Airborne 'Flying Rivers' Trace Moisture Corridors Over South America

Researchers have mapped an extensive network of airborne moisture streams spanning South America, whose branching layout mirrors the river basins found on land.

By integrating satellite‑derived water‑vapor data with high‑resolution climate models, the team tracked humid air traveling from the Atlantic and Pacific shores into the interior, uncovering steady corridors that channel moisture for hundreds of kilometres before it falls as rain.

These routes display a hierarchical pattern akin to land‑based drainage systems: minor “tributaries” of moist air coalesce into larger “confluences,” which then feed the huge “main stems” delivering water to the Amazon basin and other inland areas.

Beyond being a scientific curiosity, these atmospheric highways provide the majority of rainfall that supports South America’s rainforests, agriculture and water resources. If any segment of the network falters, rainfall downstream could diminish, jeopardizing food security and ecosystem health.

Although “atmospheric river” traditionally describes narrow, high‑intensity moisture streams influencing regions such as California, this analysis reveals that South America possesses a broad, web‑like system that functions year‑round, connecting oceanic sources to inland catchments in a previously unnoticed way.

The results are spurring recommendations to embed these flying rivers into regional climate forecasts and drought‑early‑warning frameworks, since a more accurate depiction of their behavior could enhance rainfall‑variability predictions throughout the continent.