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Träfflista för sökning "L773:1680 7316 ;pers:(Kerminen V. M)"

Sökning: L773:1680 7316 > Kerminen V. M

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1.
  • Gagne, S., et al. (författare)
  • Factors influencing the contribution of ion-induced nucleation in a boreal forest, Finland
  • 2010
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 10:8, s. 3743-3757
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the longest series of measurements so far (2 years and 7 months) made with an Ion-DMPS at the SMEAR II measurement station in Hyytiala, Southern Finland. We show that the classification into overcharged (implying some participation of ion-induced nucleation) and undercharged (implying no or very little participation of ion-induced nucleation) days, based on Ion-DMPS measurements, agrees with the fraction of ion-induced nucleation based on NAIS measurements. Those classes are based on the ratio of ambient charged particle to steady-state charged particle concentration, known as the charging state. We analyzed the influence of different parameters on the contribution of ion-induced nucleation to the total particle formation rate. We found that the fraction of ion-induced nucleation is typically higher on warmer, drier and sunnier days compared to colder days with less solar radiation and a higher relative humidity. Also, we observed that bigger concentrations of new particles were produced on days with a smaller fraction of ion-induced nucleation. Moreover, sulfuric acid saturation ratios were smaller for days with a bigger fraction of ion-induced nucleation. Finally, we propose explanations on how these different parameters could influence neutral and ion-induced nucleation, and show that the different mechanisms seem to take place at the same time during an event. For example, we propose that these observed differences could be due to high temperature and low vapors' saturation ratios (water and sulfuric acid) increasing the height of the energy barrier a particle has to reach before it can grow and thus limiting neutral nucleation.
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2.
  • Hong, J., et al. (författare)
  • Hygroscopicity, CCN and volatility properties of submicron atmospheric aerosol in a boreal forest environment during the summer of 2010
  • 2014
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 14:9, s. 4733-4748
  • Tidskriftsartikel (refereegranskat)abstract
    • A Volatility-Hygroscopicity Tandem Differential Mobility Analyzer (VH-TDMA) was applied to study the hygroscopicity and volatility properties of submicron atmospheric aerosol particles in a boreal forest environment in Hyytiala, Finland during the summer of 2010. Aitken and accumulation mode internally mixed particles (50 nm, 75 nm and 110 nm in diameter) were investigated. Hygroscopicity was found to increase with particle size. The relative mass fraction of organics and SO42- is probably the major contributor to the fluctuation of the hygroscopicity for all particle sizes. The Cloud Condensation Nuclei Counter (CCNC)-derived hygroscopicity parameter kappa was observed to be slightly higher than kappa calculated from VH-TDMA data under sub-saturated conditions, potential reasons for this behavior are discussed shortly. Also, the size-resolved volatility properties of particles were investigated. Upon heating, more small particles evaporated compared to large particles. There was a significant amount of aerosol volume (non-volatile material) left, even at heating temperatures of 280 degrees C. Using size resolved volatility-hygroscopicity analysis, we concluded that there was always hygroscopic material remaining in the particles at different heating temperatures, even at 280 degrees C. This indicates that the observed non-volatile aerosol material did not consist solely of black carbon.
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3.
  • Kerminen, V-M, et al. (författare)
  • Cloud condensation nuclei production associated with atmospheric nucleation:
  • 2012
  • Ingår i: Atmospheric Chemistry and Physics. - Copernicus Gesellschaft Gmb. - 1680-7316. ; 12:24, s. 12037-12059
  • 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.
4.
  • Kulmala, M., et al. (författare)
  • General overview:
  • 2011
  • Ingår i: Atmospheric Chemistry and Physics. - 1680-7316. ; 11:24, s. 13061-13143
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we describe and summarize the main achievements of the European Aerosol Cloud Climate and Air Quality Interactions project (EUCAARI). EUCAARI started on 1 January 2007 and ended on 31 December 2010 leaving a rich legacy including: (a) a comprehensive database with a year of observations of the physical, chemical and optical properties of aerosol particles over Europe, (b) comprehensive aerosol measurements in four developing countries, (c) a database of airborne measurements of aerosols and clouds over Europe during May 2008, (d) comprehensive modeling tools to study aerosol processes fron nano to global scale and their effects on climate and air quality. In addition a new Pan-European aerosol emissions inventory was developed and evaluated, a new cluster spectrometer was built and tested in the field and several new aerosol parameterizations and computations modules for chemical transport and global climate models were developed and evaluated. These achievements and related studies have substantially improved our understanding and reduced the uncertainties of aerosol radiative forcing and air quality-climate interactions. The EUCAARI results can be utilized in European and global environmental policy to assess the aerosol impacts and the corresponding abatement strategies.
5.
  • Kyro, E. -M, et al. (författare)
  • Trends in new particle formation in eastern Lapland, Finland : effect of decreasing sulfur emissions from Kola Peninsula
  • 2014
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 14:9, s. 4383-4396
  • Tidskriftsartikel (refereegranskat)abstract
    • The smelter industry in Kola Peninsula is the largest source of anthropogenic SO2 in the Arctic part of Europe and one of the largest within the Arctic domain. Due to socio-economic changes in Russia, the emissions have been decreasing especially since the late 1990s resulting in decreased SO2 concentrations close to Kola in eastern Lapland, Finland. At the same time, the frequency of new particle formation days has been decreasing distinctively at SMEAR I station in eastern Lapland, especially during spring and autumn. We show that sulfur species, namely sulfur dioxide and sulfuric acid, have an important role in both new particle formation and subsequent growth and that the decrease in new particle formation days is a result of the reduction of sulfur emissions originating from Kola Peninsula. In addition to sulfur species, there are many other quantities, such as formation rate of aerosol particles, condensation sink and nucleation mode particle number concentration, which are related to the number of observed new particle formation (NPF) days and need to be addressed when linking sulfur emissions and NPF. We show that while most of these quantities exhibit statistically significant trends, the reduction in Kola sulfur emissions is the most obvious reason for the rapid decline in NPF days. Sulfuric acid explains approximately 20-50% of the aerosol condensational growth observed at SMEAR I, and there is a large seasonal variation with highest values obtained during spring and autumn. We found that (i) particles form earlier after sunrise during late winter and early spring due to high concentrations of SO2 and H2SO4; (ii) several events occurred during the absence of light, and they were connected to higher than average concentrations of SO2; and (iii) high SO2 concentrations could advance the onset of nucleation by several hours. Moreover, air masses coming over Kola Peninsula seemed to favour new particle formation.
