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Solar and Space Physics: A Science for a Technological Society
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SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
8.5.4 Theory and Modeling
As noted in numerous examples within this chapter, cross-scale coupling processes are intrinsic to
IT system behavior. That is, phenomena highly structured in space and time (e.g., wave dissipation, turbulence, electric field fluctuations) can produce effects (e.g., wind circulation, chemical transport, Joule
heating, respectively) over much broader scales. By the same token, larger-scale phenomena create local
conditions that can seed development of rapidly changing structures at small spatial scales (e.g., instabilities and turbulence). The current state of affairs is that parameterizations are formulated to approximate the
bulk effects of small-scale phenomena in global models whose spatial and temporal resolutions preclude
inclusion of physics at smaller scales. Often such parameterizations make ad hoc assumptions about the
governing physics and coupling between scales, and are usually artificially tuned to yield results in globalscale models that agree better with observations.
The observational strategies suggested in this report, which place high priority on understanding how
local, regional, and global-scale phenomena couple to produce observed responses at all scales, call for
complementary development of theory and numerical modeling capabilities that enable self-consistent
treatment of cross-scale coupling processes. The fundamental physics of small-scale phenomena needs
to be developed and understood, and numerical simulations performed that validate theories and explore
parameter space dependencies. These models need to be embedded in regional-scale models so that twoway interactions are self-consistently addressed, and regional-scale models need to be nested at strategic
locations within global models to enable cross-scale coupling processes and their implications to be truly
understood and emulated.
Finally, researchers know well from terrestrial weather forecasting the concept of assimilating realtime data to nudge the solutions of physics-based models toward the observed state of the system. Global
weather models assimilate data of various types over the globe to provide local, regional, and global forecasts as part of our daily lives. A similar path needs to be followed for the IT system to attain a true space
weather forecast capability. During the next decade, assimilative models for the IT need to be developed,
and such models need to be explored to reveal the types and distributions of measurements that provide
optimal characterizations of the system at local, regional, and global scales.
In summary, and as an indication of its priorities for progress in theory and modeling, the AIMI panel
notes that:
• Comprehensive models of the AIM system would benefit from the development of embedded grid
and/or nested model capabilities, which could be used to understand the interactions between local- and
regional-scale phenomena within the context of global AIM system evolution.
• Complementary theoretical work would enhance understanding of the physics of various-scale
structures and the self-consistent interactions between them.
• Comprehensive models of the AIM system would benefit from developing assimilative capabilities
and would serve as the first genre of space weather prediction models.
8.5.5 Enabling Capabilities
The missions and initiatives outlined above will not be successful if there is not an infrastructure of
additional capabilities that enable cheaper and more frequent measurements of the AIM system, that transform measurements into scientific results, that maintain the health of the scientific community, and that
serve the needs of 21st-century society. These enabling capabilities (i.e., working group imperatives) fall
into the following categories: innovations: technology, instruments, and data systems; theory, modeling,
Solar and Space Physics: A Science for a Technological Society
202
SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
8.5.4 Theory and Modeling
As noted in numerous examples within this chapter, cross-scale coupling processes are intrinsic to
IT system behavior. That is, phenomena highly structured in space and time (e.g., wave dissipation, turbulence, electric field fluctuations) can produce effects (e.g., wind circulation, chemical transport, Joule
heating, respectively) over much broader scales. By the same token, larger-scale phenomena create local
conditions that can seed development of rapidly changing structures at small spatial scales (e.g., instabilities and turbulence). The current state of affairs is that parameterizations are formulated to approximate the
bulk effects of small-scale phenomena in global models whose spatial and temporal resolutions preclude
inclusion of physics at smaller scales. Often such parameterizations make ad hoc assumptions about the
governing physics and coupling between scales, and are usually artificially tuned to yield results in globalscale models that agree better with observations.
The observational strategies suggested in this report, which place high priority on understanding how
local, regional, and global-scale phenomena couple to produce observed responses at all scales, call for
complementary development of theory and numerical modeling capabilities that enable self-consistent
treatment of cross-scale coupling processes. The fundamental physics of small-scale phenomena needs
to be developed and understood, and numerical simulations performed that validate theories and explore
parameter space dependencies. These models need to be embedded in regional-scale models so that twoway interactions are self-consistently addressed, and regional-scale models need to be nested at strategic
locations within global models to enable cross-scale coupling processes and their implications to be truly
understood and emulated.
Finally, researchers know well from terrestrial weather forecasting the concept of assimilating realtime data to nudge the solutions of physics-based models toward the observed state of the system. Global
weather models assimilate data of various types over the globe to provide local, regional, and global forecasts as part of our daily lives. A similar path needs to be followed for the IT system to attain a true space
weather forecast capability. During the next decade, assimilative models for the IT need to be developed,
and such models need to be explored to reveal the types and distributions of measurements that provide
optimal characterizations of the system at local, regional, and global scales.
In summary, and as an indication of its priorities for progress in theory and modeling, the AIMI panel
notes that:
• Comprehensive models of the AIM system would benefit from the development of embedded grid
and/or nested model capabilities, which could be used to understand the interactions between local- and
regional-scale phenomena within the context of global AIM system evolution.
• Complementary theoretical work would enhance understanding of the physics of various-scale
structures and the self-consistent interactions between them.
• Comprehensive models of the AIM system would benefit from developing assimilative capabilities
and would serve as the first genre of space weather prediction models.
8.5.5 Enabling Capabilities
The missions and initiatives outlined above will not be successful if there is not an infrastructure of
additional capabilities that enable cheaper and more frequent measurements of the AIM system, that transform measurements into scientific results, that maintain the health of the scientific community, and that
serve the needs of 21st-century society. These enabling capabilities (i.e., working group imperatives) fall
into the following categories: innovations: technology, instruments, and data systems; theory, modeling,