What connects Earth’s largest, hottest desert to its largest tropical rain forest? The Sahara Desert is a near-uninterrupted brown band of sand and scrub across the northern third of Africa. The Amazon rain forest is a dense green mass of humid jungle that covers northeast South America. But after strong winds sweep across the Sahara, a tan cloud raises in the air, stretches between the continents, and ties together the desert and the jungle. It’s dust. And lots of it.
For the first time, a NASA satellite has quantified in three dimensions how much dust makes this trans-Atlantic journey. Scientists have not only measured the volume of dust, they have also calculated how much phosphorus – remnant in Saharan sands from part of the desert’s past as a lake bed – gets carried across the ocean from one of the planet’s most desolate places to one of its most fertile.
A new paper published Feb. 24 in Geophysical Research Letters, a journal of the American Geophysical Union, provides the first satellite-based estimate of this phosphorus transport over multiple years, said lead author Hongbin Yu, an atmospheric scientist at the University of Maryland who works at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. A paper published online by Yu and colleagues Jan. 8 in Remote Sensing of the Environment provided the first multi-year satellite estimate of overall dust transport from the Sahara to the Amazon.