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System Overview

The UAF smoke forecast system uses the Weather Research and Forecasting (WRF) model with online chemistry as core model. The ‘online’ chemistry eliminates errors due to temporal and spatial interpolation, as chemical transport processes are treated at identical WRF grid and time steps.

WRF/Chem version 3.1 has been released in April 2009. This version includes an inline plume model as a further major step forward in modeling atmospheric effects of wildfires. Plume dynamics depend strongly on initial buoyancy and turbulent mixing of plume-ambient air with fire emissions. Inaccuracies due to previously necessary parameterization in order to consider small scale plume dynamics in the significant larger scale of numerical weather models are eliminated in WRF/Chem version 3.1.

Model Initialization:

  1. The Global Forecast System model is used for meteorological initialization of WRF/Chem.
  2. Alaska above ground biomass fuel load data in 1 kilometer resolution have been derived from the global land-cover classification data for the year 2000 (GLC2000) and fuel load factors published by Wiedinmyer et al. 2006.
  3. Andrae and Merlet’s (2001) comprised necessary emission factors in order to relate various fuel-load types involved in biomass burning to emissions.
  4. Anthropogenic and sea salt emission data from the Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model are included in the emission initialization data of WRF/Chem.

Wildfire Source:

The Alaska Wildfire source information is derived from the Alaska Interagency Coordination Center (AICC), the Geographic Area Coordination Center for Alaska.

Fire data are updated continuously during the fire season, or whenever new information is gathered via aerial and ground surveys, or remote sensing sources from MODIS (MOD14 hot spot) data made available through GINA, the Geographic Information Network of Alaska.

The 2nd source of Alaska wildfire locations and properties is from remote sensing products developed at the University of Wisconsin- Madison: The experimental Wildfire Automated Biomass Burning Algorithm (WFABBA) is generating half-hourly updated fire data derived from the geostationary NOAA weather satellites GOES-11 and GOES-12. Data are typically available within 90 minutes of data acquisition.

WFABBA and AICC fire data are downloaded prior to every WRF/Chem run. The fire source data are combined and referred to the selected WRF domain.