Calculated and observed seasonal and annual krypton-85 concentrations at 30–150 km from a point source

Abstract One year of weekly average 85 Kr concentrations observed at 13 sampling locations from 30 to 150km from a quasi-continuous point source is used in a verification study involving two air pollution models. The first, a stability wind rose model, similar to those widely used for long-term regional pollution studies, overestimates the seasonal and annual values by an approximate factor of 4 on the average. Factors that contribute to the overestimation are the use of surface winds, which are slower than the stack-height winds, and a likely tendency to overestimate the frequency and duration of stable conditions. The second, a trajectory-diffusion model developed by the Air Resources Laboratories, shows good agreement with the observed concentrations. Calculated seasonal averages are generally within a factor of 2 of the observed average values. Calculated annual averages are within ± 20% of the observed average values at most stations.