Saharan Dust on the Move

A piece of Africa—actually lots of them—began to arrive in the Americas in June 2014. On June 23, a lengthy river of dust from western Africa began to push across the Atlantic Ocean on easterly winds. A week later, the influx of dust was affecting air quality as far away as the southeastern United States.

This composite image, made with data from the Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi NPP, shows dust heading west toward South America and the Gulf of Mexico on June 25, 2014. The dust flowed roughly parallel to a line of clouds in the intertropical convergence zone, an area near the equator where the trade winds come together and rain and clouds are common. In imagery captured by the Moderate Resolution Imaging Spectroradiometer (MODIS), the dust appeared to be streaming from Mauritania, Senegal, and Western Sahara, though some of it may have originated in countries farther to the east.

Saharan dust has a range of impacts on ecosystems downwind. Each year, dust events like the one pictured here deliver about 40 million tons of dust from the Sahara to the Amazon River Basin. The minerals in the dust replenish nutrients in rainforest soils, which are continually depleted by drenching, tropical rains. Research focused on peat soils in the Everglades show that African dust has been arriving regularly in South Florida for thousands of years as well.

In some instances, the impacts are harmful. Infusion of Saharan dust, for instance, can have a negative impact on air quality in the Americas. And scientists have linked African dust to outbreaks of certain types of toxic algal blooms in the Gulf of Mexico and southern Florida.

• References and Related Reading

• Earth Observatory (2012, July 21) Dust Plume over the Atlantic.
• Earth Observatory (2010, June 1) Saharan Dust Crosses the Atlantic.
• KFSM 5News (2014, June 30) Garrett’s Blog: Sahara Dust in Arkansas Accessed July 3, 2014.
• Prospero, J. et al (2014, May 28) Characterizing the annual cycle of African dust transport to the Caribbean Basin and South America and its impact on the environment and air quality. Global Biogeochemical Cycles.
• Prospero, J. et al (2013, September) Understanding the Transport and Impact of African Dust on the Caribbean Basin. Bulletin of the American Meteorological Society, 94 (9), 1329-1337.
• Seftor, C. (2014, July 1) Saharan Dust over the US. Accessed July 3, 2014.
• Seftor, C. (2014, June 26) Saharan Dust. Accessed July 3, 2014.
• The Smog Blog (2014, June 30) Saharan Dust Polluting Southern US. Accessed July 3, 2014.

NASA images by Norman Kuring, NASA’s Ocean Color web. Caption by Adam Voiland.

Instrument(s): 

Aqua - MODIS - NASA