Sensitivity of regional ozone concentrations to temporal distribution of emissions

Temporal representations of emissions bear large uncertainty. Before any costly efforts are undertaken to improve the accuracy of temporal emission profiles, however, the impact of their uncertainty on predictions of surface O-3 concentrations should be,examined. In this study, a 3-D air quality modeling system was used to probe the sensitivity of regional surface O-3 concentrations to temporal allocation of emissions over the continental US. The raw emissions inventory was processed using SMOKE and was segmented into hourly intervals using both "time-varying" and "uniform" temporal profiles of anthropogenic sources. Our simulation results show that, on average and with the grid resolution (90 km) used, regional daytime O-3 concentrations are not sensitive to changes in the temporal allocation of emissions, while nighttime O-3 concentrations are lower under "uniform" profiles than under "time-varying" profiles. (C) 2004 Elsevier Ltd. All rights reserved.