Several active fire signals in Central America are recorded by OSEI with the NOAA AVHRR Sensor on 23 April 1999.
Fig.1. NOAA image of vegetation fires in Mexico, Guatemala and Honduras on 23 April 1999
(Source: NOAA http://www.osei.noaa.gov/)
Several heat signatures (red spots), at least some of which are from areas of fire burning in Mexico, Guatemala and Honduras were detected. Some caution must be exercised in identifying all hot spots as fires, because Band 3 of the AVHRR which detects hot spots is also easily saturated by the high temperature signal of solar-heated ground. However, the presence of smoke (blue haze) over some of the hot spots indicates that some fire activity is present. The pink area in the Bay of Campeche is due to solar reflection off the water which also saturates band 3.
Most of the fires in Central America must be seen in the context of intensive land development. Fire is used as a tool in forest conversion. This is done by small farmers as well as large agro-industrial companies. The careless use of fire often allow the “prescribed” burnings to escape and become forest fires in the adjacent forests. Almost all fires inCentral America are human-caused, natural fires play a minor role in the tropical rain forest of Central America.
Under normal weather conditions the primary forest in the humid tropics does not catch fire. The hydrological cycle in the closed forests produces a very humid microclimate where unfavourable conditions for forest fire exist. But in forests where selective logging already took place the former closed canopy is disturbed. This allows more light to penetrate through the canopy and thereby changing the energy balance within the forest – the forest becomes more susceptible to drought and consequently to fire.