Issues related to the development of a coherent national strategy for climate observations are addressed in this report in the context of a subset of measurements of demonstrable importance to climate research. With the emergence of NPOESS, the increased interest in NASA collaboration with operational agencies, and recognition of the importance of observations for climate research and policy, there is an opportunity to build the space-based component of a climate observing system. In collaboration with NASA, these requirements can be extended and refined so that it will be possible to begin to assemble credible time series of climate-related variables.
In Chapter 2, Chapter 3, Chapter 4, Chapter 5, Chapter 6, Chapter 7, Chapter 8 through Chapter 9, the committee reviews eight Earth science data sets, discussing each in terms of its value for climate research and the associated requirements. The committee reviews the current status of these measurements and their associated algorithms, and also explores what the status of the requirements might be in 20 years (roughly at the end of the planned NPOESS program), when new technologies or new sampling strategies may have enhanced current data sets or enabled the delivery of new data products. The committee emphasizes that these eight measurement sets, although critical for climate research, are not necessarily the most important. Instead, the committee reviews these measurement sets to elucidate the scientific and programmatic issues associated with the integration of research and operational systems.
The eight variables were selected because they span a broad range of science issues and also because of the range of the strategies for their implementation. The first three (atmospheric sounding, sea surface temperature, and land cover) have been part of the operational POES program for decades. Each data set has been used in climate and global change research as well as operational programs. The second three (ocean color, soil moisture, and atmospheric aerosols) have been part of the NASA research missions and are proposed for inclusion in NPOESS. These variables have not been measured as part of a long time series but on single missions instead (e.g., ocean color) or else the data product is still in development (e.g., aerosols). The final two variables (stratospheric ozone and Earth radiation budget) have been part of a long series of research missions (e.g., TOMS), and although there are counterparts in the operational missions, the Earth science community has focused primarily on the research missions. For each of the three sets, there are planned improvements in EOS.
For each variable, the committee reviews current NASA and NPOESS plans for data collection and briefly discusses the primary sensors and their expected performance. (For some variables, international or commercial data sets may be relevant as well.) It also evaluates observing strategy in terms of data continuity and the types of data products that will be developed, and it compares strategies for calibration and validation6 with the plans currently laid out for the relevant NASA and NPOESS missions.
Reconciling the sometimes conflicting requirements of operations and research is a difficult task, and attempts to develop a coherent, comprehensive observing strategy often have relied on ad hoc solutions. With changes in schedules, in program structure, and in fiscal resources, it has been difficult to maintain effective coordination for a sufficient period of time. For each measurement set examined in the following chapters, and in its summation in Chapter 10, the committee highlights those areas where investments or changes in management structure may help us to realize the potential for an integrated observing system for climate research.
Keeling, C.D., J.F.S. Chin, and T.P. Whorf. 1996. Increased activity of northern vegetation inferred from atmospheric CO2 measurements. Nature 382: 146-149.
Integrated Program Office (IPO), National Polar-orbiting Operational Environmental Satellite System (NPOESS). 1996. Integrated Operational Requirements Document (IORD) I. Joint Agency Requirements Group Administrators. 61 pp. + figures.
National Oceanic and Atmospheric Administration (NOAA). 1997. Climate Measurement Requirements for the National Polar-orbiting Operational Environmental Satellite System (NPOESS), Workshop Report, Herbert Jacobowitz (ed.), Office of Research and Applications, NESDIS-NOAA, Washington, D.C.
Calibration is the process of quantitatively defining the system responses to known, controlled signal inputs, and validation is the process of assessing by independent means the quality of the data products derived from the system inputs.