||Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab. ;Computer Sciences Corp., Research Triangle Park, NC. ;National Oceanic and Atmospheric Administration, Research Triangle Park, NC. Atmospheric Sciences Modeling Div.
The Regional Acid Deposition Model (RADM) and associated Engineering Model have been developed to study episodic source-receptor relationships on a regional scale. The RADM includes transport, chemical transformation, and deposition processes as well as input of emissions into the vertical layers using a plume-rise submodel. As wind speed and direction change with height, and as atmospheric turbulence varies significantly with distance from the earth's surface, the model predictions can be affected considerably by the height at which the emissions are injected. Atmospheric emissions can be divided into area and point sources. The area sources include mobile emissions, biogenic emissions, and other emissions that are often related to the surface area of the earth. Area sources are more difficult to control and have inherent diversities in their physiochemical processes. Point sources include stacks at power plants and manufacturing facilities. Usually, point sources are the target of emission reduction programs.