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System Overview

The UAF smoke forecast system uses the Weather Research and Forecasting (WRF) model with online chemistry (WRF-Chem) 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.

An inline plume model has been implemented in WRF-Chem (initially within WRF-Chem version 3.1 in 2009) 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.

UAFSMOKE Model Initialization:

  1. The Global Forecast System model is used for meteorological initialization of WRF-Chem.
  2. Andrae and Merlet’s (2001) compiled emission factors in order to relate various fuel-load types involved in biomass burning to emissions.
  3. Anthropogenic and sea salt emission data from the Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model are included in the WRF-Chem setup.

Alaska 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.

Another source of remote sensing data of Alaska wildfire locations and properties was 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.


References:

  1. Grell G., S. Freitas, M. Stuefer, J. Fast, 2011, Inclusion of Biomass Burning in WRF-Chem: Impact of Wildfires on Weather Forecasts. Journal of Atmos. Chem. Phys., 11, 5289–5303, 2011.
  2. WRF-Chem version 3.6 Users Guide Updated 8 July 2014.