APPENDIX B

NASA Document: “Comparison of the 2000-2010 Research Strategy With Relevant Recommendations of the National Academy of Science/National Research Council”44

The National Academy of Science/National Research Council bodies have produced a number of reports that are directly relevant to the strategic planning of the US Global Change Research Program and the research activities of the NASA Earth Science Enterprise (ESE) in the next decade. These reports are listed in[the List of References]. Relevant recommendations and assessments of scientific priorities can be organized in three tiers: strategic planning principles; priority research areas, and implementation considerations.

1. GENERAL PLANNING PRINCIPLES

The principal source of overall guidance at this level is the Pathways report of the Committee on Global Change Research (CGCR, 1999). The principles laid out by the Committee are:

  • Science is the fundamental basis for the USGCRP and its component projects; research priorities and resources must be tied to scientific questions (see Recommendation 1 below).

  • The balance of activities within the program must reflect evolving scientific priorities (as defined in the "research imperatives" discussed below. Nonetheless, a more sharply focused scientific strategy for USGCRP is also required (see Recommendation 2 below).

  • Success in attacking the long-term scientific challenges of the USGCRP requires an adequate and stable level of funding.

Recommendation 1 on Research Priorities (CGCR, 1999)

Research priorities and resource allocations must be re-assessed with the objective of tying available resources directly to the major unanswered scientific questions (identified in the Pathways report). The USGCRP research strategy should be centered on sharply defined and effectively executed programs, and should recognize the essential need for focused observations, both space-based and in situ, to test scientific hypotheses and to document change.

Recommendation 2 on Key Science Questions (CGCR, 1999)

The national strategy of the USGCRP for Earth observations must be restructured and driven by the key unanswered scientific questions. Observational capability must be developed to support research addressing common themes within these scientific elements. Foremost among these themes are the following:

  • Understanding the Earth's carbon and water cycles.

  • Characterizing climate change, including the human dimension component, on temporal and spatial scales relevant to human activities (e. g. the time-scale of a human generation, on the order of 30 years without special emphasis on seasonal-to-interannual or decadal-to-century time scales).

  • Elucidating the links among radiation, dynamics, chemistry, and climate.

44  

NOTE: The material reprinted in this appendix was supplied by NASA on May 8, 2000. The wording of the NRC recommendations as presented is not always exact.



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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 APPENDIX B NASA Document: “Comparison of the 2000-2010 Research Strategy With Relevant Recommendations of the National Academy of Science/National Research Council”44 The National Academy of Science/National Research Council bodies have produced a number of reports that are directly relevant to the strategic planning of the US Global Change Research Program and the research activities of the NASA Earth Science Enterprise (ESE) in the next decade. These reports are listed in[the List of References]. Relevant recommendations and assessments of scientific priorities can be organized in three tiers: strategic planning principles; priority research areas, and implementation considerations. 1. GENERAL PLANNING PRINCIPLES The principal source of overall guidance at this level is the Pathways report of the Committee on Global Change Research (CGCR, 1999). The principles laid out by the Committee are: Science is the fundamental basis for the USGCRP and its component projects; research priorities and resources must be tied to scientific questions (see Recommendation 1 below). The balance of activities within the program must reflect evolving scientific priorities (as defined in the "research imperatives" discussed below. Nonetheless, a more sharply focused scientific strategy for USGCRP is also required (see Recommendation 2 below). Success in attacking the long-term scientific challenges of the USGCRP requires an adequate and stable level of funding. Recommendation 1 on Research Priorities (CGCR, 1999) Research priorities and resource allocations must be re-assessed with the objective of tying available resources directly to the major unanswered scientific questions (identified in the Pathways report). The USGCRP research strategy should be centered on sharply defined and effectively executed programs, and should recognize the essential need for focused observations, both space-based and in situ, to test scientific hypotheses and to document change. Recommendation 2 on Key Science Questions (CGCR, 1999) The national strategy of the USGCRP for Earth observations must be restructured and driven by the key unanswered scientific questions. Observational capability must be developed to support research addressing common themes within these scientific elements. Foremost among these themes are the following: Understanding the Earth's carbon and water cycles. Characterizing climate change, including the human dimension component, on temporal and spatial scales relevant to human activities (e. g. the time-scale of a human generation, on the order of 30 years without special emphasis on seasonal-to-interannual or decadal-to-century time scales). Elucidating the links among radiation, dynamics, chemistry, and climate. 44   NOTE: The material reprinted in this appendix was supplied by NASA on May 8, 2000. The wording of the NRC recommendations as presented is not always exact.

