File:Fires in Thailand, Cambodia, Vietnam (MODIS 2019-02-04).jpg

English: On February 1, 2019, the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired this false-color image which highlights dozens of fires burning in Cambodia, Thailand, and Vietnam.

The location, time of year, widespread nature, and number of fires suggest that these fires were deliberately set to manage land. Every January through March, vast numbers of small fires spring up across Southeast Asia. Those months usually bring cool, dry weather—perfect conditions for burning. Small farmers often use fire to clear the ground of unwanted plants, prepare land for planting, and remove debris after harvesting crops such as rice or wheat. While fire may enhance crops and grasses for pasture, fire also produces smoke that degrades air quality.

Each hot spot, which appears as a red mark, is an area where the thermal detectors on the MODIS instrument recognized temperatures higher than background. When accompanied by plumes of smoke, as in this image, such hot spots are diagnostic for fire. The false-color image uses both visible and infrared light to help enhance the visibility of fire and fire scars (areas where fire has scorched vegetation). Vegetation is green, deep water is dark blue or black, areas with scant vegetation are light green, unvegetated land appears tan, and new fire scars appear dark brown. As vegetation grows back into older fire scar the appearance lightens.