Articles | Volume 11, issue 14
Atmos. Chem. Phys., 11, 6773–6786, 2011
https://doi.org/10.5194/acp-11-6773-2011
Atmos. Chem. Phys., 11, 6773–6786, 2011
https://doi.org/10.5194/acp-11-6773-2011

Research article 18 Jul 2011

Research article | 18 Jul 2011

Aerosol flux measurements above a mixed forest at Borden, Ontario

M. Gordon, R. M. Staebler, J. Liggio, A. Vlasenko, S.-M. Li, and K. Hayden M. Gordon et al.
  • Science and Technology Branch, Environment Canada, Toronto, Canada

Abstract. Aerosol fluxes were measured above a mixed forest by Eddy Covariance (EC) with a Fast Mobility Particle Sizer (FMPS) at the Borden Forest Research Station in Ontario, Canada between 13 July and 12 August 2009. Chemically speciated flux measurements were made at a height of 29 m at the same location between 19 July and 2 August, 2006 using a Quadrupole Aerosol Mass Spectrometer (Q-AMS). The Q-AMS measured an average sulphate deposition velocity of 0.3 mm s−1 and an average nitrate deposition velocity of 4.8 mm s−1. The FMPS, mounted at a height of 33 m (approximately 10 m above the canopy top) and housed in a temperature controlled enclosure, measured size-resolved particle concentrations from 3 to 410 nm diameter at a rate of 1 Hz. For the size range 18 < D < 452 nm, 60 % of fluxes were upward. The exchange velocity was between −0.5 and 2.0 mm s−1, with median values near 0.5 mm s−1 for all sizes between 22 and 310 nm. The size distribution of the apparent production rate of particles at 33 m peaked at a diameter of 75 nm. Results indicate a decoupling of the above and below canopy spaces, whereby particles are stored in the canopy space at night, and are then diluted with cleaner air above during the day.

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