On the Turbulent Structure of Airflow within

[摘要] αTaking the observational evidences of the exponential wind velocity profile within crop canopies into account, the geometrical and dynamical haracteristics of canopy-eddies have been investigated from both theoretical and observational points of view. The length, width and depth of canopy-eddy have been suggested to be constant with height within the canopy layer and to be in proportion to (H-d), where H is the crop height and d the zero-plane displacement derived from the logarithmic velocity profile above canopies.Velocities in three directions of canopy-eddy are also suggested to decrease downward following the exponential form of exp {-α(1-Z/H)}, where Z is the height measured from the ground surface beneath the crop height plane.The connections between the exponential and the logarithmic velocity profiles within and above crop canopies and those between the canopy-eddy and the HONAMI-eddy, which causes waving-plants phenomena (HONAMI), are specifically dealt with.Applying the inertial-subrange theory of turbulence to canopy-eddies a method of evaluating the vertical transfer coefficient within crop canopies is presented and tested with earlier observations.

[学科分类] 大气科学