Abstract
A hybrid Lagrangian-Eulerian atmospheric transport-diffusion model was developed to calculate the three-dimensional distribution of atmospheric pollutants in transient-region flow fields. This Atmospheric Diffusion Particle-in-Cell (ADPIC) code was validated against several existing closed-form analytical solutions including a puff release in steady, unidirectional shear flow, and a puff release with scale-dependent horizontal and vertical eddy diffusion coefficients. These tests showed that the ADPIC results were within a 5% error when compared to the analytic solutions. Regional (100 km) tracer studies at the National Reactor Test Station Idaho Falls, Idaho, and at the Savannah River Laboratory, Aiken, S. C., were also used to compare the code against field measurements.