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 The original NASA plans for Mission to Planet Earth and the Earth Observing System was conceived as a broad-gauged data collection effort, aiming to acquire the widest possible range of measurements, with the highest achievable accuracy, spatial resolution, and consistency over a period of 15 years (about three times the expected lifetime of a space mission). The problems associated with this approach were recognized some time ago (CGCR, 1995) and the Agency has been working over the last four years to modify this approach in the direction outlined in Recommendation CGCR-1. The distinction between these classes of missions allows a sharper definition of primary mission requirements; more focused mission goals, in turn, facilitate shorter development cycles, a better articulation with the ESE Research and Analysis Program, and clearer interactions among the investigators involved in a specific measurement and the broader user community. Systematic measurements Systematic measurements are essential to specify changes in forcings caused by factors outside the Earth system (e. g. changes in incident solar radiation) and to diagnose significant changes in the behavior of major components of the Earth system, but certainly not characterizing any and all aspects of global change. In this matter, NASA followed specifically the recommendation of the Pathways report: "Priority must be given to identifying and obtaining accurate data on key variables carefully selected in view of the most critical scientific questions and practically feasible measurement capabilities". The ESE aimed to acquire consistent global records of: Key environmental variables that can now be observed globally, using mature space-based remote sensing techniques, and are most meaningful for detecting significant variations or trends in the state of the major components of the Earth system. Variables that describe important forcing factors, such as total solar radiation, aerosols, and land cover. The initial set variables comprised in the 2002-2010 ESE plan for systematic measurements (for the most part Tables 4.1 and 4.2 of the ESE Research Strategy) is similar in essence to the list of measurements highlighted in the NRC report on the Adequacy of Climate Observing Systems (CRC, 1999) (Table 1). Exploratory Measurements Building upon the findings from field measurement campaigns, exploratory satellite missions are expected to be one-time projects that can deliver conclusive scientific results and answers concerning a focused set of scientific questions, or demonstrate a new observing capability that can eventually address a hitherto unanswered Global Change research problem (e. g. demonstration of global measurements of soil moisture or other hydrologic variables from space). Exploratory process studies may embrace a wider range of inter-related environmental properties than are required for global change detection, but only for a limited period of time as needed to acquire an adequate sample of the range of natural variability. No commitment would normally be expected to continue such exploratory measurements indefinitely, although it is possible that an exploratory project could lead the scientific community or application users to call for the introduction of a new systematic measurement program for research or operational applications. Operational Precursor & Technology Demonstration Missions As appropriate for a R. & D. organization, NASA invests in innovative sensor technologies in order to develop more cost-effective versions of its pioneer scientific instruments that can be

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 used effectively by operational agencies, and test new innovative measurement techniques that may enable investigating hitherto unknown aspects of global Earth system changes. TABLE 1 Comparison of climate system variables highlighted in the NRC report: Adequacy of Climate Observing Systems with NASA systematic measurementsii NRC Report on the Adequacy of Climate Observing Systems (NRC/CRC 1998b) Systematic Observation Priorities in NASA and follow-on NPOESS Programs Parameters Climate Science Climate Impacts   Surface meteorology     Surface Meteorology Surface air temperature/humidity •   - Surface wind   • Ocean surface winds Sea level pressure •   - Precipitation   • Global precipitation Snow cover   • Snow extent Sea ice   • Sea ice extent Incident solar radiation (total and spectral) Upper air     Upper air Temperature profiles •   Atmospheric temperature Humidity/water vapor profiles •   Atmospheric humidity Hydrology     Hydrology Streamflow   • - Land water reservoirs & groundwater   • - Vegetative cover   • High and moderate resolution global mapping Oceans     Oceans Sea level   • Ocean surface topography Sea surface temperature •   Sea surface temperature Upper ocean temperature/salinity   • - Deep ocean temperature profile •   - Ocean primary productivity       Atmospheric Chemistry Ozone (total and profiles) Stratospheric chemistry monitoring       Ice Sheets & Solid Earth Ice sheet topography Earth surface deformation

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 Program Balance The hallmark of NASA's Earth science program has been and remains synergy between different kinds of observations, basic research, modeling studies, and global data analysis activities, as well as field and laboratory studies as appropriate. NASA recognizes, in particular, the synergy of remote sensing and in situ measurements and contributes to the implementation of some critical surface-based observing networks to acquire critical data to complement or validate space-based measurements, e. g. the Advanced Global Atmospheric Gases Experiment (AGAGE) network to measure trace chemical constituents such as chlorofluorocarbons, or the Aerosol Robotic Network (AERONET) to measure total aerosol absorption of solar radiation. Basic research and data analysis are the source of new scientific ideas and emerging research approaches, as well as early development of innovative observing techniques and processing algorithms. Basic research and data analysis constitute the primary component of the ESE's program to link global satellite observations, in situ process-studies, and computational models to assure the development of consistent research data sets, as well as science-based answers to global change science questions. Cross-Cutting Themes In accordance with Recommendation 2 above (CGCR, 1999), the NASA research strategy leads to the formulation of four environmental research themes which address four of the six topical research areas i of the USGCRP, as well as the three cross-cutting themes identified by the Pathways report. The fifth research theme, focused on the study of the Earth's interior (not part of the USGCRP) is founded on a long tradition of scientific excellence acquired by NASA since the beginning of space exploration, and has very significant applications in global satellite navigation systems, geodesy and natural hazard warning. In particular, the ESE's Biology and Biogeochemistry of Ecosystems and the Global Carbon Cycle research theme contributes to the national USGCRP research initiative on the Global Carbon Cycle (USGCRP, 2000), as well as studies of the other relevant biogeochemical cycles. The Earth science strategy formulates a Global Water and Energy Cycle research theme that closely matches the large-scale components of the prospective USGCRP research initiative on the Global Water Cycle (in preparation). Together, the Global Water and Energy Cycle, Oceans and Ice in the Earth System, and Atmospheric Chemistry, Aerosols and Solar Radiation research themes, along with a core-program on Global Earth System Modeling address climate and climate change prediction on all time scales relevant to human activities, thereby eliminating unnecessary separation between seasonal-to- interannual and decadal-to-century time scales. Finally the Global Water and Energy Cycle and Atmospheric Chemistry, Aerosols and Solar Radiation research themes, in particular, have clearly engaged in investigating the linkages among radiation, atmospheric dynamics and chemistry, and climate change. Ultimate Earth System Science Challenge The ESE research strategy recognizes that the ultimate challenge of Earth system science is consolidating scientific findings in different disciplines into an integrated representation of the coupled atmosphere, ocean, ice, land and biosphere system. In order to achieve this ultimate goal, the ESE effectively supports the formulation and verification of coupled Earth system

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 models which can provide the needed responses to societal demands for science-based assessments of potential future changes. (See Section 5 on Earth System Models below.) 2. SCIENCE IMPERATIVES AND QUESTIONS A number of NRC reports have reviewed the high-priority scientific issues (or research imperatives) and emerging scientific questions across the broad field of Earth system sciences (Pathways report; CGCR, 1999) or various subsets of these disciplines, such as the research topics that underpin decadal-to-century scale climate variability (BASC, 1998a) or atmospheric research in the 21st century (BASC, 1998b). It is impossible to discuss at the appropriate level of detail each of the 27 research imperatives and 210 scientific questions formulated by the Pathways report, or research topics elaborated in other relevant NRC reports. The 23 NASA Earth science research questions (see Box on the next page) are organized under five generic scientific issues that constitute a logical progression from measurement of key variables that provide a diagnostic of changes in the main components of the global Earth system, to documenting trends in forcing factors, to finally predicting future variations: How is the global Earth system changing? What are the primary forcings of the Earth system? How does the Earth system respond to natural and human-induced changes? What are the consequences of changes in the Earth system for human civilization? How well can we predict changes in the Earth system that will take place in the future? The NASA research questions cut across the research imperatives and scientific questions formulated in NRC reports, which tend to be organized along disciplinary lines. The breadth of the science domain embraced by the ESE research strategy (and supporting research implementation plan) may be gauged by considering Tables 2 to 4, which map the 23 NASA research questions (and corresponding NASA research programs) against the research imperatives or high-priority research topics listed in three major strategic reports published by the NRC: CGCR, 1999: Global Environmental Change: Research Pathways for the Next Decade (Table 2). BASC, 1998a: Decadal-to-Century Scale Climate Variability and Change: A Science Strategy (Table 3). BASC, 1998b: The Atmospheric Sciences Entering the 21st Century (Table 4). Additional high-priority scientific issues have been identified by other NRC reports from a discipline-oriented perspective, e. g. "Identify the limits of predictability of hydrologic variables, and assess the dependence of these limits upon time-scales, the source of variability, the effects of interactions among terrestrial, atmospheric, and oceanic components on variability" (Hydrologic Science Priorities for the U.S. Global Change Research Program; CHS, 1999). Such scientific problems actually underpin broad interdisciplinary research themes – ranging in this case from documenting global-scale variability and trends in the atmospheric circulation and the hydrological cycle (NASA question V.1) to characterizing the relevant atmospheric and hydrologic processes (NASA question R.1) and their local/regional consequences (NASA question C.1), and verifying the skill and time range of weather/climate predictions (NASA questions P.1 to 3). Other similar cross-cutting Earth system science issues formulated in different NRC reports are similarly addressed (at least partially) by the ESE Research Strategy.

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 NASA EARTH SCIENCE RESEARCH QUESTIONS Earth System Variability and Trends V.1 Is the global cycling of water through the atmosphere accelerating? V.2 How is the global ocean circulation varying on climatic time scales? V.3 How are global ecosystems changing? V.4 How is stratospheric ozone changing, as the abundance of ozone-destroying chemicals decreases? V.5 Are polar ice sheets losing mass as a result of climate change? V.6 What are the motions of the Earth and the Earth's interior, and what information can be inferred about Earth's internal processes? Primary Forcings of the Earth System F.1 What trends in atmospheric constituents and solar radiation are driving global climate? F.2 What are the changes in global land cover and land use, and what are their causes? F.3 How is the Earth's surface being transformed and how can such information be used to predict future changes? Earth System Responses and Feedback Processes R.1 What are the effects of clouds and surface hydrologic processes on climate change? R.2 How do ecosystems respond to environmental change and affect the global carbon cycle? R.3 Will climate variations induce major changes in the deep ocean? R.4 How do stratospheric trace constituents respond to climate change and chemical agents? R.5 Will changes in polar ice sheets cause a major change in global sea level? R.6 What are the effects of regional pollution on the global atmosphere, and the effects of global chemical and climate changes on regional air quality? Consequences of Global Changes C.1 How are variations in local weather, precipitation and water resources related to global climate change? C.2 What are the consequences of land cover and land use change? C.3 To what extent are changes in coastal regions related to climate change and sea-level rise? Global Change Prediction or Assessments P.1 To what extent can weather forecasting be improved by new global observations and advances in satellite data assimilation? P.2 To what extent can transient climate variations be understood and predicted? P.3 To what extent can long-term climatic trends be assessed or predicted? P.4 To what extent can future atmospheric chemical impacts be assessed? P.5 To what extent can future atmospheric concentrations of carbon dioxide and methane be predicted? 3. OBSERVATION STRATEGY AND IMPLEMENTATION CONSIDERATIONS Studies of variability and long-term trends in the components of the Earth system (including weather and climate, hydrologic variables, the distribution of atmospheric and oceanic trace constituents, natural and managed ecosystems) obviously depend upon the scope, quality, and long-term accuracy/consistency of available observational data records. Consequently, this

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 topic of observational requirements has been discussed in every one of the recent NRC reports listed here, and many earlier reports. The relevant recommendations are quoted below: Recommendation 3 on the Observational Strategy (CGCR, 1999): Reassess the strategy for obtaining long-term observations to define the character and magnitude of Earth system changes and give priority to identifying and obtaining accurate data on key variables selected in view of the most critical scientific questions and practical measurement capabilities, taking into account: The fact that observing systems have been designed for purposes other than long-term accuracy has undercut the long-term consistency needed for scientific understanding of global change. The overall balance between space-based and in situ observations, between operational and research observational systems, and between observation and analysis. The gaps between research and operational observation systems that could threaten needed long-term records. The end-to-end responsibility and the principal investigator mode for research observational projects. Recommendation 4 on Technical Innovation (CGCR, 1999): The restructured strategy for Earth observation must more aggressively employ technical innovation. Resources should be reallocated from large, amalgamated space-based approach to a more agile, responsive ensemble of observations. Technological advances in small satellite systems, robotics, microelectronics, and materials must be exploited to establish a sound balance between in situ ground/ocean-based, airborne, and space-based observation. Innovative treatment of the nation's research aircraft capability, piloted and robotic is advised, The R. & A. component of the effort must be recognized for its central contributions to science, public policy, and understanding of human-dimension issues. First Imperative for Atmospheric Research (BASC, 1998b): Optimize and integrate atmospheric and other Earth observation, analysis, and modeling systems. The atmospheric science community and relevant federal agencies should develop a specific plan for optimizing global observations of the atmosphere, oceans, and land. This plan should take into account requirements for monitoring weather, climate, and air quality, and for providing the information needed to improve predictive numerical models used for weather, climate atmospheric chemistry, air quality, near-Earth space physics activities. The process should involve a continuous interaction between research and operational communities and should delineate critical scientific and engineering issues. Proposed configurations of the national and international observing system should be examined with the aid of observing system simulation experiments. Second Imperative for Atmospheric Research (BASC, 1998b): Develop new observation capabilities. The federal agencies involved in atmospheric science should commit to a strategy, priorities, and a program for developing new capabilities for observing critical variables, including water in all its phases, wind, aerosols and chemical constituents, and variables related to phenomena in near-Earth space, all on spatial and temporal scales relevant to forecasts and applications. The possibilities for obtaining such observations should be considered in studying the optimum observing systems of Imperative 1.

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 Findings and Recommendation (CRC, 1999): There has been a lack of progress made by federal agencies responsible for climate observing systems, individually and collectively, in developing and maintaining a credible, integrated climate observing system, consequently limiting the ability to document adequately climate change. To remedy this situation, it is essential that these agencies work through the USGCRP process and higher government levels to accomplish the following actions: Stabilize existing observational capability. Identify critical variables that are either inadequately or not measured at all. Build climate observing requirements into operational programs as a high priority. Revamp climate research programs and some climate-critical parts of operational observing programs (through implementation of the "ten principles" for climate observation.iii Establish a funded activity for the development, implementation, and operation of climate-specific observational programs. Conclusion and Recommendations (CHS, 1999): Integrated satellite, ground network, and information management program. Recommendation 2.1: Develop effective measurement and data strategies for the terrestrial component of the water cycle, incorporating the need for detecting change as well as factors related to operational forecasting and process-level research in the design of new instrumentation. Recommendation 2.2: Study data and measurement strategies to recover and archive hydrologic data, make data available. Recommendation 2.3: Assess the current state of, and need for long-term experimental sites. Recommendation (CRC, 1999a): Initiate a research program designed to increase understanding of climate variability on dec-cen time scales, and determine predictability, and represent a balance between the following elements: A long-term stable observing system to constantly monitor, with sufficient accuracy and resolution, a subset of crucial Earth system variables (i. e. key state variables and primary forcings). A modeling activity should be an integral part of this system to add value to the observations by assimilating them into suitable models. A hierarchical program of modeling studies. Process studies. Long-term proxy data records and instrumental datasets. Priorities for observations of U.S. Global Ocean Observing System activities (OSB, 1997) Recommend that a small number of major efforts of highest priority be selected for immediate implementation: Converting relevant parts of the TOGA research observing system to operational status. Maintaining and improving global measurements of absolute and relative sea-level, surface wind stress, sea-ice extent and concentration, and satellite altimetry missions. Maintaining and improving the monitoring of global sea surface temperature and salinity, upper-ocean thermal and salinity structure, and temperature/salinity profiles at select deep-ocean sites… …and, Supporting the acquisition and processing of satellite ocean color data.

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 Consistency of systematic observations NASA is not "responsible for climate observing systems", as referred to by the NRC Climate Research Committee in its report on the Adequacy of Climate Observing System (CRC, 1999). Nonetheless NASA made the commitment, as part of its participation in the U.S. Global Change Research Program, to make the technology investments that will result in preserving the long-term continuity of key space-based measurements of the Earth system (while not to any specific instrument or spacecraft design). For this reason, the ESE takes seriously the concerns of the scientific community, expressed in the above recommendations, regarding the continuity and consistency of long-term observational records. The ESE Earth Observing System (EOS) initiative is a major development effort of the Agency to provide a wide range of global environmental data sets of unprecedented quality and accuracy, based on comprehensive on-board calibrationiv and intercomparison with other (aircraft- or surface-based) measurements, as well as thoroughly validated algorithms for data processing and retrieval of geophysical, chemical or biological information. The Enterprise is committed to making the required further investments for calibration/validation and scientific analysis of the raw measurements now being acquired by the EOS missions, as well as the necessary investments to pass this scientific and technical heritage to the operational organization – principally the Integrated Program Office for the National Polar-orbiting Operational Environmental Satellite System (NPOESS) – which has responsibility for maintaining the same measurement capabilities in the future. The ESE has selected a set of key environmental variables that have the highest significance for identifying global-scale changes in the major components of the Earth system or documenting critical forcings (atmospheric temperature and humidity fields, global precipitation, sea surface temperature, ocean winds, ocean circulation and extent of sea ice, the mass balance of ice sheets, land cover and land use, primary productivity of terrestrial and oceanic ecosystems, stratospheric ozone and related trace constituents, solar radiation, distribution of aerosols). The ESE has taken effective steps to ensure adequate continuity and consistency of these measurements, either directly through NASA-sponsored satellite missions and supporting ground-based measurements (e. g. global aerosols), or through cooperation with other research or operational space agencies (e. g. ocean surface winds in cooperation with Japan), or both. Transition to operational agencies NASA's long-term objective of ensuring the continuity of key global environmental data records calls will be served primarily by enlisting the cooperation of operational environmental agencies, particularly operational satellite operating agencies such as NOAA and comparable foreign partners (e. g. EUMETSAT in Europe) to take charge for the relevant research-quality measurements. NASA recognized that pursuing this goal requires significant investments in technology and instrument development to enable the incorporation of new, higher performance sensors in operational systems. NASA also recognized that the active involvement of cognizant scientists in the development and validation of geophysical (chemical, biological) information retrieval algorithms is also essential to ensure the scientific integrity of the products. In this context, NASA is participating with NPOESS in the development of the NPOESS Preparatory Project (NPP), a "bridging" mission that will provide continuity for EOS Terra moderate-resolution imaging spectroradiometer measurements and EOS Aqua atmospheric soundings during the period between the end of these two EOS missions and the first operational NPOESS mission. As a result, both the NPP mission and future operational

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 NPOESS missions take into account the need for accurate on-board sensor calibration procedures and precise orbit maintenance (thus eliminating the orbit-drift problem encountered with the earlier generation of polar operational environmental satellites). NPP will carry prototypes of future operational moderate-resolution multispectral imagers/radiometers and infrared atmospheric sounders developed by NPOESS, as well as an advanced technology microwave atmospheric sounder developed by NASA to replace the current AMSU/HSB sensors on EOS Aqua and operational NOAA satellites. Together, NPP and NPOESS will ensure the continuity of all EOS atmospheric sounding and moderate-resolution imaging functions, with the possible exception of the full range of ocean color measurements. In addition, NASA is developing a prototype sensor for accurate monitoring of solar radiation (Total/Spectral solar Irradiance Monitor) and is participating in the conception of the Ozone Mapping and Profiling Suite (OMPS) being developed by the NPOESS program to routinely measure the distribution of stratospheric ozone. The prototype solar irradiance monitor (TSIM) will be the main radiometer sensor on the NASA SORCE mission to continue monitoring solar radiation after the current ACRIMSat mission. Likewise, the principle of ozone UV limb sounding, to be used in the OMPS, was demonstrated by NASA on a Space Shuttle experiment. A similar transition from research observation programs to operational is being pursued, albeit more progressively, for maintaining long-term measurements of ocean topography (closely linked to the upper-ocean circulation) through a series of dedicated altimetric satellite missions on the optimum TOPEX/Poseidon inclined orbit, realized in cooperation with NOAA and international partners, as a contribution to the deployment of a permanent space-based and in situ Integrated Ocean Observing System. More Agile Research Missions The development and demonstration of innovative new technologies to reduce the cost for implementing existing measurements or enable new measurements is a major objective of the NASA Earth Science Enterprise. Already in 1996, NASA undertook the development of lighter and/or improved imaging radiometer designs to replace the Thematic Mapper instrument on the Landsat satellite series and maintain global observation of land cover and land use (a very significant forcing factor of climate and the global environment) after Landsat-7. These innovative techniques will be tested on the New Millennium Program EO-1 mission (year 2000). The NASA New Millennium Program (NMP) and the ESE Earth System Science Pathfinder (ESSP) program are the pathways through which the ESE promotes more agile procedures for the conception and realization of new, more focused satellite missions that will enable the scientific breakthroughs of the next decade. The first two ESSP missions, the Vegetation Canopy Lidar (VCL) project and the Gravity Recovery and Climate Experiment (GRACE), will demonstrate two novel remote sensing techniques. VCL will be the first global application of an active lidar sensor to probe the vertical structure of a major component of the Earth environment, in this case the vegetation canopy. In addition to accurate determination of the geoid, the GRACE will test the capability to measure from space minute changes in the Earth gravity field which reveal transient changes in the distribution of mass (notably water masses) at or near the Earth surface. The next two ESSP missions PICASSO-CENA and Cloudsat will use microwave and optical active profiling sensors to probe the structure of non-precipitating clouds and atmospheric aerosol layers over a very broad range of optical depths, leading to much more accurate

