Ensuring the Climate Record from the NPOESS and GOES-R Spacecraft: Elements of a Strategy to Recover Measurement Capabilities Lost in Program Restructuring (2008)

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1 Context NPOESS AND GOES-R IN RELATION TO CLIMATE RESEARCH The nation’s next-generation National Polar-orbiting Operational Environmental Satellite System (NPOESS) was created by the Presidential Decision Directive/National Science and Technology Council (NSTC)-2 of May 5, 1994, that merged the military and civil meteorological programs into a single program.  Within NPOESS, the National Oceanic and Atmospheric Administration (NOAA) is responsible for satellite operations, the Department of Defense (DOD) is responsible for major acquisitions, and the National Aeronautics and Space Administration (NASA) is responsible for the development and infusion of new technologies. In 2000, the NPOESS program anticipated purchasing six satellites for $6.5 billion, with a first launch in 2008. However, by November 2005, it had become apparent that NPOESS would overrun its cost estimates by at least 25 percent, triggering a so-called Nunn-McCurdy review by the DOD. In June 2006, a restructured—Nunn-McCurdy “certified”—NPOESS program was announced. Among the most important changes to the NPOESS program (see Figures 1.1 and 1.2) were the following: • The planned acquisition of six spacecraft was reduced to four. • The planned use of three Sun-synchronous orbits was reduced to two, with data from the European Meteorological Operational (MetOp) satellites provided by the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) providing data for the canceled mid-morning orbit. • The launch of the first spacecraft, NPOESS C1, was delayed until 2013. • Several sensors were canceled or descoped in capability as the program was refocused on “core” require- ments related to the acquisition of data to support numerical weather prediction. “Secondary” (non-core) sensors that would provide crucial continuity to certain long-term climate records, as well as other sensors that would have provided new measurement capabilities, are not funded in the certified NPOESS program.  Presidential Decision Directive/NSTC-2, “Convergence of U.S.-Polar-Orbiting Operation Environmental Satellite Systems” May 5, 1994.   Available at http://www.ipo.noaa.gov/About/NSTC-2.html. See U.S. House of Representatives Committee on Science, Hearing Charter, “The Future of NPOESS: Results of the Nunn-McCurdy Review   of NOAA’s Weather Satellite Program,” June 8, 2006, available at http://gop.science.house.gov/hearings/full06/June%208/charter.pdf. The NPOESS certified program now includes the following sensors: Visible/Infrared Imager/Radiometer Suite (VIIRS); Microwave Im-   ager/Sounder (MIS); Search and Rescue Satellite Aided Tracking (SARSAT); Cross-track Infrared Sounder (CrIS); Advanced Technology Microwave Sounder (ATMS); Advanced Data Collection System (ADCS); Clouds and Earth’s Radiant Energy System (CERES); Ozone 10 

CONTEXT 11 FIGURE 1.1  The NPOESS Preparatory Project and NPOESS program summary prior to the June 2006 Nunn-McCurdy program review and revisions. With the exception of CrIS, ATMS, and SESS, all key operational instruments, including SARSAT and ADCS, were intended to be flown on all three orbits. Climate and research-oriented sensors were generally designated a spot on a single satellite at any one time. The overall NPOESS constellation was designed as a stand-alone system, with the European series of MetOp satellite viewed as a separate, independent, complementary system. SOURCE: Courtesy of NOAA. Costs for NOAA’s next generation of geostationary weather satellites, GOES-R, had also risen dramati- cally, and in September 2006 NOAA canceled plans to incorporate a key instrument on the spacecraft—HES (Hyperspectral Environmental Suite). HES consisted of two components: an advanced hyperspectral sounder and a coastal waters imager. The hyperspectral sounder was intended to greatly advance current operational geosta- tionary sounding capability; its cancellation will instead end the long-term geostationary sounding record started by GOES-I. The coastal waters imager component was planned primarily to benefit coastal monitoring, manage- ment, and remediation applications. The complexity associated with combining both the hyperspectral sounding and the coastal waters imagery components into a single instrument is frequently cited as the key factor affecting programmatic risk for GOES-R. In this report, the ad hoc Committee on a Strategy to Mitigate the Impact of Sensor Descopes and Demanifests on the NPOESS and GOES-R Spacecraft reviews these recent changes to the NPOESS and GOES-R program and, as requested by NASA and NOAA (see Appendix A): 1. Prioritizes capabilities, especially those related to climate research, that were lost or placed at risk fol- lowing recent changes to NPOESS and the GOES-R series of polar and geostationary environmental monitoring satellites; and 2. Presents strategies to recover these capabilities. In preparing this report, the committee drew heavily on information gathered at a 3-day National Research Council (NRC) workshop, “Options to Ensure the Climate Record from the NPOESS and GOES-R Spacecraft,” Mapping and Profiler Suite (OMPS)-Nadir; and the Space Environment Monitor (SEM). The certified program does not fund the following sensors: Aerosol Polarimetry Sensor (APS), Total Solar Irradiance Sensor (TSIS); OMPS-Limb; Earth Radiation Budget Sensor (ERBS); Altimeter (ALT); Survivability Sensor (SuS); and Full Space Environment Sensors (SESS). At the time the Nunn-McCurdy certified program was announced, it was also stated that the program would plan for and fund the integration of the demanifested sensors onto the satellite buses, if the sensors were provided from outside the program. 

12 ENSURING THE CLIMATE RECORD FROM THE NPOESS AND GOES-R SPACECRAFT FIGURE 1.2  The NPOESS Preparatory Project and NPOESS program summary following the Nunn-McCurdy program re- view and revisions (status as of October 2006). The mid-morning satellite coverage will be provided by the European MetOp satellite series, with descoped NPOESS satellites covering the early morning and afternoon orbits. Instruments removed from the core NPOESS program plan can be integrated and flown if outside funding will support the remaining development costs, as well as the cost of the instrument and its support. The canceled CMIS sensor will be replaced by a sensor now known as MIS. Although its specifications are not yet known, MIS will by design be a less expensive instrument with less developmental risk. SOURCE: Courtesy of NOAA. held in June 2007 in Washington, D.C. (referred to in this report as the June 2007 workshop). The NRC report on that workshop (NRC, 2008) is reprinted in Appendix B. For convenience, the issues that were of particular concern to workshop participants are reprinted in Box 1.1. INPUT FROM NASA AND NOAA Among the key inputs to the NRC’s June 2007 workshop were presentations by NASA and NOAA offi- cials, especially “Mitigation Approaches to Address Impacts of NPOESS Nunn-McCurdy Certification on Joint NASA-NOAA Climate Goals,” which was derived from a NASA-NOAA draft report, “Impacts of NPOESS Nunn-McCurdy Certification on Joint NASA-NOAA Climate Goals,” referred to below as the NASA-NOAA study. The authors of the NASA-NOAA draft report envisioned a multistep study process that would lead to a Available at http://www7.nationalacademies.org/ssb/NPOESSWorkshop_Cramer_NRC_06_19_07_final.pdf and also reprinted in Appendix   C of the June 2007 workshop report. A final version of the NASA-NOAA report has not been released; a widely cited December 11, 2006, draft was posted by Climate Science   Watch at http://www.climatesciencewatch.org/file-uploads/NPOESS-OSTPdec-06.pdf. 

