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Sökning: L773:1680 7316 > Kulmala M.

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1.
  • Hakkinen, S. A. K., et al. (författare)
  • Long-term volatility measurements of submicron atmospheric aerosol in Hyytiala, Finland
  • 2012
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 12:22, s. 10771-10786
  • Tidskriftsartikel (refereegranskat)abstract
    • The volatility of submicron atmospheric aerosol particles was investigated at a boreal forest site in Hyytiala, Finland from January 2008 to May 2010. These long-term observations allowed for studying the seasonal behavior of aerosol evaporation with a special focus on compounds that remained in the aerosol phase at 280 degrees C. The temperature-response of evaporation was also studied by heating the aerosol sample step-wise to six temperatures ranging from 80 degrees C to 280 degrees C. The mass fraction remaining after heating (MFR) was determined from the measured particle number size distributions before and after heating assuming a constant particle density (1.6 g cm(-3)). On average 19% of the total aerosol mass remained in the particulate phase at 280 degrees C. The particles evaporated less at low ambient temperatures during winter as compared with the warmer months. Black carbon (BC) fraction of aerosol mass correlated positively with the MFR at 280 degrees C, but could not explain it completely: most of the time a notable fraction of this nonvolatile residual was something other than BC. Using additional information on ambient meteorological conditions and results from an Aerodyne aerosol mass spectrometer (AMS), the chemical composition of MFR at 280 degrees C and its seasonal behavior was further examined. Correlation analysis with ambient temperature and mass fractions of polycyclic aromatic hydrocarbons (PAHs) indicated that MFR at 280 degrees C is probably affected by anthropogenic emissions. On the other hand, results from the AMS analysis suggested that there may be very low-volatile organics, possibly organonitrates, in the non-volatile (at 280 degrees C) fraction of aerosol mass.
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2.
  • Hakkinen, S. A. K., et al. (författare)
  • Semi-empirical parameterization of size-dependent atmospheric nanoparticle growth in continental environments
  • 2013
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 13:15, s. 7665-7682
  • Tidskriftsartikel (refereegranskat)abstract
    • The capability to accurately yet efficiently represent atmospheric nanoparticle growth by biogenic and anthropogenic secondary organics is a challenge for current atmospheric large-scale models. It is, however, crucial to predict nanoparticle growth accurately in order to reliably estimate the atmospheric cloud condensation nuclei (CCN) concentrations. In this work we introduce a simple semi-empirical parameterization for sub-20 nm particle growth that distributes secondary organics to the nanoparticles according to their size and is therefore able to reproduce particle growth observed in the atmosphere. The parameterization includes particle growth by sulfuric acid, secondary organics from monoterpene oxidation (SORG(MT)) and an additional condensable vapor of non-monoterpene organics (background). The performance of the proposed parameterization was investigated using ambient data on particle growth rates in three diameter ranges (1.5-3 nm, 3-7 nm and 7-20 nm). The growth rate data were acquired from particle / air ion number size distribution measurements at six continental sites over Europe. The longest time series of 7 yr (2003-2009) was obtained from a boreal forest site in Hyytiala, Finland, while about one year of data (2008-2009) was used for the other stations. The extensive ambient measurements made it possible to test how well the parameterization captures the seasonal cycle observed in sub-20 nm particle growth and to determine the weighing factors for distributing the SORG(MT) for different sized particles as well as the background mass flux (concentration). Besides the monoterpene oxidation products, background organics with a concentration comparable to SORGMT, around 6x10(7) cm(-3) (consistent with an additional global SOA yield of 100 Tg yr(-1)) was needed to reproduce the observed nanoparticle growth. Simulations with global models suggest that the background could be linked to secondary biogenic organics that are formed in the presence of anthropogenic pollution.
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3.
  • 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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4.
  • Hussein, T., et al. (författare)
  • Evaluation and modeling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki - Part II : Aerosol measurements within the SAPPHIRE project
  • 2007
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 7:15, s. 4081-4094
  • Tidskriftsartikel (refereegranskat)abstract
    • This study presents an evaluation and modeling exercise of the size fractionated aerosol particle number concentrations measured nearby a major road in Helsinki during 23 August-19 September 2003 and 14 January-11 February 2004. The available information also included electronic traffic counts, on-site meteorological measurements, and urban background particle number size distribution measurement. The ultrafine particle (UFP, diameter < 100 nm) number concentrations at the roadside site were approximately an order of magnitude higher than those at the urban background site during daytime and downwind conditions. Both the modal structure analysis of the particle number size distributions and the statistical correlation between the traffic density and the UFP number concentrations indicate that the UFP were evidently from traffic related emissions. The modeling exercise included the evolution of the particle number size distribution nearby the road during downwind conditions. The model simulation results revealed that the evaluation of the emission factors of aerosol particles might not be valid for the same site during different time.
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5.
