FIRMS Frequently Asked Questions
Warning: Super-heated smoke plumes can cause artifacts in nighttime detections. See: Super heated smoke plumes cause data artifacts in nighttime detections (3 August 2018). Please also see: Are there ever false detections or data artifacts?
- Getting started
- Where can I find the MODIS and VIIRS Active Fire User guides?
- What are the key differences between NRT and Standard quality fire data?
- What does a fire detection mean on the ground?
- What are the different sources of data in FIRMS?
- How often are the active fire data acquired?
- How often is the FIRMS updated?
- What time does the satellite pass over my area?
- How are fires detected by satellite?
- Why was a particular fire not detected?
- What are the attributes / fields of the active fire data?
- I only see fire data available for the last 7 days on your website. How can I get older data?
- What projection are the shapefiles in?
- What is the detection confidence?
- Are there any restrictions on using data or imagery from FIRMS?
- Support and Mailing Lists
Who do I contact for support with FIRMS?
Click the “Feedback” link in upper right corner of any page to submit a help question.
For questions about LANCE or user registration, contact Earthdata Support.
How do I stay informed about updates, announcements, data issues, and scheduled maintenance?
Subscribe to receive notifications from LANCE and FIRMS about updates, announcements, data issues, and scheduled maintenance.
- LANCE-MODIS mailing list (For updates regarding NRT data from MODIS aboard Terra and Aqua and VIIRS/Land aboard Suomi NPP and NOAA-20; this will keep you up-to-date with data outages that may impact the MODIS and VIIRS active fire products)
- LANCE FIRMS mailing list (For general updates on the Fire Information for Resource Management System)
- LANCE Users mailing list (For general updates about LANCE)
- To subscribe: e-mail firstname.lastname@example.org (no subject or text is required)
- To unsubscribe: e-mail email@example.com (no subject or text is required)
- Please note, if you wish to receive information about data issues, use LANCE-MODIS list above
Where can I go to interact with other users and NASA subject matter experts on a variety of Earth science research and applications topics?
Please visit the Earthdata Forum at https://forum.earthdata.nasa.gov
- Caveats to consider when using active fire data from FIRMS
- Are there ever false fire detections or data artifacts?
- How do I know if a fire detection was missed due to cloud or missing data?
- How appropriate are the hotspot/fire locations for my research?
- What is the Climate Modeling Grid (CMG) fire product?
- Can active fires be detected below the forest canopy?
- Are all active fire hotspots vegetation fires?
- Can I estimate burned area from active fire data?
- Can you use the active fire data for detecting volcanoes or volcanic eruptions?
- Questions about VIIRS active fire data
- What is the VIIRS 375 m active fire product?
- What is the temporal frequency of the VIIRS 375 m fire data?
- What is the spatial resolution of the data?
- What is the difference between VIIRS 375 m and 750 m fire products?
- Will the VIIRS 375 m fire detection algorithm always outperform the 750 m algorithm?
- Are those few isolated fire pixels in the middle of the South Atlantic Ocean real?
- Are the VIIRS 375 m (and 750 m) active fire data science-ready?
- Is the VIIRS 375 m product still being refined?
- Where do I go for more information?
- Questions about MODIS active fire data
- What does a MODIS active fire detection mean on the ground?
- Are there any missing MODIS fire data?
- What does scan and track mean?
- What is the brightness temperature?
- What are MODIS collections?
- Where can I get the MODIS burned area product?
- What size fires can be detected?
- What validation of the MODIS active fire products have been performed?
- Where can I get more information on the MODIS Fire Products?
- FIRMS Fire Map
- Email Alerts
- Can you notify me when a fire occurs in my area of interest?
- Do you provide mobile / cell phone text messages?
- What are NRT email alerts?
- How do I subscribe or edit email alerts?
- How do I unsubscribe from an email alert?
- I requested a map image with my email alert, but I can't see the map in my email. Where is it?
- I received a CSV file as part of my Email Alert, can I add it as a layer in a desktop GIS?
- FIRMS US/Canada
- Why was FIRMS US/Canada developed?
- What specific areas are covered by FIRMS US/Canada?
- What are the differences between FIRMS Global and FIRMS US/Canada?
- What is the source for the USA Active Fires layer and what information does it provide?
- What is the source of the Canada Active Fires layer and what information does it provide?
- Where can I get more information about current wildfires in the U.S. and Canada?
- What is the source for U.S. Fire Weather Watches and Red Flag Warnings and what do they mean?
- What is the source for the U.S. Forecasted Fire Danger layer and information does it provide?
- What is the source for the Canada Forecasted Fire Danger layer and information does it provide?
- What is the source for the U.S. wildfire perimeters and what does it display?
- How do I interpret/use wildfire perimeter data in the context of satellite active fire detection data?
- Are additional capabilities planned for FIRMS US/Canada?
- Can MODIS and VIIRS satellite active fire detection data be made available sooner than they are currently provided on FIRMS US/Canada?
Where can I find the MODIS and VIIRS Active Fire User guides?
For the most current information, use the Active Fire User Guides:
What are the key differences between NRT and Standard quality fire data?
Standard data products are an internally consistent, well-calibrated record of Earth’s geophysical properties to support science. Near real-time (NRT) fire products are generated within approximately 3 hours of a satellite observation to meet the needs of the applications community. To facilitate this, a number of changes have been made to the standard processing approach: Data downlinked from the satellite are sorted, processed, and delivered in an expedited manner (as Session-based Production Data Sets).
