Seasonal cycle and interannual variability in the Amazon hydrologic cycle

Edited: 2011-02-18
TitleSeasonal cycle and interannual variability in the Amazon hydrologic cycle
Publication TypeJournal Article
Year of Publication1999
AuthorsZeng, N.
JournalJournal of Geophysical Research
Volume104
Pagination9097-9106
Keywordsenso, terrestrial_water
AbstractAn analysis of the Amazon basin hydrologic cycle has been carried out using the NASA/Goddard Earth Observing System (GEOS-1) atmospheric reanalysis, observed rainfall of Xie and Arkin [1996], and historical Amazon River discharge. Over a seasonal cycle the precipitation is found to vary by 5 mmd-1, and the runoff is found to vary by 2 mmd-1, while the evaporation largely remains constant. On interannual timescales the hydrologic variability both in the atmosphere and at the land surface is found to be closely related to El Niño-Southern Oscillation (ENSO). The correlation between the Southern Oscillation Index and Xie and Arkin precipitation is 0.8 for the period 1985-1993 and 0.56 for the period 1979-1996. The precipitation lags behind the Southern Oscillation Index by 3-4 months while the Amazon River discharge lags behind the precipitation by another 3 months. The lagged relationship suggests interesting dynamic mechanisms. The reanalysis moisture convergence and observed discharge are used to diagnose basin average soil water storage. The year to year variation in the annual mean soil water storage is ~200 mm, comparable to the change within a climatological seasonal cycle. In one case, the basin soil water storage increases by 462 mm from September 1987 to March 1989, suggesting the remarkable ability of the tropical rain forest environment to store and take up water.
URLhttp://adsabs.harvard.edu/abs/1999JGR...104.9097Z
DOI10.1029/1998JD200088