Vertical variability and effect of stability on turbulence characteristics down to the floor of a pine forest

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Launiainen, Samuli ; Vesala, Timo ; Mölder, Meelis ; Mammarella, Ivan ; Smolander, Sampo ; Rannik, Üllar ; Kolari, Pasi ; Hari, Pertti ; Lindroth, Anders ; Katul, Gabriel G. (2011)

Among the fundamental problems in canopy turbulence, particularly near the forest floor, remain the local diabatic effects and linkages between turbulent length scales and the canopy morphology. To progress on these problems, mean and higher order turbulence statistics are collected in a uniform pine forest across a wide range of atmospheric stability conditions using five 3-D anemometers in the subcanopy. The main novelties from this experiment are: (1) the agreement between second-order closure model results and measurements suggest that diabatic states in the layer above the canopy explain much of the modulations of the key velocity statistics inside the canopy except in the immediate vicinity of the trunk space and for very stable conditions. (2) The dimensionless turbulent kinetic energy in the trunk space is large due to a large longitudinal velocity variance but it is inactive and contributes little to momentum fluxes. (3) Near the floor layer, a logarithmic mean velocity profile is formed and vertical eddies are strongly suppressed modifying all power spectra. (4) A spectral peak in the vertical velocity near the ground commensurate with the trunk diameter emerged at a moderate element Reynolds number consistent with Strouhal instabilities describing wake production.DOI: 10.1111/j.1600-0889.2007.00313.x
  • References (93)
    93 references, page 1 of 10

    Albertson, J. D., Katul, G. G. and Wiberg, P. 2001. Relative importance of local and regional controls on coupled water, carbon, and energy fluxes. Adv. Water Resour. 24, 1103-1118.

    Allen, L. H., Jr. 1968. Turbulence and wind spectra within a japanese larch plantation. J. Appl. Meteorol. 7, 73-78.

    Amiro, B. D. and Davis, P. A. 1988. Statistics of atmospheric turbulence within a natural black spruce forest canopy. Boundary-Layer Meteorol. 44, 267-283.

    Amiro, B. D. 1990. Comparison of turbulence statistics within three boreal forest canopies. Boundary-Layer Meteorol. 51, 99-121.

    Antonia, R. A. 1981. Conditional sampling in turbulence measurements. Annu. Rev. Fluid Mech. 13, 131-156.

    Aubinet, M., Grelle, A., Ibrom, A., Rannik, U¨ ., Monchrieff, J. and coauthors. 2000. Estimates of the annual net carbon and water exchange of forests: the EUROFLUX methodology. Adv. Ecol. Res. 30, 113- 178.

    Aubinet, M., Heinesch, B. and Yernaux, M. 2003. Horizontal and vertical CO2 advection in a sloping forest. Boundary-Layer Meteorol. 108, 397-417.

    Baldocchi, D. D. and Hutchison, B. A. 1988. Turbulence structure in an almond orchard: spatial vatiation in spectra and coherence. BoundaryLayer Meteorol. 42, 293-311.

    Baldocchi, D. D., Finnigan, J. J., Wilson, K., Paw, U. K. T. and Falge, E. 2000. On measuring net ecosystem carbon exchange over tall vegetation on complex terrain. Boundary-Layer Meteorol. 96, 257- 291.

    Baldocchi, D. D. and Meyers, T. P. 1988a. Turbulence structure in a deciduous forest. Boundary-Layer Meteorol. 43, 345-364.

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