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Ensuring the Climate Record from
the NPP and NPOESS Meteorological Satellites
Executive Summary
INTRODUCTION
Researchers studying the issues surrounding global climate change have a particular
need for the kind of repetitive, long-term, high-quality measurements that can be provided
from the vantage point of space. Operational weather satellites provide perhaps the only
means for securing these measurements. The next generation of operational sensing
systems is currently being designed, and the National Polar-orbiting Operational
Environmental Satellite System (NPOESS), scheduled for launch beginning in 2009, is an
important component of this operational monitoring system. NPOESS is being developed
with the goal of meeting the converged operational data needs of the National Oceanic
and Atmospheric Administration (NOAA) and the Department of Defense (DOD), as well
as some of the data needs of the National Aeronautics and Space Administration (NASA)
Earth observation programs.
In a joint mission to facilitate the transition of appropriate "research" satellite
measurements into the operational domain, NASA and the NPOESS Integrated Program
Office (IPO) are developing the NPOESS Preparatory Project (NPP). NASA and NOAA
are supporting the NPP as part of a program of risk reduction demonstration and
validation for NPOESS sensors, algorithms, and processing. The NPP satellite,
scheduled for launch in 2005, will include critical sensors that are planned for flights on
NPOESS. In addition, the NPP mission is expected to provide an early test of space and
ground segments for NPOESS.
The NPOESS IPO has begun working with the members of the climate research
community to define operational climate measurement needs. The IPO has also begun to
assess the implications of these needs for NPOESS instrument design. However, it is
equally important to ensure that the data systems will meet climate research needs. At
the request of NOAA and NASA, the Space Studies Board's Committee on Earth Studies
conducted a short-duration study of issues related to ensuring the climate record from the
planned NPP and NPOESS satellites (see Appendix A for a statement of task). This
report presents the committee's recommendations; it draws heavily on background
material presented at the 2-day workshop that the committee hosted on February 7-8,
2000, and on discussions during and after the workshop.1 It also draws on investigations
by the committee for the two-part report Issues in the Integration of Research and
Operational Satellite Systems for Climate Research.2
Climate Data Records
In briefings to the committee, NASA and NOAA officials acknowledged that there is no
operational ground system infrastructure for U.S. climate data and services. The climate
research community therefore requires satellite data from NPP and NPOESS that can be
used to generate climate data records (CDRs), data whose quality is known quantitatively
and for which temporal and spatial biases are minimized (or at least quantified). CDR
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production will require considerable scientific insight, including the blending of multiple
data sources, error analyses, and access to raw data sets. Moreover, information on
sensor design, operation, and calibration will also be necessary to develop a consistent
CDR across multiple sensors.
NASA intends for environmental data records (EDRs)3—the priority data products that
will be produced from NPOESS data—to be utilized to the maximum extent possible to
meet CDR requirements. However, NASA also expects to cap the resources available for
CDR processing to ensure that the EDR production requirements are met. Although
NPP- and NPOESS-derived EDRs may have considerable scientific value, CDRs are far
more than a time series of EDRs. While the lines may be indistinct, there remain
fundamental differences between products that are generated to meet short-term needs
(EDRs) and those for which consistency of processing over years to decades is an
essential requirement. Given the experience of climate researchers, it is unlikely that the
standard EDRs will meet the quality requirements for CDRs, particularly in the area of
data refinement and reprocessing as algorithms mature. Moreover, production and
refinement of CDRs through reprocessing may be difficult (or unaffordable) in the present
plans.
Long-Term Archiving and the National Climatic Data Center
NOAA is the federal agency with responsibility for archiving environmental satellite data,
and its National Climatic Data Center (NCDC) is a potential repository of data to support
climate research in the coming NPP/NPOESS era. Currently, NCDC has a total digital
archive of approximately 700 terabytes (TB). Data from the scheduled launch in 2005 of
the NPP satellite will add another 90 TB annually; if managed by NCDC, data from
NPOESS in the 2009 time frame would add yet another 228 TB annually.
