Climatological and statistical characteristics of the Haines Index for North America

摘要

The Haines Index is an operational tool for evaluating the potential contribution of dry, unstable air to thedevelopment of large or erratic plume-dominated wildfires. The index has three variants related to surface elevation, andis calculated from temperature and humidity measurements at atmospheric pressure levels. To effectively use the HainesIndex, fire forecasters and managers must be aware of the climatological and statistical characteristics of the index for theirlocation. However, a detailed, long-term, and spatially extensive analysis of the index does not currently exist. To meetthis need, a 40-year (1961-2000) climatology of the Haines Index was developed for North America. The climatology isbased on gridded (2.5 deg latitude x 2.5 deg longitude) temperature and humidity fields from the NCEP/NCAR reanalysis. Theclimatology illustrates the large spatial variability in the Haines Index both within and between regions using the differentindex variants. These spatial variations point to the limitations of the index and must be taken into account when usingthe Haines Index operationally.