A thick plume of dust blew off the coast of Mauritania in western Africa on October 2, 2007. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite observed the dust plume as it headed toward the southwest over the Atlantic Ocean.
In this image, the dust varies in color from nearly white to medium tan. The dust plume is easier to see over the dark background of the ocean, but the plume stretches across the land surface to the east, as well. The dust plume’s structure is clearest along the coastline, where relatively clear air pockets separate distinct puffs of dust. West of that, individual pillows of dust push together to form a more homogeneous plume. Near its southwest tip, the plume takes on yet another shape, with stripes of pale dust fanning out toward the northwest. Occasional tiny white clouds dot the sky overhead, but skies are otherwise clear.
Sandy Mauritania provides ample material for dust storms. According to Encyclopedia Britannica, Mauritania possesses three kinds of landscape. One type is a skeletal soil where the underlying rock outcrops have weathered slightly, and saline soils from evaporated lakes rest on the surface. Another type is a reg, a desert “pavement” of tightly packed round pebbles. The third type of landscape is sand dunes. Sand covers most of the country, especially in its eastern region.
Saharan dust is a trans-oceanic traveler, periodically crossing the Atlantic during Northern Hemisphere summer. Satellite imagery of dust storms have helped scientists better understand the wide-ranging influence of Earth’s largest desert on distant locations. Scientists have connected Saharan dust storms to red tides in the Gulf of Mexico, to disease outbreaks on Caribbean coral reefs, and to soil fertility in the Amazon Rainforest. Some scientists also believe that Saharan dust outbreaks influence the formation of hurricanes in the Atlantic Ocean.
Image courtesy Jeff Schmaltz, MODIS Rapid Response Team, NASA GSFC