CONTEXT 13 NASA-NOAA roadmap by the end of 2007. Unfortunately, that work had not been completed as of the time this committee’s report went to press, nor were drafts or conclusions of the study made available to the committee (because of those conclusions’ connection to information embargoed pending announcement of the President’s fiscal year 2009 budget). By design, the NASA-NOAA study focused narrowly on impacts of the Nunn-McCurdy NPOESS program certification on two climate-research-related objectives: 1. Flight of critical climate sensors that had been planned for NPOESS and that represent the continuation of NASA’s Earth Observing System (EOS) capabilities, and 2. Flight of those sensors that represent a fundamental contribution to NOAA’s climate mission and that include both heritage satellite and in situ observing systems. However, as stated in the NASA-NOAA draft report itself, the analysis did not consider the agencies’ broader mandates, nor did it consider international contributions beyond those already identified in the European MetOp (Meteorological Operational satellite) program. In addition, the analysis focused primarily on options to remanifest sensors on NPOESS or on free-flyer spacecraft, with less attention given to options to mitigate the impacts of de- scoping of the remaining sensors, or to the impacts resulting from elimination of the originally planned NPOESS mid-morning orbit. The authors of the NASA-NOAA report completed their initial work prior to the January 2007 release of the NRC decadal survey report Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond (NRC, 2007); consequently, they could not analyze either the potential contributions of survey-recommended missions or the potential to remanifest certain sensors on survey-recommended spacecraft. In October 2007, NASA, NOAA, and Integrated Program Office representatives briefed the committee to provide updates on the status of the various instruments and study activities.  However, the results of preliminary studies undertaken by the agencies to examine the feasibility of remanifesting selected NPOESS sensors on future decadal-survey-recommended missions were not made available to the committee. Further, the specifications for a key instrument, the Microwave Imager and Sounder (MIS), had not yet been announced at the time the present report went to press. These information gaps did not detract from the committee’s science-based prioritization of the climate research capabilities to be recovered from those lost as a result of NPOESS program restructuring; however, they obviously restricted the committee’s analysis of mitigation strategies. ONGOING COMMUNITY CONCERN It is important to note that community concerns about the adequacy of NPOESS for climate research existed even before the 2006 program restructuring, as is evident, for example, in the NRC decadal survey on Earth sci- ence and applications from space (NRC, 2007), which includes the following statement (at p. 263) from the Panel on Climate Variability and Change: Regardless of the descoping, the NPOESS program lacks essential features of a well-designed climate-observing system: • NPOESS lacks a transparent program for monitoring sensor calibration and performance and for verifying the products of analysis algorithms. Moreover, it lacks the direct involvement of scientists who have heretofore played a fundamental role in developing climate-quality records from space-borne observations. NOAA has initiated plans for scientific-data stewardship (NRC, 2004b), but the plans are in their infancy, and NOAA’s commitment to ensuring high-quality climate records remains untested and inadequately funded (NRC, 2005). At the committee’s October 2007 meeting, Bryant Cramer (NASA) and Michael Tanner (NOAA) provided an update on the NOAA-NASA   remanifesting study, James Gurka (NOAA) provided an update on GOES-R HES recovery status, Stanley Schneider (NPOESS IPO) and Karen St. Germain (NPOESS IPO) provided updates on recent NPOESS program developments, and Jeffrey Privette (NOAA) discussed Climate Data Record generation activities. At the committee’s December 2007 meeting, Maj. Christopher Brann (NPOESS IPO) and David Kunkee (Aerospace Corp.) briefed the committee on MIS procurement and status. 

