Abstract
Diffusion experimental data in the atmospheric surface layer from ground level line sources are examined by using analytical solutions of the Fickian equation.
Following problems are discussed.
(1) Should we approximate the eddy diffusivity of matters in the vertical direction Kz with a function of downwind distance or with that of height?
(2) Should we put wind shear in the equation?
The results are as follows:
(1) In the case of diffusion from line sources, the agreement of prediction, in which Kz is a function of height, with the experimental data is not better than that in which Kz is a function of downwind distance.
(2) The agreement of prediction, in which wind shear is included, with the experimental data is not better than that of constant wind velocity in the area.
(3) The Walters type solution which is solved on the assumption of Kz=K0·xn and constant wind velocity in the area is useful and practical enough in the prediction from line sources.
