Source Term Estimation of Atmospheric Pollutants Using an Ensemble of HYSPLIT Concentration Simulations

In support of Comprehensive Nuclear-Test-Ban Treaty (CTBT) monitoring and nuclear event detection, this study works toward source term estimation (STE) of dispersive pollutants using a novel method|an ensemble of forward trajectory concentration simulations using a meteorology-coupled dispersion model. Traditionally a mathematically and physically rigorous problem, STE of a plume of atmospheric pollutants can be solved in a variety of ways depending on what is known regarding the emission, but little has been studied on the sensitivity between the horizontal resolution of the meteorology data in relation to the dispersion model and the results derived from known concentrations at multiple locations. This study tackles both these issues of resolution and observation sensitivities by employing the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, coupled with data from the 1983 Cross-Appalachian Tracer Experiment (CAPTEX), to determine the location of the experimental tracer releases. This is accomplished by conducting an ensemble of HYSPLIT forward concentration simulations using a grid of first-guess locations and storing the model-derived concentration values in a source-receptor matrix (SRM). The model rank for each simulation is calculated using ground measurements, and the location yielding the highest model rank is determined to be the source. Simultaneously, this study produces information regarding source-receptor relationships to terrain features. Furthermore, the study then applies the SRM methodology to locate the detonation location of two nuclear tests conducted in the 1950s at the Nevada Test Site (NTS). Knowing the sensitivity of the STE solution based on the number of available measurements is useful for determining the location of a release of radionuclides into the atmosphere in support of nuclear treaty monitoring