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Introduction
A broad range of empirical and modeling evidence suggests that there may be many predictable modes of fluctuation on seasonal-to-interannual time scales. One such mode, ENSO, a strong interannual variation in climate centered in the tropical Pacific, has been the subject of intensive research that has led to skillful and useful predictions. The NRC's publication on "Learning to Predict Climate Variations Associated with El Niño and the Southern Oscillation" elaborates, in considerable detail, current understanding on this subject (NRC, 1996). Once other predictable modes are identified and modeled, the societal benefit from improved forecasts utilizing information about these additional elements or modes will be increased.
At present, our most advanced understanding of climate system variations on seasonal-to-interannual time scales concerns the coupling between the ocean and atmosphere of the tropical Pacific Ocean. Consequently, it is coupled variations in this region that we are most successful at forecasting on such time scales. Over the past decade, the WCRP TOGA program helped produce significant advances in our understanding and ability to predict ENSO. Building on the success of TOGA, seasonal-to-interannual research and prediction efforts need to be expanded to cover the global domain and should include a concerted study of phenomena in addition to ENSO that impact short-term climate variability. This is the base objective of the GOALS program (NRC, 1994a). TOGA concentrated on the coupling between the tropical atmosphere and the ocean. Expanding on the scientific scope of TOGA, GOALS also considers the interactions between the land and the atmosphere and between the midlatitude ocean and the atmosphere, as well as interactions of snow cover over land, and oceanic ice fields
with the atmosphere and the ocean. Land surface processes, including vegetation and the biosphere, are explicit elements of GOALS and are to be studied in conjunction with GEWEX.
U.S. GOALS is a contribution to the international CLIVAR programme (WCRP, 1995), comprising three major sub-programs: (1) GOALS, (2) DecCen, and (3) Anthropogenic Climate Change (ACC). To facilitate a planning process for research into climate variability on seasonal-to-interannual time scales, the NRC established the GOALS Panel. Under the oversight of BASC, through its CRC, the panel was charged to:
- Provide overall scientific leadership and regular guidance on long-range scientific policy, planning, progress, and priorities to the proposed U.S. GOALS Project Office and involved agencies on behalf of the CRC.
- Report regularly to inform the CRC on the panel's involvement in U.S. GOALS plans and activities and to receive guidance from the CRC on GOALS matters in the context of the overall U.S. climate research program.
- Advise on U.S. participation and providing the U.S. inputs to the international GOALS program planning.
The current document follows directly from the panel's charge. The principal purpose of the document is to provide a strategy for U.S. participation in GOALS/CLIVAR, which should endure for the 15-year duration of the program. At the same time, it is realized that during a program of such length, an evolution of emphases and priorities will occur as knowledge accumulates and new views develop. This document emphasizes explicit and necessary first steps and initial priorities.
As part of the planning process for U.S. GOALS, this report presents a strategy for pursuing the scientific objectives of the U.S. component of GOALS, as described in a previous report (NRC, 1995). Its purpose is to facilitate the development of implementation plans for GOALS while encouraging innovative strategies. It does this by setting forth the scientific objectives and basis of GOALS, clarifying the temporal and spatial focus of the program, and describing the extent and type of work envisioned under the six elements of U.S. GOALS described in Section 4.