NASA - Visible Infrared Imaging Radiometer Suite
Satellite brightness and temperature anomaly detection data of fires in June.
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 1:30pm and 1:30am. NOAA-20 operates about 50 minutes ahead of Suomi NPP. Thanks to its polar orbit, mid-latitudes will experience 3-4 looks a day.
Latitude
Center of nominal 375 m fire pixel
Longitude
Center of nominal 375 m fire pixel
Bright_ti4
Brightness temperature I-4 VIIRS I-4 channel brightness temperature of the fire pixel measured in Kelvin.
Scan
The algorithm produces approximately 375 m pixels at nadir. Scan and track reflect actual pixel size.
Track
The algorithm produces approximately 375 m pixels at nadir. Scan and track reflect actual pixel size.
Acq_Date
Date of VIIRS acquisition.
Acq_Time
Time of acquisition/overpass of the satellite (in UTC).
Satellite
N= Suomi National Polar-orbiting Partnership (Suomi NPP),
1=NOAA-20 (designated JPSS-1 prior to launch)
Confidence
This value is based on a collection of intermediate algorithm quantities used in the detection process. It is intended to help users gauge the quality of individual hotspot/fire pixels. Confidence values are set to low, nominal and high. Low confidence daytime fire pixels are typically associated with areas of sun glint and lower relative temperature anomaly (<15K) in the mid-infrared channel I4. Nominal confidence pixels are those free of potential sun glint contamination during the day and marked by strong (>15K) temperature anomaly in either day or nighttime data. High confidence fire pixels are associated with day or nighttime saturated pixels.
Please note: Low confidence nighttime pixels occur only over the geographic area extending from 11deg E to 110 deg W and 7 deg N to 55 deg S. This area describes the region of influence of the South Atlantic Magnetic Anomaly which can cause spurious brightness temperatures in the mid-infrared channel I4 leading to potential false positive alarms. These have been removed from the NRT data distributed by FIRMS.
Version
Version identifies the collection (e.g. VIIRS Collection 1) and source of data processing: Near Real-Time (NRT suffix added to collection) or Standard Processing (collection only).
"1.0NRT" - Collection 1 NRT processing.
"1.0" - Collection 1 Standard processing
Bright_ti5
I-5 Channel brightness temperature of the fire pixel measured in Kelvin.
FRP
FRP depicts the pixel-integrated fire radiative power in MW (megawatts). FRP depicts the pixel-integrated fire radiative power in MW (megawatts). Given the unique spatial and spectral resolution of the data, the VIIRS 375 m fire detection algorithm was customized and tuned in order to optimize its response over small fires while balancing the occurrence of false alarms. Frequent saturation of the mid-infrared I4 channel (3.55-3.93 µm) driving the detection of active fires requires additional tests and procedures to avoid pixel classification errors. As a result, sub-pixel fire characterization (e.g., fire radiative power [FRP] retrieval) is only viable across small and/or low-intensity fires. Systematic FRP retrievals are based on a hybrid approach combining 375 and 750 m data. In fact, starting in 2015 the algorithm incorporated additional VIIRS channel M13 (3.973-4.128 µm) 750 m data in both aggregated and unaggregated format.
DayNight
D= Daytime fire,
N= Nighttime fire