Riverine Flow and Lake Level Variability in Southern South America

Abstract

Considerable attention was directed during the 1920s to the remote connection that appeared to exist between the Southern Oscillation (SO) and anomalous rainfall over southern Brazil, Paraguay, and northern Argentina [Mossman, 1924]. It was Gilbert Thomas Walker's group, then in India seeking the prediction of monsoonal dynamics, that made the observation—seen with skepticism—that high volumes of flow along the Paraná River, as measured at the downstream Rosario (Argentina) gauging station, tended to occur during the negative phase of the SO, when surface level pressure (SLP) was anomalously high around Australia [Bliss, 1928]. Such high surface level pressures, when associated with unusual low pressure along South America's coast, tended to cause droughts in regions bordering the equatorial Pacific Ocean and heavy rainfall in other parts of the Americas and the world.