| 1. |
- Asmi, A., et al.
(författare)
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Number size distributions and seasonality of submicron particles in = rope 2008-2009
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:11, s. 5505-5538
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Tidskriftsartikel (refereegranskat)abstract
- Two years of harmonized aerosol number size distribution data from 24 = ropean field monitoring sites have been analysed. The results give a = mprehensive overview of the European near surface aerosol particle = mber concentrations and number size distributions between 30 and 500 = of dry particle diameter. Spatial and temporal distribution of = rosols in the particle sizes most important for climate applications = e presented. We also analyse the annual, weekly and diurnal cycles of = e aerosol number concentrations, provide log-normal fitting parameters = r median number size distributions, and give guidance notes for data = ers. Emphasis is placed on the usability of results within the aerosol = delling community.
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| 2. |
- Beddows, D. C. S., et al.
(författare)
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Variations in tropospheric submicron particle size distributions across the European continent 2008-2009
- 2014
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14:8, s. 4327-4348
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Tidskriftsartikel (refereegranskat)abstract
- Cluster analysis of particle number size distributions from background sites across Europe is presented. This generated a total of nine clusters of particle size distributions which could be further combined into two main groups, namely: a south-to-north category (four clusters) and a west-to-east category (five clusters). The first group was identified as most frequently being detected inside and around northern Germany and neighbouring countries, showing clear evidence of local afternoon nucleation and growth events that could be linked to movement of air masses from south to north arriving ultimately at the Arctic contributing to Arctic haze. The second group of particle size spectra proved to have narrower size distributions and collectively showed a dependence of modal diameter upon the longitude of the site (west to east) at which they were most frequently detected. These clusters indicated regional nucleation (at the coastal sites) growing to larger modes further inland. The apparent growth rate of the modal diameter was around 0.6-0.9 nm h(-1). Four specific air mass back-trajectories were successively taken as case studies to examine in real time the evolution of aerosol size distributions across Europe. While aerosol growth processes can be observed as aerosol traverses Europe, the processes are often obscured by the addition of aerosol by emissions en route. This study revealed that some of the 24 stations exhibit more complex behaviour than others, especially when impacted by local sources or a variety of different air masses. Overall, the aerosol size distribution clustering analysis greatly simplifies the complex data set and allows a description of aerosol aging processes, which reflects the longer-term average development of particle number size distributions as air masses advect across Europe.
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| 3. |
- Kerminen, V-M, et al.
(författare)
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Cloud condensation nuclei production associated with atmospheric nucleation : a synthesis based on existing literature and new results
- 2012
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 12:24, s. 12037-12059
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Tidskriftsartikel (refereegranskat)abstract
- This paper synthesizes the available scientific information connecting atmospheric nucleation with subsequent cloud condensation nuclei (CCN) formation. We review both observations and model studies related to this topic, and discuss the potential climatic implications. We conclude that CCN production associated with atmospheric nucleation is both frequent and widespread phenomenon in many types of continental boundary layers, and probably also over a large fraction of the free troposphere. The contribution of nucleation to the global CCN budget spans a relatively large uncertainty range, which, together with our poor understanding of aerosol-cloud interactions, results in major uncertainties in the radiative forcing by atmospheric aerosols. In order to better quantify the role of atmospheric nucleation in CCN formation and Earth System behavior, more information is needed on (i) the factors controlling atmospheric CCN production and (ii) the properties of both primary and secondary CCN and their interconnections. In future investigations, more emphasis should be put on combining field measurements with regional and large-scale model studies.
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| 4. |
- Lappalainen, H. K., et al.
(författare)
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Overview: Recent advances in the understanding of the northern Eurasian environments and of the urban air quality in China - a Pan-Eurasian Experiment (PEEX) programme perspective
- 2022
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 22:7, s. 4413-4469
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Tidskriftsartikel (refereegranskat)abstract
- The Pan-Eurasian Experiment (PEEX) Science Plan, released in 2015, addressed a need for a holistic system understanding and outlined the most urgent research needs for the rapidly changing Arctic-boreal region. Air quality in China, together with the long-range transport of atmospheric pollutants, was also indicated as one of the most crucial topics of the research agenda. These two geographical regions, the northern Eurasian Arctic-boreal region and China, especially the megacities in China, were identified as a "PEEX region". It is also important to recognize that the PEEX geographical region is an area where science-based policy actions would have significant impacts on the global climate. This paper summarizes results obtained during the last 5 years in the northern Eurasian region, together with recent observations of the air quality in the urban environments in China, in the context of the PEEX programme. The main regions of interest are the Russian Arctic, northern Eurasian boreal forests (Siberia) and peatlands, and the megacities in China. We frame our analysis against research themes introduced in the PEEX Science Plan in 2015. We summarize recent progress towards an enhanced holistic understanding of the land-atmosphere-ocean systems feedbacks. We conclude that although the scientific knowledge in these regions has increased, the new results are in many cases insufficient, and there are still gaps in our understanding of large-scale climate-Earth surface interactions and feedbacks. This arises from limitations in research infrastructures, especially the lack of coordinated, continuous and comprehensive in situ observations of the study region as well as integrative data analyses, hindering a comprehensive system analysis. The fast-changing environment and ecosystem changes driven by climate change, socio-economic activities like the China Silk Road Initiative, and the global trends like urbanization further complicate such analyses. We recognize new topics with an increasing importance in the near future, especially "the enhancing biological sequestration capacity of greenhouse gases into forests and soils to mitigate climate change" and the "socio-economic development to tackle air quality issues".
