Climatic variability of a fire-weather index based on turbulent kinetic energy and the Haines Index

Abstract

Combining the Haines Index (HI) with near-surface turbulent kinetic energy (TKE_s) through a product of the two values (HITKE_s) has shown promise as an indicator of the atmospheric potential for extreme and erratic fire behavior in the U.S. Numerical simulations of fire-weather evolution during past wildland fire episodes in the U.S. indicate that large wildfires and periods of rapid fire growth are often associated with and accompanied by periods of significant near-surface atmospheric turbulence. These findings provide new insight into the variability of ambient atmospheric turbulence during wildfire events over relatively short time periods. However, the ultimate application of a fire-weather index based on the product of the HI and TKE_s in fire-weather forecasts requires an understanding of where and when high values of the index typically occur. This study examines the spatial and temporal variability of TKE_s and HITKE_s values over the U.S. using North American Regional Reanalysis (NARR) data. Study results indicate that there are preferred locations and periods for large TKE_s and HITKE_s values, the temporal variability of TKE_s and HITKE_s is regionally dependent, and there has been a general increase in TKE_s and HITKE_s values over much of the U.S. over the last 30 years.

Citation

Heilman, Warren E.; Bian, Xindi. 2010 Climatic variability of a fire-weather index based on turbulent kinetic energy and the Haines Index. In: Proceedings of the 3rd fire behavior and fuels conference; 2010 October 25-29; Spokane, WA. Birmingham AL: International Association of Wildland Fire. 8 p. [On CD-ROM].