There are currently no funds to archive NPP or NPOESS data, and although NASA and
NOAA have a memorandum of understanding (MOU) regarding the eventual archiving of
Earth Observing System (EOS) data by NOAA, it is on a best-effort basis. Although plans
are being discussed, there is no implementation strategy within NASA or NOAA to
archive even the raw data records (RDRs, analogous to Level 1 data) from these
missions. There are also no plans to store sensor design information and calibration and
ancillary data necessary to develop CDRs. Ominously, from a climate research
perspective, the prospects for developing CDR and long-term archive (LTA) plans for
NPP and NPOESS are ever more doubtful, given that plans for the EOS Terra and Aqua
(formerly known as AM-1 and PM-1) data sets are not yet firmly in place.
Guiding Principles
NASA and NOAA have experienced both success and failure in recent attempts to
develop data systems. The committee believes that much can be learned from these
experiences but notes that the fundamental objective of establishing a set of data
systems and services to meet the needs of climate research will require more than MOUs
and larger magnetic tape silos. New services must be supported that are not available in
the present mix of NASA research mission data systems and NOAA long-term archives.
New scientific and policy demands are being placed on these systems, and new
management and technical approaches must be established. Increasing funding is a
necessary condition; however, the committee does not believe that funding alone is
sufficient. While encouraged by NASA and NOAA's recent attention to preserving the
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climate record of NPP, NPOESS, and EOS, the committee believes that an enormous
investment in Earth observations is at serious risk.
Based on an examination of prior studies, as well as discussions at its February 7-8,
2000, workshop, the committee identified a set of principles it believes can help ensure
the preservation of the climate record from NPP and NPOESS:
Accessible and policy-relevant environmental information must be a well-maintained part
of our national scientific infrastructure.
The federal government should (1) provide long-term data stewardship, (2) certify open,
flexible standards, and (3) ensure open access to data. The government does not
necessarily need to control the implementation of every task and service for a climate
data system. Rather, it should undertake those activities and services that cannot be
done in a competitive academic or commercial environment.
Because the analysis of long-term data sets must be supported in an environment of
changing technical capability and user requirements, any data system should focus on
simplicity and endurance.
Adaptability and flexibility are essential for any information system if it is to survive in a
world of rapidly changing technical capabilities and science requirements.
Experience with actual data and actual users can be acquired by starting to build small,
end-to-end systems early in the process. EOS data are available now for prototyping new
data systems and services for NPP and NPOESS.
Multiple sources of data and services are needed to support development of climate data
records (CDRs). The quality of the CDRs will improve as more research groups work with
the various input data sets, and the overall system will be more robust if it does not rely
on a monolithic implementation. Fostering open competition for services promotes
innovation and new ideas.
Science involvement is essential at all stages of development and implementation.
Having climate data record developers and users assisting in the specification, design,
building, and testing of the system will help ensure its usefulness to the research
community.
RECOMMENDATIONS
The committee's study of issues related to the preservation of the climate record from
future NASA and NOAA satellites was necessarily brief and drew heavily on previous
work and the 2-day workshop. In addition, the committee drew on the lessons learned to
date with NASA's EOS Data and Information System. Underlying the committee's
recommendations is its belief in the critical need and unique potential for data from NPP
and NPOESS to satisfy the demands of the climate research community. In particular,
the committee believes that prudent planning and modest investments early in the
program will allow the NPOESS system to continue essential climate research-quality
data records and develop new records based on the rich blend of planned instruments.
Climate research will require a variety of services, ranging from careful long-term
stewardship of the basic data sets to intensive data analysis and algorithm refinement.
The committee believes these complex scientific and information system activities are
best broken into two more manageable pieces-the long-term archive (LTA) and the active
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archive-instead of formed into a comprehensive, single-system solution. Climate research
requires an integration of the more stable, long-term functionality of the LTA and the
flexibility of the active archives to pursue and develop new capabilities.