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| 5. |
- Manninen, H. E., et al.
(författare)
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EUCAARI ion spectrometer measurements at 12 European sites - analysis of new particle formation events
- 2010
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 10:16, s. 7907-7927
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Tidskriftsartikel (refereegranskat)abstract
- We present comprehensive results on continuous atmospheric cluster and particle measurements in the size range similar to 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.
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| 6. |
- Paasonen, P., et al.
(författare)
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On the roles of sulphuric acid and low-volatility organic vapours in the initial steps of atmospheric new particle formation
- 2010
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 10:22, s. 11223-11242
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Tidskriftsartikel (refereegranskat)abstract
- Sulphuric acid and organic vapours have been identified as the key components in the ubiquitous secondary new particle formation in the atmosphere. In order to assess their relative contribution and spatial variability, we analysed altogether 36 new particle formation events observed at four European measurement sites during EUCAARI campaigns in 2007-2009. We tested models of several different nucleation mechanisms coupling the formation rate of neutral particles (J) with the concentration of sulphuric acid ([H2SO4]) or low-volatility organic vapours ([org]) condensing on sub-4 nm particles, or with a combination of both concentrations. Furthermore, we determined the related nucleation coefficients connecting the neutral nucleation rate J with the vapour concentrations in each mechanism. The main goal of the study was to identify the mechanism of new particle formation and subsequent growth that minimizes the difference between the modelled and measured nucleation rates. At three out of four measurement sites - Hyytiala (Finland), Melpitz (Germany) and San Pietro Capofiume (Italy) - the nucleation rate was closely connected to squared sulphuric acid concentration, whereas in Hohenpeissenberg (Germany) the low-volatility organic vapours were observed to be dominant. However, the nucleation rate at the sulphuric acid dominant sites could not be described with sulphuric acid concentration and a single value of the nucleation coefficient, as K in J=K [H2SO4](2), but the median coefficients for different sites varied over an order of magnitude. This inter-site variation was substantially smaller when the heteromolecular homogenous nucleation between H2SO4 and organic vapours was assumed to take place in addition to homogenous nucleation of H2SO4 alone, i.e., J=K-SA1[H2SO4](2)+K-SA2[H2SO4][org]. By adding in this equation a term describing homomolecular organic vapour nucleation, K-s3[org](2), equally good results were achieved. In general, our results suggest that organic vapours do play a role, not only in the condensational growth of the particles, but also in the nucleation process, with a site-specific degree.
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| 7. |
- Yli-Juuti, T., et al.
(författare)
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Growth rates of nucleation mode particles in Hyytiala during 2003-2009 : variation with particle size, season, data analysis method and ambient conditions
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:24, s. 12865-12886
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Tidskriftsartikel (refereegranskat)abstract
- The condensational growth rate of aerosol particles formed in atmospheric new particle formation events is one of the most important factors influencing the lifetime of these particles and their ability to become climatically relevant. Diameter growth rates (GR) of nucleation mode particles were studied based on almost 7 yr of data measured during the years 2003-2009 at a boreal forest measurement station SMEAR II in Hyytiala, Finland. The particle growth rates were estimated using particle size distributions measured with a Differential Mobility Particle Sizer (DMPS), a Balanced Scanning Mobility Analyzer (BSMA) and an Air Ion Spectrometer (AIS). Two GR analysis methods were tested. The particle growth rates were also compared to an extensive set of ambient meteorological parameters and trace gas concentrations to investigate the processes/constituents limiting the aerosol growth. The median growth rates of particles in the nucleation mode size ranges with diameters of 1.5-3 nm, 3-7 nm and 7-20 nm were 1.9 nm h(-1), 3.8 nm h(-1), and 4.3 nm h(-1), respectively. The median relative uncertainties in the growth rates due to the size distribution instrumentation in these size ranges were 25 %, 19 %, and 8 %, respectively. For the smallest particles (1.5-3 nm) the AIS data yielded on average higher growth rate values than the BSMA data, and higher growth rates were obtained from positively charged size distributions as compared with negatively charged particles. For particles larger than 3 nm in diameter no such systematic differences were found. For these particles the uncertainty in the growth rate related to the analysis method, with relative uncertainty of 16 %, was similar to that related to the instruments. The growth rates of 7-20 nm particles showed positive correlation with monoterpene concentrations and their oxidation rate by ozone. The oxidation rate by OH did not show a connection with GR. Our results indicate that the growth of nucleation mode particles in Hyytiala is mainly limited by the concentrations of organic precursors.
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