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Ensuring the Climate Record from the NPP and NPOESS Meteorological Satellites 1 Introduction Researchers studying the issues surrounding global climate change have a particular need for the kind of repetitive, long-term, high-quality measurements that can be provided from the vantage point of space. Operational weather satellites provide perhaps the only means for securing these measurements. The next generation of operational sensing systems is currently being designed, and the National Polar-orbiting Operational Environmental Satellite System (NPOESS), scheduled for launch beginning in 2009, will be an important component of this operational monitoring system. NPOESS is being developed with the goal of meeting the converged operational data needs of NOAA and DOD, as well as some of the data needs of NASA's Earth observation programs. In a joint mission to transition appropriate research satellite measurements into the operational domain, NASA and the NPOESS Integrated Program Office are developing the NPOESS Preparatory Project (NPP). NOAA is supporting the NPP as part of its risk reduction demonstration and validation for NPOESS sensors, algorithms, and processing. Included in the NPP is the planned launch in 2005 of critical sensors that are planned for flights on NPOESS. The intent is to develop an operational prototype for the provision of satellite-based climate data as well to conduct an early test of space and ground segments for NPOESS. At this time, attention is being given to defining operational climate measurement needs and assessing their implications for instrument design. However, it is equally important to ensure that the data systems will meet climate research needs. At the request of NOAA and NASA, the Space Studies Board's Committee on Earth Studies conducted a short-duration study of issues related to ensuring that the planned NPP and NPOESS satellites will produce a suitable climate record. This report presents the committee's recommendations; it draws heavily on the background material presented at a 2-day workshop that the committee hosted on February 7-8, 2000,1 and on the discussions that came out of that workshop. In addition, it draws on the committee's investigations in connection with a recent two-part report: Issues in the Integration of Research and Operational Satellite Systems for Climate Research.2 Of particular relevance to the present report are discussions in the aforementioned reports of how to execute long-term science monitoring in an operational framework and the particular needs of climate researchers for long- term, well-calibrated, reliable data sets. Investments of several billion dollars have been made in the past 10 years for both NASA and NOAA satellite data systems. The committee believes it is imperative that the nation build on these investments as well as learn from past successes and failures. Any data and information system that intends to serve climate research needs should, if possible, be designed and implemented in the context of existing and planned systems. Moreover, a climate research information strategy will need to address two challenges that have not yet been addressed by the present constellation of satellite data systems. First, the volumes of data that must be archived and made accessible for decades to centuries are far larger than present long-term archives such as the archive at the NOAA National Climatic Data Center (NCDC). Second, much of climate research requires long-term, consistent (or at least well-characterized) time series.3
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NOAA is the federal agency with the responsibility for archiving environmental satellite data, and its NCDC is a potential repository for data to support climate research in the coming NPOESS era. NCDC presently archives about 2 terabytes (TB) per year of Polar-orbiting Operational Environmental Satellite (POES) data. However, as a repository for NPP and NPOESS data, it would need to archive approximately 2 TB per day of data. There are presently no funds for NOAA to archive NPP or NPOESS data. In addition, there are no firm plans to archive sensor design information and the calibration and ancillary data necessary to develop what the committee terms "climate data records" (CDRs). Climate research will require a variety of services, ranging from stable, long-term stewardship of the basic data sets to intensive data analysis and algorithm refinement. As discussed in subsequent chapters, the committee believes it would be best to break these complex scientific and information system activities into two more manageable pieces—the long-term archive (LTA) and the active archive—instead of attempting to build a comprehensive, single-system solution. The next chapter of this report, Chapter 2, provides details of NASA and NOAA preliminary data system plans for NPP and NPOESS, including their plans for long-term and active archives. However, as noted in the text, these plans are not necessarily focused on the requirements of CDRs. Chapter 3 discusses the requirements for climate data services in the context of the existing plans for production, archiving, and distribution of CDRs. The committee's findings and recommendations are presented in Chapter 4. The acronyms and abbreviations used in the report are listed in Appendix C. 1 See Appendix B for the workshop agenda and a list of participants. 2 National Research Council, Committee on Earth Studies. 2000. Issues in the Integration of Research and Operational Satellite Systems for Climate Research: I. Science and Design, in press; Issues in the Integration of Research and Operational Satellite Systems for Climate Research: II. Implementation, in press. 3 National Research Council, Board on Sustainable Development. 1999. Global Environmental Change: Research Pathways for the Next Decade. Washington, D.C.: National Academy Press.