Photochemical Modeling of Two 1984 SCCCAMP Ozone Episodes

Abstract

Data collected during the 1984 SCCCAMP Exploratory Study were used to develop two multiple-day ozone modeling episodes for the Urban Airshed Model (UAM). An operational model performance evaluation was performed for the 5–7 and 16–17 September 1984 episodes. Peak 1-h average ozone concentrations were reproduced on the five simulation days with accuracies (paired in time and space) ranging from 0% to −30%. The mean bias in hourly averaged ozone concentrations ranged from −6% to +11%, and the mean gross errors varied between 23% and 38%. UAM performance for ozone concentrations with the two September episodes is comparable with other recent photochemical model evaluations. Lack of sufficient measurements for model performance testing of other important photochemical species (e.g., NO, NO2, volatile organic compounds) and for carrying out compensatory error analysis and related diagnostic and mechanistic investigations precluded a more rigorous scientific evaluation of UAM performance with the 1984 SCCCAMP database.