Ecosystem services for poverty alleviation in Amazonia: a report of a capacity-building project to design a research agenda on the links between the natural capital of Amazonian forests and water, food, health, livelihood, climate and energy securities

Abstract

This is an observational study of the large scale moisture transport over South America, with some analyses of its relation to subtropical rainfall. The concept of Aerial Rivers is proposed, and used as a framework, under which a symmetry/analogy is identified between the main pathways of moisture flow in the atmosphere and surface rivers. Opposite to surface rivers, Aerial Rivers gain water through evaporation and lose it through precipitation. The magnitude of the vertically integrated moisture transport is equivalent to river discharge and precipitable water in the atmosphere is analogous to the height of the liquid column. Multiplication of precipitable water by an equivalent speed gives discharge. Trade wind flow into Amazonia and the north/northwesterly flow to the subtropics, east of the Andes, are Aerial Rivers. The trade winds show difluence when entering the continent, like water flowing from a river into a lake. We say there is an Aerial Lake of moisture over Amazonia, deeper in the central western region, where precipitable water is highest. In the dry season, moisture from the aerial lake goes mostly northeastwards. However there is weaker flow over southern Amazonia, which according to the data used is a source of moisture, which heads towards the subtropics. The subtropical Aerial River discharge is comparable to that of the Amazon River. The amount of moisture coming from Amazonia has large spread, introducing important variability to the discharge. Correlations between flow from Amazonia and subtropical rainfall are not strong. However, some months within the set of dry seasons showed strong increase (decrease) occurring together with important increase (decrease) in subtropical rainfall.