THE BUDGETS OF TURBULENT KINETIC-ENERGY AND REYNOLDS STRESS WITHIN AND ABOVE A DECIDUOUS FOREST

Mean turbulence statistics obtained within and above a deciduous forest are used to examine the components in the budget equations for turbulent kinetic energy (TKE) and tangential shear stress. Comparisons from the measurements are made with predictions from a higher-order closure model for canopy flow. Wake-generated turbulence was found to exceed shear-produced turbulence in all but the upper level of the canopy. Beneath the tree crowns, turbulent transport was the dominant source of TKE and tangential shear stress. Below approximately 75% of the canopy height, the magnitude of all the TKE and shear stress budget components is small compared with values above this height, and the vertical gradients of second-and third-order moments are small. The turbulence statistics observed within the deciduous forest are remarkably similar to that observed within a tropical forest, which has a similar distribution of leaf area. When compared with results from experiments conducted in other canopies, the importance of the quantity and vertical distribution of the plant area in determining the turbulence structure is reinforced.