A coupled transilience model for turbulent air flow within plant canopies and the planetary boundary layer

Stull's transilient turbulence theory (T-theory) was originally developed to study turbulent air flow in the planetary boundary layer (PBL). The present work extends this model to study the interaction of turbulent air flow within a plant canopy and in the PBL. Additional mechanisms for the causes of wind shear-like leaf drag and destabilizing air flow, such as solar radiation absorption by leaves, which in turn warms the surrounding air, are included. Stull's key concept of transilient coefficients, which describe nonlocal eddy transport, is retained. However, the precise calculations of these coefficients have been modified according to the physical situation. The numerical simulations based on our coupled model are capable not only of simulating turbulent air flow in the PBL, but they can also reproduce the counter-thermal gradient flows within plant canopies and agree well with experimental observation data collected in the Black Moshannon Forest in Pennsylvania, USA. (C) 1997 Published by Elsevier Science B.V.