This paper will describe advances being made in the Department of Energy's operational National Atmospheric Release Advisory Center (NARAC) atmospheric dispersion modeling system at Lawrence Livermore National Laboratory (LLNL). The NARAC system is used to provide detailed assessments of the consequences of atmospheric releases of hazardous materials for real-time emergency response, pre-planning and post-incident assessments, and research. At the core of this system are the coupled meteorological data assimilation and dispersion models ADAPT/LODI and an in-house version of the Naval Research Laboratory's COAMPS weather forecast model. New capabilities are being added to these models, with a particular focus on the incorporation of spatially inhomogeneous physics needed to support simulations over multiple space and time scales. This includes the development of turbulence parameterizations that utilize measured velocity variances, surface-energy budget methods using standard meteorological observations and land-use data, or weather prediction model output. Urban canopy parameterizations have been developed which simulate the area-averaged effects of metropolitan areas on flow and dispersion. Rain-rate data have been coupled to a particle-size and rain-rate dependent precipitation scavenging algorithm. These modeling capabilities are supported by NARAC's real-time meteorological data acquisition system and databases of geographical, land-use/land-cover, elevation, source term and health-effect level information. For high-resolution simulations, COAMPS and LODI have been parallelized for both multi-processor and high performance (massively parallel) computing platforms. In addition, COAMPS and ADAPT output have been coupled to LLNL's parallelized computational fluid dynamics model, FEM3MP, which provides building-scale simulations for scenario planning and site vulnerability analyses.

This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.