Selected Aspects of Oceanic Influences on Climate Variability in South America

This paper examines climate variability with emphasis on central and southeastern South America in the context of river streamflow (Paraná, Paraguay, Uruguay, and Negro rivers). It is shown that these rivers have significant interannual cycles (3.5 and 6 years), a near-decadal cycle (9 years) and a 15-year cycle. It is argued that these cycles in river streamflow are linked to sea surface temperatures anomalies associated, respectively, with El Niño/Southern Oscillation (ENSO), the tropical North Atlantic, and a global-scale mode of SST variability. There is also an upward trend in riverflows that tends to level in recent times. This is also consistent with trends in SST.

The current understanding of the paths of those influences from the ocean on the climate over land is reviewed and the promises and difficulties of methods for research on the unknown aspects are discussed.