Burn Severity – A qualitative assessment of the heat pulse directed toward the ground during a fire. Burn severity relates to soil heating, large fuel and duff consumption, consumption of the litter and organic layer beneath trees and isolated shrubs, and mortality of buried plant parts.

Composite Burn Index (CBI) – A numerical, synoptic rating calculated from a field-based estimate of fire effects on individual strata within a plot or site in a burned area. Estimates the overall impact to a site based on post-fire conditions averaged across the burnable portion of the site.

Differenced Normalized Burn Ratio (dNBR) – a differenced NBR image, or change image, created where the post-fire NBR is subtracted from the pre-fire NBR. The dNBR may be used to discriminate burned from unburned areas and identify vegetation burn severity classes. For MTBS, the dNBR is calculated as:

dNBR = NBR pre-fire – NBR post-fire

Extended Assessment – Fire mapping assessments that rely on satellite data typically acquired during the growing season following a fire in order to include delayed first order effects (e.g., latent tree mortality) and dominant second order effects that are ecologically significant (e.g., initial site response and early secondary effects).

Fire Atlas – A compendium of geospatial layers, maps, and tabular information that illustrate fire activity at the individual fire level for a given geographic area and/or period of time.

Fire Effects – The physical, biological, and ecological impacts of fire on the Environment (NWCG Glossary of Wildland Fire Terminology).

Fire Effects, First Order – Those effects manifested on the biophysical components or systems that existed at the time of the fire. First order fire effects are the direct result of the combustion processes, including plant injury and death, fuel consumption, and smoke production (Reinhardt and others 2001).

Fire Severity – Degree to which a site has been altered or disrupted by fire; loosely, a product of fire intensity and residence time.

Initial Assessment – Fire mapping assessments that rely on satellite data typically acquired at the first opportunity after fire to capitalize on the maximum post-fire data signal and is used primarily in ecosystems that exhibit rapid post-fire vegetation response (i.e. herbaceous and particular shrubland systems).

Landsat Imagery – Thematic Mapper (TM), Enhanced Thematic Mapper (ETM), and Operational Land Imager (OLI) image data from the Landsat 5, Landsat 7, and Landsat 8 satellites, respectively. Image scenes have a footprint area of approximately 34,000 square kilometers and a pixel resolution of 30 meters. Spectral information is contained in several bands representing distinct wavelengths in the visible, infrared, and thermal portions of the electromagnetic spectrum.

MTBS Fire Occurrence Database (FOD) – Relevant spatial and aspatial fire occurrence data description elements for each fire mapped by the MTBS project. Data elements include the latitude/longitude of the centroid of the MTBS fire perimeter centroid.

Normalized Burn Ratio (NBR) – a normalized index that emphasizes the spectral response of fire-affected vegetation by leveraging Landsat TM/ETM bands 4 (near-infrared) and 7 (mid-infrared) in an effort to provide the best contrast between photosynthetically healthy and burned vegetation. For MTBS, an NBR is calculated for each pre-fire and post-fire scene as:

NBR = (TM4 - TM7) ÷ (TM4 + TM7)

Prescribed Fire – Any fire ignited by management actions to meet specific objectives (NWCG Glossary of Wildland Fire Terminology).

Relative differenced Normalized Burn Ratio (RdNBR) – a normalized version of the dNBR that removes the biasing effect of the pre-fire conditions (Miller et al 2009). The algorithm for RdNBR is calculated as: RdNBR = dNBR / SquareRoot(ABS(NBR pre-fire / 1000))

Remote Sensing Index – A mathematical calculation derived from two or more image bands. Typically used to enhance the spectral properties of a feature or condition of interest on the ground, i.e., burn scars.

Spatial Resolution – The areal extent of the smallest unit, pixel, or feature that can be resolved on an image, map, or surface. Typically expressed as a measure of distance, i.e., 30 meter pixel, but can also be expressed as a unit of area.

Thematic Resolution – The finest level of content for a given map or thematic layer attribute.

Wildfire – An unplanned, unwanted wildland fire including unauthorized human-caused fires, escaped wildland fire use events, escaped prescribed fire projects, and all other wildland fires where the objective is to put the fire out (NWCG Glossary of Wildland Fire Terminology).

Wildland Fire – Any non-structure fire that occurs in the wildland. Three distinct types of wildland fire have been defined and include wildfire, wildland fire use, and prescribed fire (NWCG Glossary of Wildland Fire Terminology).

Wildland Fire Use – The application of the appropriate management response to naturally-ignited wildland fires to accomplish specific resource management objectives in predefined designated areas outlined in Fire Management Plans (NWCG Glossary of Wildland Fire Terminology).