8

Report of the Panel on Atmosphere-Ionosphere-Magnetosphere Interactions

8.1 SUMMARY OF AIMI SCIENCE PRIORITIES AND IMPERATIVES FOR THE 2013-2022 DECADE

Informed by observations and modeling efforts that have occurred during the past decade, there is increasing recognition among scientists of the atmosphere-ionosphere-magnetosphere (AIM) system as a complex and active element of space weather, and as a region where important science questions with broad applicability across our solar system can be answered. Earth’s space environment, or geospace, is unique in many ways: the interconnected behavior of the plasma and neutral gas in the AIM system, the strong signature of lower atmospheric conditions in space, and the development of massive plasma structures with embedded variability at multiple scales are just a few examples. The pursuit toward understanding energy transfer and physical manifestations in near-Earth space has yielded and will continue to offer insights into fundamental processes that occur at other planets and bodies in our solar system and indeed throughout the universe. There are also practical reasons to study the AIM system. The space-based assets for observation and communication of human activities all operate in geospace and therefore must be designed or otherwise protected from the hazards and unpredictability that this energetic, nonlinear system produces. Advances in scientific understanding of the AIM system enable the development of a capability for the prediction of geospace conditions.

In this chapter, the decadal survey’s Panel on Atmosphere-Ionosphere-Magnetosphere Interactions (AIMI) articulates its science goals and aspirations for the decade ahead and suggests an implementation strategy to achieve that vision. Building on the significant accomplishments of the previous decade, the panel presents an interlinked and achievable research program to address the most compelling science questions in the field. Summarized below are the AIMI panel’s science priorities, imperatives, and recommendations to the survey committee for the 2013-2022 decade.

The three major AIMI science priorities for the 2013-2022 decade are as follows:

AIMI Science Priority 1. Determine how the ionosphere-thermosphere system regulates the flow of solar energy throughout geospace.



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8 Report of the Panel on Atmosphere- Ionosphere-Magnetosphere Interactions 8.1  SUMMARY OF AIMI SCIENCE PRIORITIES AND IMPERATIVES FOR THE 2013-2022 DECADE Informed by observations and modeling efforts that have occurred during the past decade, there is increasing recognition among scientists of the atmosphere-ionosphere-magnetosphere (AIM) system as a complex and active element of space weather, and as a region where important science questions with broad applicability across our solar system can be answered. Earth’s space environment, or geospace, is unique in many ways: the interconnected behavior of the plasma and neutral gas in the AIM system, the strong signature of lower atmospheric conditions in space, and the development of massive plasma structures with embedded variability at multiple scales are just a few examples. The pursuit toward under- standing energy transfer and physical manifestations in near-Earth space has yielded and will continue to offer insights into fundamental processes that occur at other planets and bodies in our solar system and indeed throughout the universe. There are also practical reasons to study the AIM system. The space-based assets for observation and communication of human activities all operate in geospace and therefore must be designed or otherwise protected from the hazards and unpredictability that this energetic, nonlinear system produces. Advances in scientific understanding of the AIM system enable the development of a capability for the prediction of geospace conditions. In this chapter, the decadal survey’s Panel on Atmosphere-Ionosphere-Magnetosphere Interactions (AIMI) articulates its science goals and aspirations for the decade ahead and suggests an implementation strategy to achieve that vision. Building on the significant accomplishments of the previous decade, the panel presents an interlinked and achievable research program to address the most compelling science questions in the field. Summarized below are the AIMI panel’s science priorities, imperatives, and recom- mendations to the survey committee for the 2013-2022 decade. The three major AIMI science priorities for the 2013-2022 decade are as follows: A  IMI Science Priority 1. Determine how the ionosphere-thermosphere system regulates the flow of solar energy throughout geospace. 149

