EXTENSIONS OF FINITE RATE DIFFUSION-THEORY TO A CONTINUOUS PLUME FROM A GROUND-BASED SOURCE IN THE ATMOSPHERIC SURFACE-LAYER

Numerical predictions of the convection diffusion equations are analyzed for the case of a continuous source located at the ground for adiabatic conditions in the atmospheric surface layer. Trends in the shape of the vertical concentration distribution are consistent with the pairings dz OVER BAR /dt equals b//1u//*, (dx/dt)//z// OVER BAR equals u(cz OVER BAR ) and d sigma //z/dt equals b//2u//*, (dx/dt)// sigma equals u(c sigma //z) in which c approximately equals 1. 0, b//1 equals 0. 40, b//2 equals 0. 576 with x, z the downwind and vertical distance coordinates; z OVER BAR sigma //z the mean height and root mean square width of the vertical distribution, respectively; t, the time; u the mean wind speed and u//* the friction velocity. Integration of the above leads to formulae which provide fairly close agreement with experimental data. Trends in plume vertical structure can be satisfactorily explained in terms of the behavior of the wavefront.