We studied mean wind velocity profiles measured on a 60m height tower built in the forest reserve Jar£ (10005'S, 61035'W), belonging to IBAMA institution, located in the Brazilian north-western state of Rondonia. The data were collected during LBA (Large Scale
Biosphere-Atmosphere Experiment in Amazonia) wet season campaign. The nine cup anemometers whose measurements were used in this work were vertically placed in a way to provide good calculation of the mean velocity wind profile inflexion point value. This allow us to obtain well fitted third degree polinomial functions for the vertical wind profiles. Thus, it was possible to determine with reasonable prevision the following physical parameters: inflexion-point height, zi; inflexion point height wind velocity, ui; mean wind shear at the canopy top z=h, sh = (d<u>/dz) ; characteristic length scale, Lh = <uh>/sh, where z is the above surface height. This is useful to obtain above and below canopy nondimensional wind velocity, u/ui, as a function of a nondimensional inside canopy depth (z - zi)/Lh. The results for more than 300 data points seem to confirm the suggestions that the wind shear in the canopy top and the inflexion point in the wind velocity vertical profile synthetize the basic informations concerning the dynamics of turbulent interactions between the flow above and below the Amazonian forest canopy in Rondonia.