The first four recommendations of the committee are presented in order of priority. The
last four, which are not prioritized, focus on programmatic and management structures to
meet these essential requirements for a climate data system.
Recommendation 1. NOAA should begin now to develop and implement the
capability to preserve in perpetuity the basic satellite measurements (radiances
and brightness temperatures).
The development of long-term, consistent time series based on CDRs requires access to
the lowest level of data available. In general, this means the raw data records (RDRs), or
Level 1A data. The low-level data can be used to develop refined CDRs as scientific and
technical understanding of Earth processes and sensor performance improves over time.
The committee recommends that NOAA do the following:
Archive both current and future data sets, including those from both research and
operational satellite missions, in an LTA.
Archive information on sensor development, calibration, operation product validation, and
appropriate metadata along with the basic radiances.
Migrate data sets to new, computer-compatible media on a regular basis, such that data
sets are refreshed every 2 to 3 years consistent with the pace of technology evolution.
Organize data in the LTA based on user access patterns to optimize data retrieval.
Recommendation 2. NOAA should guarantee climate researchers affordable
access to all RDRs in the long-term archive, with an emphasis on large-volume
data access.
Development of CDRs requires access to enormous data volumes, but it is likely that only
a small number of researchers will need such extensive access to the raw data. Thus, a
well-designed set of basic services would meet this basic function without being too
costly. The committee recommends that NOAA act on the following:
Award the LTA functions on a competitive basis to both government and private
organizations to promote innovation.
Start the development of the LTA immediately with a simple set of end-to-end capabilities
to gain experience and modify the plans and implementation accordingly. (End-to-end is
defined as being from sensor aperture to the desktop of the climate information user.)
Recommendation 3. NASA, in cooperation with NOAA, should support the
development and evaluation of CDRs, as well as their refinement through data
reprocessing.
Because the CDR process is driven by science understanding, there will be a continuing
need for the involvement of researchers. The NOAA/NASA Pathfinder shows that the
agencies can generate critical data sets for transitioning research products into
operational data products. Over the next decades, the committee expects that a few
experimental CDRs may become effectively "operational" products and will be produced
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by NOAA. The committee recommends that NASA, in cooperation with NOAA, take
action as follows:
Periodically select science investigations and provide adequate support to develop and
evaluate new CDRs.
Preserve sensor calibration and operating information, as well as metadata and ancillary
data fields, in a manner that allows reprocessing the CDRs.
Evaluate on a regular basis the organization of data sets in the LTA in light of actual data
usage patterns to improve reprocessing and access efficiency.
Recommendation 4. NOAA and NASA should define and develop a basic set of
user services and tools to meet specific functions for the science community, with
NOAA assuming increasing responsibility for this activity as data migrates to the
long-term archive.
NASA's Distributed Active Archives Centers, as well as components of NASA's Earth
Science Information Partners, are gaining experience with responding to data requests
and setting up user services. Although the focus is on the order entry process (catalog,
data location, browse, etc.), more attention needs to be given to quality assurance and
the order fulfillment process (metadata, subsetting, electronic data delivery, etc.).
Emphasis should be given to reducing cost through automation. It is essential that the
large-volume data sets from the archive be affordable for the science user community.
The committee recommends that NOAA and NASA do the following:
Select teams on a competitive basis that will identify and provide specific user services
and tools (see Appendix D). As part of an ongoing process of system evaluation and
improvement, these teams would assist in identifying and providing essential user
services. Based on a rigorous analysis of a user model for climate research, they would
make recommendations on characteristics such as data subsetting and browse
capabilities.
Support and maintain a balance between internal and external expertise at the
government data centers.
Examine the feasibility of providing open electronic access to a rolling archive of RDRs
and EDRs through the NESDIS Central that is planned for NPOESS and NPP.
Recommendation 5a. NASA, in cooperation with the Integrated Program Office,
should develop the NPOESS Preparatory Project as an integral component of a
climate data system.
