questions remain about the nucleation rate of sulphuric acid particles and the mechanisms responsible, including the roles of galactic cosmic rays and other chemical species such as ammonia. Here we present the first results from the CLOUD experiment at CERN. We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100–1,000-fold. Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. We find that ion-induced binary nucleation of H_(2)SO_(4)–H_(2)O can occur in the mid-troposphere but is negligible in the boundary layer. However, even with the large enhancements in rate due to ammonia and ions, atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary-layer nucleation.
1,071 citations
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University of Helsinki1, Finnish Meteorological Institute2, University of Tartu3, Meteor4, Hungarian Academy of Sciences5, Netherlands Organisation for Applied Scientific Research6, Royal Netherlands Meteorological Institute7, University of Crete8, National University of Ireland, Galway9, Lund University10, Leibniz Association11, Blaise Pascal University12, University of Grenoble13, Paul Scherrer Institute14, University of Eastern Finland15, Stockholm University16
TL;DR: In this paper, the authors present comprehensive results on continuous atmospheric cluster and particle measurements in the size range ∼1-42 nm within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) project.
Abstract: We present comprehensive results on continuous atmospheric cluster and particle measurements in the size range ∼1-42 nm within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) project. We focused on characterizing the spatial and temporal variation of new particle formation events and relevant particle formation parameters across Europe. Different types of air ion and cluster mobility spectrometers were deployed at 12 field sites across Europe from March 2008 to May 2009. The measurements were conducted in a wide variety of environments, including coastal and continental locations as well as sites at different altitudes (both in the boundary layer and the free troposphere). New particle formation events were detected at all of the 12 field sites during the year-long measurement period. From the data, nucleation and growth rates of newly formed particles were determined for each environment. In a case of parallel ion and neutral cluster measurements, we could also estimate the relative contribution of ion-induced and neutral nucleation to the total particle formation. The formation rates of charged particles at 2 nm accounted for 1-30% of the corresponding total particle formation rates. As a significant new result, we found out that the total particle formation rate varied much more between the different sites than the formation rate of charged particles. This work presents, so far, the most comprehensive effort to experimentally characterize nucleation and growth of atmospheric molecular clusters and nanoparticles at ground-based observation sites on a continental scale. © Author(s) 2010.
263 citations
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TL;DR: In this article, a review of 260 publications on the formation of 2-nm intermediate ions, growth rates of sub-3 nm ions, and information on the chemical composition of the ions is presented.
Abstract: . This review is based on ca. 260 publications, 93 of which included data on the temporal and spatial variation of the concentration of small ions ( −3 . However, concentrations up to 5000 cm −3 have been observed. The results are in agreement with observations of ion production rates in the atmosphere. We also summarised observations on the conversion of small ions to intermediate ions, which can act as embryos for new atmospheric aerosol particles. Those observations include the formation rates ( J 2 [ion]) of 2-nm intermediate ions, growth rates (GR[ion]) of sub-3 nm ions, and information on the chemical composition of the ions. Unfortunately, there were only a few studies which presented J 2 [ion] and GR[ion]. Based on the publications, the formation rates of 2-nm ions were 0–1.1 cm −3 s −1 , while the total 2-nm particle formation rates varied between 0.001 and 60 cm −3 s −1 . Due to small changes in J 2 [ion], the relative importance of ions in 2-nm particle formation was determined by the large changes in J 2 [tot], and, accordingly the contribution of ions increased with decreasing J 2 [tot]. Furthermore, small ions were observed to activate for growth earlier than neutral nanometer-sized particles and at lower saturation ratio of condensing vapours.
246 citations
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University of Helsinki1, Finnish Meteorological Institute2, North-West University3, Carnegie Mellon University4, Forschungszentrum Jülich5, University of Eastern Finland6, University of Tartu7, Paul Scherrer Institute8, University of Vienna9, National Center for Atmospheric Research10, Deutscher Wetterdienst11, Max Planck Society12
TL;DR: The results obtained during the EUCAARI project indicate that sulphuric acid plays a central role in atmospheric nucleation as discussed by the authors, but also vapours other than sulphurica are needed to explain the nucleation and the subsequent growth processes.
