An atmospheric dispersion index for prescribed burning

A numerical index that estimates the atmosphere1s capacity to disperse smoke from prescribed burning is described. The physical assumptions and mathematical development of the index are described in detail. The index is expressed as a positive integer in such a way that doubling the index implies a rtoubling of the estimated atmospheric capacity. The dispersion index is conceptually similar to ventilation factor but is better able to describe diurnal changes within the lower atmosphere. The index provides a guide to the effect of prescribed burning activity on atmospheric smoke concentration during a portion of a day. The index does not replace smoke dispersion models designed to analyze smoke concentration from individual fires at specific locations, nor does it describe smoke effects on visibility.