NPP represents a unique opportunity to test both scientific and programmatic interfaces
related to an integrated data systems strategy. It will bridge the gap between the NASA
research missions and the NPOESS operational missions. There is potential to begin the
development of long-term, high-quality CDRs and an associated data system for climate
research, but it is an opportunity that could be missed. The committee recommends that
NASA, in cooperation with the NPOESS IPO, proceed as follows:
Develop and implement a prototyping activity to link the NPP Science Data Segment with
the NOAA LTA. This activity should start with NASA EOS data sets, including
Atmospheric Infrared Sounder (AIRS)/Advanced Microwave Sounding Unit
(AMSU)/MODIS in anticipation of the NPP data sets, including CriS/ATMS/VIIRS.
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Put aside reserve funds from data system development to support evolutionary
development activities as the program matures to ensure that the system is not locked in
with no resources for subsequent enhancement.
Develop prototype user services for NPP climate data records.
Recommendation 5b. Select, on a competitive basis, and then support an NPP
science team as soon as possible.
The team should consist of sensor experts, algorithm developers, and science data
users. Because the functions will require different levels of involvement in the sensor
development and operation process, they will require different levels of support. The
team would advise on the NPP data system needs, including scientific data processing,
archiving, and distribution requirements.
Recommendation 6. NOAA, in cooperation with NASA, should invest in early,
limited capability prototypes for both long-term archiving and the NPP data
system.
Data systems that do not develop, test, and evaluate on a frequent, regular basis are
nearly always late and over budget. System development costs generally increase as the
cube of the number of years in development. A climate data system will build on existing
components and existing capabilities, but new functions and new interfaces must be
developed and implemented to meet the requirements for climate research. The
committee recommends that NOAA, in cooperation with NASA, take action as follows:
Competitively select and support a science data team to assist a NOAA long-term
archiving program on the following:
—Archive requirements for long-term data sets, including RDRs, metadata, and
ancillary data fields;
—Archiving of CDRs, algorithms, and processing environments;
—Data structure and organization to facilitate access and reprocessing;
—Flexible, open standards to facilitate data access and refinement;
—Data reprocessing priorities; and
—Minimal user services and tools.
Require the NPOESS total system performance requirements (TSPR) contractor to work
with the science data team to facilitate CDR production and archiving from both NPP and
NPOESS.
Develop flexible standards and formats that allow new services to be developed in the
future.
Begin to develop a small number of CDRs using the LTA services.
Recommendation 7. NASA and NOAA should develop and support activities that
will enable a blend of distributed and centralized data and information services for
climate research.
NASA and NOAA should consider a hybrid mode of operation rather than building a rigid,
centralized system or relying on structure to emerge from an uncoordinated set of data
systems. The government should ensure and manage the activities it does best, while
fostering innovation and flexibility in those parts of the overall system that do not need to
be closely managed. The committee recommends that NASA and NOAA proceed as
follows:
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Implement the NPP data system as a federation of linked activities, such as that
proposed in the NewDISS framework.
Where appropriate, build on existing and planned capabilities, including EOSDIS, the
Earth Science Information Partners, NASA's Distributed Active Archive Centers, and
NOAA's Data Centers, and develop new capabilities as user experience is gained.
1
See Appendix B for the workshop agenda and a list of participants.
2
National Research Council (NRC), Space Studies Board. 2000. Issues in the Integration
of Research and Operational Satellite Systems for Climate Research: I. Science and
Design, in press; National Research Council (NRC), Space Studies Board. 2000. Issues
in the Integration of Research and Operational Satellite Systems for Climate Research: II.
Implementation, in press.
3
As defined by the NPOESS IPO, EDRs are data records that contain the environmental
parameters or imagery required to be generated as user products as well as any ancillary
data required to identify or interpret these parameters or images. EDRs are generally
produced by applying an appropriate set of algorithms to raw data records.