Abstract: . Within the project EUCAARI (European Integrated project on Aerosol Cloud Climate and Air Quality interactions), atmospheric nucleation was studied by (i) developing and testing new air ion and cluster spectrometers, (ii) conducting homogeneous nucleation experiments for sulphate and organic systems in the laboratory, (iii) investigating atmospheric nucleation mechanism under field conditions, and (iv) applying new theoretical and modelling tools for data interpretation and development of parameterisations. The current paper provides a synthesis of the obtained results and identifies the remaining major knowledge gaps related to atmospheric nucleation. The most important technical achievement of the project was the development of new instruments for measuring sub-3 nm particle populations, along with the extensive application of these instruments in both the laboratory and the field. All the results obtained during EUCAARI indicate that sulphuric acid plays a central role in atmospheric nucleation. However, also vapours other than sulphuric acid are needed to explain the nucleation and the subsequent growth processes, at least in continental boundary layers. Candidate vapours in this respect are some organic compounds, ammonia, and especially amines. Both our field and laboratory data demonstrate that the nucleation rate scales to the first or second power of the nucleating vapour concentration(s). This agrees with the few earlier field observations, but is in stark contrast with classical thermodynamic nucleation theories. The average formation rates of 2-nm particles were found to vary by almost two orders of magnitude between the different EUCAARI sites, whereas the formation rates of charged 2-nm particles varied very little between the sites. Overall, our observations are indicative of frequent, yet moderate, ion-induced nucleation usually outweighed by much stronger neutral nucleation events in the continental lower troposphere. The most concrete outcome of the EUCAARI nucleation studies are the new semi-empirical nucleation rate parameterizations based on field observations, along with updated aerosol formation parameterizations.
128 citations
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TL;DR: In this paper, a new instrumental setup called Ion-DMPS is described, which can be used to detect contribution of ion-induced nucleation on atmospheric new particle formation events.
Abstract: . The importance of ion-induced nucleation in the lower atmosphere has been discussed for a long time. In this article we describe a new instrumental setup – Ion-DMPS – which can be used to detect contribution of ion-induced nucleation on atmospheric new particle formation events. The device measures positively and negatively charged particles with and without a bipolar charger. The ratio between "charger off" to "charger on" describes the charging state of aerosol particle population with respect to equilibrium. Values above one represent more charges than in an equilibrium (overcharged state), and values below unity stand for undercharged situation, when there is less charges in the particles than in the equilibrium. We performed several laboratory experiments to test the operation of the instrument. After the laboratory tests, we used the device to observe particle size distributions during atmospheric new particle formation in a boreal forest. We found that some of the events were clearly dominated by neutral nucleation but in some cases also ion-induced nucleation contributed to the new particle formation. We also found that negative and positive ions (charged particles) behaved in a different manner, days with negative overcharging were more frequent than days with positive overcharging.
122 citations
Cited by
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01 Jan 2014
TL;DR: Myhre et al. as discussed by the authors presented the contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) 2013: Anthropogenic and Natural Radiative forcing.
Abstract: This chapter should be cited as: Myhre, G., D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang, 2013: Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Coordinating Lead Authors: Gunnar Myhre (Norway), Drew Shindell (USA)
3,684 citations
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TL;DR: It is found that a direct pathway leads from several biogenic VOCs, such as monoterpenes, to the formation of large amounts of extremely low-volatility vapours, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies.
Abstract: Forests emit large quantities of volatile organic compounds (VOCs) to the atmosphere. Their condensable oxidation products can form secondary organic aerosol, a significant and ubiquitous component of atmospheric aerosol, which is known to affect the Earth's radiation balance by scattering solar radiation and by acting as cloud condensation nuclei. The quantitative assessment of such climate effects remains hampered by a number of factors, including an incomplete understanding of how biogenic VOCs contribute to the formation of atmospheric secondary organic aerosol. The growth of newly formed particles from sizes of less than three nanometres up to the sizes of cloud condensation nuclei (about one hundred nanometres) in many continental ecosystems requires abundant, essentially non-volatile organic vapours, but the sources and compositions of such vapours remain unknown. Here we investigate the oxidation of VOCs, in particular the terpene α-pinene, under atmospherically relevant conditions in chamber experiments. We find that a direct pathway leads from several biogenic VOCs, such as monoterpenes, to the formation of large amounts of extremely low-volatility vapours. These vapours form at significant mass yield in the gas phase and condense irreversibly onto aerosol surfaces to produce secondary organic aerosol, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies. We further demonstrate how these low-volatility vapours can enhance, or even dominate, the formation and growth of aerosol particles over forested regions, providing a missing link between biogenic VOCs and their conversion to aerosol particles. Our findings could help to improve assessments of biosphere-aerosol-climate feedback mechanisms, and the air quality and climate effects of biogenic emissions generally.
1,340 citations
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CERN1, Goethe University Frankfurt2, University of Beira Interior3, University of Leeds4, Helsinki Institute of Physics5, University of Helsinki6, University of Vienna7, University of Innsbruck8, Paul Scherrer Institute9, Leibniz Association10, University of Milan11, California Institute of Technology12, Lebedev Physical Institute13, University of Eastern Finland14, Earth System Research Laboratory15, Finnish Meteorological Institute16
TL;DR: First results from the CLOUD experiment at CERN are presented, finding that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100–1,000-fold and ion-induced binary nucleation of H2SO4–H2O can occur in the mid-troposphere but is negligible in the boundary layer.
