Science and Technology Branch, Environment Canada, Toronto, Canada
Received: 16 Jul 2010 – Discussion started: 01 Oct 2010
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.
Revised: 04 Jul 2011 – Accepted: 08 Jul 2011 – Published: 18 Jul 2011
Gordon, M., Staebler, R. M., Liggio, J., Vlasenko, A., Li, S.-M., and Hayden, K.: Aerosol flux measurements above a mixed forest at Borden, Ontario, Atmos. Chem. Phys., 11, 6773-6786, doi:10.5194/acp-11-6773-2011, 2011.