One key difference between the MODIS/Aqua NRT and Standard (Science Quality) Fire Products is the accuracy of the Fire locations (positions or geolocation). Unlike MODIS/Terra, VIIRS/Suomi NPP, and VIIRS/NOAA-20, the position of the Aqua satellite is not as well known when the NRT Fire Product is produced. Most of the time, the additional error introduced in the reported Fire location is small (< 100 m), but in some situations this position error may be large (several kilometers). In particular, the larger errors may occur after spacecraft maneuvers and during space weather events. The NRT Fire location accuracy is also degraded for MODIS/Terra, VIIRS/Suomi NPP, and NOAA-20 after spacecraft maneuvers, but the time period is typically shorter (< 2 hours for MODIS/Terra, VIIRS/Suomi NPP, and NOAA-20 vs. up to 12 hours for MODIS/Aqua). When the Standard Fire product are later processed, the best available satellite position data is used and the quality assurance team removes data degraded by spacecraft maneuvers. In addition, the Standard Fire products are typically later reprocessed and the Fire positions may be even more accurate in the reprocessed products.
Routines used to derive Level 2 products (such as fire) do not make use of ancillary data, and so their codes are identical to the ones used in standard operations. However, please note:
- The data distributed via the FIRMS download tool does not contain the static sources/inferred hotspot "type" (described in page 36 of the MODIS Active Fire User Guide)
- The day/night column (also described on page 36 of the MODIS Active Fire User Guide) is currently calculated differently. The standard processing algorithm uses the solar zenith angle (SZA) to threshold the day/night value; if the SZA exceeds 85 degrees it is assigned a night value. SZA values less than 85 degrees are assigned a day time value. For the NRT algorithm the day/night flag is assigned by ascending (day) vs descending (night) observation. It is expected that the NRT assignment of the day/night flag will be amended to be consistent with the standard processing
What does a fire detection mean on the ground?
Satellites take a ‘snapshot’ of events as they pass over Earth. Each hotspot/active fire detection represents the center of a pixel flagged as containing one or more fires or other thermal anomalies (such as volcanoes). For MODIS the pixel is approximately 1 km and for VIIRS the pixel is approximately 375 m. The “location” is the center point of the pixel (not necessarily the coordinates of the actual fire). The actual pixel size varies with the scan and track (see: What does scan and track mean?). The fire is often less than the size of the pixel (see: What size fires can be detected?). We are not able to determine the exact fire size; what we do know is that at least one fire is located within the flagged pixel. Sometimes you will see several active fires in a line. This generally represents a fire front.
What are the different sources of fire data in FIRMS?
- MODIS NRT C6.1 (MCD14DL) are the NRT MODIS (Terra and Aqua) Collection 6.1 data processed by NASA LANCE FIRMS
- MCD14ML provided by FIRMS are a subset of the standard quality data processed by the MODIS Fire Team Science Computing Facility at the University of Maryland. These are available with a 2-3 month lag through the Archive Download Tool and can be viewed and queried in Fire Map
- VIIRS 375 m NRT active fire data are available from Suomi NPP (VNP14IMGTDL_NRT) and NOAA-20 (VJ114IMGTDL_NRT). These are processed by NASA LANCE FIRMS
How often are the active fire data acquired?
The MODIS instruments aboard the Terra and Aqua EOS satellites acquire data continuously, providing global coverage every 1-2 days. Terra (EOS AM) passes over the equator at approximately 10:30 a.m. and 10:30 p.m., Mean Local Time (MLT), each day; Aqua (EOS PM) passes over the equator at approximately 1:30 p.m. and 1:30 a.m., MLT. There are at least 4 daily MODIS observations for almost every area on the equator, with the number of observations increasing (due to overlapping orbits) closer to the poles.
The VIIRS instruments aboard the Suomi NPP and NOAA-20 satellites also acquire data continuously. The 3,040 km VIIRS swath enables ≈15% image overlap between consecutive orbits at the equator, thereby providing full global coverage every 12 hours. Suomi NPP has a nominal (equator-crossing) observation times at 1:30 p.m., MLT, and 1:30 a.m., MLT. NOAA-20 operates about 50 minutes ahead of Suomi NPP. Thanks to its polar orbit, mid-latitudes will experience 3-4 looks a day.
How often is FIRMS updated?
The FIRMS fire map is updated every 5 minutes, but please note that the data are derived from instruments onboard polar orbiting satellites (MODIS aboard Terra and Aqua and VIIRS aboard Suomi NPP and NOAA-20), and generally these have 2 overpasses a day (more towards the poles - see How often are the active fire data acquired?). FIRMS generally makes the data available within 3 hours of a satellite observation (on a best effort basis). See also What time does the satellite pass over my area?
The SHP KML CSV files are currently updated every 60 minutes. The near real-time alerts are run every 5 minutes.
What time does the satellite pass over my area?
In FIRMS Fire Map and NASA Worldview you can overlay the daily orbit tracks to see satellite acquisition times for your area of interest. Daily Terra, Aqua, Suomi NPP, and NOAA-20 global and regional orbit tracks are provided by the Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison.
For what dates are the fire data available?
MODIS data are available from November 2000 (for Terra) and from July 2002 (for Aqua) to the present. VIIRS 375 m data are currently available from 20 January 2012 to the present.
How are fires detected by satellite?
Fire detection is performed using a contextual algorithm that exploits the strong emission of mid-infrared radiation from fires. The MODIS algorithm examines each pixel of the MODIS swath, and ultimately assigns to each pixel of the following classes: missing data, cloud, water, non-fire, fire, or unknown. More information can be found in: Giglio, L., Descloitres, J., Justice, C. O., & Kaufman, Y. (2003). An enhanced contextual fire detection algorithm for MODIS. Remote Sensing of Environment, 87: 273-282. doi: 10.1016/S0034-4257(03)00184-6
In keeping with MODIS, the VIIRS algorithm is a hybrid thresholding and contextual algorithm using radiometric signals from 4 micron and 11 micron bands (M13 and M15, respectively) and additional bands and a suite of tests for internal cloud mask and rejection of false alarms. The product consists of simple file containing primarily latitude and longitude data for those pixels classified as thermal anomalies. More information can be found in: Schroeder, W., Oliva, P., Giglio, L., & Csiszar, I. A. (2014). The New VIIRS 375m active fire detection data product: algorithm description and initial assessment. Remote Sensing of Environment, 143: 85-96. doi: 10.1016/j.rse.2013.12.008 PDF
Why was a particular fire not detected?
