Evaluation of the Inline WRF−HYSPLIT Model for Short- and Medium-Range Transport and Dispersion over Complex Topography

An evaluation of the new, inline WRF-HYSPLIT model, which couples the Weather Research and Forecasting model (WRF) and the Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT), is conducted for short- and medium-range atmospheric transport and dispersion over complex topography. The WRF-HYSPLIT model, developed by the Air Resources Laboratory of the National Oceanographic and Atmospheric Administration (NOAA), implements HYSPLIT within the main computational loop of WRF, allowing it to take advantage of the meteorological model’s small time-steps and native vertical grid. This inline model has been shown to have some advantages over the traditional off-line implementation of the HYSPLIT model, particularly for meso-gamma-scale, short-range, transport and dispersion predictions. Building off this previous work, the current study investigates WRF-HYSPLIT, using data collected from the 2010 Colorado Springs Tracer Experiment (COSTEX). For this field experiment, 30-min continuous releases of perfluorocarbon tracers are tracked over a 3.5-hour period using a network of 10 stations located up to 50 km downstream from the source. In particular, COSTEX atmospheric tracer data from 18, 21, and 23 October 2010 are used. An ensemble approach is implemented in order to assess the predictability of the plume over complex topography for both the inline WRF-HYSPLIT model and the traditional, offline HYSPLIT approach. Statistical comparisons of the plumes’ morphology are also conducted. Preliminary testing shows the WRF-HYSPLIT to have some advantages over the traditional implementation of HYSPLIT for mesoscale dispersion.