Long-Term Sustained Observations for Climate
An important additional theme in NASA-NOAA collaboration arises from the need for long-term sustained observations of climate. A climate data record may be defined as “a time series of measurements of sufficient length, consistency, and continuity to determine climate variability and change.”1 Notably, climate records require support beyond provision of the observations themselves through careful attention to prelaunch sensor characterization, calibration, archiving, and reprocessing (Box B.1). Climate data are revised, reprocessed, and improved based on incremental understanding of the sensors and their space environment, improved calibrations, and development of new algorithms.
By their very nature, climate data records require continual active stewardship by the research community. In contrast, data used in operational settings typically have a short shelf life, highlighting an inherent peril in any proposal to collect climate data records in the context of an operational activity. Providing the climate records that are necessary for documenting, understanding, and dealing with policy issues thus requires interagency collaboration whereby both NASA and NOAA (and other agencies with climate interest) continue to remain closely involved. Thus interagency collaboration here goes beyond a transfer of research to operations and, instead, requires continuing close collaboration.
The situation was well stated in a 2008 report from the National Research Council (NRC), Ensuring the Climate Record from the NPOESS and GOES-R Spacecraft: Elements of a Strategy to Recover Measurement Capabilities Lost in Program Restructuring:2
Much of climate science depends on long-term, sustained measurement records. Yet, as noted in many previous NRC and agency reports, the nation lacks a clear policy to address these known national and international needs. A coherent, integrated, and viable long-term climate observation strategy should explicitly seek to balance the myriad science and applications objectives basic to serving the variety of climate data stakeholders. The program should, for example, consider the appropriate balance between (1) new sensors for technological innovation, (2) new observations for emerging science needs, (3) long-term sustainable science-grade environmental observations, and (4) measurements that improve support for decision making to enable more effective climate mitigation and adaptation regulations. The various agencies have differing levels of expertise associated with each of these programmatic elements, and a long-term strategy should seek to capitalize on inherent organizational strengths where appropriate.
What Is a Climate Data Record?
Climate research and monitoring often require the detection of very small changes against a naturally noisy background. For example, sea surface temperatures can change by several kelvin (K) between daytime and nighttime or from year to year, whereas the climate signal of interest may change only 0.1 K over a decade. Moreover, changes in sensor performance or data processing algorithms often introduce changes greater than the climate signal. In addition to noise, spatial, temporal, and instrumental biases in the measurements confound climate researchers.
A climate data record (CDR) is a time series that tries to account for these sources of error and noise, producing a stable, high-quality data record with quantified error characteristics. A CDR is suitable for studying interannual to decadal variability. A CDR requires considerable refinement of the raw data, generally the blending of multiple data streams. These streams may come from multiple copies of the same sensor, or they may be ancillary data fields that are used to correct the primary data stream. Thorough analysis of sensor performance and improved processing algorithms are also required, as are quantitative estimates of spatial and temporal errors.
SOURCE: National Research Council, Ensuring the Climate Record from the NPP and NPOESS Meteorological Satellites, National Academy Press, Washington, D.C., 2000, available at http://www.nap.edu/catalog/12263.html, pp. 23-24.™
From the point of view of this report on interagency collaboration, it is clear that the elements of a strategy such as that proposed in Ensuring the Climate Record from the NPOESS and GOES-R Spacecraft must include clear agency roles and responsibilities, international coordination, an integrated approach across in situ and space-based observations, a systems design of the architecture for sustained climate observations, and community involvement in the development of climate data records. Due to the complexity of the systems and the multiple communities involved, some level of redundancy between agencies must be included. The establishment of clear roles for one agency should not be interpreted to preclude the other agency from pursuing activities that complement its mission.
There is recognition by the management of both NASA’s Earth Science Division and NOAA’s National Environmental Satellite Data and Information Service (NESDIS) that sustained and improved measurements are required to answer fundamental science and policy questions. This is reflected in NASA’s practice of extending missions (e.g., TOPEX/Poseidon) past their performance period if they are providing scientific data and in NOAA’s support of long-term observations relevant to climate and the production of climate data records. However, NASA’s lack of funding and institutional interest to launch new instruments to continue existing measurement records and the lack of funding and expertise within NOAA to take on this responsibility are already affecting the continuity of climate data. NOAA, NASA, and other involved agencies have not yet come to agreement on how both operational and sustained climate data are to be provided. In the committee’s view, a more systematic and sustained approach is warranted to facilitate NASA-NOAA collaborations. This might be achieved through a natural extension of the collaboration mechanisms already created under Section 306 of the 2005 NASA Authorization Act.3
Section 306, titled “Coordination with the National Oceanic and Atmospheric Administration,” of the NASA Authorization Act of 2005 provides that the NASA and NOAA Administrators “review and monitor missions of the two agencies to ensure maximum coordination in the design, operation, and transition of missions where appropriate.” In addition, section 306 calls for an evaluation of relevant NASA science missions for their potential operational capabilities and asks NASA and NOAA to “prepare transition plans for the existing and future Earth observing systems found to have potential operational capabilities.” The full bill, which became Public Law 109-155 on December 30, 2005, is available at http://www.gpo.gov/fdsys/pkg/PLAW-109publ155/pdf/PLAW-109publ155.pdf.
Earth observations in support of climate and global change research are an emerging national imperative that engages a number of federal agencies. However, high-level policy direction appears to be necessary to ensure that the high-precision measurements required by the climate research community are sustained along with the routine (operational) observations of weather-related variables. Drawing on a decade of previous NRC studies4 as well as its own experience, the committee found that:
This is a governance problem, not an issue of basic expertise. It is further challenged by conflicting agency aspirations, especially regarding new funding for specific research areas like climate studies.
A higher-level policy structure could prevent situations where agencies or contractors seek legislation to secure desired responsibilities and their associated funding.
There is a current lack of sufficient in-house expertise within NOAA/NESDIS to address the full range of issues required for sustained space-based climate monitoring as distinct from satellite observations to support the National Weather Program.
An efficient, long-term spaceborne environmental data acquisition system that has the ability to integrate new measurements could provide a framework for interagency collaboration. Such a data acquisition system currently does not exist, and no steps are being taken to develop it.
It may not be necessary or even desirable to have all the expertise in one agency; however, operational agencies should be aggressively involved from the outset in the technologies they need to have implemented and tested and should be responsible for providing resources that are commensurate with their needs.