There are several reasons why MODIS or VIIRS may not have detected a certain fire: The fire may have started and ended between satellite observations; cloud cover, heavy smoke, or tree canopy may completely obscure a fire; occasionally the instruments are inoperable and can observe nothing during these times (see data outages and known issues for MODIS and VIIRS); or the fire may have been too small or too cool to be detected. The VIIRS 375 m active fire product provides a greater response over fires of relatively small areas due to its higher spatial resolution and it has improved nighttime performance. For more information on the minimum size of fire that can be detected using MODIS data see "What is the smallest fire size that can be detected?" and "How do I know if a fire detection was missed due to cloud or missing data?"
What are the attributes / fields of the active fire data?
I only see fire data available for the last 7 days on your website. How can I get older data?
Data for the last 2 months can be downloaded as text (TXT) files and older data can be obtained through the MODIS Fire Archive Download Tool or from MODIS directly from the MODIS Fire Team Science Computing Facility at the University of Maryland. MODIS data are available from from November 2000 (for Terra) and from July 2002 (for Aqua) to the present. VIIRS 375 m data are currently available from 20 January 2012 to the present.
What projection are the shapefiles in?
The shapefiles are in the Geographic WGS84 projection.
What is the detection confidence?
The confidence value was added to help users gauge the quality of individual fire pixels is included in the Level 2 fire product. The confidence field should be used with caution; it is likely that it will vary in meaning in different parts of the world. Nevertheless some of our end users have found such a field to be useful in excluding false positive occurrences of fire. They are different for MODIS and VIIRS.
For MODIS, the confidence value ranges from 0% to 100% and can be used to assign one of the three fire classes (low-confidence fire, nominal-confidence fire, or high-confidence fire) to all fire pixels within the fire mask. In some applications errors of commission (or false alarms) are particularly undesirable, and for these applications one might be willing to trade a lower detection rate to gain a lower false alarm rate. Conversely, for other applications missing any fire might be especially undesirable, and one might then be willing to tolerate a higher false alarm rate to ensure that fewer true fires are missed. Users requiring fewer false alarms may wish to retain only nominal- and high-confidence fire pixels and treat low-confidence fire pixels as clear, non-fire, land pixels. Users requiring maximum fire detectability who are able to tolerate a higher incidence of false alarms should consider all three classes of fire pixels.
For VIIRS, the confidence values are set to low, nominal, and high; they are based on a collection of intermediate algorithm quantities used in the detection process and are intended to help users gauge the quality of individual hotspot/fire pixels. Low confidence daytime fire pixels are typically associated with areas of Sun glint and lower relative temperature anomaly (<15 K) in the mid-infrared channel I4. Nominal confidence pixels are those free of potential Sun glint contamination during the day and marked by strong (>15 K) temperature anomaly in either day or nighttime data. High confidence fire pixels are associated with day or nighttime saturated pixels.
The confidence value is application specific. This isn't very helpful, but unfortunately there's no way to establish an optimal cutoff a priori. Users have to adopt an empirical approach—what threshold works best for what I'm trying to do? Unfortunately the confidence values in the product do not directly correspond to the statistical confidence levels in reference to Type I and Type II errors.
Are there any restrictions on using data or imagery from FIRMS?
NASA supports an open data policy and we encourage the appropriate use of data and graphics from FIRMS; when doing so, please take a moment to make sure you get the correct citation—see the Citation Policy. Please also read the LANCE Disclaimer and the About FIRMS web page.
What caveats should be considered when using active fire data from FIRMS?
Are there ever false fire detections or data artifacts?
To avoid the occurrence of false alarms over bright/reflective surfaces (e.g., metallic factory rooftops), the VIIRS and MODIS algorithms use slightly more conservative tests to avoid the effects of Sun glint.
Super Heated Smoke Plumes
A few VIIRS active fire pixels are occasionally located outside the reported perimeter of a large wildfire. If this happens, users may need to look for additional clues to see if it is a data artifact. There have been a few instances when tall superheated plumes carrying large volumes of hot material into the air are formed over large and intense wildfires; when these occur the VIIRS instrument detects the surface fire along with part of the plume and categorizes them as active fires. Those occurrences typically share the following set of conditions:
(i) Nighttime detection. This is the period during which the VIIRS active fire product is particularly responsive to heat sources thereby favoring plume detection. However, this can also occur during the day time with;
(ii) Very large wildfires undergoing explosive growth and accompanied by rapid/vertically elongated plume development. Enough hot material must entrain the plume creating a distinguishable thermal signal (i.e., one that significantly exceeds the fire-free surface background);
(iii) High scan angle. This is what will ultimately produce the detections extending beyond the actual fire perimeter.
The parallax effect causes the tall/superheated plume detection pixel(s) to be displaced laterally when projected onto the surface. Displaced pixels will be located on the fire perimeter’s side further away from the image center and closer to the swath’s edge. If those conditions apply, look for alternative observations (previous/next observation) acquired closer to nadir and try and prioritize the use of the fire detection data accordingly. Unfortunately, the VIIRS active fire algorithm isn’t currently able to distinguish nighttime surface fire pixels from the isolated plume detections due to strong similarities between their radiometric signatures.
- Is the VIIRS 375 m product still being refined?
- What is the detection confidence?
- False fires due to super heated smoke plume in nighttime detections (3 August 2018)
- Note on False Fires in VIIRS/NOAA-20 (17 July 2020)
How do I know if a fire detection was missed due to cloud or missing data?
An indication of cloud cover or missing data can be obtained by viewing the co-incident MODIS or VIIRS imagery in FIRMS Fire Map or Worldview. To take cloud and missing data in to account, it may be more appropriate to use one of the 1 km Level 3 or CMG fire products (see the discussion in the MODIS Fire User Guide).
