A dispersion forecasting system supported by NW-AIRQUEST


Introduction to ClearSky

ClearSky is a Decision Support System developed in response to the needs of state and tribal air-quality managers, to support their management of smoke from agricultural burning. Such burning is commonly used in the Inland Northwest region for clearing fields of post-harvest residue. This system was developed at the Laboratory for Atmospheric Research at Washington State University in consultation with NW-AIRQUEST, a regional consortium of air-quality managers and scientists.

ClearSky version 1 originally utilized daily numerical weather forecasts, from MM5 (Mesoscale Meteorological Model version 5) then operated at the University of Washington, and the CALMET and CALPUFF models to simulate the dispersion of smoke from agricultural burning, providing results as PM2.5 as micrograms per cubic meter in the surface layer on an hourly basis for multiple burning scenarios (Jain et al., 2007), using PM2.5 emissions based on research by Air Sciences Inc. (2003) and Johnson and Golob (2004).

ClearSky version 2 is a major update featuring changes in every aspect of the system:

  • Meteorology, Emissions and Air Quality results are all computed on a regional 4-km grid that matches that used in AIRPACT.
  • Meteorology now comes from the current WRF (Weather Research and Forecasting) model operated at the University of Washington Department of Atmospheric Sciences, processed through the MCIP meteorological processor to produce 4-km gridded hourly fields of required met fields.
  • Emissions specification is informed by local research on emission rates for wheat and Kentucky bluegrass.
  • The SMOKE (Sparse Matrix Optimized Kernel for Emissions Processing) model is used to apply the hourly WRF meteorology to calculate plume rise behavior that reflects the forecast meteorology.
  • The CMAQ (Community Multi-scale Model for Air Quality) model, in this application built for non-reactive tracer dispersion, is used to calculate the dispersion of agricultural smoke and simulate (predict) hourly.
  • Air-quality professionals responsible for decisions on agricultural burning at the University of Washington have access to a website where they can create specific burning scenarios for modeling.
  • Results from user-submitted and default (used daily) scenarios are provided daily on a project website.

Those interested in utilizing the ClearSky2 system in their area are encouraged to contact the developers at the Laboratory for Atmospheric Research.


Air Sciences Inc., 2003. Cereal-grain residue open field burning study. Report for: Washington Department of Ecology, Washington Association of Wheat Growers, and US Environmental Protection Agency, Region 10. Project No. 152-02.

Johnston, W.J. and Golob, C.T., 2004. Quantifying post-harvest emissions from bluegrass seed production field burning (Washington State University, Department of Crop & Soil Science). Final report for Grass Seed Cropping Systems for a Sustainable Agriculture, Washington Department of Ecology, Idaho Department of Environmental Quality, Washington Turfgrass Seed Commission, and Coeur d'Alene Tribe.

Jain, R., Vaughan, J., Heitkamp, K., Ramos, C., Claiborn, C., Schreuder, M., Schaaf, M., and Lamb, B. Development of the ClearSky smoke dispersion forecast system for agricultural field burning in the Pacific Northwest, Atmos. Environ., 41, 7645-6761, 2007, doi:10.1016/j.atmosenv.2007.04.058.

Civil & Environmental Engineering, PO Box 642910, Washington State University, Pullman WA 99164-2910, 509-335-2576