Atmos. Chem. Phys. Discuss., 9, 18965-18984, 2009
www.atmos-chem-phys-discuss.net/9/18965/2009/
doi:10.5194/acpd-9-18965-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Measurements of coarse mode and primary biological aerosol transmission through a tropical forest canopy using a dual-channel fluorescence aerosol spectrometer
A. M. Gabey, M. W. Gallagher, J. Whitehead, and J. Dorsey
Centre for Atmospheric Science, University of Manchester, Manchester M13 9PL, UK

Abstract. Aerosol in the size range 0.8–20 μm was characterized according to optical equivalent diameter, DP, morphology and the presence of biological material, the latter determined by recording fluorescence excited by ultraviolet light pulses at two different wavelengths. Single-particle measurements were performed within and subsequently above a tropical rainforest in Borneo, Malaysia, in June and July 2008. In both locations the aerosol number size distribution exhibited a primary biological aerosol (PBA) mode sized 2 μm<DP<20 μm and much larger in number within the forest than above it, suggesting the PBA originates below the canopy. PBA was observed to dominate the total number at DP>2 μm and possessed a wider morphological range than non-PBA. It also accounted for around 80% of the total number in the understory and 40% of the total number above canopy. Canopy transmission efficiencies for the total aerosol number and PBA are calculated to be 0.48±0.19 and 0.31±0.15 respectively, with the former appearing to peak during the daytime because of a lack of PBA emission below the canopy.

Citation: Gabey, A. M., Gallagher, M. W., Whitehead, J., and Dorsey, J.: Measurements of coarse mode and primary biological aerosol transmission through a tropical forest canopy using a dual-channel fluorescence aerosol spectrometer, Atmos. Chem. Phys. Discuss., 9, 18965-18984, doi:10.5194/acpd-9-18965-2009, 2009.
 
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