The tan landscape of south-central Brazil was speckled with red hotspots in mid-July 2016 as smudges of smoke hung over the greener coastal area near Rio de Janeiro. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured this true-color image on July 15.
Each red hotspot marks an area where the thermal bands on the instrument detected high temperatures. When accompanied by smoke, as can be seen in this image at higher resolutions, such hotspots are diagnostic for actively burning fire.
The time of year, the location, and the pattern of these hotspots also suggest that they represent agricultural fires – fires that are deliberately set to manage cropland and pasture. The image is centered over a rich agricultural region, where corn, wheat, rice, soybeans, and other crops are planted, among other crops. In such locations, fire can be used to remove old vegetation after harvest, to prepare land for planting, to renew pastureland, to open new fields for use, as well as other management goals. While properly managed agricultural fires stay under control and serve a purpose, they can also easily slip out of control and become destructive wildfires, especially when rain has been scarce and vegetation is dry.
The winter season in central Brazil has been warm, with temperatures in the mid-80s or higher, low relative humidity, and scant rainfall, according to the Soybean and Corn Advisor website. They also report that although this is typically the dry season, this year’s dry season started earlier than normal and it has been dryer than normal – making a perfect setup for fires.