HYSPLIT Smoke Calculation Originated from a Prescribed Burn
The HYSPLIT model can be run to estimate the spatial and temporal evolution of smoke (as PM2.5) originated from a prescribed burn. The location and the area of the burn are the only required inputs.
Emissions and heat release
PM2.5 emissions and heat release are estimated from the emissions processing portion of the U.S. Fire Service’s (USFS) BlueSky smoke modeling Framework (Larkin et al., 2008, O’Neill et al. 2008) based on fire size and location. BlueSky https://tools.airfire.org/websky/v1/#status is a fire and smoke prediction tool that was originally developed for land and air quality managers to assist with wildfire containment and prescribed burning decisions while at the same time attempting to minimize impacts of the smoke on the local population. The USFS system links together models of fire characteristics, meteorology, emissions estimation, smoke dispersion, and graphical display of output products. The ARL adaptation of BlueSky uses its emissions estimation component, which consists of the Emissions Production Module (EPM) integrated with the CONSUME model (Sandberg and Peterson 1984), and the National Fire Danger Rating System (NFDRS, Cohen and Deeming 1985) fuel loadings database. The BlueSky emissions module currently has capabilities to create emissions for CO, CO2, CH4, Non Methane Hydrocarbons (NMHC), PM, PM2.5 and PM10. ARL’s implementation incorporates only the PM2.5 emissions for the predictions; however, the incorporation of multiple species is being tested for implementation in future versions.
Plume rise is computed assuming an air parcel’s rise based only on the buoyancy terms (Briggs, 1969; Arya, 1999) using the fire heat release (from BlueSky), the wind velocity, and the friction velocity during the day and the static stability at night. During the day the plume rise is limited to the top 75% of the mixed layer while at night the plume rise can be up to two times the mixed layer depth. In the smoke prediction computation, smoke particles are released at the final plume rise height from the center of each emission grid cell that contains the fire location.
Transport and Dispersion
Smoke estimations are produced by the HYSPLIT dispersion model, a hybrid between Lagrangian and Eulerian approaches. Advection and diffusion calculations are made in a Lagrangian framework following the transport, while concentrations are calculated on a fixed grid. The transport and dispersion of a pollutant can be calculated by assuming the release of puffs with either a predefined Gaussian or top-hat (zero outside, one inside) horizontal distribution that increases with time, or from the turbulent dispersal of an initial fixed number of particles, or by combining both puff and particle methods by assuming a puff distribution in the horizontal and particle dispersion in the vertical direction. In this way, the greater accuracy of the vertical dispersion parameterization of the particle model is combined with the advantage of having fewer pollutant puffs to represent the horizontal distribution. Further detailed descriptions of the HYSPLIT model can be found in Draxler and Hess (1997, 1998).Northwest International Section, Portland, OR. Air Pollution Control Association, Pittsburgh, PA.
Arya, S.P. (1999), Air Pollution Meteorology and Dispersion. Oxford University Press, New York, 310 p.
Briggs, G.A. (1969), Plume rise. USAEC Critical Review Series, TID-25075, National Technical Information Service, Springfield, VA, 81 pp.
Cohen, J.D., and J.E. Deeming (1985), The National Fire-Danger Rating System: Basic equations. Pacific Southwest Forest and Range Experiment Station, General Technical Report PSW-82, Berkeley, CA.
Draxler, R.R. and G.D. Hess (1998), An overview of the HYSPLIT_4 modelling system for trajectories, dispersion, and deposition. Aust. Meteor. Mag. 47, 295-308.
Draxler, R.R. and G.D. Hess (1997), Description of the HYSPLIT_4 modeling system. NOAA Technical Memo ERL ARL-224, December, 24 p.
Larkin, Narasimhan & O’Neill, Susan & Solomon, Robert & Raffuse, Sean & Strand, Tara & Coe, Dana & Krull, Candace & Rorig, Miriam & Peterson, Janice & Ferguson, Sue. (2009). The BlueSky smoke modeling framework. Int. J. Wildland Fire. 18. 10.1071/WF07086.
O’Neill, S.M., and Coauthors (2008), Regional real-time smoke prediction systems. Wildland Fires and Air Pollution, A. Bytnerowicz et al., Eds., Developments in Environmental Science Series, Vol. 8, Elsevier, 499-534.
Sandberg, D.V., and J. Peterson (1984), A source-strength model for prescribed fires in coniferous logging slash. In: Proceedings, 21st Annual Meeting of the Air Pollution Control Association, Pacific