The Amazon and La Plata River Basins as Moisture Sources of South America: Climatology and Intraseasonal Variability

Divyansh Chug, Francina Dominguez, Zhao Yang

Research output: Contribution to journalArticlepeer-review


Land-atmosphere interactions are critical for precipitation (PPT) over South America where terrestrial evapotranspiration (ET) constitutes a significant fraction of moisture for rainfall over the ecologically and socio-economically vital Amazon (AMZ) and La Plata (LPB) river basins. We quantify the contribution of ET from AMZ and LPB to PPT over the continent with a focus on the intraseasonal time scale. Using numerical water tracers embedded in the Weather Research and Forecasting model we track the moisture originating from the two basins. Our findings indicate that approximately 40% of annual rainfall over the eastern foothills of the Andes originates as AMZ ET, and nearly 30% of rainfall over northern Argentina originates as LPB ET. Analysis of moisture transport during both phases of the dominant intraseasonal oscillation pattern over South America reveals an intraseasonal “sloshing” of LPB moisture between the South Atlantic convergence zone (SACZ) and southeastern South America (SESA) regions. AMZ and LPB each supply approximately 6% of moisture for SACZ PPT during periods of intraseasonal enhancement (positive anomalies), highlighting the importance of moisture from the Atlantic Ocean. For the SESA region, LPB supplies 26% of the moisture for PPT during periods of intraseasonal enhancement while AMZ supplies 5%.

Original languageEnglish (US)
Article numbere2021JD035455
JournalJournal of Geophysical Research: Atmospheres
Issue number12
StatePublished - Jun 27 2022


  • intra-seasonal variability
  • land-atmosphere interactions
  • south America hydroclimate
  • terrestrial moisture
  • water vapor tracers

ASJC Scopus subject areas

  • Geophysics
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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