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150 SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY A  IMI Science Priority 2. Understand how tropospheric weather influences space weather. A  IMI Science Priority 3. Understand the plasma-neutral coupling processes that give rise to local, regional, and global-scale structures and dynamics in the AIM system. These priorities emerge from the five AIMI science goals described in Section 8.4, “Science Goals and Priorities for the 2013-2022 Decade,” and from the panel’s assessment of the resources required to address them, and lead to the following imperatives: A  IMI Imperative 1. Close a critical gap in the NASA Heliophysics Systems Observatory with a mis- sion that determines how solar energy drives ionospheric-thermospheric variability and that lays the foundation for a space weather prediction capability. A  IMI Imperative 2. Provide a broad and robust range of space-based, suborbital, and ground-based capabilities that enable frequent measurements of the AIM system from a variety of platforms, catego- ries of cost, and levels of risk. A  IMI Imperative 3. Integrate data from a diverse set of observations across a range of scales, coordi- nated with theory and modeling efforts, to develop a comprehensive understanding of plasma-neutral coupling processes and the theoretical underpinning for space weather prediction. A  IMI Imperative 4. Conduct a theory and modeling program that incorporates accumulated under- standing and extends the legacy of observations into physics-based models that are utilized for new scientific insight and operational specification and forecast capabilities. These imperatives represent a balanced strategy for addressing the panel’s priority science; they are not listed in any particular order. The requirements underlying the imperatives span five categories: spaceflight missions; Explorers, suborbital, and other platforms; ground-based facilities; theory and modeling; and enabling capabilities. Priorities within each of these categories are summarized in turn below. 8.1.1  Spaceflight Missions No new NASA missions are under development or are currently planned for the future that address any of the AIMI science priorities articulated above. This deficiency represents an acute imbalance in the study of the Sun-Earth system that impedes researchers’ ability to resolve complex AIM system behavior that impacts geospace dynamics and the operation of ground- and space-based assets on which society depends. A critical AIMI imperative therefore is that a mission addressing the response of the ionosphere- thermosphere (IT) system to variable forcing be put forth as the highest priority of the solar and space physics decadal survey. The most compelling AIM science questions of the coming decade are best addressed with a Geospace Dynamics Constellation (GDC) mission nominally consisting of six identical satellites in high-latitude equally spaced circular orbits, with the goal of understanding how winds, temperature, composition, chemistry, charged particles, and electric fields interact to regulate the observed global response of the IT. This mission will also provide new insights into the IT response to dynamical coupling with the lower atmo- sphere. If this mission must be delayed at all due to budgetary constraints, then a revitalized heliophysics

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REPORT OF THE PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS 151 instrument and technology development program must support GDC’s implementation later in this decade. In that case, the AIMI panel suggests that the DYNAMIC (Dynamical Neutral Atmosphere-Ionosphere Coupling) mission be put forth as the decadal survey’s number-one priority for the 2013-2022 decade. DYNAMIC is a pair of satellites in low-Earth orbits separated by 6 hours of local time, carrying the instru- ments to measure the critical energy inputs to the AIM system from the spectrum of waves entering from below. Although the primary focus is to understand how lower-atmosphere variability drives IT variability, DYNAMIC will also measure important properties of the IT response to variable magnetospheric forcing. Additional NASA missions that address another high-priority science challenge of the next decade— understanding the two-way interaction between the ionosphere-thermosphere and the magnetosphere—are also described in this chapter. These missions and the associated science are also potential candidates for the Explorer program. 8.1.2  Explorers, Suborbital, and Other Platforms The relative proximity of the AIM system makes it amenable to observational strategies involving a wide variety of platforms. This attribute is a significant strength in crafting a program that is responsive to budgetary realities and to the changing climate of programmatic risk factors. The following AIMI panel priorities reflect this crucial flexibility: • Explorer program enhancement (highest priority). Enhance the Heliophysics Explorer line to execute a broad range of science missions that can address important AIMI science challenges. Mission classes should range from a tiny Explorer that takes advantage of miniaturized sensors and alternative platforms and hosting opportunities, up to a medium Explorer that could address multiple science challenges for the decade. • Constellations of satellites. Develop the means to effectively and efficiently implement constellation missions, including proactive development of small-satellite capabilities and miniaturized sensors and pursuit of cost-effective alternatives such as commercial constellations. • Suborbital research. Maintain a strong suborbital research program. Continue development of observatory-class capabilities, such as a high-altitude sounding rocket and long-duration balloons, and expand funding for science payload development for these platforms. • Strategic hosted payloads. Develop a strategic capability to make global-scale AIMI imaging mea- surements from host spacecraft, notably those in high Earth orbit and geostationary Earth orbit, as is cur- rently done in support of solar (GOES SXT) and magnetospheric (TWINS, GOES, LANL) research. 8.1.3  Ground-Based Facilities New ground-based instrumentation and associated research programs can also address an array of AIMI science questions in this decade. These facilities will play a major role in an overall strategy to understand the origins of plasma-neutral structures over local (tens to hundreds of kilometers), regional (hundreds to thousands of kilometers), and global scales (thousands to tens of thousands of kilometers), as well as the interactions between structures over these different scales. In particular, several prospective facilities are particularly compelling for advancing AIMI panel science priorities: • Autonomous American sector network. Develop, deploy, and operate a network of 40 or more autonomous observing stations extending from pole to pole through the (North and South) American lon-

