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Summary This report was prepared in response to a request that the National Research Council (NRC) assess whether the FY 1991 plan for the U.S. Global Change Research Program (USGCRP) is a sound approach to reducing the scientific uncertainties regarding global change issues. The charge included several specific questions concerning the plans for the Earth Observing System a large, single initiative of NASA- in the context of the USGCRP. The report was prepared by two coordinated panels established under the auspices of the NRC Committee on Global Change. ASSESSMENT OF TElE EY 1991 USGCRP The findings of the Panel to Review the FY 1991 U.S. Global Change Research Program are summarized as follows. The interagency USGCRP, as described in the President's FY 1991 budget, defines an appropriate first step toward a sound national program to reduce the scientific uncertainties associated with global change issues. The program is clearly aimed at advancing our understanding of the Earth system. The FY 1991 plan reflects the priorities established by the sci- entific community over the past decade, primarily through the NRC, and an unprecedented level of interagency coordination realized through the Committee on Earth and Environmental Sciences (CEES). The plan is also coincident with the goals and activities of the international commu- nity, through organized projects of the International Geosphere-Biosphere Program and the World Climate Research Program. 1

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2 The panel gave particular attention to the question of whether the FY 1991 program reflects appropriate balances in allocating resources. A specific issue was whether an appropriate balance was struck between initial investments in long-lead time, space-based efforts and investments in more immediate research endeavors. It is the view of the panel that the initial investments, though heavy, are both prudent and unavoidable, given that continuous, long-term, space-based observations of fundamental environmental parameters are essential to achieving the underlying goals of the program. Space-based observations will continue to require significant funding, but appropriate balance will also entail substantial growth in funding for other aspects of the program in the future to ensure that data acquired from space are used fully and that the broader progam objectives are met. The program also acknowledges other, equally important long-term investments for which long-lead planning is required. Most important among these are investments in education to build the cadre of scientists and technicians needed to carry out the program, and investments in fundamental research to increase the body of knowledge on which reliable projections of future change must be based. Other elements of program balance considered by the panel included the balances between extra-mural and agency-based research; between "big" and "little" science; between established and emerging programs; and among observations, process studies, and modeling elements of the program; and among the seven science priorities identified in the plans for the USGCRP. We also examined the processes for coordination and review of the program, the involvement of the scientific community in program planning and review, mechanisms for scientific assessment and the delivery of policy advice, interactions among participating agencies, the need for international collaboration, the availability of human resources needed to meet program goals, and the status of "contributing" programs. We reached a number of conclusions and recommendations as summarized below. While the USGCRP includes observations, process studies and modeling, the FY 1991 program emphasizes observational programs be- cause of the initiation of the Earth Observing System and Earth Probes series and the expense of space-based observing systems. The heavy em- phasis on observations, necessary to initiate long-lead time, space-based capability, should be balanced as the program develops in the future by increased emphasis on process studies and modeling. The program would benefit from a better definition of the required national Earth system modeling capability and a workable plan for inter- preting and delivering the results in forms useful to policymakers. These

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3 omissions should be addressed soon if the program is to meet its announced objectives. The USGCRP is organized around seven scientific priorities. We conclude that the ranking of science priorities is consistent with the goals of the program and the consensus of the scientific community involved in global change research. The program would be strengthened if the science element focused on the study of how human activities influence and are influenced by global change ("human interactions") were better defined and more adequately funded. Priorities within the USGCRP must be kept flexible so that the program can remain responsive to research findings and unanticipated needs. The collaboration among agencies involved in the USGCRP has thus far been exemplary regarding definition and planning at the program level. The CEES has been an effective mechanism for this collaboration. The next challenge is to extend the collaborative approach to the specific activities or projects at the level of the Task Groups that now define activities within the science elements of the program. An ideal would be a "zero-based" project definition within each science element to discourage the re-labeling of prior agency initiatives only peripherally related to the goals of the program. . A key example of where interagency collaboration is required is the development of an overall observational strategy, including space-based and in situ measurements, to monitor global change and collect data pertinent to process studies and modeling activities. USGCRP planning documents distinguish between "focused" (i.e., central) and "contributing" (i.e., supportive) programs. The focused ele- ments do not represent the entirety of the required research, and many contributing programs and complementary activities in the President's bud- get must also be sustained if the program is to succeed. These contributing programs should be identified in a consistent manner. International collaboration on global change is required both to secure data on a global scale and to share human and financial resources. Cooperation with developing countries in global change research should be strengthened to ensure their involvement. U.S. support for international efforts, including an appropriate share of the support of program and project offices, should be made an explicit element of annual budgets. The role of the scientific community outside the participating agen- cies in providing for independent scientific review of the overall program should be more clearly defined, including the role of the NRC, and mech- anisms for carrying out the reviews should be established. The USGCRP must strengthen the involvement and support of the academic research community, preferably through explicit programs

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4 of extramural support in each of the agencies, to meet the long-term need for new scientists and technicians in the program and to ensure the participation of an adequate base of research scientists. Agencies with programs in the "focused" category (e.g., those programs included in the budget whose goals are regarded by CEES as central to the USGCRP) should be guided by extramural advisory panels to ensure appropriate focus and flexibility. THE EARTH OBSERVING SYSTEM IN THE CONTEXT OF THE USGCRP The findings of the Panel to Review NASA:s Earth Observing System in the Context of the USGCRP are summarized as follows. NASA's Earth Observing System (EOS) is intended as a major step in the evolution of the science and technology of global remote sensing. Its objective is to provide the user community (science, industry, policy) with the first comprehensive long-term measurement and data system specifi- cally aimed at global change issues. EOS will also serve as a test bed for development of the next generation of operational Earth-observing instru- ments. The EOS Data and Information System (EOSDIS) is intended to provide means by which the scientific community can gain access to data obtained from EOS and elsewhere for use in documenting, monitoring, and modeling global environmental change and the Earth system. Currently, EOS is at the point in the NASA process where instruments have been selected for development, but not yet selected for flight. Thus the information we had for this review was a "snapshot" in time of an ongoing process of development. All details of the mission have not yet been established, and even some of the major decisions have not yet been made. Mindful of this situation, we dealt with the information as part of a changing process, so that what we have provided here is an assessment that should itself be viewed as a snapshot of a developing program. Our charge specified four questions, which are addressed in Chap- ters 5 through 8, respectively. We reached the following conclusions and recommendations. . The set of instruments proposed and under consideration for flight would provide measurements of a number of high priority environmental parameters in the USGCRP framework. The complete set of measure- ments to be made from EOS spacecraft will depend on success in the development of the selected instruments and on other factors. EOS will not, however, provide all the space-based measurements required for un- derstanding global change. Indeed, some parameters must be measured by space-based instruments on other satellites and in other orbits. Therefore, EOS must be Dewed in the context of other space-based measurement

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s systems of both the United States and other nations participating in global change research that will fly either before or during the proposed EOS measurement period. Documenting global change will require both space-based and in situ measurement programs, i.e., in the atmosphere, on the surface of the Earth, and on and in the oceans. The two types of measurements com- plement each other and a combination is essential; neither on its own is sufficient for the purposes of the USGCRP. There is as yet no compre- hensive observational strategy that relates the total U.S. space-based ob- serving program to the in situ measurements required for a comprehensive USGCRP, or that relates the U.S. measurement program to international efforts, both space-based and in situ. Such a multifaceted strategy is es- sential, and the agencies involved in the USGCRP should develop it soon based on work done to date. The strategy should allow for the evolution of observational goals and technologies. Certain sets of data should be collected simultaneously, depending primarily on the importance of studying the interactions within natural processes occurring over short time scales, and on the interdependence of certain sets of measurements. for precise quantitative interpretation. The panel reviewed the arguments for simultaneity as applied to measurements aimed at studying the role of clouds in the climate and the hydrologic cycle and the fluxes of trace gases in biogeochemical cycles. We concluded that for measurements critical to these two high priority areas of research in the USGCRP, there is a need for several sets of instruments to make simultaneous measurements. These arguments lead to a set of overlapping requirements for a suite of instruments that should be flown on the same satellite. We are not aware of similar arguments for the measurements needed to address other scientific objectives of the USGCRP, such as those directed at the chemists, of the atmosphere and the dynamics of its upper reaches. While simultaneous measurement by individual pairs of instruments may be indicated for other scientific objectives, neither the scientific investigations nor the measurements themselves appear to demand the breadth of simultaneity essential to the study of the role of clouds in the climate and the biogeochemical dynamics of trace gases. For the two high priority areas described above, we concluded that the number of instruments that must fly together requires at least one large satellite. Dividing the proposed instruments for these measurements among several smaller satellites and flying them in close formation is technically feasible, but even the smallest coherent set of instruments for one of the small satellites is still sufficiently large to require a launch vehicle larger than the Delta rocket. ~ The scientific requirements for continuity in data sets have led the community of researchers and NASA to plan for a long time-series

