BUDGET OF VELOCITY VARIANCES ACROSS A FOREST EDGE: A COMPARISON BETWEEN FIELD, WIND TUNNEL AND NUMERICAL SIMULATION STUDIES

摘要

Airflow experiences a drastic adjustment when it flows across a vegetation discontinuity, for example a forest edge. The fact that different velocity components take different rates in their adjustments has been recognized in many studies. As one example, by investigating the statistics of field data, Irvine et al. (1997) reported that the adjustment of streamwise velocity variance was faster than that of vertical velocity variance in the turbulent flow across a forest edge. They also suggested that the flow distortion at the edge was responsible for the different adjusting rates. In order to understand the controlling mechanisms of flow adjustment in the transition zone, budget analyses of velocity variances will be presented and a comparison of budgets between field, wind tunnel and numerical simulation studies will be made in this paper.