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152 SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY gitudinal sector. The network nodes should be populated with heterogeneous instrumentation capable of measurements, including winds, temperatures, emissions, scintillations, and plasma parameters, for study of a variety of local and regional ionosphere-thermosphere phenomena over extended latitudinal ranges. • Whole-atmosphere lidar observatory. Create and operate a lidar observatory capable of measuring gravity waves, tides, wave-wave and wave-mean flow interactions, and wave dissipation and vertical cou- pling processes from the stratosphere to 200 km. Collocation with a research facility such as an incoherent scatter radar (ISR) installation would enable study of a number of local-scale plasma-neutral interactions relevant to space weather. • NSF medium-scale research facility program. The above two facilities are candidates for support by the NSF Geospace Program and would require that a medium-scale (~$40 million to $50 million) research facility funding program be instituted at NSF to fill the gap between the Major Research Instrumentation (MRI; $100 million) programs. • Southern-Hemisphere expansion of incoherent scatter radar (ISR) network. In addition to the two facilities listed above, expansion of the now proven Advanced Modular Incoherent Scatter Radar (AMISR) technology to southern polar latitudes (i.e., Antarctica) would provide for the first-ever view of detailed ionosphere processes in the southern polar hemisphere, thus contributing a critical missing component to the Heliophysics Systems Observatory. • Ionospheric modification facilities. Fully realize the potential of ionospheric modification techniques through colocation of modern heating facilities with a full complement of diagnostic instruments including incoherent scatter radars. This effort requires coordination between NSF and DOD agencies in the planning and operation of existing and future ionospheric modification facilities. 8.1.4  Theory and Modeling Cross-scale coupling processes are intrinsic to AIM system behavior. Phenomena and processes that are highly structured in space and time (e.g., wave dissipation, turbulence, electric field fluctuations) can produce effects (e.g., wind circulations, chemical transport, Joule heating, respectively) over much larger scales. At the same time, larger-scale phenomena create local conditions that can either promote or suppress development of rapidly changing structures at small spatial scales (e.g., instabilities and turbulence). The observational strategies presented in this report place high priority on understanding how local, regional, and global-scale phenomena couple to produce observed responses across scales. These strategies call for complementary development of theory and numerical modeling capabilities that enable comprehensive treatment of cross-scale coupling processes, together with new data synthesis technologies that combine multiple, hetero-scale data sources into a common framework for understanding critical aspects of the AIM system. Therefore, to support the synergistic program of space-based investigations and ground-based facilities, the AIMI panel has the following priorities regarding theory and modeling: • Model development. 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. • Theory. Complementary theoretical work would enhance understanding of the physics of various- scale structures and the self-consistent interactions between them. • Assimilative capabilities. Comprehensive models of the AIM system would benefit from developing assimilative capabilities and would serve as the first genre of space weather prediction models.

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REPORT OF THE PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS 153 Further priorities concerning theory and modeling are provided in Section 8.5.4, “Theory and Modeling.” 8.1.5  Enabling Capabilities The missions and initiatives described above require additional capabilities and infrastructure 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 priorities) fall into the following categories: • Innovations: technology, instruments, and data systems; • Theory, modeling, and data exploitation; • Research to operations, and operations to research; and • Education and workforce. The panel’s priorities in these areas are detailed in Section 8.5.5, “Enabling Capabilities.” 8.2  MOTIVATIONS FOR STUDY OF ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS Electromagnetic radiation from the Sun is the source of energy for photosynthesis and life. However, the Sun’s other energetic outputs produce conditions and events that can be disruptive and even cata- strophic to society. Hurricanes and tornadoes are examples of extreme and dangerous terrestrial weather events that occur on the surface of Earth. But our planet is also embedded in the streaming plasma and magnetic field of the Sun’s outer corona (Figure 8.1), which can lead to hazardous weather in space with similarly catastrophic consequences. Although Earth’s magnetic field serves as a protective cocoon that is difficult for the Sun’s plasma and magnetic field to penetrate, transmission of a few percent of this energy into near-Earth space can produce large effects. Reconnection between the magnetic fields of the Sun and Earth causes electric fields, currents, and energetic particles to be created. The source of magnificent auroral displays, energetic particles, can pen- etrate satellite electronics and solar cells and disrupt or sometimes even terminate their operation. Electric currents flowing through the auroral ionosphere heat the atmosphere and produce global changes in upper- atmosphere density that make it difficult to predict the future locations of satellites and potential collisions between them. Electrical connections between the near-Earth space environment and the ionosphere can also disrupt the operation of communications and navigation systems, and cell phones, and even induce dangerous levels of currents in the U.S. power distribution system. Energetic particle precipitation into the upper atmosphere can also initiate a chain of events that lead to massive depletions of stratospheric ozone in the polar regions. These are only a few of the consequences that emerge from a complex web of interactions occurring within this active region called geospace and that motivate us to understand our home in the solar system (M1) and to predict the changing space environment and its societal impact (M2).1 The focus of the AIMI panel and the subject of this chapter is the region of geospace where atmosphere- ionosphere-magnetosphere interactions occur. That region extends from roughly the top of the stratosphere (at about 50 km) to several thousand kilometers, where the presence of the neutral atmosphere ceases to exert any significant control over the system. As will be discussed in more detail in this chapter, this 1  The motivations referred to in this section are those outlined in the introduction to Part II of this report: M1. Understand our home in the solar system; M2. Predict the changing space environment and its societal impact; M3. Explore space to reveal universal physical processes.

