On one side of the Atlantic is one of the driest splotches of land on Earth. On the other side is one of the wettest and most fertile. Despite the miles of open ocean separating the Sahara and Amazon, the two locales do share a commonality -- nutrient-rich dust.
As a new simulation by engineers at NASA reveals massive clouds of dust are carried across the ocean by trans-Atlantic winds to the Amazon basin. There they are deposited, and the minerals and nutrients carried within (chiefly phosphorous) are absorbed by the plants in the Amazon's rainforest.
Because of the high competition for nutrients in the Amazon, the soil there is depleted. Aside from the dust-delivered phosphorous, decomposing plant materials are the only way the soil gets replenished. So this trans-Atlantic dust delivery is important.
"We know that dust is very important in many ways," confirmed lead study author Hongbin Yu, an atmospheric scientist at the University of Maryland. "It is an essential component of the Earth system."
"Dust will affect climate and, at the same time, climate change will affect dust," added Yu, who conducts research at NASA's Goddard Space Flight Center in Greenbelt. "First we have to try to answer two basic questions. How much dust is transported? And what is the relationship between the amount of dust transport and climate indicators?"
To answer these questions, NASA scientists built computer models recreating the dust transfer. The models were supplied with data collected by instruments on NASA's Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellites.
They calculated that roughly 182 million tons of dust are picked up by the winds on the western edge of the Sahara each year. From Africa, they're carried 1,600 miles across the Atlantic. Some of the dust is lost en route, flushed out by rain storms. But 132 million tons remain airborne by the time the dust rain arrives on South America's east coast. There, atop the Amazon, 27.7 million tons are deposited. The train continues across the continent, and another 43 million tons filter out over the Caribbean.
But these calculations are based on data collected between 2007 and 2013. And they are averages. There is a lot of variation from year to year, researchers say -- depending on weather patterns.
Scientists are hoping to use data analysis techniques similar to those used in the latest dust study in order to understand the movement of and interaction between other aerosols, like smoke and pollution.
The latest research was published this week in the journal Geophysical Research Letters.