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6.
  • Makkonen, R., et al. (författare)
  • Air pollution control and decreasing new particle formation lead to strong climate warming
  • 2012
  • Ingår i: Atmospheric Chemistry and Physics. - Copernicus GmbH. - 1680-7316. ; 12:3, s. 1515-1524
  • Tidskriftsartikel (refereegranskat)abstract
    • The number concentration of cloud droplets determines several climatically relevant cloud properties. A major cause for the high uncertainty in the indirect aerosol forcing is the availability of cloud condensation nuclei (CCN), which in turn is highly sensitive to atmospheric new particle formation. Here we present the effect of new particle formation on anthropogenic aerosol forcing in present-day (year 2000) and future (year 2100) conditions. The present-day total aerosol forcing is increased from -1.0 W m(-2) to -1.6 W m(-2) when nucleation is introduced into the model. Nucleation doubles the change in aerosol forcing between years 2000 and 2100, from +0.6 W m(-2) to +1.4 W m(-2). Two climate feedbacks are studied, resulting in additional negative forcings of -0.1 W m(-2) (+10% DMS emissions in year 2100) and -0.5 W m(-2) (+50% BVOC emissions in year 2100). With the total aerosol forcing diminishing in response to air pollution control measures taking effect, warming from increased greenhouse gas concentrations can potentially increase at a very rapid rate.
7.
  • Makkonen, R., et al. (författare)
  • BVOC-aerosol-climate interactions in the global aerosol-climate model ECHAM5.5-HAM2
  • 2012
  • Ingår i: Atmospheric Chemistry and Physics. - Copernicus Gesellschaft Gmb. - 1680-7316. ; 12:21, s. 10077-10096
  • Tidskriftsartikel (refereegranskat)abstract
    • The biosphere emits volatile organic compounds (BVOCs) which, after oxidation in the atmosphere, can partition on the existing aerosol population or even form new particles. The large quantities emitted provide means for a large potential impact on both aerosol direct and indirect effects. Biogenic responses to atmospheric temperature change can establish feedbacks even in rather short timescales. However, due to the complexity of organic aerosol partitioning, even the sign of these feedbacks is of large uncertainty. We use the global aerosol-climate model ECHAM5.5-HAM2 to explore the effect of BVOC emissions on new particle formation, clouds and climate. Two BVOC emission models, MEGAN2 and LPJ-GUESS, are used. MEGAN2 shows a 25% increase while LPJ-GUESS shows a slight decrease in global BVOC emission between years 2000 and 2100. The change of shortwave cloud forcing from year 1750 to 2000 ranges from -1.4 to -1.8 W m(-2) with 5 different nucleation mechanisms. We show that the change in shortwave cloud forcing from the year 2000 to 2100 ranges from 1.0 to 1.5 W m(-2). Although increasing future BVOC emissions provide 3-5% additional CCN, the effect on the cloud albedo change is modest. Due to simulated decreases in future cloud cover, the increased CCN concentrations from BVOCs can not provide significant additional cooling in the future.
8.
  • Manninen, H. E., et al. (författare)
  • EUCAARI ion spectrometer measurements at 12 European sites - analysis of new particle formation events
  • 2010
  • Ingår i: Atmospheric Chemistry and Physics. - Copernicus GmbH. - 1680-7316. ; 10:16, s. 7907-7927
  • 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.
9.
  • Nieminen, T., et al. (författare)
  • Parameterization of ion-induced nucleation rates based on ambient = servations
  • 2011
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 11:7, s. 3393-3402
  • Tidskriftsartikel (refereegranskat)abstract
    • Atmospheric ions participate in the formation of new atmospheric aerosol particles, yet their exact role in this process has remained unclear. Here we derive a new simple parameterization for ion-induced nucleation or, more precisely, for the formation rate of charged 2-nm particles. The parameterization is semi-empirical in the sense that it is based on comprehensive results of one-year-long atmospheric cluster and particle measurements in the size range similar to 1-42 nm within the EUCAARI (European Integrated project on Aerosol Cloud Climate and Air Quality interactions) project. Data from 12 field sites across Europe measured with different types of air ion and cluster mobility spectrometers were used in our analysis, with more in-depth analysis made using data from four stations with concomitant sulphuric acid measurements. The parameterization is given in two slightly different forms: a more accurate one that requires information on sulfuric acid and nucleating organic vapor concentrations, and a simpler one in which this information is replaced with the global radiation intensity. These new parameterizations are applicable to all large-scale atmospheric models containing size-resolved aerosol microphysics, and a scheme to calculate concentrations of sulphuric acid, condensing organic vapours and cluster ions.
10.
  • Paasonen, P., et al. (författare)
  • On the roles of sulphuric acid and low-volatility organic vapours in the initial steps of atmospheric new particle formation
  • 2010
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 10:22, s. 11223-11242
  • 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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