| 1. |
- Artaxo, Paulo, et al.
(author)
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Tropical and Boreal Forest – Atmosphere Interactions : A Review
- 2022
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In: Tellus. Series B, Chemical and physical meteorology. - : Stockholm University Press. - 0280-6509 .- 1600-0889. ; 74:1, s. 24-163
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Research review (peer-reviewed)abstract
- This review presents how the boreal and the tropical forests affect the atmosphere, its chemical composition, its function, and further how that affects the climate and, in return, the ecosystems through feedback processes. Observations from key tower sites standing out due to their long-term comprehensive observations: The Amazon Tall Tower Observatory in Central Amazonia, the Zotino Tall Tower Observatory in Siberia, and the Station to Measure Ecosystem-Atmosphere Relations at Hyytiäla in Finland. The review is complemented by short-term observations from networks and large experiments.The review discusses atmospheric chemistry observations, aerosol formation and processing, physiochemical aerosol, and cloud condensation nuclei properties and finds surprising similarities and important differences in the two ecosystems. The aerosol concentrations and chemistry are similar, particularly concerning the main chemical components, both dominated by an organic fraction, while the boreal ecosystem has generally higher concentrations of inorganics, due to higher influence of long-range transported air pollution. The emissions of biogenic volatile organic compounds are dominated by isoprene and monoterpene in the tropical and boreal regions, respectively, being the main precursors of the organic aerosol fraction.Observations and modeling studies show that climate change and deforestation affect the ecosystems such that the carbon and hydrological cycles in Amazonia are changing to carbon neutrality and affect precipitation downwind. In Africa, the tropical forests are so far maintaining their carbon sink.It is urgent to better understand the interaction between these major ecosystems, the atmosphere, and climate, which calls for more observation sites, providing long-term data on water, carbon, and other biogeochemical cycles. This is essential in finding a sustainable balance between forest preservation and reforestation versus a potential increase in food production and biofuels, which are critical in maintaining ecosystem services and global climate stability. Reducing global warming and deforestation is vital for tropical forests.
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| 2. |
- Bilde, M., et al.
(author)
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Saturation Vapor Pressures and Transition Enthalpies of Low-Volatility Organic Molecules of Atmospheric Relevance: From Dicarboxylic Acids to Complex Mixtures
- 2015
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In: Chemical Reviews. - : American Chemical Society (ACS). - 0009-2665 .- 1520-6890. ; 115:10, s. 4115-4156
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Research review (peer-reviewed)abstract
- There are a number of techniques that can be used that differ in terms of whether they fundamentally probe the equilibrium and the temperature range over which they can be applied. The series of homologous, straight-chain dicarboxylic acids have received much attention over the past decade given their atmospheric relevance, commercial availability, and low saturation vapor pressures, thus making them ideal test compounds. Uncertainties in the solid-state saturation vapor pressures obtained from individual methodologies are typically on the order of 50-100%, but the differences between saturation vapor pressures obtained with different methods are approximately 1-4 orders of magnitude, with the spread tending to increase as the saturation vapor pressure decreases. Some of the dicarboxylic acids can exist with multiple solid-state structures that have distinct saturation vapor pressures. Furthermore, the samples on which measurements are performed may actually exist as amorphous subcooled liquids rather than solid crystalline compounds, again with consequences for the measured saturation vapor pressures, since the subcooled liquid phase will have a higher saturation vapor pressure than the crystalline solid phase. Compounds with equilibrium vapor pressures in this range will exhibit the greatest sensitivities in terms of their gas to particle partitioning to uncertainties in their saturation vapor pressures, with consequent impacts on the ability of explicit and semiexplicit chemical models to simulate secondary organic aerosol formation.
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| 3. |
- Kulmala, Markku, et al.
