The Relationship Between Peak and Mean Concentrations

presented. It is shown that the simplified normal bivariate distribution describing the average concentration pattern is composed of various short-term periodic distributions which may differ from it significantly. A descriptive, empirical method is described which indicates an exponential relationship exists between these shorter time or peak concentrations and average conditions. The slope of the exponent appears to be proportional to the stability or the gustiness. Downwind, the peaks are normally within an order of magnitude greater than average concentrations, whereas crosswind, the peaks may be several orders of magnitude larger. (auth)