Ensemble Air Quality Forecasting: Effects of Perturbations in Meteorology and Emissions

Abstract

Model-based air quality forecasts are affected by uncertainties in both meteorology and emissions. In this study, we analyze the impacts of these uncertainties on ozone (O₃) forecasts over the Northeastern U.S. during a 45 day period in the summer of 2008. The meteorological uncertainty is prescribed through the use of 12 different weather forecasts from a short-range ensemble forecasting system differing in their initial conditions and physics options. To quantify the effects of emission uncertainties, we computed O₃ sensitivities towards variations in anthropogenic NO_x and VOC emissions using the Direct Decoupled Method (DDM). Results show that the perturbations in meteorology tend to have a larger impact on O₃ forecasts than the emission perturbations considered in this study.