A Storm of Sand: The Powerful Intercontinental Reach of Saharan Dust

Satellites observed Saharan dust moving from Morocco across the Atlantic, highlighting the Sahara’s role as a major dust source.

This dust affects weather across the globe, and a recent study has shown how varying concentrations of Saharan dust can either suppress or enhance rainfall in tropical storms.

Saharan Dust Events Captured by Satellite

Dense bands of dust streamed offshore from southern Morocco in the summer of 2024. The VIIRS (Visible Infrared Imaging Radiometer Suite) on the Suomi NPP satellite acquired this image of a plume of Saharan dust as winds lofted it over the Atlantic Ocean on August 24, 2024.

The Sahara Desert is Earth’s largest source of airborne dust, and the particles can travel for thousands of miles. From late spring to early fall, it is common for the dry, dusty Saharan Air Layer to carry the particles westward across the Atlantic Ocean high in the atmosphere. With different wind patterns in the winter and spring, dust emerging from North Africa can drift over the United Kingdom and western Europe at relatively low altitudes.

Seasonal Patterns and Impacts of Saharan Dust

Saharan Air Layer activity subsides after mid-August, according to NOAA, making it less likely that the plume shown here is bound for a transoceanic journey. Instead, it arcs to the north after blowing out over the ocean. Earlier in the summer, however, several clouds of fine dust from the Sahara reached the United States, creating hazy skies over Texas.

Scientists are interested in summertime Saharan dust events in part because of the influence they can have on large storm systems. Dry, stable, dust-laden air can inhibit tropical cyclone formation in the North Atlantic. And in a new study, researchers found that dust can modulate the amount of rainfall brought by these storms.

Influence of Saharan Dust on Weather Patterns

Using a machine-learning model based on meteorological data, NASA’s IMERG (Integrated Multi-Satellite Retrievals for GPM) precipitation estimates, and other satellite measurements, the study’s authors found that dust optical depth—a measure of how much light filters through a dusty plume—was a key predictor of rainfall from tropical cyclones. They concluded that, at lower amounts, dust particles promote the formation of rain-producing clouds, while at higher concentrations, the sunlight-blocking effects of dust serve to suppress precipitation.

NASA Earth Observatory image by Lauren Dauphin, using VIIRS data from NASA EOSDIS LANCE, GIBS/Worldview, and the Suomi National Polar-orbiting Partnership.

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