How appropriate are the hotspot/fire locations for my research?
The MODIS and VIIRS fire locations are good for determining the location of active fires, providing information on the spatial and temporal distribution of fires, and comparing data between years. The active fire pixel locations may not always be the most appropriate source of fire related information; the data do not provide any information on cloud cover or missing data. Depending on the analysis you are performing, it is sometimes possible to derive misleading or even incorrect results by ignoring the other types of pixels. In some cases it is more appropriate to use one of the Level 3 or CMG fire products. For more discussion on this, see FAQ "What is the Climate Modeling Grid (CMD) fire product? and "What is the difference between NRT and Standard quality fire data?"
What is the Climate Modeling Grid (CMG) fire product?
The CMG fire products are gridded statistical summaries of fire pixel information intended for use in regional and global modeling. The products are currently generated at 0.5 degree spatial resolution for time periods of 1 calendar month (MOD14CMH/MYD14CMH) and 8 days (MOD14C8H/MYD14C8H). Higher resolution 0.25 degree CMG fire products will eventually be produced as well. More information can be found in the MODIS Collection 6 Active Fire Product User's Guide.
Can active fires be detected below the forest canopy?
The likelihood of detecting a fire beneath the tree canopy is unknown, but likely to be very low. Understory fires are typically small, and with the tree canopy obstructing the view of the fire, detection will be very unlikely.
Are all active fire hotspots vegetation fires?
No. An active fire represents the center of a pixel flagged as containing 1 or more actively burning hotspots /fires. In most cases fires are vegetation fires, but sometimes it is a volcanic eruption or the flare from a gas well. There is no way of knowing which type of thermal anomaly is detected based on the MODIS or VIIRS data alone.
Can I estimate burned area from active fire data?
It is not recommended to use active fire locations to estimate burned area due to spatial and temporal sampling issues. Determining this to an acceptable degree of accuracy is generally not possible due to nontrivial spatial and temporal sampling issues. For some applications, however, acceptable accuracy can be achieved, although the effective area burned per fire pixel is not simply a constant, but rather varies with respect to several different vegetation and fire-related variables. See Giglio et al. (2006) for more information.
See "Where can I get the MODIS burned area product?"
Can you use the active fire data for detecting volcanoes or volcanic eruptions?
The algorithm routinely detects active volcanoes but the active fire product has not been validated against independent data for its ability to detect volcanoes. There is a separate near-real time MODIS product (MODVOLC) specifically for volcanoes—see http://modis.higp.hawaii.edu/.
Questions about VIIRS active fire data
The Visible Infrared Imaging Radiometer Suite (VIIRS) is an instrument aboard the Suomi National Polar-orbiting Partnership (Suomi NPP) and NOAA-20 weather satellites. VIIRS was launched on Suomi NPP on October 28, 2011, and again on NOAA-20 (formally known as Joint Polar Satellite System-1 [JPSS-1]) on November 18, 2017. The VIIRS instrument will be launched on JPSS-2 in 2022 and join NOAA-20 and Suomi NPP in the same orbit.
What is the VIIRS 375 m Active Fire Product?
The VIIRS 375 m (VNP14IMGTDL_NRT) active fire product is the latest product to be added to FIRMS. It provides data from the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor aboard the joint NASA/NOAA Suomi National Polar-orbiting Partnership (Suomi NPP) and NOAA-20 satellites. The 375 m data complements MODIS fire detections; they both show good agreement in hotspot detection, but the improved spatial resolution of the 375 m data provides a greater response over fires of relatively small areas and provides improved mapping of large fire perimeters. The 375 m data also has improved nighttime performance. Consequently, these data are well suited for use in support of fire management (e.g., near real-time alert systems), as well as other science applications requiring improved fire mapping fidelity.
What is the temporal frequency of the VIIRS 375 m fire data?
The VIIRS instrument aboard the Suomi NPP and NOAA-20 satellites acquire data continuously. The 3,040 km VIIRS swath enables ≈15% image overlap between consecutive orbits at the equator, thereby providing full global coverage every 12 hours. Suomi NPP has a nominal (equator-crossing) observation times at 1:30 p.m. and 1:30 a.m., Mean Local Time (MLT); NOAA-20 operates about 50 minutes ahead of Suomi NPP. Thanks to its polar orbit, mid-latitudes will experience 3-4 looks a day.
What is the spatial resolution of the data?
The 375 m data describe the nominal resolution after native data are spatially aggregated (see figure below).
The aggregation scheme changes across three distinct image regions. In the first region (nadir to 31.59° scan angle), three native pixels are aggregated in the along scan (cross-track) direction to form one data sample in the Level 1 image. In the second region (31.59° to 44.68° scan angle), two native pixels are aggregated to form one data sample. Finally in the third and last region (44.68° to 56.06° - edge of swath) one native pixel will result in one data sample. All five 375 m channels are aggregated onboard the spacecraft before the data are transmitted to the ground stations, whereas a subset of the VIIRS 750 m data (dual-gain channels only) are aggregated on the ground.
What is the main difference between the VIIRS 375 m and 750 m active fire data?
The two data products use similar methodologies to detect active fire pixels although differences in the spectral characteristics of the VIIRS channels used in each case led to unique algorithms. Because of its improved spatial resolution, the 375 m algorithm will tend to detect more fire pixels compared to the 750 m data set. That difference is particularly pronounced during the nighttime part of the orbit when the occurrence of smaller/cooler fires will favor the 375 m product.
Will the VIIRS 375 m fire detection algorithm always outperform the 750 m one?
Generally speaking, the higher resolution product will achieve higher probability of fire detection in both day and nighttime scenes. However, areas subject to strong solar reflectance associated with Sun glint could see a few 750 m fire pixels without a corresponding 375 m fire detection. This is attributed to the relatively shorter wavelength of the 375 m mid-infrared channel used in the fire algorithm, which will experience greater influence of the solar component. In order to minimize the associated consequences, namely the occurrence of false alarms over bright/reflective surfaces (e.g., metallic factory rooftops), the 375 m algorithm uses slightly more conservative tests to avoid the effects of Sun glint over those areas.
