NASA Satellites Find Balance in South America's Water Cycle
W. Timothy Liu, NASA Jet Propulsion Laboratory
Combining the monthly rate of mass change from GRACE data, the transport of moisture across the coastline from QuikSCAT wind vector and SSM/I water vapor, and river discharge climatology, integrated over the entire continent of S. America, W.T. Liu et al.  showed the fundamental water balance. Regional rainfall measured by TRMM was also related to moisture transported from the surrounding oceans.
Details can be found in the paper:
W.T. Liu, X. Xie, W. Tang, and V. Zlotnicki, 2006: Spacebased observations of oceanic influence on the annual variation of South American water balance. Geophys. Res. Lett., 33, L08710, doi:10.1029/2006GL025683. (PDF file)