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6 of measurements. EOS plans call for a 15-year record of observations using series of identical satellites, each with a 5-year lifetime, for each set of measurements. Measurements to carry out the USGCRP emphasis on the role of clouds and the fluxes of trace gases, for example, are planned for a series of large spacecraft called the EOS-A series. It seems likely that scientific understanding and technical capabilities will change during the course of the EOS program. Accordingly, although continuity of specific data sets will be an important consideration, it may also be desirable to alter the instruments or the platforms, or both, at some time in the future. NASA is designing the spacecraft and instruments to have common interfaces, which should make future interchange of instruments easier than on past missions. Currently, however, the program contains no process that would enable it to evolve in response to new scientific understanding, concepts, or technology as they emerge during the life of the EOS program. Scientific arguments for simultaneity in terms of the other research objectives of the second proposed satellite series, EOS-B, have not been developed by NASA; it currently appears that these objectives could also be achieved with a number of smaller, independent satellites. NASA:s current assessment of comparative costs, as presented to us, suggests that flying the projected EOS-B instruments on large spacecraft is the least expensive option, although the differences in cost among some alternative configurations appear to be relatively small. In principle, the science investigations proposed for EOS-B could be done by a suite of smaller satellites. Since a number of the instruments do not require extensive development, these could perhaps be launched sooner. The first EOS satellite is scheduled to be launched in 1998. In the interim, significant opportunities exist for gathering key global change data through a number of U.S. and foreign research and operational satellite missions. Such missions include Upper Atmosphere Research Satellite, The Ocean Typography Experiment/Poseidon, and some of the Earth Probes. However, we note a gap in the critical area of Earth radiation budget measurements. It is intended that some of the EOS instruments should continue to monitor certain environmental parameters so that the precursor missions flying similar instruments will be prerequisites, not substitutes. We believe that, if budget constraints arise, it would be more desirable to delay the launch of EOS spacecraft than to forego or diminish the effectiveness of the near-term missions. The continuity and reliability of data used to monitor global change as it occurs are particularly important. NASA needs a more thorough contingent y plan in the event of failures. When the potential for long-term drift in instruments is considered, it is clear that the issue of calibration warrants continuing attention. 0, ~) ~

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7 The preeminent challenge to global change research is the synthesis of diverse types of information from many different sources. The EOS Data and Information System (EOSDIS) will be a pioneering effort in this regard; the intended scope of the system far exceeds that of any existing civilian data management system. Investing in the early development of EOSDIS is appropriate and necessary for the long-term success of the EOS data collection, manage- ment, and modeling effort as well as for the USGCRP. Investment, however, does not guarantee success. While relevant experience for developing EOS- DIS exists, no operational paradigm for the management and dissemination of such large scientific damsels currently exists. EOSDIS is planned as and must be an evolving entity. NASA should not attempt to define the total system specifications of EOSDIS at the outset and then assume that they will not be altered throughout the remainder of the program. EOSDIS should include and accommodate more than just data from EOS sensors in order to meet the needs of the USGCRP. The agencies prominent in the collection and dissemination of data NASA, NOAA, NSF, and USGS have a special responsibility to continue to work together and with the international community to assure that all relevant data and information are available to EOSDIS for global change research. The management of very large databases with provisions for index- ing, browsing, visualization, and other capabilities should be viewed as a research issue. Current understanding of how to meet the challenge is not mature. A program of research and prototyping is needed to guide the evolution of the proposed data management capabilities. We welcome NASAs policies regarding access to EOSDIS data and data products, which are aimed at making them equally available to all users and to researchers at nominal costs of reproduction and delivery. Means should be found to include commercialized I~ndsat data in EOSDIS. Because the implementation of EOSDIS poses significant, contin- uing challenges, EOSDIS should have an ongoing mechanism for acquiring independent advice from the user community. The EOS Investigators' Sci- ence Advisory Panel for EOSDIS has successfully focused the concerns of a broader research community, and the panel should continue to be a long- term advisory element in the planning and implementation of EOSDIS. The panel should include some scientists who are not EOS investigators, but who are active in fields within the range of scientific disciplines involved in global change research, as well as in research on data and information management

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