Are those few isolated fire pixels in the middle of the South Atlantic Ocean real?
Those occurrences are typically associated with spurious fire detections due to the South Atlantic Magnetic Anomaly. The 375 m active fire algorithm contains a specific filter to flag those occurrences as low confidence detections. However, in some cases (average 2-3 pixels every night) the spurious signal generated in the input Level 1 data is confused for a regular fire pixel and therefore assigned a nominal confidence flag. Note that verified true positives can also be found over South Atlantic Ocean waters along the southeast coast of Brazil and the west coast of Africa where oil rigs normally operate.
Are the VIIRS 375 m (and 750 m) active fire data science-ready?
The VIIRS active fire data have been extensively tested since routine production of the mission’s data record started in 19 January 2012. Numerous bad scan episodes (i.e., pixel clusters containing spurious radiances extending across the swath) were found in the Level 1 input data during the initial 18-24 months of the time series (Csiszar, et al., 2014). Those anomalies were gradually addressed by the VIIRS science team and their occurrence has dropped to virtually zero with the implementation of revised Level 1 data processing packages in 2015. Initial assessment of both VIIRS 375 m and 750 m was implemented over a few experimental sites indicating consistent fire detection and characterization performance. Additional data comparison analyses were implemented using near coincident Aqua/MODIS and TET-1 (German Aerospace Center) active fire data, which again showed consistent performance of the VIIRS active fire products across different observation conditions. Consequently, we consider the current data of good enough quality for use in fire management applications and scientific studies. However, users must be aware of the data quality limitations involving the archived data. NASA will be spearheading future data reprocessing efforts in order to generate a consistent time series for the VIIRS Level 1 and 2 data.
Is the VIIRS 375 m product still being refined?
Absolutely. The current suite represents the second release of the VNP14IMG and VNP14 active fire algorithms; data imperfections can—and likely will—occur. As with other satellite data products, the VIIRS active fire algorithm development undergoes routine quality control during which data issues such as omission errors, false alarms, and other anomalies are investigated and addressed. New versions of the products will be released once algorithm revisions are implemented and tested. Users are encouraged to report back to the science team when encountering potential data discrepancies.
Where do I go for more information?
Schroeder, W., Oliva, P., Giglio, L., & Csiszar, I. A. (2014). The New VIIRS 375m active fire detection data product: Algorithm description and initial assessment. Remote Sensing of Environment, 143: 85–96. https://doi.org/10.1016/j.rse.2013.12.008
Questions about MODIS Active Fire Data
The Moderate Resolution Imaging Spectroradiometer (MODIS) is a payload imaging sensor that was launched into Earth orbit by NASA in 1999 aboard the Terra (EOS AM) satellite and in 2002 aoard the Aqua (EOS PM) satellite. Please refer to the Near Real-Time Data FAQ section for more information about MODIS.
If you wish to view the MODIS reflectance imagery that corresponds to the active fire detections, please go to Worldview.
What does a MODIS active fire detection mean on the ground?
Satellites take a ‘snapshot’ of events as they pass over earth. Each hotspot/active fire detection represents the center of a 1 km (approx.) pixel flagged as containing one or more fires or other thermal anomalies (such as volcanoes). The “location” is the center point of the pixel (not necessarily the coordinates of the actual fire). The actual pixel size varies with the scan and track (see: What does scan and track mean?). The fire is often less than 1 km in size (see: What size fires can be detected?). We are not able to determine the exact fire size; what we do know is that at least one fire is located within that 1 km pixel. Sometimes you will see several active fires in a line. This generally represents a fire front.
Are there any missing MODIS fire data?
Terra was launched 18 December 1999 and Aqua was launched 4 May 2002. High quality active fire observations are available from the Terra satellite starting November 2000 and from the Aqua satellite starting 4 July 2002 onwards.
In the fire data archive, there are several days where data were not collected and days with lower than usual fire counts due to reasons such as sensor outage. These include, but are not limited to: 15 April 2001, 15 June to 3 July 2001, and 19 to 28 March 2002.
What does scan and track mean?
The scan value represents the spatial-resolution in the East-West direction of the scan and the track value represents the North-South spatial resolution of the scan. It should be noted that the pixel size is not always 1 km across the scan track. The pixels at the “Eastern” and the “Western” edges of the scan are bigger than 1 km. It is 1 km only along the nadir (exact vertical from the satellite). Thus, the values shown for scan and track represent the actual spatial resolution of the scanned pixel.
What is the brightness temperature?
The brightness temperature of a fire pixel is measured (in Kelvin) using the MODIS channels 21/22 and channel 31. Brightness temperature is actually a measure of the photons at a particular wavelength received by the spacecraft, but presented in units of temperature.
What are MODIS collections?
Reprocessing of the entire MODIS data archive is periodically performed to incorporate better calibration, algorithm refinements, and improved upstream products into all MODIS products. The updated MODIS data archive resulting from each reprocessing is referred to as a collection. Later collections supersede all earlier collections. For Terra MODIS, Collection 1 consists of the first products generated following launch. Terra MODIS data were reprocessed for the first time in June 2001 to produce Collection 3. Note that this first reprocessing was numbered Collection 3, rather than Collection 2, as one would expect. Collection 3 was also the first produced for the Aqua MODIS products. Collection 4 reprocessing was initiated in December 2002 for Terra MODIS and somewhat later for the Aqua MODIS. Collection 5 began reprocessing in early 2007. Improvements in Collection 5 included adding the Fire Radiative Power value to the fire detections and refining the detection confidence to more accurately identify questionable active fire pixels. Collection 6 is the latest collection and uses the most up-to-date algorithms. In terms of fire detections, the key differences between Collection 5 and Collection 6 are that: Collection 6 extends processing to oceans and other large bodies, including detection of off-shore gas flaring; there is also a reduction in false alarms in the Amazon caused by small forest clearings and there will be an improved cloud mask.
