Simulate regional PM10 dust dispersion from agricultural tilling operations using Hysplit4

Particulate matter (PM) of aerodynamic diameter less than or equal to 10 microns, PM10, is regulated by the U.S. Environmental Protection Agency (EPA) as part of the National Ambient Air Quality Standard (NAAQS) pollutants. PM10 emitted from agriculture field operations (e.g., disking, listing, leveling, planting, harvesting) can be dispersed downwind in the far-field (i.e., > 1 km). This paper used the Hysplit4 (HYbrid Single-Particle Lagrangian Integrated Trajectory) model to estimate regional dust dispersion from a disking operation. Hyplit4 is a dynamic regional model. It can have a minimum time step of 1 minute, which is an advantage compared to the Gaussian EPA models (Fugitive Dust Model, FDM; Industrial Source Complex Model, ISC3) that have a minimum time step of 1 hour. To evaluate the Hysplit4 simulations, disking operations from a cotton field at Las Cruces, N.M., were conducted, and an airplane flying at between 250 m and 900 m and downwind several kilometers sampled PM10 concentrations. Primary comparisons show that, although the model simulated reasonable shapes of the plumes, the model may not capture the surface layer micrometeorology, and a surface layer model may be coupled with the regional model or to raise the dust source to an appropriate higher height in the regional model may improve the model performance.