American low-level jets in observation and theory: The Alls Project (Invited Presentation)

Selected past studies of South American Low-Level-Jets (LLJs) are summarized, and compared with other LLJ systems. The East Andean LLJ is particularly important as a moisture pipeline connecting Amazonia to the fertile de La Plata river basin. Diurnal oscillations of related moisture budgets dominate monthly averages in Reanalysis data sets. The confidence in such analyses is low because of large discrepancies between separate equally credible analyses, and sparce observational data. Recent enhancement of observations near the east-Andean foothills reveals a rich spectrum of LLJ phenomena. Available data suggest that jets in this location can be stronge st in late afternoon rather than early morning, as observed in most other LLJ systems. The vertical structure is also much deeper than that characterizing North American cases. More observations are critically important to determine the extent to which these preliminary results are representative, and to map the horizontal structure of South American LLJs. Plans for enhanced field activities will be described.