Climatological analysis of turbulent kinetic energy as a fire-weather index using the North American regional reanalysis dataset

Recent studies have examined the feasibility of using near-surface turbulent kinetic energy (TKE) alone or in combination with the well-known Haines Index (HI) as an indicator of the atmospheric potential for extreme and erratic fire behavior. High resolution atmospheric mesoscale model simulations of fire-weather evolution during past wildland fire episodes in the north central and northeastern U.S. suggest that periods of rapid fire growth are often accompanied by periods of significant near-surface turbulence. The simulations also indicate that the duration of episodes of high near-surface TKE during large wildfire events in this region is highly variable. While these findings have provided new insight into ambient turbulence variability during wildfires, little is known about the spatial and temporal climatological patterns of atmospheric TKE in different regions of the U.S. The recent release of the North American Regional Reanalysis (NARR) dataset, an atmospheric and land surface hydrology dataset at 32 km resolution that covers the 1979-present period and includes TKE and temperature and dew point temperature data for computing the HI, provides an excellent opportunity for examining the spatial and temporal climatological patterns of TKE and HI x TKE values over different regions of North America. For this study, NARR-based monthly mean near-surface and upper-air TKE values and computed HI values at 3-hourly intervals were examined to identify the preferred locations, seasons, and time periods for large TKE and large HI x TKE values in the U.S.