A comparison of precipitation datasets for the Amazon basin

Six different estimates of precipitation (three based entirely on rain gauge measurements, one based on a combination of rain gauge measurements and satellite data, and two based on reanalyzed meteorological datasets) for the Amazon basin are compared. Altogether, these different estimates have a mean value of 2130 mm/yr. The long-term spatial patterns of annual precipitation within the basin are in good agreement for datasets based on rain-gauges, while data from the reanalyzed meteorological datasets appear to have significant spatial biases resulting from the influence of the spectral representation of topography. While the long-term average precipitation climatology of the Amazon basin appears to be consistently described by the six different datasets, the interannual variability in precipitation (as represented by the four datasets that contain precipitation time-series information with various lengths of record) has significant regional discrepancies. These results suggest that some caution be exercised when using precipitation time-series data over the Amazon basin.