The introduction of a new understanding of atmospheric boundary layers (ABLs) has caused a major change in the view of the diffusion of pollutants. The turbulence parameters now standard in ABL work, have provided a method for systematically organizing diffusion parameters. Concurrently with these advances, alternatives to the operational models have emerged, but existing experimental data sets are inadequate for model comparisons and evaluations. The most important knowledge gap is the lack of an adequate specification of the relevant meteorology both at the point of release and downwind. A second major inadequacy is experimental measurements of plume characteristics up to 100 km from the release point. There is also a great need for formulating new operational based models upon this newly acquired experimental data and the new alternative approaches. Finally, it is recognized that a modest but steady effort is necessary.

Cover title. "November 1985." Also available online. Location last verified 11/24/10. Includes bibliographical references. "EPA-600/3-85/072."