| 1. |
- Kulmala, Markku, et al.
(författare)
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Direct Observations of Atmospheric Aerosol Nucleation
- 2013
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 339:6122, s. 943-946
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Tidskriftsartikel (refereegranskat)abstract
- Atmospheric nucleation is the dominant source of aerosol particles in the global atmosphere and an important player in aerosol climatic effects. The key steps of this process occur in the sub-2-nanometer (nm) size range, in which direct size-segregated observations have not been possible until very recently. Here, we present detailed observations of atmospheric nanoparticles and clusters down to 1-nm mobility diameter. We identified three separate size regimes below 2-nm diameter that build up a physically, chemically, and dynamically consistent framework on atmospheric nucleation-more specifically, aerosol formation via neutral pathways. Our findings emphasize the important role of organic compounds in atmospheric aerosol formation, subsequent aerosol growth, radiative forcing and associated feedbacks between biogenic emissions, clouds, and climate.
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| 2. |
- Kulmala, Markku, et al.
(författare)
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Measurement of the nucleation of atmospheric aerosol particles
- 2012
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Ingår i: Nature Protocols. - : Springer Science and Business Media LLC. - 1754-2189 .- 1750-2799. ; 7:9, s. 1651-1667
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Tidskriftsartikel (refereegranskat)abstract
- The formation of new atmospheric aerosol particles and their subsequent growth have been observed frequently at various locations all over the world. The atmospheric nucleation rate (or formation rate) and growth rate (GR) are key parameters to characterize the phenomenon. Recent progress in measurement techniques enables us to measure atmospheric nucleation at the size (mobility diameter) of 1.5 (+/- 0.4) nm. The detection limit has decreased from 3 to 1 nm within the past 10 years. In this protocol, we describe the procedures for identifying new-particle-formation (NPF) events, and for determining the nucleation, formation and growth rates during such events under atmospheric conditions. We describe the present instrumentation, best practices and other tools used to investigate atmospheric nucleation and NPF at a certain mobility diameter (1.5, 2.0 or 3.0 nm). The key instruments comprise devices capable of measuring the number concentration of the formed nanoparticles and their size, such as a suite of modern condensation particle counters (CPCs) and air ion spectrometers, and devices for characterizing the pre-existing particle number concentration distribution, such as a differential mobility particle sizer (DMPS). We also discuss the reliability of the methods used and requirements for proper measurements and data analysis. The time scale for realizing this procedure is 1 year.
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| 3. |
- Kulmala, Markku, et al.
(författare)
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Opinion : The strength of long-term comprehensive observations to meet multiple grand challenges in different environments and in the atmosphere
- 2023
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Ingår i: Atmospheric Chemistry And Physics. - 1680-7316 .- 1680-7324. ; 23:23, s. 14949-14971
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Tidskriftsartikel (refereegranskat)abstract
- To be able to meet global grand challenges (climate change; biodiversity loss; environmental pollution; scarcity of water, food and energy supplies; acidification; deforestation; chemicalization; pandemics), which all are closely interlinked with each other, we need comprehensive open data with proper metadata, along with open science. The large data sets from ground-based in situ observations, ground and satellite remote sensing, and multiscale modeling need to be utilized seamlessly. In this opinion paper, we demonstrate the power of the SMEAR (Station for Measuring Earth surface-Atmosphere Relations) concept via several examples, such as detection of new particle formation and the particles' subsequent growth, quantifying atmosphere-ecosystem feedback loops, and combining comprehensive observations with emergency science and services, as well as studying the effect of COVID-19 restrictions on different air quality and climate variables. The future needs and the potential of comprehensive observations of the environment are summarized.
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| 4. |
- Vuollekoski, Henri, et al.
(författare)
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Atmospheric nucleation and initial steps of particle growth : Numerical comparison of different theories and hypotheses
- 2010
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Ingår i: Atmospheric research. - : Elsevier BV. - 0169-8095 .- 1873-2895. ; 98:2-4, s. 229-236
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Tidskriftsartikel (refereegranskat)abstract
- New particle formation in boreal forest environment in Hyytiala Finland was studied in an aerosol dynamical model Basing on the concepts of activation or kinetic collision of two preexisting clusters at 1 5 nm several semi-empirical nucleation rate formulae were parameterized The mechanisms had linear or squared dependence on the concentration of sulphuric acid or a low volatile organic vapor or both and they all showed good agreement with field measurements A new method for examining the power dependence of apparent formation rate (at 2 nm or 3 nm) on sulphuric acid concentration was developed The new method produced exponents 1 6-2 1 for cluster activation and exponents 2 4-3 1 for kinetic collision which suggests that the activation scenarios are in better agreement with experimental observations that imply exponents around 1-2 However, It was found that if low volatile organic vapors with concentrations exceeding that of sulphuric acid are present, they have a major role in shaping the temporal behavior of the apparent formation rates causing error in the exponent analyses Finally, a sensitivity study showed that the analyzed exponents grew even further if the size of the critical cluster was assumed smaller that 1 5 nm
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