Complex-Terrain Dispersion Model

The paper describes the current state of EPA's Complex Terrain Disperson Model (CTDM), which has been under development during the past five years. The CTDM employs the concept of a dividing streamline height (a function of wind and temperature profiles), below which plume segments pass round the sides of a hill and/or above which they pass up and over the top. The model is currently constrained to simulate concentrations on the windward side of isolated terrain. The paper includes a comparison of CTDM concentration estimates with concentrations observed during a recent tracer study from a power plant in the Sierra-Nevada Mountains.