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 determination of cloud and aerosol particle properties and, in conjunction with EOS Aqua, a precise determination of the impact of water in all three phases on the Earth energy balance. The NMP Geostationary Infrared Fourier Transform Spectrometer demonstration mission marks the renewed interest of NASA in developing the sensory capabilities of geostationary orbital platforms to investigate the structure of organized weather systems and their relationship to changes in the general circulation. Advanced Technology Upstream investments in innovative measurement methods at a lower level of technological readiness are conducted under the NASA Core Technology Program and the ESE Instrument Incubator Program, aiming to develop new airborne and space-based remote sensing capabilities for the future (e. g. advanced microwave aperture synthesis and radar systems to probe the moisture content of soils, advanced Doppler lidar systems to directly measure tropospheric winds in clear air, advanced differential absorption lidars to probe the composition of the lower troposphere, or advanced gravity sensors to detect the gravitational signature of changes in the Earth global environment). These investments are expected to enable, in particular, a major step forward in global measurement of hydrologic variables such as global precipitation, continent-scale soil moisture, ground freeze-thaw transitions, snow water equivalent, stage height of large rivers and inland water bodies. These development are meant to support the "global hydrology" component of a new Global Water Cycle Research initiative, now being planned by the USGCRP at the behest of the NRC Committee on Global Change Research (CGCR, 1999) and Committee on Hydrologic Science (CHS, 1999). 4. DATA SYSTEMS Both the Pathways report (CGCR, 1999) and the report on the Adequacy of Climate Observing Systems (CRC, 1999) highlights the importance of convenient access to available data sets by the broad community of scientific investigators (not necessarily involved in data acquisition themselves) and the crucial need for effective data management and dissemination systems. Recommendation 5 on Data Systems (CGCR, 1999) The USGCRP must revitalize its strategy for data systems used in global change research. Emphasis must be placed on designing and selecting flexible and innovative systems that appropriately reflect focused responsibility for data character, provide open access to the scientific community and the public, and rapidly evolve to exploit technological developments. 45 NASA has invested considerable resource and time in developing and implementing a comprehensive EOS Data & Information System (EOSDIS) that integrates flight operations, data acquisition, processing, archiving and distribution functions for the EOS program. This system is currently fulfilling the EOS program requirements for the first series of EOS missions. In view of the complexity of the task, this dedicated EOSDIS was developed over a number of years, on the basis of state-of-the-art technology at the inception of the project. The long-term evolution of the ESE data system toward one that makes increasing use of new technologies and 45   NOTE: The last sentence of the recommendation was omitted. It reads, “In particular, the USGCRP must closely monitor the progress of the innovative ‘federation' concept for data systems.”

