A Discussion on recent research in air pollution - Determination of industrial stack heights

Abstract

One field of application of micrometeorological methods and results is that of air pollution meteorology. The number of problems where these method have been employed successfully increased considerably during the last few years. In this connexion I would like to discuss the outlines of a method of supplying meteorological information to air pollution authorities which enables them to decide on minimum heights of industrial stacks. This method has recently been proposed by a working group of meteorologists to the ‘V.D.I.-Kommission Reinhaltung der Luft It should be added here, that this kind of information must not necessarily be the only type of information on which the authorities can base their decision but can be supplemented by other information. One of the most frequent questions the meteorologist is being asked in connexion with air pollution problems is the following: given an industrial source, which is emitting noxious gases under known technical conditions—such as efflux velocity, efflux temperature, total flue gas volume, source strength of the gas considered—how high must the source be, so that a certain surface concentration of this material is exceeded only in a limited number of cases ? This question seems to be simple and straightforward, but the meteorological problems involved are not easily solved. Besides, the economical consequences of the given answer are not negligible. The time averaged concentration field at the surface z = 0 in lee of an isolated, elevated and continuous point source in case of reflexion of the gas at the surface is given by •f(*,y,0) J | | | — — p-exp exp ( - ], 7TU(Ty(x) (Ts{x)T2a}(*)j M 2<rf(*)r where J is the time averaged concentration, Q the intensity of the source, u the mean wind velocity, which is assumed to be constant throughout the layer in which the diffusion takes place (here u is taken as a vertical mean of the time averaged wind velocity weighted with the vertical concentration distribution), cry,cre the standard deviations of the horizontal and vertical Gaussian concentration distribution, respectively, and h the effective source height above ground.