  • Kalivitis, Nikos, et al. (författare)
  • Night time enhanced atmospheric ion concentrations in the marine boundary layer
  • 2012
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 12:8, s. 3627-3638
  • Tidskriftsartikel (refereegranskat)abstract
    • Measurements of atmospheric ions in the size range 0.8-42 nm were conducted at the environmental research station of the University of Crete at Finokalia from April 2008 to April 2009 in the frame of the EUCAARI project. Both positive and negative atmospheric ions were found to have a clear annual cycle, with minimum concentrations in summer. Their concentrations were found to vary with the prevailing meteorology and the abundance of aerosol particles in the atmosphere. High concentrations of ions were observed during new particle formation events. There were 53 nucleation events recorded. It was found that under certain atmospheric conditions enhanced ion concentrations can be observed during night. Overall, 39 night-time events were observed, all of them observed for the negatively charged particles while only 21 were observed for the positively charged particles. Night-time enhanced ion concentrations were more frequent during spring and autumn and no such events were recorded from July to September. A strong anti-correlation was found between air ion concentrations, especially at cluster sizes (1.25-1.66 nm), and condensation and coagulation sinks. Enhanced ion concentrations at night were found to be more frequent when air masses had traveled over the island of Crete, indicating possible association with local biogenic sources.
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6.
  • Kim, J., et al. (författare)
  • Hygroscopicity of nanoparticles produced from homogeneous nucleation in the CLOUD experiments
  • 2016
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 16:1, s. 293-304
  • Tidskriftsartikel (refereegranskat)abstract
    • Sulfuric acid, amines and oxidized organics have been found to be important compounds in the nucleation and initial growth of atmospheric particles. Because of the challenges involved in determining the chemical composition of objects with very small mass, however, the properties of the freshly nucleated particles and the detailed pathways of their formation processes are still not clear. In this study,we focus on a challenging size range, i.e., particles that have grown to diameters of 10 and 15 nm following nucleation, and measure their water uptake. Water uptake is useful information for indirectly obtaining chemical composition of aerosol particles. We use a nanometer-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) at sub-saturated conditions (ca. 90% relative humidity at 293 K) to measure the hygroscopicity of particles during the seventh Cosmics Leaving OUtdoor Droplets (CLOUD7) campaign performed at CERN in 2012. In CLOUD7, the hygroscopicity of nucleated nanoparticles was measured in the presence of sulfuric acid, sulfuric acid-dimethylamine, and sulfuric acid-organics derived from alpha-pinene oxidation. The hygroscopicity parameter kappa decreased with increasing particle size, indicating decreasing acidity of particles. No clear effect of the sulfuric acid concentration on the hygroscopicity of 10 nm particles produced from sulfuric acid and dimethylamine was observed, whereas the hygroscopicity of 15 nm particles sharply decreased with decreasing sulfuric acid concentrations. In particular, when the concentration of sulfuric acid was 5.1 x 10(6) molecules cm(-3) in the gas phase, and the dimethylamine mixing ratio was 11.8 ppt, the measured kappa of 15 nm particles was 0.31 +/- 0.01: close to the value reported for dimethylaminium sulfate (DMAS) (kappa(DMAS) similar to 0.28). Furthermore, the difference in kappa between sulfuric acid and sulfuric acid-dimethylamine experiments increased with increasing particle size. The kappa values of particles in the presence of sulfuric acid and organics were much smaller than those of particles in the presence of sulfuric acid and dimethylamine. This suggests that the organics produced from alpha-pinene ozonolysis play a significant role in particle growth even at 10 nm sizes.
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7.
  • Kulmala, M., et al. (författare)
  • General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) - integrating aerosol research from nano to global scales
  • 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.
8.
  • Kulmala, M., et al. (författare)
  • Introduction : The Pan-Eurasian Experiment (PEEX) - multidisciplinary, multiscale and multicomponent research and capacity-building initiative
  • 2015
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 15:22, s. 13085-13096
  • Tidskriftsartikel (refereegranskat)abstract
    • The Pan-Eurasian Experiment (PEEX) is a multidisciplinary, multiscale and multicomponent research, research infrastructure and capacity-building program. PEEX has originated from a bottom-up approach by the science communities and is aiming at resolving the major uncertainties in Earth system science and global sustainability issues concerning the Arctic and boreal pan-Eurasian regions, as well as China. The vision of PEEX is to solve interlinked, global grand challenges influencing human well-being and societies in northern Eurasia and China. Such challenges include climate change; air quality; biodiversity loss; urbanization; chemicalization; food and freshwater availability; energy production; and use of natural resources by mining, industry, energy production and transport sectors. Our approach is integrative and supra-disciplinary, recognizing the important role of the Arctic and boreal ecosystems in the Earth system. The PEEX vision includes establishing and maintaining long-term, coherent and coordinated research activities as well as continuous, comprehensive research and educational infrastructure and related capacity-building across the PEEX domain. In this paper we present the PEEX structure and summarize its motivation, objectives and future outlook.
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9.
  • Kulmala, M., et al. (författare)
  • Introduction: European Integrated Project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) : integrating aerosol research from nano to global scales
  • 2009
  • Ingår i: Atmospheric Chemistry And Physics. - 1680-7316. ; 9, s. 2825-2841
  • Tidskriftsartikel (refereegranskat)abstract
    • The European Aerosol Cloud Climate and Air Quality Interactions project EUCAARI is an EU Research Framework 6 integrated project focusing on understanding the interactions of climate and air pollution. EUCAARI works in an integrative and multidisciplinary way from nano-to global scale. EUCAARI brings together several leading European research groups, state-of-the-art infrastructure and some key scientists from third countries to investigate the role of aerosol on climate and air quality. Altogether 48 partners from 25 countries are participating in EUCAARI. During the first 16 months EUCAARI has built operational systems, e. g. established pan-European measurement network for Lagrangian studies and four stations in developing countries. Also an improved understanding of nanoscale processes (like nucleation) has been implemented in global models. Here we present the research methods, organisation, operations and first results of EUCAARI.
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10.
  • 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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