Fires and Smoke in Sumatra
Numerous fires caused by a prolonged dry spell across Malaysia (top right) and Sumatra (center) were billowing thick, choking smoke out over the Indian Ocean (left) and the Strait of Malacca (between Sumatra and Malaysia) in this true-color Terra MODIS image acquired on March 9, 2005. Active fires detected by MODIS have been marked with red dots. The smokiest fires are burning along the eastern coastline of Sumatra in the Riau province. This low-lying coastal region is home to a variety of moist vegetation ecosystems, including peat forests, which are particularly smoky when burned. The intense smoke is produced not only by burning trees, but from the burning of the peat soil itself.
Peat is composed of layers of undecayed plant matter. The layers accumulate in places where decompostion is slowed down, such as very cold areas, or areas where the soil is often waterlogged. During severe dry spells, the peat can dry out and become very flammable, similar to coal, which over millions of years peat will turn into if left alone. It is possible that the smokiest fires pictured in this image include fires burning in peat. Peat fires are also very hard to extinguish, as the fires can continue in the peat matter underground for an extended period of time.