PARTICLE-IN-CELL VS STRAIGHT-LINE AIRFLOWnGAUSSIAN CALCULATIONS OF CONCENTRATION ANDnDEPOSITION OF AIRBORNE EMISSIONS OUT TO 70 KMnFOR TWO SITES OF DIFFERING METEOROLOGICALnAND TOPOGRAPHICAL CHARACTER

摘要

Two numerical models for the calculation of air concentration and ground deposition of airborne effluent releases are compared. The Particle-in-Cell (PIC) model and the Straight-Line Airflow Gaussian model were used for the simulation. Two sites were selected for comparison:the Hudson River Valley, New York, and the area around the Savannah River Plant, South Carolina. Input for the models was synthesized from meteorological data gathered in previous studies by various investigators. It was found that the PIC model more closely simulated the three-dimensional effects of the meteorology and topography. Overall, the Gaussian model calculated higher concentrations under stable conditions with better agreement between the two methods during neutral to unstable conditions. In addition, because of its consideration of exposure from the returning plume after flow reversal, the PIC model calculated air concentrations over larger areas than did the Gaussian model.