Characterization of Source Emissions using Short Duration Measurements and Model Predictions

Coupled mesoscale atmospheric and Lagrangian particle dispersion models are used routinely to estimate source term emissions from downwind concentration measurements. At distances where a plume has become well mixed within the environment, longer duration sample collections can be utilized to quantify the source emission. Attribution using long duration samples, or averaging multiple short duration samples, reduces sensitivity to random model errors and unknown environmental conditions, although these have disadvantages when source emissions vary with time. Lower concentration emissions require sampling closer to the source in order to provide a sufficient signal to noise ratio for analysis. Decreasing distance from the source, and temporal variations in emissions complicate source term estimates obtained from downwind measurements. Ensemble modeling methods can be employed to improve source term estimates by quantifying expected variability in these measurements and bounding emission predictions. Sensitivity in source characterization will be analyzed using high resolution ensemble modeling of source emissions at Savannah River Site (SRS) for short duration measurements within ten kilometers from a source. Turbulence measurements from sonic anemometers and mixed layer height obtained from ceilometer will be used to evaluate meteorological model uncertainty.