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EVALUATION OF THE REGIONAL OXIDANT MODEL (VERSION 2.1) USING AMBIENT AND DIAGNOSTIC SIMULATIONS
Citation:
Pierce, T., K. Schere, D. Doll, AND W. Heilman. EVALUATION OF THE REGIONAL OXIDANT MODEL (VERSION 2.1) USING AMBIENT AND DIAGNOSTIC SIMULATIONS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-90/046.
Description:
The latest version of EPA's Regional 0xidant Model, R0M2.1 was evaluated to determine and to document its accuracy. n this evaluation, model estimates were compared with ambient measurements of hourly surface ozone collected on 26 days during the summer of 1985 in the northeastern United States. he observed and modeled maximum daytime concentrations agreed on average within 2 ppb (79 ppb versus 77 ppb), but the model tended to underestimate the concentrations at the higher extremes of the frequency distribution, particularly in the southern and western portions of the model domain. stimated and observed spatial patterns for three day maximum ozone generally showed good agreement. 0M2.l improved noticeably over R0M2.O with regard to the orientation of the high-ozone plumes in the Northeast Corridor. nique aspect of the ambient evaluation was an assessment of the model's ability to estimate boundary conditions for the Urban Airshed Model. ear New York City, estimated and observed boundary conditions agreed to within 4 ppb (57 ppb versus 61 ppb). odel performance degraded, however, during some situations with dynamic mesoscale wind flow conditions. eries of diagnostic tests was also done on R0M2.l to investigate the accuracy of its numerical solution algorithms. hen the model was subjected to extremely steep concentration gradients (steeper than those observed in the ambient atmosphere), the model did not conserve mass during a 48 h simulation, deviating by as much as 18% from the initialized value. owever, tests with a mass-corrected version of the full simulation model showed that predicted ozone values deviated only slightly (less than 4%) from the original model.