Huge clouds of dust from the Sahara desert are blown across the Atlantic Ocean every year, creating massive plumes that can be seen from space. Now, for the first time, a NASA satellite has calculated how much of it ends up in the Amazon rainforest, which depends on the delivery to keep its soil fertile.
The glowing arcs above are slices of dust clouds in the atmosphere, imaged along lines of longitude. Between 2007 and 2013, the satellite, called CALIPSO, bounced lasers off the dust and analysed reflected light to find that about 27.7 million tons of dust reaches the Amazon basin every year.
Due to the region's high rainfall, phosphorus in the soil – which is essential for plant growth – is washed away by local rivers. But luckily, the Saharan delivery contains about the same amount of the lost element, replenishing its supply.
Close to 43 million tons of dust is carried even farther than the Amazon, settling over the Caribbean Sea.
Journal reference: Geophysical Research Letters, DOI: 10.1002/2015GL063040
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