Atmos. Chem. Phys. Discuss., 10, 30613-30650, 2010
© Author(s) 2010. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Inclusion of biomass burning in WRF-Chem: impact of wildfires on weather forecasts
G. Grell1, S. R. Freitas2, M. Stuefer3, and J. Fast4
1Earth Systems Research Laboratory of the National Oceanic and Atmospheric Administration (NOAA), and Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, CO 80305-3337, USA
2Center for Weather Forecasting and Climate Studies, INPE, Cachoeira Paulista, Brazil
3University of Alaska, Fairbanks, Alaska, USA
4Pacific Northwest National Laboratory, USA

Abstract. A plume rise algorithm for wildfires was included in WRF-Chem, and applied to look at the impact of intense wildfires during the 2004 Alaska wildfire season on weather simulations using model resolutions of 10 km and 2 km. Biomass burning emissions were estimated using a biomass burning emissions model. In addition a 1-D time dependent cloud model was used online in WRF-Chem to estimate injection heights as well as the final emission rates. It was shown that with the inclusion of the intense wildfires of the 2004 fire season in the model simulations the interaction of the aerosols with the atmospheric radiation lead to significant modifications of vertical profiles of temperature and moisture in cloud-free areas. On the other hand, when clouds were present, the high concentrations of fine aerosol (PM2.5) and the resulting large numbers of Cloud Condensation Nuclei (CCN) had a strong impact on clouds and microphysics, with decreased precipitation coverage and precipitation amounts during the first 12 h of the integration, but significantly stronger storms during the afternoon hours.

Citation: Grell, G., Freitas, S. R., Stuefer, M., and Fast, J.: Inclusion of biomass burning in WRF-Chem: impact of wildfires on weather forecasts, Atmos. Chem. Phys. Discuss., 10, 30613-30650, doi:10.5194/acpd-10-30613-2010, 2010.
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