ATSR Active Fire Algorithm

The ATSR night time data used contains 4 bands: 1.6, 3.7, 11.0, 12.0 micrometers.
The ATSR instrument has a 1km resolution.

2 straightforward algorithms have been tested in this project:

Algorithm 1: Hot spot if: 3.7 micrometers > 312 Kelvins (Saturation)
Algorithm 2: Hot spot if: 3.7 micrometers > 308 Kelvins

The detection capabilities depend on the fire temperature, and can be estimated as follows: 0.1 ha at 600K to 0.01 ha at 800K, for a background temperature of 300K.

The user of the Fire product must take into account the algorithm limitations due to cloud presence, atmospheric effects, bidirectionality of emissivity. Fire temperature and extension are not taken into account in the processing.

Nevertheless the advantages of ATSR are the following:

Due to Night Time detection, no artefact due to solar reflection.
No false alarm (no commission error) with algorithm 1: data reliability.
Only quasi-nadir viewing pixels are analysed: less pixel size and bidirectional problems expected.
No drift of the ERS orbit allows year to year comparison.
High radiometric sensitivity allows detection of little/not extended fires.

Known problems: