tant. Forecast lead times and operational flexibility in managing water systems interact to determine the range of possible actions and the possible benefits.
Atmospheric involvement in water resources extends to certain aspects of the nation's ground water supply as well. Emerging research problems involve aspects of multiphase ground water flow and coupled mass-biochemical contaminant transport that come into play as rainwater is absorbed by the ground and transported laterally through underground rock strata. Robust description and understanding of these complex phenomena involve laboratory and field experiments and the development of mathematical and numerical models capable of simulating unsteady processes with time constants varying over many orders of magnitude.
With the atmosphere providing the rapid transport portion of the hydrological cycle, it is evident that atmospheric science, in collaboration with hydrology and soil science, must focus more sharply on the complex issues associated with understanding, predicting, and managing the fluxes of water on which society depends.
Part of the World Climate Research Program, the Global Energy and Water Cycle Experiment (GEWEX), was initiated in 1988 to observe and model the hydrological cycle and energy fluxes in the atmosphere, at the land surfaces and in the upper oceans. GEWEX will significantly increases our understanding of the water-energy cycle and thus provide the basis for a more sophisticated water management system.
Beginning with the Industrial Revolution, environmental quality has been increasingly threatened. With the expansion of worldwide industry, new threats to environmental quality pose new research questions. One example is the economic development along the western rim of the Pacific Ocean and the concomitant increase in the emission of gases produced by combustion and industrial processes. The rapid expansion of emissions in this region is now, or will soon be, mirrored elsewhere around the world during the twenty-first century, a trend that seems likely to result in chemical and climate impacts on both regional and global scales.
These increasing emissions pose new questions concerning the regional, hemispheric, and global consequences of rapidly intensifying sources of pollution. What will the fate of these materials be as they move across the globe? Will they reach the Arctic? Will they wash out and fertilize specific regions of the ocean? How and at what rate will gaseous sulfur convert to particulates? Will dispersion and conversion rates differ in El Niño years?
The potential impacts of these emissions, both globally and locally, merit considerable study. To be effective, this study should be carried out in a highly collaborative mode, with social scientists, economists, and others.