MODIS Process Version For the standard quality data there is also a production code version number, e.g., 6.02 (Collection 6.0 process version 2).
Where can I get the MODIS burned area product?
MODIS Active Fire & Burned Area Products web site and the MODIS Burned Area User Guide (Updated May 2013) and the MODIS Collection 6 Active Fire Product User's Guide.
What size fires can be detected?
In any given scene the minimum detectable fire size is a function of many different variables (scan angle, biome, Sun position, land surface temperature, cloud cover, amount of smoke and wind direction, etc.), so the precise value will vary slightly with these conditions. MODIS routinely detects both flaming and smoldering fires 1000 m2 in size. Under very good observing conditions (e.g., near nadir, little or no smoke, relatively homogeneous land surface, etc.) flaming fires one tenth this size can be detected. Under pristine (and extremely rare) observing conditions even smaller flaming fires 50 m2 can be detected. It is not recommended to estimate burned area from the active fire data, see: Can I estimate burned area using the active fire data?.
Unlike most contextual fire detection algorithms designed for satellite sensors that were never intended for fire monitoring (e.g., AVHRR, VIRS, ATSR), there is no upper limit to the largest and/or hottest fire that can be detected with MODIS.
The diagram shows the day and night relationship of fire size and fire temperature, in different biomes, to the probability of being detected by MODIS (Giglio, et al. (2003)).
What validation of the MODIS active fire products has been performed?
Validation of the Terra MODIS Fire Product has primarily been performed using coincident observations from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER); see the MODIS Land Team Validation page, and publications by Csiszar, et al. (2006) and two publications from Morisette, et al. (2005) for details. A very brief discussion of the general validation procedure, with some preliminary results, can be found in the Justice, et al. (2002) publication.
Where can I get more information on the MODIS Fire Products?
For more information on the active fire product and other MODIS fire products, please refer to the papers by Louis Giglio found here as well as the MODIS Active Fire Burned Area Products website and the MODIS Burned Area User Guide (Updated May 2013) and the MODIS Collection 6 Active Fire Product User's Guide.
FIRMS Fire Map
Can I download the fire data from the FIRMS Fire Map?
Active fire data are not currently available for download via Fire Map. However, active fire locations are available for download for the last 24 hours, last 48 hours, and last 7 days on the Active Fire Data page. Older data can be obtained through the Archive Download Tool.
You can create a customized view of imagery and geospatial data in the Fire Map viewer focused on a particular area of interest and share it with others as a PNG, JPG, GIF, or GeoTIFF image. To save and share an image of your map, click the screenshot icon at the bottom of the viewer and select your preferred option. Alternatively, you can create a unique URL for your customized view to share via email or social media by clicking the share icon at the bottom of the viewer.
What are the different sources of fire data in Fire Map?
What does today vs 24 hours mean?
"Today" will show active fire detection data from 0000 GMT to present. “24 hours” will display active fire detection data from 0000 GMT yesterday to present.
What is the best way to view smoke in Fire Map?
To view smoke add one of the corrected reflectance layers from MODIS or VIIRS from "backgrounds". In addition, you could add the OMPS Aerosol Index and OMPS Aerosol Index (PyroCumuloNimbus) from the "overlays" section. OMPS AI detects and measures the density of smoke and suspended particles in the vertical air column in the atmosphere. Typical values of the aerosol index range from 0 to 5 and indicate dust storms or biomass burning smoke located in the lower troposphere (1-3 km). For AI values significantly higher than 5, use the OMPS Aerosol Index (PyroCumuloNimbus) layer. Larger AI values between 5 and 10 usually indicate dense smoke from intensely burning fires that reach higher in the troposphere. Once the AI 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.
The Aerosol Index layer is useful for identifying and tracking smoke from wildfires or biomass burning events as well as dust from desert dust storms and the long-range transport of volcanic ash from volcanic eruptions. Values of 5.0 indicate heavy concentrations of aerosols that could reduce visibility or impact human health.
Can you notify me when a fire occurs in my area of interest?
We have developed a global fire email alert system to notify users when a fire occurs in or near a specified area of interest, country, or protected area. You can subscribe to receive near-real time, daily, or weekly email alerts in English, Spanish, or French.
To subscribe or learn more about the email based alert system, please see the FIRMS Email Alerts page.
Do you provide mobile/cell phone text messages?
No. We do not currently provide SMS text messages. In the past, we helped develop such a service in collaboration with ESKOM and CSIR Meraka in South Africa for the protection of power lines in remote areas from wildfires by informing operators in the field about fire events in near-real time. For more information see: Davies, D. K., H. F. Vosloo, et al. (2008). Near real-time fire alert system in South Africa: from desktop to mobile service. Proceedings of the 7th ACM conference on Designing interactive systems Cape Town, South Africa ACM: 315-322. doi: 10.1145/1394445.1394479
What are the near-real time email alerts?
The fire points are sent out in an email as soon as they are processed by LANCE. Alerts are sent only if a fire/hotspot was detected. The number of alerts varies according to geographic location: There are more frequent satellite observations at high latitudes. Near real-time alerts are usually sent within 3 hours of satellite observation for fires detected using MODIS aboard Aqua and Terra, and within 4 hours for fires detected using data from VIIRS aboard Suomi NPP and NOAA-20. Near real-time alerts are subscribed to and managed by the user just the same way as the daily and weekly detection summaries.
How do I subscribe or edit email alerts?
Go to the FIRMS Email Alerts page.
- Enter the email address where you want to receive the email alerts and click “Proceed”.
- If you have not yet subscribed you will be asked to enter your Name, Organization, and Country. Click on “Save” after you have entered your information.
