This animation shows fire activity in Africa from January 1, 2002 to December 31, 2002. The fires are shown as tiny particles with each particle depicting the geographic region in which fire was detected. The color of a particle represents the number of days since a sizable amount of fire was detected in that region, with red representing less than 20 days, orange representing 20 to 40 days, yellow representing 40 to 60 days, and gray to black representing more than 60 days. This data was measured by the MODIS instrument on the Terra satellite. MODIS detects fires by measuring the brightness temperature of a region in several frequency bands and looking for hot spots where this temperature is greater than the surrounding region.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 220.127.116.11.0