(author)
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Overview of the biosphere-aerosol-cloud-climate interactions (BACCI) studies
- 2008
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In: Tellus. Series B: Chemical and Physical Meteorology. - : Stockholm University Press. - 0280-6509 .- 1600-0889. ; 60:3, s. 300-317
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Research review (peer-reviewed)abstract
- Here we present research methods and results obtained by the Nordic Centre of Excellence Biosphere-Aerosol-Cloud-Climate Interactions (BACCI) between 1 January 2003 and 31 December 2007. The centre formed an integrated attempt to understand multiple, but interlinked, biosphere-atmosphere interactions applying inter and multidisciplinary approaches in a coherent manner. The main objective was to study the life cycle of aerosol particles and their importance on climate change. The foundation in BACCI was a thorough understanding of physical, meteorological, chemical and ecophysiological processes, providing a unique possibility to study biosphere-aerosol-cloud-climate interactions. Continuous measurements of atmospheric concentrations and fluxes of aerosol particles and precursors and, CO2/aerosol trace gas interactions in different field stations (e.g. SMEAR) were supported by models of particle thermodynamics, transport and dynamics, atmospheric chemistry, boundary layer meteorology and forest growth. The main progress was related to atmospheric new particle formation, existence of clusters, composition of nucleation mode aerosol particles, chemical precursors of fresh aerosol particles, the contribution of biogenic aerosol particles on the global aerosol load, transport, transformation and deposition of aerosol particles, thermodynamics related to aerosol particles and cloud droplets, and the microphysics and chemistry of cloud droplet formation.
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| 4. |
- Stolzenburg, Dominik, et al.
(author)
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Atmospheric nanoparticle growth
- 2023
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In: Reviews of Modern Physics. - 0034-6861 .- 1539-0756. ; 95:4
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Research review (peer-reviewed)abstract
- New particle formation of liquid or solid nanoparticles from gas-phase precursors is a decisive process in Earth’s atmosphere and is considered one of the largest uncertainties in climate change predictions. Key for the climate relevance of new particle formation is the growth of freshly formed molecular clusters, as it determines the survival of these particles to cloud condensation nuclei sizes, where they can contribute to the aerosol-indirect effect. This review lays out the fundamental definitions of nanoparticle growth and addresses the rapidly emerging field of new particle formation studies with a focus on the diverse processes contributing to nanoparticle growth, explicitly comparing the latest experimental findings and their implementation in large-scale models. Atmospheric nanoparticle growth is a complex phenomenon including condensational and reactive vapor uptake, aerosol coagulation, and sink processes. It is linked to thermodynamics, cluster- and phase-transition physics. Nanoparticle growth rates measured from the evolution of the particle-size distribution describe growth as a collective phenomenon, while models often interpret them on a single-particle level and incorporate it into highly simplified size-distribution representations. Recent atmospheric observations show that sulfuric acid together with ammonia and amines, iodic acid, and oxidized organic species can contribute to nanoparticle growth, whereas most models describe the growth effects from a limited subset of this variety of condensable vapors. Atmospheric simulation chamber experiments have clarified the role of ions, intermolecular forces, the interplay of acids and bases, and the contribution of different types of organic vapors. Especially in the complex thermodynamics of organic vapor condensation, the field has had noteworthy advances over the last decade. While the experimental field has achieved significant progress in methodology and process level understanding, this has not led to a similar improvement in the description of the climate impact of nanoparticle formation in large-scale models. This review sets the basis to better align experimental and modeling studies on nanoparticle growth, giving specific guidance for future studies aiming to resolve the questions as to why the climate response in large-scale models seems to be buffered against high survival probabilities and why the global growth observations herein show surprisingly low variation.
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| 5. |
- Vehkamäki, Hanna, et al.
(author)
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Thermodynamics and kinetics of atmospheric aerosol particle formation and growth
- 2012
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In: Chemical Society Reviews. - : Royal Society of Chemistry (RSC). - 0306-0012 .- 1460-4744. ; 41:15, s. 5160-5173
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Research review (peer-reviewed)abstract
- In this tutorial review we summarize the standard approaches to describe aerosol formation from atmospheric vapours and subsequent growth - with a particular emphasis on the interplay between equilibrium thermodynamics and non-equilibrium transport. We review the use of thermodynamics in describing phase equilibria and formation of aerosol particles from supersaturated vapour via nucleation. We also discuss the kinetics of cluster formation and transport phenomena, which are used to describe dynamic mass transport between the gaseous and condensed phases in a non-equilibrium system. Finally, we put these theories into the context of atmospheric observations of aerosol formation and growth.
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