Efforts to understand climate variability and predict future climate change have highlighted many aspects of the hydrologic cycle and the exchange of energy and water at the atmosphere-surface interface as areas of critically needed study. The very nature of weather and climate demands that an international perspective and a comprehensive research approach be applied to understand these important issues. In response to this need, the international partners of the World Climate Research Program developed GEWEX (Global Energy and Water Experiment) as a major focus of international study. As the first of five continental-scale experiments, the GEWEX Continental Scale International Project (GCIP) was established to quantitatively assess the hydrologic cycle and energy fluxes of the Mississippi River basin. GCIP focuses on understanding the annual, interannual, and spatial variability of hydrology and climate within the Mississippi River basin; the development and evaluation of regional coupled hydrologic/atmospheric models; the development of data assimilation schemes; and the development of accessible, comprehensive databases. Improved water resource management on seasonal to interannual time scales is also a key GCIP goal. This book reviews the GCIP program, describes progress to date, and explores promising opportunities for future progress.

Water managers rely on predicting changes in the hydrologic cycle on seasonal-to-interannual time frames to prepare for water resource needs. Seasonal to interannual predictability of the hydrologic cycle is related to local and remote influences involving land processes and ocean processes, such as the El Niño Southern Oscillation. Although advances in understanding land-surface processes show promise in improving climate prediction, incorporating this information into water management decision processes remains a challenge since current models provide only limited information for predictions on seasonal and longer time scales. To address these needs, the Global Energy and Water Cycle Experiment (GEWEX) Americas Prediction Project (GAPP) was established in 2001 to improve how changes in water resources are predicted on intraseasonal-to-interannual time scales for the continental United States. The GAPP program has developed a science and implementation plan to guide its science activities, which describes strategies for improving prediction and decision support in the hydrologic sciences. This report by the National Research Council provides a review of the GAPP Science and Implementation Plan, outlining suggestions to strengthen the plan and the GAPP program overall.

Currently, the Departments of Defense (DOD) and Commerce (DOC) acquire and operate separate polarorbiting environmental satellite systems that collect data needed for military and civil weather forecasting. The National Performance Review (NPR) and subsequent Presidential Decision Directive (PDD), directed the DOD (Air Force) and the DOC (National Oceanic and Atmospheric Administration, NOAA) to establish a converged national weather satellite program that would meet U.S. civil and national security requirements and fulfill international obligations. NASA's Earth Observing System (EOS), and potentially other NASA programs, were included in the converged program to provide new remote sensing and spacecraft technologies that could improve the operational capabilities of the converged system. The program that followed, called the National Polar-orbiting Operational Environmental Satellite System (NPOESS), combined the follow-on to the DOD's Defense Meteorological Satellite Program and the DOC's Polar-orbiting Operational Environmental Satellite (POES) program. The tri-agency Integrated Program Office (IPO) for NPOESS was subsequently established to manage the acquisition and operations of the converged satellite. Issues in the Integration of Research and Operational Satellite Systems for Climate Research analyzes issues related to the integration of EOS and NPOESS, especially as they affect research and monitoring activities related to Earth's climate and whether it is changing.

Water vapor plays a vital role in shaping weather and climate on Earth. Hence, monitoring water vapor is critical if we are to explain and predict the behavior of the climate system. Unfortunately, measuring and analyzing water vapor on the time and space scales needed for this purpose have proven elusive. Therefore, it is appropriate and timely for the international climate research community, through the Global Energy and Water Cycle Experiment (GEWEX), to focus a project around water vapor. To this end, a GEWEX Global Water Vapor Project (GVaP) has been proposed, and draft Science and Implementation Plans have been developed. As requested by the U.S. Global Change Research Program (USGCRP), the National Research Council's (NRC) GEWEX Panel has reviewed these plans with an eye toward U.S. priorities.