A Lagrangian solution to the relationship between a distributed source andconcentration profile

A new solution is presented to the problem of relating source strength and concentration profiles within a plant canopy. The solution is based on the Lagrangian dispersion theory developed by G. I. Taylor in 1921. A dispersio n matrix is derived that relates the source and concentration profiles base d on profiles of the turbulent length and velocity scales. The matrix trans lates the effects of persistence (a temporal effect) into spatial coordinat es and represents the change from near-field to far-field in a continuous f ashion, successfully accounting for both regimes. A test of the new model u sing wind-tunnel data showed excellent quantitative agreement between model and measurements. A comparison was also made with M. R. Raupach's localize d near-field theory, which underestimated the near-field effect in the wind -tunnel data and relative to the new model.