Post-wildfire impacts on microclimate—a numerical investigation

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Tuesday, 19 January 2010: 8:45 AM
B211 (GWCC)
Elizabeth Mulvihill Page, UCAR/COMET, Boulder, CO; and W. R. Cotton

Wildfires burn thousands of acres of land every year, and regions subjected to severe fire behavior experience significant changes in landscape characteristics. Wildfire burn scars show decreased vegetation through burning, and darkening of the soil surface and drying of sub surface soil layers. This study explores the changes to the microclimate and local heat budget of the region as a result of these environmental changes.

The Colorado State University Regional Atmospheric Modeling System was used to simulate the physical processes at work in the burn scar environment. The effects of the burn scar were evaluated by first examining the surface temperature field changes due to reduced albedo and soil moisture. To further evaluate the heating effects, sensible heat flux and latent heat flux were assessed. The horizontal wind field was analyzed for changes due to the presence of the burn scar. The vertical velocity pattern was then examined to see whether upward motion was induced by the differential heating over the domain.

The results show that the burn scar significantly affected the microclimate of the environment. The increased sensible heat flux and temperatures over the burn scar resulted in convective development and cloud formation. Sensitivity tests revealed some effects of soil moisture changes in the burn scar while distinct differences were seen with a stronger initialization wind field.