The Sahara's Dust Crosses an Ocean to Feed the Amazon

Описание: Every year about 180 million tonnes of Saharan dust leave Africa on the trade winds, and about 28 million tonnes settle on the Amazon basin.
In that dust is about 22,000 tonnes of phosphorus, the nutrient the rainforest's old soils run short of.
Full film:    • The Biggest Desert on Earth Isn't the Sahara  

The figures are 2007-2013 averages from laser measurements by NASA's CALIPSO satellite, and the range is wide: the Amazon's share is estimated at 8 to 48 million tonnes a year. Part of the dust lifts from dry lake beds such as the Bodélé Depression in Chad, one of several sources; which one matters most is still argued. The phosphorus is less than a tenth of one percent of the dust, yet it is roughly what the basin loses each year to rain and flooding. And the Sahara, the largest hot desert, is not the largest desert on Earth: the full film measures which one is.

The dust's path is drawn in outline; the phosphorus marks are not to scale.
MEASURED: Earth's wonders, at true scale.

Sources:
• NASA, "NASA Satellite Reveals How Much Saharan Dust Feeds Amazon's Plants" (2015): https://www.nasa.gov/missions/calipso...
• H. Yu et al., "The fertilizing role of African dust in the Amazon rainforest", Geophysical Research Letters (2015): https://www.osti.gov/pages/biblio/122...
• H. Yu et al., "Disproving the Bodélé Depression as the primary source of dust fertilizing the Amazon rainforest", Geophysical Research Letters (2020): https://agupubs.onlinelibrary.wiley.c...
• NASA Earth Observatory, "Bodele Depression Dust Feeds Amazon" (2007): https://science.nasa.gov/earth/earth-...
• National Geographic Education, "Deserts": https://education.nationalgeographic....
Elevation: Mapzen Terrain Tiles (AWS Open Data) from SRTM, GMTED2010, ETOPO1/GEBCO and national DEMs.

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