Ease of availability of data is critical to the success of NASA's MTPE. The EOS Data and Information System (EOSDIS) (eosdis link) is being designed to be responsive to this requirement. At present, a so-called Version 0 of EOSDIS manages data from NASA's past and current Earth science research satellites and field measurement programs. During the EOS era proper, EOSDIS will allow command and control of satellites and instruments, and will generate data products based on orbital observations. In addition, EOSDIS will generate data sets made by assimilation of satellite and in situ observations into global climate models.

EOSDIS's services will include:

• User Support
• Data Archive Management and Distribution
• Information Management
• Product Generation
• Spacecraft Command and Control
• Data Capture and Telemetry Processing

Present plans for EOSDIS are based on an open system, with distributed architecture. This permits the allocation of EOSDIS elements to various locations to take best advantage of different institutional capabilities and science expertise.

EOSDIS consists of several components including:

1. A core system (ECS), which provides the Science Data Processing Segment (SDPS), the Flight Operation Segment (FOS), and the Communications and System Management Segment (CSMS).
2. Eight Distributed Active Archive Centers (DAACs);
3. Scientific Computing Facilities (SCFs);
4. the EOS Data and Operations System (EDOS); and EOS Networks

Together, these components will address all command and control; data acquisition, transport, reduction, storage, and visualization; and user access needs.

As has been noted earlier, the basic impetus for the kinds of studies we have been describing is to provide input to planners and policy makers. Having access to raw (or even processed) data is of little use to such groups. What they need is the ability to use those data in a way that would help them make decisions about allocation and, perhaps, regulation or our resources. This translates into questions like: "If we do not curb automobile use what will be the effect of auto emissions on atmospheric composition and temperatures over the next 5-10 years?" Or, "If we continue to allow deforestation in the Pacific northwest, what will be the effect on biodiversity, land cover, land use, and water run-off patterns?"

No one can actually predict the future to a high degree of accuracy, but we are able to create mathematical models that can generate useful predictive functions. Such models can be as simple as that shown in the first figure, which describes the distribution of incoming Solar energy through major portions of the Earth's systems. It's kind of like balancing the books: The sum of all components thought to use Solar energy must equal the amount of incoming Solar radiation. If they don't add up, either our model is completely wrong, or we're missing something.

Christopherson, R.W., GEOSYSTEMS: An Introduction to Physical Geography, 2nd Ed. © 1994. Reproduced by permission of Prentice Hall, Upper Saddle River, New Jersey)

But the models we need for Earth system predictive capability are much more complex than what we have shown here. Such models must take into account not only energy budgets, but sources and sinks of carbon and other biogeochemically related materials, effects of temperature on wind speed and direction, precipitation patterns, land use patterns, speed and direction of oceanic currents, increases in so-called greenhouse gases, and more. A full understanding of how these components interact with each other will further support our willingness to trust the output from such models. An example of the complexity of these models, along with a color-coded indication of how EOS and other MTPE platforms will contribute to a better understanding, is shown in the figure below, which is based on the Bretherton diagram:

It is because of the complexity of such models that multitudes of timely data from so many different sources over a relatively long period are required, supported by a highly advanced data and information system that will ingest, process, and distribute those data to interested parties around the world.

Based on the predictive models described above, we must make decisions based on our understanding of the potential magnitude of global change in order that planners and policy-makers can define strategies for mitigation or adaptation. These strategies may have widely different economic and societal impact, involving health, standard of living, and quality of life. EOS studies will address vulnerabilities of water resources, agriculture and ecosystems to climate change, and provide fundamental data sets on land cover change, and measures of sea level change. These measurements and the resulting predictive models will address such topics as marine productivity, ozone depletion, air quality, and allow monitoring of resources, as well. These activities will give us the tools we need to understand our Earth system and its many subsystems, and to understand the role we play in modifying such systems, and the roles they play in their effects on our daily lives.

As you no doubt would guess, NASA has a current, extensive homepage dedicated to EOS Project Science (http://eospso.gsfc.nasa.gov/). There you will find in depth coverage and reviews of such topics as Earth System Science, EOS Investigations, Mission Profiles, Airborne Simulator imagery, Data Products, Educational Material, Publications and Sources, and connectable EOS-related servers. Some of the images and textual information in this Section were drawn from these sources. You are invited to browse the EOS homepage to expand your awareness of the status and future plans of the GCRP, MTPE, and EOS which together constitute one of the most ambitious and involved research programs in the history of mankind.

Before closing, we bring to your attention another related program that will rely on a variety of satellites and sensors, and the participation of many nations, to monitor and assess aspects of environmental monitoring that relate to natural and manmade disasters. This program is an outgrowth of agreements worked out during a May 1996 Workshop on International Cooperation in Space. The results of their recommendations for use of remote sensing for this purpose are summarized in the table shown here. Other satellites have since been included in the list, and EOS will be a major contributor to monitoring capabilities. (See also the summary of satellite programs planned over the next ten years given in Section 20 [p. 20-1]).

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