Open AccessSeasonal cycle and interannual variability in the Amazon hydrologic cycle
Author(s) -
Zeng Ning
Publication year - 1999
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1998jd200088
Subject(s) - water cycle , precipitation , environmental science , surface runoff , climatology , amazon rainforest , period (music) , annual cycle , drainage basin , water storage , el niño southern oscillation , water content , seasonality , potential evaporation , atmosphere (unit) , structural basin , hydrology (agriculture) , atmospheric sciences , geology , geography , meteorology , ecology , paleontology , statistics , physics , cartography , geotechnical engineering , mathematics , geomorphology , acoustics , inlet , biology
An 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 mm d −1 , and the runoff is found to vary by 2 mm d −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.