The U.S. EPA Regional Oxidant Model (ROM) and NEROS data base are described. The model incorporates a comprehensive description of the physical and chemical processes thought to be important to tropospheric O3 production on 1000 km scales. The data base employed for the first application of the ROM was collected during the summers of 1979 and 1980 in the Northeast U.S. It contains meteorological and air quality data from regular monitoring networks and from enhanced networks or special field project measurements during that period. The evaluation procedure that will be used to determine the ROM performance on this data base is outlined. A number of episodes will be simulated from the period July 23 through August 16, 1980, for which performance statistics will be developed. The evaluation of any given day within an episode will proceed in two distinct stages. The first stage will focus on model performance for an individual model realization, irrespective of all other realizations. Model realizations for a given day are functions of the possible flow fields that existed for the day. The second stage will attempt to evaluate model performance using the full probabilistic abilities of the ROM that consider all realizations concurrently. The focus of the evaluation will be on O3. The exact pathway through the evaluation study will be determined by the resources available at the time.

"August 1985." Includes bibliographical references (p. 73-74) "EPA/600/3-85/067."