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Ensuring the Climate Record from the NPP and NPOESS Meteorological Satellites Executive Summary 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, is an important component of this operational monitoring system. NPOESS is being developed with the goal of meeting the converged operational data needs of the National Oceanic and Atmospheric Administration (NOAA) and the Department of Defense (DOD), as well as some of the data needs of the National Aeronautics and Space Administration (NASA) Earth observation programs. In a joint mission to facilitate the transition of appropriate "research" satellite measurements into the operational domain, NASA and the NPOESS Integrated Program Office (IPO) are developing the NPOESS Preparatory Project (NPP). NASA and NOAA are supporting the NPP as part of a program of risk reduction demonstration and validation for NPOESS sensors, algorithms, and processing. The NPP satellite, scheduled for launch in 2005, will include critical sensors that are planned for flights on NPOESS. In addition, the NPP mission is expected to provide an early test of space and ground segments for NPOESS. The NPOESS IPO has begun working with the members of the climate research community to define operational climate measurement needs. The IPO has also begun to assess the implications of these needs for NPOESS 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 the climate record from the planned NPP and NPOESS satellites (see Appendix A for a statement of task). This report presents the committee's recommendations; it draws heavily on background material presented at the 2-day workshop that the committee hosted on February 7-8, 2000, and on discussions during and after the workshop.1 It also draws on investigations by the committee for the two-part report Issues in the Integration of Research and Operational Satellite Systems for Climate Research.2 Climate Data Records In briefings to the committee, NASA and NOAA officials acknowledged that there is no operational ground system infrastructure for U.S. climate data and services. The climate research community therefore requires satellite data from NPP and NPOESS that can be used to generate climate data records (CDRs), data whose quality is known quantitatively and for which temporal and spatial biases are minimized (or at least quantified). CDR
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production will require considerable scientific insight, including the blending of multiple data sources, error analyses, and access to raw data sets. Moreover, information on sensor design, operation, and calibration will also be necessary to develop a consistent CDR across multiple sensors. NASA intends for environmental data records (EDRs)3—the priority data products that will be produced from NPOESS data—to be utilized to the maximum extent possible to meet CDR requirements. However, NASA also expects to cap the resources available for CDR processing to ensure that the EDR production requirements are met. Although NPP- and NPOESS-derived EDRs may have considerable scientific value, CDRs are far more than a time series of EDRs. While the lines may be indistinct, there remain fundamental differences between products that are generated to meet short-term needs (EDRs) and those for which consistency of processing over years to decades is an essential requirement. Given the experience of climate researchers, it is unlikely that the standard EDRs will meet the quality requirements for CDRs, particularly in the area of data refinement and reprocessing as algorithms mature. Moreover, production and refinement of CDRs through reprocessing may be difficult (or unaffordable) in the present plans. Long-Term Archiving and the National Climatic Data Center NOAA is the federal agency with responsibility for archiving environmental satellite data, and its National Climatic Data Center (NCDC) is a potential repository of data to support climate research in the coming NPP/NPOESS era. Currently, NCDC has a total digital archive of approximately 700 terabytes (TB). Data from the scheduled launch in 2005 of the NPP satellite will add another 90 TB annually; if managed by NCDC, data from NPOESS in the 2009 time frame would add yet another 228 TB annually. There are currently no funds to archive NPP or NPOESS data, and although NASA and NOAA have a memorandum of understanding (MOU) regarding the eventual archiving of Earth Observing System (EOS) data by NOAA, it is on a best-effort basis. Although plans are being discussed, there is no implementation strategy within NASA or NOAA to archive even the raw data records (RDRs, analogous to Level 1 data) from these missions. There are also no plans to store sensor design information and calibration and ancillary data necessary to develop CDRs. Ominously, from a climate research perspective, the prospects for developing CDR and long-term archive (LTA) plans for NPP and NPOESS are ever more doubtful, given that plans for the EOS Terra and Aqua (formerly known as AM-1 and PM-1) data sets are not yet firmly in place. Guiding Principles NASA and NOAA have experienced both success and failure in recent attempts to develop data systems. The committee believes that much can be learned from these experiences but notes that the fundamental objective of establishing a set of data systems and services to meet the needs of climate research will require more than MOUs and larger magnetic tape silos. New services must be supported that are not available in the present mix of NASA research mission data systems and NOAA long-term archives. New scientific and policy demands are being placed on these systems, and new management and technical approaches must be established. Increasing funding is a necessary condition; however, the committee does not believe that funding alone is sufficient. While encouraged by NASA and NOAA's recent attention to preserving the
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climate record of NPP, NPOESS, and EOS, the committee believes that an enormous investment in Earth observations is at serious risk. Based on an examination of prior studies, as well as discussions at its February 7-8, 2000, workshop, the committee identified a set of principles it believes can help ensure the preservation of the climate record from NPP and NPOESS: Accessible and policy-relevant environmental information must be a well-maintained part of our national scientific infrastructure. The federal government should (1) provide long-term data stewardship, (2) certify open, flexible standards, and (3) ensure open access to data. The government does not necessarily need to control the implementation of every task and service for a climate data system. Rather, it should undertake those activities and services that cannot be done in a competitive academic or commercial environment. Because the analysis of long-term data sets must be supported in an environment of changing technical capability and user requirements, any data system should focus on simplicity and endurance. Adaptability and flexibility are essential for any information system if it is to survive in a world of rapidly changing technical capabilities and science requirements. Experience with actual data and actual users can be acquired by starting to build small, end-to-end systems early in the process. EOS data are available now for prototyping new data systems and services for NPP and NPOESS. Multiple sources of data and services are needed to support development of climate data records (CDRs). The quality of the CDRs will improve as more research groups work with the various input data sets, and the overall system will be more robust if it does not rely on a monolithic implementation. Fostering open competition for services promotes innovation and new ideas. Science involvement is essential at all stages of development and implementation. Having climate data record developers and users assisting in the specification, design, building, and testing of the system will help ensure its usefulness to the research community. RECOMMENDATIONS The committee's study of issues related to the preservation of the climate record from future NASA and NOAA satellites was necessarily brief and drew heavily on previous work and the 2-day workshop. In addition, the committee drew on the lessons learned to date with NASA's EOS Data and Information System. Underlying the committee's recommendations is its belief in the critical need and unique potential for data from NPP and NPOESS to satisfy the demands of the climate research community. In particular, the committee believes that prudent planning and modest investments early in the program will allow the NPOESS system to continue essential climate research-quality data records and develop new records based on the rich blend of planned instruments. Climate research will require a variety of services, ranging from careful long-term stewardship of the basic data sets to intensive data analysis and algorithm refinement. The committee believes these complex scientific and information system activities are best broken into two more manageable pieces-the long-term archive (LTA) and the active
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archive-instead of formed into a comprehensive, single-system solution. Climate research requires an integration of the more stable, long-term functionality of the LTA and the flexibility of the active archives to pursue and develop new capabilities. The first four recommendations of the committee are presented in order of priority. The last four, which are not prioritized, focus on programmatic and management structures to meet these essential requirements for a climate data system. Recommendation 1. NOAA should begin now to develop and implement the capability to preserve in perpetuity the basic satellite measurements (radiances and brightness temperatures). The development of long-term, consistent time series based on CDRs requires access to the lowest level of data available. In general, this means the raw data records (RDRs), or Level 1A data. The low-level data can be used to develop refined CDRs as scientific and technical understanding of Earth processes and sensor performance improves over time. The committee recommends that NOAA do the following: Archive both current and future data sets, including those from both research and operational satellite missions, in an LTA. Archive information on sensor development, calibration, operation product validation, and appropriate metadata along with the basic radiances. Migrate data sets to new, computer-compatible media on a regular basis, such that data sets are refreshed every 2 to 3 years consistent with the pace of technology evolution. Organize data in the LTA based on user access patterns to optimize data retrieval. Recommendation 2. NOAA should guarantee climate researchers affordable access to all RDRs in the long-term archive, with an emphasis on large-volume data access. Development of CDRs requires access to enormous data volumes, but it is likely that only a small number of researchers will need such extensive access to the raw data. Thus, a well-designed set of basic services would meet this basic function without being too costly. The committee recommends that NOAA act on the following: Award the LTA functions on a competitive basis to both government and private organizations to promote innovation. Start the development of the LTA immediately with a simple set of end-to-end capabilities to gain experience and modify the plans and implementation accordingly. (End-to-end is defined as being from sensor aperture to the desktop of the climate information user.) Recommendation 3. NASA, in cooperation with NOAA, should support the development and evaluation of CDRs, as well as their refinement through data reprocessing. Because the CDR process is driven by science understanding, there will be a continuing need for the involvement of researchers. The NOAA/NASA Pathfinder shows that the agencies can generate critical data sets for transitioning research products into operational data products. Over the next decades, the committee expects that a few experimental CDRs may become effectively "operational" products and will be produced
