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- Ruuskanen, T. M., et al.
(författare)
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Concentrations and fluxes of aerosol particles during the LAPBIAT measurement campaign at Varrio field station
- 2007
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Ingår i: Atmospheric Chemistry And Physics. - 1680-7316 .- 1680-7324. ; 7:14, s. 3683-3700
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Tidskriftsartikel (refereegranskat)abstract
- The LAPBIAT measurement campaign took place in the Varrio SMEAR I measurement station located in Eastern Lapland in the spring of 2003 between 26 April and 11 May. In this paper we describe the measurement campaign, concentrations and fluxes of aerosol particles, air ions and trace gases, paying special attention to an aerosol particle formation event broken by a air mass change from a clean Arctic air mass with new particle formation to polluted one approaching from industrial areas of Kola Peninsula, Russia, lacking new particle formation. Aerosol particle number flux measurements show strong downward fluxes during that time. Concentrations of coarse aerosol particles were high for 1-2 days before the nucleation event (i.e. 28-29 April), very low immediately before and during the observed aerosol particle formation event (30 April) and increased moderately from the moment of sudden break of the event. In general particle deposition measurements based on snow samples show the same changes. Measurements of the mobility distribution of air ions showed elevated concentrations of intermediate air ions during the particle formation event. We estimated the growth rates in the nucleation mode size range. For particles <10 nm, the growth rate increases with size on 30 April. Dispersion modelling made with model SILAM support the conclusion that the nucleation event was interrupted by an outbreak of sulphate-rich air mass in the evening of 30 April that originated from the industry at Kola Peninsula, Russia. The results of this campaign highlight the need for detailed research in atmospheric transport of air constituents for understanding the aerosol dynamics.
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- Vogt, Matthias, et al.
(författare)
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The relationship between 0.25-2.5 mu m aerosol and CO2 emissions over a city
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:10, s. 4851-4859
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Tidskriftsartikel (refereegranskat)abstract
- Unlike exhaust emissions, non-exhaust traffic emissions are completely unregulated and in addition, there are large uncertainties in the non-exhaust emission factors required to estimate the emissions of these aerosols. This study provides the first published results of direct measurements of size resolved emission factors for particles in the size range 0.25-2.5 mu m using a new approach to derive aerosol emission factors based on carbon dioxide (CO2) emission fluxes. Aerosol fluxes were measured over one year using the eddy covariance method at the top of a 105m high communication tower in Stockholm, Sweden. Maximum CO2 and particle fluxes were found when the wind direction coincided with the area of densest traffic within the footprint area. Negative fluxes (uptake of CO2 and deposition of particles) coincided with periods of sampling from an urban forest area. The fluxes of CO2 were used to obtain emission factors for particles by assuming that the CO2 fluxes could be directly related to the amount of fuel burnt by vehicles in the footprint area. The estimated emission factor for the fleet mix in the measurement area was, in number 1.8 x 10(11) particle veh(-1) km(-1) (for 0.25-2.5 mu m size range). Assuming spherical particles of density 1600 kg m(-3) this corresponds to 27.5 mg veh(-1) km(-1). For particles (0.8-2.5 mu m) the emission factors were 5.1 x 10(9) veh(-1) km(-1) for number and 11.5 mg veh(-1) km(-1) for mass. But a wind speed dependence was noted for high wind speeds. Thus, for wind speeds larger than 9 ms(-1), as measured in the tower at 105m (U-105), the emission factor for particle number and mass was parameterised as: E-f(Number, 0.8-2.5 mu m) = (6.1 +/- 1.7)10(9)U(105)-50+/-188 and E-f(Mass, 0.8-2.5 mu m) = (20+/-12)U-105-171+/-122.
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