A Model For Scalar Advection Inside Canopies And Application To Footprint Investigation

  • Sites: US-GMF
  • Publication Type: JOUR
  • Authors: Lee, X.

  • In this paper, a model is presented for scalar advection inside canopies. A key result is an advection/diffusion equation that captures the persistence effect of the diffusion plume from elevated sources through a near-field modifier. The model is applicable to various source configurations including line source, plane and canopy sources with finite fetch, and horizontally extensive canopy source. Model prediction agrees reasonably well with the observations of a line and a plane heat source in a wind tunnel canopy.

    The two-dimensional flux footprint in the xz plane in homogeneous turbulence is expressed in analytical form and that in canopy turbulence is computed from the numerical solution of the advection/diffusion equation. The footprint calculations suggest that inclusion of flow inhomogeneity leads to a stronger near-field effect than in homogeneous turbulence, resulting in a maximum contribution to the observed flux to come from sources further away from the measurement tower. The flux measured within the roughness sublayer is weighted more heavily by contributions from sources in the lower canopy in unstable conditions and from the upper canopy in stable conditions. The flux footprint is less sensitive to source height in neutral air than in stratified air. The cross-wind integrated footprint reported in the literature is a special case of the present model.


  • Journal: Agricultural And Forest Meteorology
  • Funding Agency: —
  • Citation Information:
  • Volume: 127
  • No: 3-4
  • Pages: 131-141
  • Publication Year: 2004
  • DOI: 10.1016/j.agrformet.2004.07.009