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- Nguyen, Quynh T., et al.
(författare)
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Seasonal variation of atmospheric particle number concentrations, new particle formation and atmospheric oxidation capacity at the high Arctic site Villum Research Station, Station Nord
- 2016
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 16:17, s. 11319-11336
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Tidskriftsartikel (refereegranskat)abstract
- This work presents an analysis of the physical properties of sub-micrometer aerosol particles measured at the high Arctic site Villum Research Station, Station Nord (VRS), northeast Greenland, between July 2010 and February 2013. The study focuses on particle number concentrations, particle number size distributions and the occurrence of new particle formation (NPF) events and their seasonality in the high Arctic, where observations and characterization of such aerosol particle properties and corresponding events are rare and understanding of related processes is lacking. A clear accumulation mode was observed during the darker months from October until mid-May, which became considerably more pronounced during the prominent Arctic haze months from March to mid-May. In contrast, nucleation- and Aitken-mode particles were predominantly observed during the summer months. Analysis of wind direction and wind speed indicated possible contributions of marine sources from the easterly side of the station to the observed summertime particle number concentrations, while southwesterly to westerly winds dominated during the darker months. NPF events lasting from hours to days were mostly observed from June until August, with fewer events observed during the months with less sunlight, i.e., March, April, September and October. The results tend to indicate that ozone (O3) might be weakly anti-correlated with particle number concentrations of the nucleation-mode range (10-30ĝ€nm) in almost half of the NPF events, while no positive correlation was observed. Calculations of air mass back trajectories using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for the NPF event days suggested that the onset or interruption of events could possibly be explained by changes in air mass origin. A map of event occurrence probability was computed, indicating that southerly air masses from over the Greenland Sea were more likely linked to those events.
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- Wang, Fenjuan, et al.
(författare)
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Particle formation events measured at a semirural background site in Denmark
- 2013
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 1614-7499 .- 0944-1344. ; 20:5, s. 3050-3059
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Tidskriftsartikel (refereegranskat)abstract
- The particle formation and growth events observed at a semirural background site in Denmark were analyzed based on particle number size distribution data collected during the period from February 2005 to December 2010. The new particle formation (NPF) events have been classified visually in detail according to 3D daily plots in combination with an automatic routine. A clear seasonal variation was found in the way that events occurred more frequently during the warm season from May to September and especially in June. The mean values of the apparent 6 nm particle formation rates, the growth rate and the condensation sink were about 0.36 cm(-3) s(-1), 2.6 nm h(-1), 4.3 x 10(-3) s(-1), respectively. A positive relationship of oxidation capacity (O-X = O-3 + NO2) of the atmosphere and the appearance of NPF events was found indicating that the oxidation of the atmosphere was linked to the formation of new particles. An analysis of a 3-day backward trajectories revealed that NW air masses from the North Sea were giving the highest probability of NPF events, namely between 20 and 40 %.
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