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Viewing smoke in FIRMS using corrected reflectance imagery
Wildland fires can be a significant source of smoke that not only impairs our ability to enjoy clear vistas, but the gases and particulate matter it contains can be harmful to public health. When you see smoke in the sky it may be originating from a relatively local fire or a fire that is occurring several hundred miles away. True color composite imagery acquired by Terra MODIS, Aqua MODIS, S-NPP VIIRS or NOAA-20 VIIRS are provided as “Backgrounds” layers in FIRMS and FIRMS US/Canada Fire Maps. These layers display a "natural color image" of the Earth’s surface as it would look to the human eye from space. Consequently, it is easy to see smoke using this type of imagery in clear sky conditions. The time of observation for these four satellites occur at different times during the day, so they can be used to identify current sources of wildland fire smoke and visualize its transport across long distances. Use the Orbit Tracks and Overpass Times layers to determine the daily overpass time for each satellite.
Viewing smoke in FIRMS using aerosol indices
The standard Aerosol Index (AI) derived from S-NPP OMPS observations can also be used for identifying and tracking smoke as well as other aerosols. The OMPS Al, available as an “Overlays” layer in the FIRMS and FIRMS US/Canada Fire Maps, detects and measures the density of smoke and suspended particles in the vertical air column in the atmosphere. Typical values of the AI range from 0 to 5 and indicate dust storms or biomass burning smoke located in the lower troposphere (1-3 km). Values of 5.0 indicate heavy concentrations of aerosols that could reduce visibility or impact human health. For AI values significantly higher than 5 use the OMPS PyroCumuloNimbus, or pyroCb, AI layer. Larger pyroCb AI values between 5 and 10 usually indicate dense smoke from intensely burning fires that reach higher in the troposphere. Once the index gets above 10, the smoke has likely been produced from a pyroCb event, with dense smoke lofted into the upper troposphere and, often, into the stratosphere.
Wildland fire smoke visible in S-NPP VIIRS true color imagery acquired on July 11, 2021 (top). Active fire detections are displayed as red points. The aerosol index derived from S-NPP OMPS observations collected at the same time as the VIIRS imagery is provided for comparison (bottom). The high index values over Utah, Colorado, Wyoming and Montana indicate high concentrations of aerosols and are a result from fire activity in the Pacific Northwest and northern California. High aerosol index values in the eastern Dakotas, Minnesota and western Ontario are sourced from wildland fire activity in eastern Manitoba and western Ontario.
Get information and zoom to extent of wildland fires
The new FIRMS US/Canada fire map includes the location and details of wildland and prescribed fires. Locations of currently/recently active incidents larger than 100 acres (40.5 hectares) are displayed as fire icons when you open the US & Canada Fire Map. Click USA Active Fires and Canada Active Fires layers to toggle them off.
Click on a fire location to view the name, discovery date/time and current size of the fire. This information is routinely updated and maintained in systems of record managed by US and Canadian wildland fire management agencies. Clicking the View Situation Report link spawns a national situation report which may contain specific reporting information about the fire of interest. Additionally, by clicking the ZOOM TO LOCATION button, your map extent will automatically zoom to the extent of that fire.
Clicking on a fire location provides information about the fire and the option to zoom to the map extent of the selected fire.
Perimeters for current US wildland fires
For wildland fires currently occurring in the US larger than 100 acres in size, fire perimeters are provided for context. These data are typically compiled by federal, state and local fire management agencies on a routine basis during the life of an incident, however, they may not be available for all incidents. These data are typically updated daily from multiple sources and indicate the current extent of the fire and containment lines. Click on USA Fire Perimeter layer to display the fire perimeter data in the FIRMS US/Canada Fire Map.
When using perimeters in the context of satellite active fire detection data, this can indicate where a fire is active within the perimeter and if it is growing outside of it. Additionally, if the fire perimeter is not fully covered by cumulative active fire detections, gaps in that coverage may indicate where the fire has grown in between observations by polar-orbiting satellite sensors like MODIS and VIIRS, cloud cover at the time of satellite overpass occluded observations when the fire was actively burning, or fire activity was smaller and/or less intense at the time of satellite overpass or was not detectable under the vegetation canopy. Isolated active fire detection pixels outside of the perimeter can be indicative of detections occuring towards the edge of a swath which results geolocational errors due to the increasingly distorted field of view in the scan track direction, particularly for MODIS.
Visualization of MODIS and VIIRS active fire detection data in the context of a current perimeter for a wildland fire.
The FIRMS team has introduced several new features and capabilities to both FIRMS Global and FIRMS US/Canada. We’ll continue to highlight these new additions over several future posts.
In this post, we would like to highlight the Time Since Detection classification for MODIS and VIIRS active fire detection data that is available in the fire map for FIRMS Global and FIRMS US/Canada. This classification symbolizes active fires based on their time of detection relative to the current time. This enables users to visualize recent fire progression and currently active fire fronts for wildland fires. The temporal classification displays active fire detections occurring in the past 0 to 6 hours (deep red), detections occurring 6 to 12 hours earlier (red) and 12 to 24 hours earlier (orange), and detections occurring previous to the last 24 hour period (yellow).
Setting the Time Since Detection Classification in FIRMS
- Open the fire map viewer for FIRMS Global or FIRMS US/Canada
- Select the Time Since Detection choice from the pick list associated for a particular satellite/sensor source in the FIRMS display control window to apply this classification to the active fire detection data for that source layer
- To apply it for all the MODIS and VIIRS active fire detection layers, click the Time Based button at the top of in the FIRMS display control window
Examples of active fire data displayed with the time since detection classification:
Examples for setting the time since detection classification in FIRMS
SNPP and NOAA-20 VIIRS active fire detection locations in Northern California symbolized by their time since detection at ~17:00 PDT June 30, 2021
SNPP and NOAA-20 VIIRS active fire detection locations in Western Ontario symbolized by their time since detection at ~19:00 CDT June 30, 2021
FIRMS has added additional capability to integrate satellite active fire detection data as streaming web services. Several new geospatial web services are now available to meet the needs of end users in visualizing and analyzing these data in the context of geospatial information in desktop or web mapping applications.
New Web Map Services
In addition to legacy FIRMS Web Map Services (WMS) that provide MODIS and VIIRS active fire detection data for the past 24, 48, 72 hours or the past 7 days, new services are provided that display these data relative to their time since detection. New WMS options enable visualization of cumulative MODIS and VIIRS active fire data for the current calendar year in two temporal classifications that depict the data in its relative time since detection. Please see the WMS information page for FIRMS US/Canada and FIRMS Global for service connection information and tutorials on how to access the services.
Temporal classifications for the new MODIS and VIIRS active fire detection web map services available in FIRMS.
New Web Feature Services
FIRMS has also introduced new regional Web Feature Services (WFS) that stream the centroids of active fire detection pixels for MODIS and VIIRS as geographic point features. The services allow end users to manipulate and analyze features in the services using a geospatial client. These services are configured to enable access to MODIS or VIIRS active fire data for the past 24 hours or the past 7 days. Please see the WFS information page for FIRMS US/Canada and FIRMS Global for service connection information and tutorials on how to access the services.
FIRMS US/Canada is a new version of Fire Information for Resource Management System (FIRMS) focused on the US and Canada, developed in partnership between NASA and the US Forest Service. The beta version was released in January 2021 providing expanded capabilities including additional map layers.
Visit https://firms.modaps.eosdis.nasa.gov/usfs/ or read more: NASA, Forest Service Partnership Expands Active Fire Mapping Capabilities