Abstract: Atmospheric aerosols exert an important influence on climate through their effects on stratiform cloud albedo and lifetime and the invigoration of convective storms. Model calculations suggest that almost half of the global cloud condensation nuclei in the atmospheric boundary layer may originate from the nucleation of aerosols from trace condensable vapours, although the sensitivity of the number of cloud condensation nuclei to changes of nucleation rate may be small. Despite extensive research, fundamental questions remain about the nucleation rate of sulphuric acid particles and the mechanisms responsible, including the roles of galactic cosmic rays and other chemical species such as ammonia. Here we present the first results from the CLOUD experiment at CERN. We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100–1,000-fold. Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. We find that ion-induced binary nucleation of H_(2)SO_(4)–H_(2)O can occur in the mid-troposphere but is negligible in the boundary layer. However, even with the large enhancements in rate due to ammonia and ions, atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary-layer nucleation.
1,071 citations
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University of Oxford1, University of Reading2, Stony Brook University3, Imperial College London4, Rutherford Appleton Laboratory5, Free University of Berlin6, University of Massachusetts Amherst7, Oeschger Centre for Climate Change Research8, University of Arizona9, University of Giessen10, National Center for Atmospheric Research11, Goddard Institute for Space Studies12, University of Amsterdam13, University of California, San Diego14
TL;DR: In this paper, the development of this review article has evolved from work carried out by an international team of the International Space Science Institute (ISSI), Bern, Switzerland, and from work performed under the auspices of Scientific Committee on Solar Terrestrial Physics (SCOSTEP) regarding climate and weather of the Sun-Earth System (CAWSES).
Abstract: The development of this
review article has evolved from work carried out by an international
team of the International Space Science Institute (ISSI),
Bern, Switzerland, and from work carried out under the auspices
of Scientific Committee on Solar Terrestrial Physics (SCOSTEP)
Climate and Weather of the Sun‐Earth System (CAWSES‐1).
The support of ISSI in providing workshop and meeting facilities
is acknowledged, especially support from Y. Calisesi and V. Manno.
SCOSTEP is acknowledged for kindly providing financial assistance
to allow the paper to be published under an open access
policy. L.J.G. was supported by the UK Natural Environment
Research Council (NERC) through their National Centre for Atmospheric
Research (NCAS) Climate program. K.M. was supported
by a Marie Curie International Outgoing Fellowship within the
6th European Community Framework Programme. J.L. acknowledges
support by the EU/FP7 program Assessing Climate Impacts
on the Quantity and Quality of Water (ACQWA, 212250) and from
the DFG Project Precipitation in the Past Millennium in Europe
(PRIME) within the Priority Program INTERDYNAMIK. L.H.
acknowledges support from the U.S. NASA Living With a Star
program. G.M. acknowledges support from the Office of Science
(BER), U.S. Department of Energy, Cooperative Agreement
DE‐FC02‐97ER62402, and the National Science Foundation. We
also wish to thank Karin Labitzke and Markus Kunze for supplying
an updated Figure 13, Andrew Heaps for technical support, and
Paul Dickinson for editorial support. Part of the research was
carried out under the SPP CAWSES funded by GFG. J.B. was
financially supported by NCCR Climate–Swiss Climate Research.
1,045 citations
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TL;DR: Air pollutants consist of a complex combination of gases and particulate matter, which is emitted directly into the atmosphere or formed in the atmosphere through gas-to-particle conversion (secondary) (Figure 1).
Abstract: Urban air pollution represents one of the greatest environmental challenges facing mankind in the 21st century. Noticeably, many developing countries, such as China and India, have experienced severe air pollution because of their fast-developing economy and urbanization. Globally, the urbanization trend is projected to continue: 70% of the world population will reside in urban centers by 2050, and there will exist 41 megacities (with more than 10 million inhabitants) by 2030. Air pollutants consist of a complex combination of gases and particulate matter (PM). In particular, fine PM (particles with the aerodynamic diameter smaller than 2.5 μm or PM_(2.5)) profoundly impacts
human health, visibility, the ecosystem, the weather, and the climate, and these PM effects are largely dependent on the aerosol properties, including the number concentration, size, and chemical composition. PM is emitted directly into the atmosphere (primary) or formed in the atmosphere through
gas-to-particle conversion (secondary) (Figure 1). Also,
primary and secondary PM undergoes chemical and physical
transformations and is subjected to transport, cloud processing, and removal from the atmosphere.
931 citations