Flying Rivers (Aerial Rivers)

node · earth · Amazon Basin, Cerrado and the La Plata basin

The airborne transport of water vapour across South America, from the tropical Atlantic westward over the Amazon and then, blocked by the Andes, southeastward toward the subtropics. Arraut and colleagues described this in 2012 as a system of aerial rivers and aerial lakes: narrow, fast corridors of vapour transport with slower reservoirs of moisture between them, structurally analogous to a surface drainage network but running in the opposite direction relative to the continent. The southbound limb is carried by the South American Low-Level Jet running along the eastern flank of the Andes, and it delivers moisture to the Cerrado, southern Brazil, Paraguay and northern Argentina - the agricultural and hydroelectric core of the continent. The volume comparison usually made is that the forest returns more water to the atmosphere each day than the Amazon River discharges to the ocean. Whether or not the arithmetic is exactly right, the structural claim is the one that matters: a farm in Sao Paulo and a turbine in Parana are downstream of a forest two thousand kilometres away, by air.