Today’s Image of the Day from NASA Earth Observatory features a plume of Saharan dust that has traveled out of North Africa and across the Mediterranean into Western Europe. According to NASA, the dust turned skies orange, blanketed cities, impaired air quality, and stained ski slopes.
“The plume was driven by an atmospheric river arising from Storm Celia, which brought strong winds, rain, and snow to the Canary Islands. Atmospheric rivers, normally associated with extreme moisture, can also carry dust,” reports NASA.
You can think of an atmospheric river as the confluence of a dust river and a water vapor river within a single storm environment, explained Bin Guan, an atmospheric scientist at NASA’s Jet Propulsion Laboratory.
“The same atmospheric dynamics that give rise to a water vapor river – specifically strong winds – can act to pick up and transport dust as the storm moves across desert areas.”
Guan’s research shows that in the last 40 years, nearly 80 percent of atmospheric rivers over northwestern Africa have led to extreme dust events over Europe.
“Each year, more than 100 million tons of dust blow out of North Africa, lofted from the Sahara Desert by strong seasonal winds. At least a few times a year, strong and persistent winds from the south drive Saharan dust north toward Europe,” says NASA.
“The dust plays a major role in Earth’s climate and biological systems, absorbing and reflecting solar energy and fertilizing ocean ecosystems with iron and other minerals that plants and phytoplankton need to grow.”
At the same time, however, dust storms can have a negative impact on air quality and human health. Beyond polluting the air, the dust can darken the snowpack and lead to more rapid snowmelt compared to a pristine atmospheric river, said Guan.
“In a 2021 dust event, Guan and colleagues found that dust deposition led to snow darkening in the Alps, decreasing the reflectance, or albedo, of the snow by 40 percent and warming the surface. Together, this reduced the snow depth in the Alps by half in less than a month,” reports NASA.
The full effects of this year’s storm have yet to be seen but compared to the 2021 event, this storm seems to be carrying more dust than water vapor, explained Guan. “The water vapor river over northern Africa does not appear to be particularly strong compared to last year’s – it’s an arid region, after all. The dust river is likely more intense.”
The image was captured on March 15 by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the NOAA-20 spacecraft.
Image Credit: NASA Earth Observatory