Over the longer term, USGCRP agencies are exploring ways to maintain the long-
term data records necessary for documenting and understanding global change.
NASA, NOAA, and DOD, the partners in the National Polar-orbiting Operational
Environmental Satellite System (NPOESS), are exploring ways to extend the long-
term measurements of key global change parameters beyond the EOS AM-1 and
PM-1 time frame to provide a bridge into the post-2008 NPOESS era.
Internationally the United States participates with other nations in the Committee
on Earth Observation Satellites, which has called for developing an Integrated
Global Observing Strategy (IGOS) to link space and in-situ observations in a com-
mon strategic framework. The United States also participates in the international
coordination of the Global Climate Observing System (GCOS), the Global Ocean
Observing System (GOOS), and the Global Terrestrial Observing System (GTOS).
The broader objective of IGOS is to develop a comprehensive strategy for integrat-
ed space-based and in-situ observations to monitor the interactive Earth system
holistically, addressing the needs of scientific research and those of the broad com-
munity of users involved in operational resource management, international assess-
ments, and policy development.

U.S. centers. The U.S. is now relying heavily on these foreign modeling centers in producing scenarios of how climate will evolve in the future. The NRC report ⚫ went on to state that

...insufficient human and computational resources are being devoted to
high-end, computer intensive, comprehensive modeling, perhaps, in part,
because of the absence of a nationally coordinated modeling strategy...In
order to optimally use existing scientific capabilities, adequate resources,
including greatly improved supercomputing capabilities, need to be provid-
ed to the climate modeling community. The reliance of the United States
upon other countries for high-end climate modeling must be redressed.

The USGCRP agencies are working to provide short-term relief to the current computing capacity shortfall in the Nation's leading climate modeling centers. However, incremental changes to current capability and program structure will not be adequate to the long-term task. A more substantial response to this need is underway.

With DOE and NSF taking the lead, the USGCRP has been developing a long-range, Accelerated Climate Prediction Initiative (ACPI). The ACPI takes an integrated view of the improvements required to accelerate progress in climate simulation and projection of climate change. Interrelated activities in model development and evaluation, simulations, and projections, and analysis and assessment will be addressed by concurrent improvements in the models themselves, data availability and usefulness, computer speed and memory, collaboration and data management capabilities, and widespread institutional interaction. The USGCRP agencies will develop a more integrated modeling strategy, including improved program integration and development of overall USGCRP climate modeling priorities that are closely linked to overall USGCRP climate system research objectives.

Major steps forward in large-scale U.S. climate modeling will require major increases in computational resources and a coupling of increased computational capability with increased scientific knowledge of climatological phenomena. Indeed, the specifically articulated goals of the ACPI are to: (1) accelerate progress in general circulation model development and application; (2) reduce substantially the uncertainties in model-based projections of global environmental change on the full range of relevant timescales; and (3) increase the availability and usability of global change projections to the broader environmental research and environmental assessment communities.

It is estimated that these goals will require, from the hardware side, horizontal model resolutions of 30 km in the atmosphere, 1 km of the land surface, and 5-10 km in the ocean. These needs, added to the requirements of multiple ensemble runs for statistical confidence, dictate the imperative for teraflop (trillions of operations per second) computational capability.

To achieve this enhancement of the Nation's climate modeling capabilities,

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Earth System Modeling and Simulation