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by NOAA. The committee recommends that NASA, in cooperation with NOAA, take action as follows: Periodically select science investigations and provide adequate support to develop and evaluate new CDRs. Preserve sensor calibration and operating information, as well as metadata and ancillary data fields, in a manner that allows reprocessing the CDRs. Evaluate on a regular basis the organization of data sets in the LTA in light of actual data usage patterns to improve reprocessing and access efficiency. Recommendation 4. NOAA and NASA should define and develop a basic set of user services and tools to meet specific functions for the science community, with NOAA assuming increasing responsibility for this activity as data migrates to the long-term archive. NASA's Distributed Active Archives Centers, as well as components of NASA's Earth Science Information Partners, are gaining experience with responding to data requests and setting up user services. Although the focus is on the order entry process (catalog, data location, browse, etc.), more attention needs to be given to quality assurance and the order fulfillment process (metadata, subsetting, electronic data delivery, etc.). Emphasis should be given to reducing cost through automation. It is essential that the large-volume data sets from the archive be affordable for the science user community. The committee recommends that NOAA and NASA do the following: Select teams on a competitive basis that will identify and provide specific user services and tools (see Appendix D). As part of an ongoing process of system evaluation and improvement, these teams would assist in identifying and providing essential user services. Based on a rigorous analysis of a user model for climate research, they would make recommendations on characteristics such as data subsetting and browse capabilities. Support and maintain a balance between internal and external expertise at the government data centers. Examine the feasibility of providing open electronic access to a rolling archive of RDRs and EDRs through the NESDIS Central that is planned for NPOESS and NPP. Recommendation 5a. NASA, in cooperation with the Integrated Program Office, should develop the NPOESS Preparatory Project as an integral component of a climate data system. NPP represents a unique opportunity to test both scientific and programmatic interfaces related to an integrated data systems strategy. It will bridge the gap between the NASA research missions and the NPOESS operational missions. There is potential to begin the development of long-term, high-quality CDRs and an associated data system for climate research, but it is an opportunity that could be missed. The committee recommends that NASA, in cooperation with the NPOESS IPO, proceed as follows: Develop and implement a prototyping activity to link the NPP Science Data Segment with the NOAA LTA. This activity should start with NASA EOS data sets, including Atmospheric Infrared Sounder (AIRS)/Advanced Microwave Sounding Unit (AMSU)/MODIS in anticipation of the NPP data sets, including CriS/ATMS/VIIRS.
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Put aside reserve funds from data system development to support evolutionary development activities as the program matures to ensure that the system is not locked in with no resources for subsequent enhancement. Develop prototype user services for NPP climate data records. Recommendation 5b. Select, on a competitive basis, and then support an NPP science team as soon as possible. The team should consist of sensor experts, algorithm developers, and science data users. Because the functions will require different levels of involvement in the sensor development and operation process, they will require different levels of support. The team would advise on the NPP data system needs, including scientific data processing, archiving, and distribution requirements. Recommendation 6. NOAA, in cooperation with NASA, should invest in early, limited capability prototypes for both long-term archiving and the NPP data system. Data systems that do not develop, test, and evaluate on a frequent, regular basis are nearly always late and over budget. System development costs generally increase as the cube of the number of years in development. A climate data system will build on existing components and existing capabilities, but new functions and new interfaces must be developed and implemented to meet the requirements for climate research. The committee recommends that NOAA, in cooperation with NASA, take action as follows: Competitively select and support a science data team to assist a NOAA long-term archiving program on the following: —Archive requirements for long-term data sets, including RDRs, metadata, and ancillary data fields; —Archiving of CDRs, algorithms, and processing environments; —Data structure and organization to facilitate access and reprocessing; —Flexible, open standards to facilitate data access and refinement; —Data reprocessing priorities; and —Minimal user services and tools. Require the NPOESS total system performance requirements (TSPR) contractor to work with the science data team to facilitate CDR production and archiving from both NPP and NPOESS. Develop flexible standards and formats that allow new services to be developed in the future. Begin to develop a small number of CDRs using the LTA services. Recommendation 7. NASA and NOAA should develop and support activities that will enable a blend of distributed and centralized data and information services for climate research. NASA and NOAA should consider a hybrid mode of operation rather than building a rigid, centralized system or relying on structure to emerge from an uncoordinated set of data systems. The government should ensure and manage the activities it does best, while fostering innovation and flexibility in those parts of the overall system that do not need to be closely managed. The committee recommends that NASA and NOAA proceed as follows:
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Implement the NPP data system as a federation of linked activities, such as that proposed in the NewDISS framework. Where appropriate, build on existing and planned capabilities, including EOSDIS, the Earth Science Information Partners, NASA's Distributed Active Archive Centers, and NOAA's Data Centers, and develop new capabilities as user experience is gained. 1 See Appendix B for the workshop agenda and a list of participants. 2 National Research Council (NRC), Space Studies Board. 2000. Issues in the Integration of Research and Operational Satellite Systems for Climate Research: I. Science and Design, in press; National Research Council (NRC), Space Studies Board. 2000. Issues in the Integration of Research and Operational Satellite Systems for Climate Research: II. Implementation, in press. 3 As defined by the NPOESS IPO, EDRs are data records that contain the environmental parameters or imagery required to be generated as user products as well as any ancillary data required to identify or interpret these parameters or images. EDRs are generally produced by applying an appropriate set of algorithms to raw data records.