AERODYNAMIC CHARACTERIZATION OF MODEL TREE CANOPIES IN A WIND-TUNNEL

The aerodynamic characteristics of 'model' tree canopies within a wind tunnel are reported. Wind speed profiles above and within canopies co mprising Norway spruce (Picea abies) and Holm oak (Quercus ilex) sapli ngs were determined by hot wire and hot film anemometry at a free-stre am air velocity subsequently used for experiments on the dry depositio n of aerosol particles to both canopies. Friction velocities (U) of 1 28 and 104 cm s-1 were observed for Norway spruce and Holm oak, respec tively. Vertical distributions of wind speed (U) and turbulence intens ity (i) within the canopies were similar in form and magnitude to thos e reported in the literature for full-sized forest canopies, suggestin g that the sapling canopies provide a realistic 'model' with which to investigate the process of dry deposition.