Analysis of Elemental and Organic Carbon Emissions in St. Louis Using a Hybrid Inverse Model Combining Particle Back-Trajectories and Forward Eulerian Simulations

Hourly concentrations of elemental and organic carbon aerosols were measured at the East-St. Louis supersite during 2001 and 2002. High resolution mesoscale meteorological simulations were used to obtain particle back-trajectories from the measurement site and forward Eulerian simulations of known local and regional sources. Forest fire emissions are included in the analysis using the FINN emissions model and forward simulations. A hybrid inverse model is used to identify potential source locations based on the trajectories, and scaling factors on a-priori emissions in the forward Eulerian model. Bootstrapping is applied to the selection of grid points as well as to the selection of measurement times in order to obtain uncertainty bounds on the estimates. The method is used to estimate the diurnal pattern of area emissions, the emissions of regional sources and the impacts of forest fires.