An analysis of the Amazon basin hydrologic cycle has been carried out using the NASA/GEOS1 atmospheric reanalysis, observed rainfall of Xie and Arkin, and historical Amazon river discharge. Over a seasonal cycle, the precipitation is found to vary by 5 mm day 1, the runo by 2 mm day 1 while the evaporation largely remains constant. On interannual time scales, the hydrologic variability both in ...

Emerging problems of environmental change and of long range hydrologic forecasting demand knowledge of the hydrologic cycle at global rather than catchment scale. Changes in atmosphere and/or landscape characteristics modify the earth's metabolism through changes in its biogeochemical cycles. The most basic of these is the water cycle which directly affects the global circulation of both atmosp...

[1] Rising surface air temperatures in response to anthropogenic forcing are intensifying the global hydrologic cycle. Some of the more dramatic signs of climate change are increasing precipitation, evaporation, and freshwater discharge in continental river basins draining to high-latitude oceans. At regional scales, however, an acceleration of the hydrologic cycle is not always detected. In co...

Scientists and engineers understand and communicate hydrologic concepts with the one-word or two-word form of ‘‘groundwater’’ or ‘‘ground water,’’ with care toward consistency in their usage. Both forms certainly mean the same thing. Scientists and engineers also want to improve the public’s scientific understanding of water resources to ensure their future quality and availability. Language pr...

The availability of new observational data from field programs has yielded new insights into the relationships between cloud microphysics and cloud radiative effects. Tests in single-column mode, carried out in the maritime tropics, in polar regions, and in mid-latitudes, have shown that parameterizations based on these new results can significantly reduce typical model biases in cloud-modulate...