- You will be taken to the subscription summary page, where the user can create a new subscription or view existing subscriptions. The user can create several subscriptions, and they will be added to their subscription summary profile.
- Click on the “Create a New Subscription” link to take the user to the interface to subscribe to an email alert.
Creating a new subscription:
- Choose your area of interest. Choose between:
- Custom Region
- Protected Area
- Customize your email alert by changing your subscription preferences:
- Name your alert (optional): You can choose to give your alert a name for you to easily reference.
- Output map size: You may choose to receive a map in the email and different sized maps are available.
- Background image: This refers to the background image on which the fires will be overlaid in the map in the email.
- Language preference: English, Spanish, and French.
- Alert type: Daily, Weekly, or Near-Real Time.
- Daily: Fire detections are sent in a summary email every morning EDT (USA) with fire detections from the previous 24 hours.
- Weekly: A week’s worth of fire points detected for the specified area are sent to you on Monday mornings EDT (USA).
- Near-real time: The fire points are sent out in an email as soon as they are processed by LANCE (within 3 hours of satellite observation). The number of emails vary depending on whether or not there was a fire in the specified area, whether or not it was detected, and the geographical location of the area (there are more frequent observations at high latitudes, and 4 daily observations for most places on the equator).
- Email preferences: You can choose to receive an email with a map and text or with text only.
- Attach .CSV file: By default this option is flagged, meaning that the subscriber will also receive a CSV file containing the fire location information.
- Help with subscription preferences: Clicking on the hyperlinked text of the subscription preferences will open pop-up messages containing the description and usage of the preference.
- Email confirmation and final subscription: You can choose not to receive an email confirming that you have subscribed successfully to an alert. The final signoff is completed by clicking either “Save Subscription” or “Cancel” (deletes all selections).
- Subscription confirmations: The successful subscription is identified by two steps, the first of which is the confirmation page and a confirmation email (if this was selected). The confirmation page provides a link to let you return to the ‘Add, view, or edit your subscription’ page.
- Choose your area of interest. Choose between:
How do I unsubscribe from an email alert?
Go to the FIRMS Email Alerts page.
- Enter the email address where that you want to unsubscribe from and click “Proceed”.
- You should see a list of all alerts associated with this email address.
- Using the "delete" option on right hand side of the page, you can unsubscribe the alert. Alternatively you can change the status of the alert from "active" to "inactive" if you are planning to re-activate the alert in the near future.
I requested a map image with my email alert but I can’t see the map in my email alert, where is it?
Please check the settings in your email client. Your email client may be blocking images from being displayed in your email as a security measure. You will have to enable the choice to view images in your email. Your email client may also be sending the email alert to your spam/junk folder as a security measure and it is likely that you will also not be able to view the map image if the email is in your spam/junk folder. You should add the FIRMS email address and/or email domain to the safe senders list so it will deliver the email to your inbox and display images. You can also view the map by clicking on the link below the map image “View Map Image on FIRMS server”; this will open the map in your browser. Map images are stored for 14 days on the FIRMS server.
I requested a CSV file with my email alert but I can’t see the file attached to my email alert, where is it?
If the number of fires in the alert exceeds 90,000 a link to download the CSV file will be provided instead of an attachment. CSV files are stored for 14 days on the FIRMS server.
I have received a CSV file as part of my Email Alert, can I add it as a layer in a Desktop GIS software?
A CSV or Comma Separated Value file, is a text file in which separate fields are delimited by commas. This type of file can be used to store simple tabular data efficiently, minimizing file size. CSV files are easily opened with DB administration software such as PostgreSQL or MS Access, or by spreadsheet software such as MS Excel. This type of file can also be used to easily plot point data on desktop GIS software, given, as the active fire data does, that the tabular data contain X and Y coordinate information. The active fire data contains latitude and longitude location coordinates and the attributes of the detected fires.
Why was FIRMS US/Canada developed?
FIRMS US/Canada is the result of an agreement between the U.S. Forest Service and NASA to modernize the Forest Service's distribution of active fire information by leveraging the LANCE's web-based active fire mapping tools and capabilities for disseminating data, products and services.
The significance of this NASA-Forest Service partnership goes beyond the creation of FIRMS US/Canada. It establishes a single, authoritative source of near real-time fire mapping, visualization, and geospatial data products and information for the United States and Canada jointly supported and enabled by both agencies. This enhanced cooperation will boost the availability of selected contextual geospatial data to increase the utility of near real-time fire geospatial data products, as well as increase opportunities, under the auspices of LANCE, to evaluate and integrate additional sources of NASA, NOAA, and international space agency satellite data of value to the user community.
What specific areas are covered by FIRMS US/Canada?
FIRMS US/Canada includes coverage for the continental United States, Alaska, Hawaii, Puerto Rico, and Canada. Due to the geographic extent of these areas of interest, Mexico and Caribbean countries are also included
What are the differences between FIRMS Global and FIRMS US/Canada?
Just like FIRMS, FIRMS US/Canada provides active fire data generally within 3 hours of a satellite observation from MODIS aboard NASA’s Aqua and Terra satellites and VIIRS aboard the Suomi NPP and NOAA-20 satellites. Imagery is typically available within 3 to 4 hours and can be viewed on the interactive Fire Map application.
In addition, FIRMS US/Canada meets the new Forest Service requirements by offering additional contextual layers and enhancements, including classifying fires to show time since detection to depict active fire fronts, incident locations and other information for current large fires in the US and Canada. FIRMS US/Canada provides current and historical corrected reflectance imagery from NASA and NOAA satellites, U.S. and Canada administrative ownership boundaries, daily fire danger forecasts, and current National Weather Service fire weather watch and red flag warning areas.
What is the source for the USA Active Fires layer and what information does it provide?
