Climatology

The Atmospheric Component of Wildland Fire Risk in a Future Climate

The potential for wildland fire depends on both fuel loads and on atmospheric conditions. Prior research on temporal variations in fire regimes has primarily focused on fuel loads, and in general has neglected the atmospheric component of fire risk. In contrast, this study, which is funded by the Joint Fire Science Program, specifically investigates the historical variations and potential future changes in the atmospheric potential for large or dangerous fires in North America. The Haines Index, a frequently used tool in wildfire weather forecasting and monitoring, is used as an indicator of the atmospheric potential for fire. The Haines Index characterizes the potential impact of dry, unstable air on wildfires and is calculated from temperature and dewpoint in the lower troposphere. The three main components of the research project are:

Evaluation of Computational Methods for the Low Elevation Haines Index. The Haines Index was designed to use readily available observations from upper air soundings. Changes in the standard levels reported as part of rawinsonde observations have meant that pressure levels originally chosen for calculating the low elevation variant of the Haines Index are no longer reported. As part of this project, alternative approaches for calculating the low elevation version of Haines Index are compared to the original formulation.

Historical Climatology of the Haines Index for North America. In order to employ Haines Index observations and forecasts in an effective and meaningful manner, fire forecasters and managers must be aware of the climatological characteristics of the index for their location. However, a comprehensive, long-term climatology of the Haines Index is lacking. To address this need, a 40-year (1961-2000) climatology for North America is being constructed using temperature and humidity fields from the National Centers for Environmental Prediction/ National Center for Atmospheric Research (NCEP/NCAR) reanalysis. The climatology is in the form of an electronic atlas that focuses on the variations in the frequency and persistence of the Haines Index at annual, seasonal, and monthly time periods.

Potential Future Changes in the Atmospheric Component of Fire Risk. The Haines Index is being calculated from coarse-scale future simulations from several General Circulation Models (GCMs) and from fine-scale simulations from a regional climate model (MM5) that is driven by a larger-scale GCM. The projected values of the Haines Index are used to evaluate the sensitivity of current Haines Index patterns to a changing climate and to assess the range of uncertainty associated with projections of the Haines Index for a future climate.

For more information, please visit the project website at: http://www.haines.geo.msu.edu/.