Size-resolved fluxes of sub-100-nm particles over forests

Sara Pryor, Rebecca Jane Barthelmie, A.M. Spaulding, Søren Ejling Larsen, A. Petroff

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Dry deposition of atmospheric particles is critically dependent on particle size and plays a key role in dictating the mass and number distributions of atmospheric particles. However, modeling dry deposition is constrained by a lack of understanding of controlling dependencies and accurate size-resolved observations. We present size-resolved particle number fluxes for sub-100-nm particle diameters (Dp) over a deciduous forest derived using eddy covariance applied to data from a fast mobility particle sizer. The size-resolved particle number fluxes in 18 diameters between 8 and 100 nm were collected during leaf-on and are statistically robust. Particle deposition velocities normalized by friction velocity (v d +) are approximately four times smaller than comparable values for coniferous forests reported elsewhere. Comparison of the data with output from a new one-dimensional mechanistic particle deposition model designed for broadleaf forest exhibits greater accord with the measurements than two previous analytical models, but modeled v d + underestimate observed values by at least a factor of two for all Dp between 6 and 100 nm. When size-resolved particle deposition velocities for Dp <100 nm are normalized by friction velocity, the key controlling role of particle diffusivity is strongly manifest. On the basis of analyses of these new measurements and recently published size-resolved particle number fluxes from a conifer forest, we present working parameterizations for size-resolved particle deposition velocities over forests that could reasonably be applied in regional and global atmospheric chemistry transport models.
    Original languageEnglish
    JournalJournal of Geophysical Research: Atmospheres
    Volume114
    Pages (from-to)D18212
    ISSN2169-9380
    DOIs
    Publication statusPublished - 2009

    Keywords

    • Wind energy
    • Meteorology

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