Numerical Simulations of Atmospheric Transport and Diffusion over Coastal Complex Terrain

Abstract

The purpose of this study was to demonstrate the feasibility of operating the three-dimensional atmospheric models HOTMAC (higher-order turbulence model for atmospheric circulation) and RAPTAD (random puff transport and diffusion) to forecast the transport and dispersion of airborne hazardous materials at Vandenberg Air Force Base, California (VAFB). HOTMAC provides three-dimensional distributions of the mean and turbulence variables to RAPTAD, which simulates transport and diffusion of airborne materials. To test the HOTMAC-RAPTAD model results, data were selected from the Mountain Iron (MI) diffusion experiments that were conducted at VAFB during 1965 and 1966. The data included surface winds, upper-air soundings, and ground-level exposure values of fluorescent particles. Conclusions of this study include: HOTMAC and RAPTAD predictions of the ground-level exposure values were as good as those obtained by diagnostic and empirical models and were the best practical solution where wind data were not available. The HOTMAC and RAPTAD modeling system would be a useful addition to enhance current emergency response management capabilities.