Dust from the hot Saharan Desert of northern Africa has a connection to a much different climate in South America, according to a study by NASA scientists.
Using satellite data, the study has found that the dust is acting as fertilizer for South America's Amazon rainforest about 1,600 miles away to the west over the Atlantic Ocean. Specifically, it's providing some much needed phosphorous to the soils of the Amazon. NASA says that nutrients such as phosphorous are limited in the Amazon since rainfall sends it from the forest floor into nearby streams or rivers.
An estimated 22,000 tons of phosphorous reach the Amazon each year from the Saharan dust, according to Hongbin Yu, an atmospheric scientist at the University of Maryland who works at NASA's Goddard Space Flight Center. Yu says that this is equivalent to the amount of phosphorous lost due to rainfall runoff in the Amazon
Why does the Saharan dust contain so much phosphorous? It comes from lake beds of northern Africa's past, particularly the Bodélé Depression in Chad which is rich in the nutrient, NASA says.
The plumes of dust can sometimes be seen on satellite images like the one below when they first emerge from Africa. From there, the dust particles are transported westward into parts of the Caribbean, northern South America and even Florida.
http://www.weather.com/science/environment/news/saharan-dust-feeds-amazon-fertilizer-nasa
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