FIRMS: How often are the active fire data acquired?

[Earthdata - wxedward]

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. The MODIS instrument swath is 2,330 km. Terra passes over the equator at approximately 10:30 a.m. and 10:30 p.m., Mean Local Time (MLT), each day; Aqua 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 passes over the equator at approximately 1:30 p.m. and 1:30 a.m., MLT; NOAA-20 passes over the equator at approximately 12:40 p.m. and 12:40 a.m., operating about 50 minutes ahead of Suomi NPP. Thanks to its polar orbit, mid-latitudes will experience 3-4 looks a day.