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 architecture is currently being addressed. The development effort is conducted by the Project Implementation segment of the ESE and is not specifically discussed by the NASA Earth Science Research Strategy. 5. EARTH SYSTEM MODELS Numerical modeling is an essential tool of Earth system science and a pervasive concern in Global Change Research, as emphasized by the Pathways report (see Box below) and other NRC documents. Recommendation 6 on Earth System Modeling (CGCR, 1999) The USGCRP must foster the development and application of at the space and time scales needed to understand and project the mechanisms controlling changes in the state of Earth system, thus providing the information required to support policy processes. The USGCRP must give increased emphasis to models that treat multiple stresses on systems. It must secure adequate computing resources so that large-scale, complex models can be rigorously tested under multiple forcings. The ESE is fully aware of this importance of this activity and the need for adequate computing facilities in order to pursue it effectively. NASA is a significant user of state-of-the-art computer facilities and looks to enhancing its capabilities in this domain to run advanced Earth system models and data assimilation systems, in the context of evolving computer hardware and software. The NASA Earth Science Enterprise is supporting principally three major global modeling and data assimilation efforts at the Goddard Institute for Space Studies and the Goddard Space Flight Center (and a focused global ocean circulation data assimilation project at the Jet Propulsion Laboratory). NASA recognizes that advances in computer technology will enable and drive future developments in Earth system modeling, especially models that embrace a wide enough range of spatial and temporal scales to explicitly simulate the dynamical connections between different natural categories of phenomena, from changes in the atmospheric circulation and climate to organized weather systems, to the dynamics of individual convective clouds, and eventually microscale physical, hydrological, chemical, and biological processes. Progress along this path will call for progressively more realistic representations of linkages between different types of Earth system processes, and increased emphasis on the physics, chemistry, biology of microscale processes. To this effect, the NASA strategy promotes synergy between model and experimental research. and the direct participation of process modelers in the conception and implementation of relevant observational studies in the field or from space. A hallmark of the ESE modeling strategy is an emphasis on testing or verifying model results against observations of the global Earth system. NASA will support preferentially model developments that can routinely exploit the information collected by NASA global observing systems and utilize modern data assimilation systems similar in purpose to those used today for numerical weather prediction. NOTES i Biology and Biogeochemistry of Ecosystems, Change in the Climate System on Seasonal-to-Interannual and Decadal-to-Centennial Timescales, Change in the Chemistry of the Atmosphere.

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 ii NASA measurements shown in italic are not highlighted as high priority requirements in the quoted NRC report focused on climate science and impacts. iii Ten principles for climate observation: Management of network changes: assess the impact of changes Parallel testing of new system with the old. Metadata: document each observing system and its operating procedures. Data quality and continuity: assess data quality and homogeneity as part of normal operation. Integrated environmental assessment: anticipate requirements for climate monitoring. Historical significance; maintain observing systems that have provided homogeneous data for long periods. Complementary data: give priority to data-poor regions, poorly observed variables, active regions. Climate requirements: introduce climatological requirements at the outset of network design. Continuity of purpose: maintain stable, long-term commitment to climate-related observations. Data and metadata access: develop data management systems to facilitate access, use, and interpretation of data. iv See, for example, the special issue of the Journal of Atmospheric and Oceanic Technology on the calibration of EOS instruments (JAS, vol. 13, pp. 273-399, 1996). LIST OF REFERENCES BASC, 1998a: Decadal-to-Century Scale Climate Variability and Change: A Science Strategy; National Research Council, Board on Atmospheric Sciences and Climate, Panel on Climate Variability on Decadal-to-Century Time Scales. BASC, 1998b: The Atmospheric Sciences Entering the 21st Century; National Research Council, Board on Atmospheric Sciences and Climate CGCR, 1995: A Review of the U.S. Global Change Research Program and NASA's Mission to Planet Earth; National Research Council, Committee on Global Change Research. CGCR, 1999: Global Environmental Change: Research Pathways for the Next Decade ; National Research Council, Committee on Global Change Research. CHS, 1999: Hydrologic Science Priorities for the U.S. Global Change Research Program; National Research Council, Board on Atmospheric Sciences and Climate and Water Science and Technology Board, Committee on Hydrologic Science CRC, 1998a: A Scientific Strategy for U.S. Participation in the Global Ocean-Atmosphere-Land System (GOALS) Study; National Research Council, Board on Atmospheric Sciences and Climate, Climate Research Committee. CRC, 1998b: Capacity of U.S. Climate Modeling to Support Climate Change Assessment Activities; National Research Council, Board on Atmospheric Sciences and Climate, Climate Research Committee.

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Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010 CRC, 1999: Adequacy of Climate Observing Systems; National Research Council, Board on Atmospheric Sciences and Climate, Climate Research Committee. CRC, 2000: Reconciling Observations of Global Temperature Change; National Research Council, Board on Atmospheric Sciences and Climate, Climate Research Committee. OSB, 1997: The Global Ocean Observing System; National Research Council, Ocean Studies Board. OSB, 1999: From Monsoons to Microbes, Understanding the Ocean's Role in Human Health; National Research Council, Ocean Studies Board. USGCRP, 2000: U. S. Carbon Cycle Science Plan, U.S. Global Change Research Program Office, Washington, DC.