14 ENSURING THE CLIMATE RECORD FROM THE NPOESS AND GOES-R SPACECRAFT BOX 1.1 Summary of Issues Noted by June 2007 Workshop Participants • Preservation of long-term climate records.  Many participants noted that the demanifesting of climate sensors from NPOESS has placed many long-term climate records at risk, including multidecadal records of total solar irradiance, Earth radiation budget, sea surface temperature, and sea ice extent. Some of these most fundamental data records require observational overlap to retain their value and require immediate attention to ensure their continuation. To ensure continuity of critical long-term climate measurements, many participants also stressed the need to pursue international partnerships and, when feasible, the leveraging of foreign Earth observation missions. • The potential benefits of relatively minor and low-cost changes to the NPOESS program.  In several cases, a workshop participant suggested small nonhardware changes to NPOESS that could address areas of climate interest. Such changes included improving prelaunch characterization and documentation of all NPOESS instru- ments, adding minor software improvements to VIIRS1 to make the data more climate-relevant, and downlinking full-resolution spectral data from the Cross-track Infrared Sounder (CrIS)2 to enable creation of additional climate products. • The potential role of spacecraft formation flying in mitigation strategies.  Formation flight can allow for the synergistic combination of measurements from multiple satellites, sometimes launched years apart. To allow for subsequent formation flight with NPOESS platforms, some participants suggested consideration of the requisite orbit maintenance and operations requirements as part of the mitigation strategy for restoring deleted NPOESS and GOES-R climate observing capabilities. • Mitigation options beyond changes to NPOESS.  While particular long-term records can be secured via the remanifesting of certain sensors onto NPOESS, many participants noted that requirements for several could not be addressed even with the original suite of NPOESS instruments. Long-term records of sea level and ocean vector winds, for example, require different orbits and/or instruments to address critical climate observation needs. As a result, some participants heavily favored dedicated altimetry and scatterometry missions to fill this need. Further, some participants noted the critical importance of hyperspectral sounder measurements to climate science, suggesting restoration of CrIS/ATMS to the early-morning NPOESS orbit as well as the earli- est-possible flight of a geostationary hyperspectral sounder to further improve temporal resolution. • The challenge of creating climate data records.  Although NPP- and NPOESS-derived environmental data records (EDRs) may have considerable scientific value, climate data records (CDRs)3 are far more than a time series of EDRs. Many participants at the workshop emphasized the fundamental differences between products that are generated to meet short-term needs (EDRs) and those for which consistency of processing and repro- cessing over years to decades is an essential requirement (CDRs). Creation and maintenance of CDRs require • NPOESS does not ensure the overlap that is required to preserve climate data records (CDRs). Instead, the NPOESS system is designed for launch on failure of a few key sensors. Failure of NPOESS instruments required for CDRs will probably result in gaps of many months, which will make it difficult to connect long-term climate records and future measurements. • The NPOESS commitment to radiometric calibration is unclear, particularly for the VIIRS visible and near-infrared channels used to determine surface albedo, ocean color, cloud properties, and aerosol properties. VIIRS may be flown as the NOAA AVHRRs were flown, with only preflight calibrations, leaving the in-orbit calibrations of those channels to drift. Furthermore, in its current configuration, VIIRS lacks the channels now on MODIS in the 6.7-µm band of water vapor used to detect winds in polar regions and in the 4.3- and 15-µm bands of CO 2 used to obtain cloud heights, particularly heights of relatively thin cirrus. • NPOESS only partly addresses the needed measurements of the stratosphere and upper troposphere. The primary variables of the stratosphere—temperature, ozone abundance, and some aerosol properties—will not be provided 

CONTEXT 15 algorithms, data-handling systems, calibration/validation, archival standards, access protocols, and prelaunch characterization that are different from those for operational data products. • The specifications of the MIS instrument.  The specifications of the MIS (Microwave Imager and Sounder) instrument on NPOESS, which is to replace the now canceled CMIS (Conical Microwave Imager and Sounder) instrument, were not known at the time of the workshop. Thus, participants were unable to fully analyze miti- gation options. In addition, several participants warned about the consequences of not having an all-weather sea surface temperature retrieval capability, emphasizing the importance of retaining a low-frequency 6.9 GHz channel as the instrument is reconsidered. • Sustaining climate observations.  In the view of many participants, the loss of climate observations from NPOESS is of international concern and also imperils U.S. climate science leadership. Further, many partici- pants noted that discussions at the workshop were focused on solving near-term climate measurement continu- ity issues, but that there would remain a longer-term problem of sustaining support for climate science. Issues noted included finding an appropriate balance between new and sustained climate observations and manag- ing infusion of technology into long-term observational programs (including the challenges of doing so with a multi-spacecraft—block-buy—procurement). Workshop discussions also included what many participants cited as a key challenge: accommodating research needs within an operational program. Some participants argued that the relative priority of climate measurement needs would have to be heightened across the implementing agencies if climate and operational weather functions remain combined. Their concern was that in exploiting the commonalities of weather and climate observations, the unique needs of climate scientists would be overlooked. The perceived lack of attention to climate science needs within the Integrated Program Office, particularly cali- bration and validation requirements, led many participants to favor free-flyer options over integration with the NPOESS platforms. The Visible/Infrared Imager/Radiometer Suite (VIIRS) collects visible/infrared imagery and radiometric data. A key sensor 1 on the NPOESS spacecraft, VIIRS contributes to 23 environmental data records (EDRs) and is the primary instrument asso­ ciated with 18 EDRs. See description at http://www.ipo.noaa.gov/Technology/viirs_summary.html. 2 In conjunction with the Advanced Technology Microwave Sounder (ATMS), the Cross-track Infrared Sounder (CrIS) ­collects atmospheric data to permit the calculation of temperature and moisture profiles at high temporal (~daily) resolution. See discussion at http://www.ipo.noaa.gov/Technology/cris_summary.html. 3 See NRC, Ensuring the Climate Record from the NPP and NPOESS Meteorological Satellites, National Academy Press, Washington, D.C., 2000, and NRC, Climate Data Records from Environmental Satellites: Interim Report, The National Acad- emies Press, Washington, D.C., 2004. SOURCE: NRC (2008), pp. 2-3. by NPOESS, because of the loss of OMPS-Limb, APS, and CrIS/ATMS. Other elements are poorly addressed by NPOESS plans, notably measurements of upper-troposphere and stratosphere water vapor, aerosols, and the abundance of ozone-depleting compounds. Perhaps the most important limitation of the NASA-NOAA study is its focus on near-term solutions to what are, in fact, structural problems associated with the provision of climate-quality measurements from systems designed to meet national objectives more closely associated with the needs of the operational weather forecast community. As discussed below in this report, and as noted repeatedly by participants in the June 2007 workshop, restoration of certain measurement capabilities is a necessary, but far from sufficient, step in a program to create climate-quality data records from satellite observations. The unique needs of the climate community have been discussed in many NRC reports (NRC, 2000a,b, 2004a,b, 2007, 2008). The problem of ensuring climate data re- 

16 ENSURING THE CLIMATE RECORD FROM THE NPOESS AND GOES-R SPACECRAFT cords is embedded in larger issues of how to improve what has historically been a difficult and unpredictable path to transition NASA research capabilities to operational use (NRC, 2003). As noted in congressional testimony by a co-chair of the 2007 Earth Science and Applications from Space decadal survey: There is a lack of clear agency responsibility for sustained research programs and the transitioning of proof-of-concept measurements into sustained measurement systems. To address societal and research needs, both the quality and the continuity of the measurement record must be assured through the transition of short-term, exploratory capabilities, into sustained observing systems. The elimination of the requirements for climate research-related measurements on NPOESS is the most recent example of the failure to sustain critical measurements.  REFERENCES NRC (National Research Council). 2000a. Issues in the Integration of Research and Operational Satellite Systems for Climate Research: Part I. Science and Design. National Academy Press, Washington, D.C. NRC. 2000b. Issues in the Integration of Research and Operational Satellite Systems for Climate Research: Part II. Implementation. National Academy Press, Washington, D.C. NRC. 2003. Satellite Observations of the Earth’s Environment: Accelerating the Transition of Research to Operations. The National Academies Press, Washington, D.C. NRC. 2004a. Climate Data Records from Environmental Satellites: Interim Report, The National Academies Press, Washington, D.C. NRC. 2004b. Utilization of Operational Environmental Satellite Data: Ensuring Readiness for 2010 and Beyond. The National Academies Press, Washington, D.C. NRC. 2005. Earth Sciences and Applications from Space: Urgent Needs and Opportunities to Serve the Nation. The National Academies Press, Washington, D.C. NRC. 2007. Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond. The National Academies Press, Washington, D.C. NRC. 2008. Options to Ensure the Climate Record from the NPOESS and GOES-R Spacecraft: A Workshop Report. The National Academies Press, Washington, D.C. Testimony of Richard A. Anthes before the Subcommittee on Space and Aeronautics Committee on Science and Technology, U.S. House   of Representatives, June 28, 2007.