NASA's Aqua satellite passed over the western part of Africa on February 10, 2013, and captured many areas of agricultural fires and smoke plumes in several countries including Sierra Leone, Liberia, Guinea, Cote d'Ivoire, and Mali. These agricultural fires are set by farmers to clear lands and to bring nutrients back to the soil. The downside is that they also create air pollution which can be carried by wind patterns to other areas far from their source.
The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument that flies aboard NASA's Aqua satellite captured the image of smoke and fires which are designated by the multiple red pixels. These pixels are heat signatures detected by MODIS. The image is false-colored to make the red areas stand out more.
Image: NASA/Jeff Schmaltz, MODIS Rapid Response Team Text: NASA's Goddard Space Flight Center/Lynn Jenner