The next generation of integrated air quality modeling: EPAʹs models-3

The U.S. Environmental Protection Agency is developing a third-generation modeling system, termed Models-3. This paper provides an overview of the concepts behind this effort. The modeling challenge is large and is addressed at two main user groups, regulatory analysts and scientists. New technology and tools from the federal High Performance Computing and Communications Program present an opportunity to effectively address computational constraints and the modeling challenge, simultaneously. Two goals of the Advanced Air Quality Modeling Project are (1) provide an effective decision support system and (2) provide a framework to support the evolvement of models and modeling systems. The information needed for a decision support system is described and its elements are defined. The need to be able to significantly evolve the air quality models is discussed next, followed by the presentation of a general software approach for avoiding modeling system obsolescence. In the final section, key modeling considerations and target capabilities are outlined to show the directions being undertaken to initiate Models-3.