Two‐dimensional transport of dust from an infinite line source at ground level

Solutions are provided for the two‐dimensional diffusion equation of dust over a rough ground surface, which acts as a dust source of varying strengths, under the effect of horizontal wind and gravitational attraction. A general analytic expression for the two‐dimensional dust concentration is obtained. In the case of a constant source strength the solution takes a particularly simple form. It is shown that the one‐dimensional result derived previously for the vertical transport of dust can easily be deduced as a special case of this expression. The profiles of the concentration above the roughness height are evaluated numerically and are found to depend strongly on downwind positions and on wind speed. The numerical values of the concentration at a particular downwind position are found to be smaller than those predicted by the one‐dimensional theory.