The basin of Amazons could be identified, for the first time, as the region of dominant origin of the water that falls in the Atacama desert (Chile), according to a study by German scientists published today by Geophysical Research Letters.
From the jungle, the elevated water vapor travels more than 2,000 kilometers west, across the Andes, and southeast over the Pacific to form rainfall over the Atacama Desert.
The team, led by Christoph Böhm, from the Institute for Geophysics and Meteorology at the University of Cologne, has identified so-called Moisture Conveyor Belts (MCBs) as the main mechanism for precipitation, accounting for 40-80%.
Apart from the poles, this desert is the driest region on Earth, with annual rainfall of less than 2 liters per square meter.
Up to now, two water supply routes to the desert had been identified: summer rains due to humid winds from the east (Alto Boliviano) and winter rains associated with the trajectories of storms from the west.
The authors consider that a third mechanism could now be included, that of the Amazon that, through MCBs, gives rise to extreme precipitation events, Böhm explained in a statement.
These are special meteorological phenomena that present strong water vapor transport over long distances and without much exchange with the underlying humid Pacific air throughout the journey.
When the band of water vapor originating in the Amazon basin reaches the Atacama from the northwest, the air flow has to cross the coastal mountain range up to 2,500 meters, thus the air is forced to rise, which causes a cooling and the formation of precipitation.
Böhm indicated that the more intense the precipitation, the more likely it is to be associated with that moisture conveyor belt and pointed out a specific case in which a region in the driest part of the desert received more than 50 liters per square meter, which exceeded the annual average ten times.
For species highly adapted to dryness, the sudden availability of water can cause death, but at the same time these rainy episodes trigger biological explosions like the spectacular flowery desert.
In addition, the runoff generated by heavy rainfall is capable of displacing debris and reshaping the landscape. Traces of such activities, such as pollen and organic carbon deposition or moved material of different grain sizes, manifest themselves on the desert floor and are preserved through long-lasting dryness.