The USA Active Fires layer is based on information from the Integrated Reporting of Wildland Fire Information (IRWIN) service maintained by the U.S. Department of Interior Office of Wildland Fire. IRWIN harvests and integrates information from numerous federal, state, and local wildfire reporting systems in near real-time to provide a single source of current information about all reported wildfire incidents. The USA Active Fires layer displays the location of current wildfires greater than 100 acres (40 hectares) in size and selected descriptive information, including fire name, latest reported size, and date/time of ignition. The displayed wildfire location is typically based on the identified or assumed point of origin of the fire.
What is the source of the Canada Active Fires layer and what information does it provide?
The Canada Active Fires layer is based on information from the Canadian Wildland Fire Information System Active Wildfires dataset coordinated and maintained by the Canadian Interagency Forest Fire Center (CIFFC) and Natural Resources Canada. Reported wildfire locations are updated and provided daily by partner provincial and territorial fire management agencies and Parks Canada. The Canada Active Fires layer displays the location of current wildfires greater than 100 acres (40 hectares) in size and selected descriptive information, including fire name/ID, latest reported size, and date/time of ignition.
Where can I get more information about current wildfires in the U.S. and Canada?
Additional information about current large wildfires in the United States can be found in the Incident Management Situation Report published by the National Interagency Coordination Center. Additional information about current large wildfires in Canada can be found in the National Fire Situation Report published by the Canadian Interagency Forest Fire Center (CIFFC).
What is the source for USA Fire Weather Watches and Red Flag Warnings and what do they mean?
The National Weather Service (NWS) is the source for fire weather watches and red flag warnings. A fire weather watch or red flag warning is issued by local/regional NWS forecast offices when the combination of dry fuels and weather conditions in designated NWS fire weather zones support extreme fire danger. Criteria for fire weather watches and red flag warnings vary by NWS office, but are typically based on the presence of fuel characteristics favorable for large fire growth, as determined by the land management agencies, and NWS-established critical thresholds for temperature, sustained winds, and relative humidity. Fire weather watches are issued up to 72 hours before these conditions are expected to occur while red flag warnings are issued when these conditions are expected to occur or are occurring within the next 24 hours. A similar layer for Canada is currently not available.
What is the source for the USA Forecasted Fire Danger layer and what information does it provide?
The Forecasted Fire Danger layer is based on the National Fire Danger Rating System (NFDRS), which produces several components and indexes (e.g., ignition probability, fire rate of spread, etc.) that collectively describe current and potential fire danger conditions. Daily forecasted fire danger updates are used by wildland fire management agencies to assess current fire danger at local and national levels and inform decisions on an area’s fire protection needs. NFDRS fire danger is expressed as an adjective class rating that normalizes rating classes across different fuel models, indexes, and station locations.
What is the source for the Canada Forecasted Fire Danger layer and what information does it provide?
The Canada Fire Danger forecast layer is a relative index of how easy it is to ignite vegetation, how difficult a fire may be to control, and how much damage a fire may do. These ratings, updated and mapped daily, are based on the effects of fuel moisture and weather conditions on fire behavior as determined by the Canadian Forest Fire Weather Index (FWI) System. Fire danger conditions are classified by the provincial and territorial fire management agencies and the choice and interpretation of classes may vary between provinces.
What is the source for the United States wildfire perimeters and what does it display?
The US Fire Perimeter layer displays the extent of current wildfires based on perimeter data from National Incident Feature Service (NIFS) maintained by the National Interagency Fire Center. Incident management teams for individual wildfire incidents are the source for these data. Input data/information sources for routine perimeter updates conducted by incident management teams, as well as the update frequency, can vary.
How do I interpret/use wildfire perimeter data in the context of satellite active fire detection data?
Wildfire perimeters for individual fires are typically updated once daily using relatively large scale data (airborne infrared flights, airborne or terrestrial GPS, etc.), but may be updated more or less frequently in particular circumstances. MODIS and VIIRS active fire detection data introduce additional factors that can contribute spatial and temporal alignment between these data and perimeters for ongoing wildfire incidents. These factors include:
- Timing of satellite observations: MODIS and VIIRS are onboard polar-orbiting satellite platforms that do not provide persistent observations. They only detect the location and extent of active fires at the time of a satellite overpass. This may result in gaps in active fire detection data within perimeters.
- Properties of fire activity and active fire detection data resolution: The size and intensity of fires at the time of a satellite overpass, including small, very hot fires and larger, smoldering fires, can both trigger fire detection algorithms. In both conditions, the detected fire activity will be indicated at the spatial resolution of the thermal bands (375 m for VIIRS and 1 km for MODIS). In other words, a small, intense fire occupying a fraction of the pixel or a broader, cooler-burning fire occupying most of the pixel will both be represented as a fire at the spatial resolution of the data. This typically results in cumulative active fire detection data overestimating the size of a wildfire and not aligning with the perimeter boundaries.
- Satellite observation conditions: Atmospheric conditions, including clouds and heavy smoke, can partially or fully obscure fire activity at the time of a satellite overpass and hinder its detection. This omission of potentially detected fire activity can result in gaps in active fire detection data within perimeters. Additionally, the view geometry becomes more distorted with increasing distance from the nadir of the satellite observation. As a result, active fire detections in pixels towards the outer edges of the satellite view swath will be shifted/displaced outwards and fall outside the wildfire perimeter.
Are additional capabilities planned for FIRMS US/Canada?
Yes. The beta release of FIRMS US/Canada was completed in January 2021. Ongoing development activities include introduction of more remote sensing layers in the fire map viewer, particularly additional sources of near real-time satellite imagery and fire-relevant science data products, and enhancements to data downloads and user-defined fire alerts.
Can MODIS and VIIRS satellite active fire detection data be made available sooner than they are currently provided on FIRMS US/Canada?
NASA LANCE, NASA FIRMS, and the Forest Service are currently investigating options to integrate sources of real-time, direct readout data from MODIS and VIIRS for North America. When implemented, active fire detection data would potentially be available within 30-60 minutes of a satellite overpass.