Impact of smoke from the ALASKA 2004 wildfires on radiation and cloud microphysics using WRF-Chem

The Weather Research and Forecasting chemistry (WRF-Chem) model is a community modeling system that includes many different choices for the treatment of gas phase chemistry and aerosols. The chemical and aerosol pollutants are transported and react in "online" fashion with the meteorological forecast model. In other words, the interaction and transport of meteorological, chemical, and aerosol species are calculated using the same physical parameterizations with no need to interpolate in time and/or space. The modeling system may be used from global to Large Eddy simulation scales, and incorporates the direct and indirect effects of aerosols. Recently, wild fires were included into this modeling system. A numerical tool was developed to generate emission data for several types of grid projection for global and regional models. The biomass burning emission model (3BEM) uses remote sensing fire count data together with global carbon density to determine the timing, location and intensity of fire emissions and to initiate a plume rise module. In our case, the sub grid scale plume rise of vegetation fires is included by embedding a 1D cloud resolving model, with appropriate lower boundary conditions, in each column of a 3D host model. The host model provides the environmental conditions, and the plume rise is simulated explicitly. The final height of the plume is then used in the source emission field of the host model to determine the effective injection height of the material emitted during the flaming phase. We will discuss results from fully interactive weather/chemistry simulations on various scales. We chose simulations with current operational horizontal resolutions of approximately 10 km and cloud resolving simulations with much higher horizontal resolutions (2km). Results from fully interactive simulations will be compared with simulations that do not include wildfires.