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154 SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY Solar Energetic Particle Chain Solar Radiation Chain Solar Wind/Magnetosphere Chain Lower Atmospheric Chain FIGURE 8.1  A depiction of the atmosphere-ionosphere-magnetosphere (AIM) system and the major processes that occur within that system. Absorption of short-wavelength solar radiation accounts for a large fraction of the heat input. Energetic particles, mostly from the magnetosphere, enhance the ionospheric conductance at high latitudes and modify the electrical currents that flow between the ionosphere and magnetosphere. Magnetospheric convection imposes electric fields that Figure 8-1 revised drive currents in the lower part of the ionosphere and set the ionospheric plasma into motion at higher altitudes, with a portion escaping into geospace and beyond. These injections of energy drive a global thermospheric circulation that redistributes heat and molecular species upwelling from the heated regions and also excites a spectrum of waves that redistribute energy both locally and globally. Planetary waves, tides, and gravity waves propagate upward from the lower atmosphere, deposit momentum into the mean circulation, and generate electric fields via the dynamo mechanism in the lower ionosphere. Dynamo electric fields are also created by disturbance winds. Neutral winds and electric fields from these combined sources redistribute plasma over local, regional, and global scales and sometimes create conditions for instabil- ity and production of smaller-scale structures in neutral and plasma components of the system. SOURCE: Courtesy of Joe Grebowsky, NASA Goddard Space Flight Center. region of geospace possesses several distinguishing characteristics that define it as a domain for compel- ling scientific inquiry and warrant the attention of a decadal survey with an explicit focus on solar and space physics’ connections to a technological society. Notably, this region serves as a “final link” in the transfer of energy within the solar-terrestrial chain. The primary drivers for variability in the region consist of direct solar energy in the form of extreme ultraviolet (EUV) and ultraviolet (UV) radiation, solar energy

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REPORT OF THE PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS 155 transformed into the charged particles and fields that permeate the magnetosphere, and solar-driven waves propagating upward from the lower atmosphere (see Figure 8.1). Responses to these drivers are determined by interacting dynamical, chemical, and electrodynamic processes that occur over a wide range of spatial and temporal scales, and moreover are strongly influenced by the presence of a strong magnetic field. Often these processes involve nonlinearity and feedback, and it is thus evident that this complex system can often exhibit emergent behavior.2 In fact, scientific investiga- tions of this geospace region resolve and interpret the system’s response to variable forcing, and ultimately unravel the complex chains of events leading to the observed, emergent behavior. (Several examples of emergent behavior are provided in this chapter.) Given this complexity, one can appreciate the difficulties of predicting the variability of neutral and plasma densities to the accuracies required to support orbital, reentry, communications, and navigation systems in operational settings. Thus, as this chapter unfolds, it will become evident that the study of atmosphere-ionosphere-magnetosphere interactions presents chal- lenging scientific problems that are fundamental to understanding planetary atmospheres and exospheres and that underlie the ability to predict environmental conditions that serve operational needs. In addition, the processes studied in this context can often be translated to other planetary bodies, and in this way geospace serves as a local laboratory to reveal and study universal physical processes (M3). The following section of this chapter summarizes the main scientific achievements of the past decade, reflecting back on the recommendations of the previous decadal survey. This lays the foundation for the subsequent section, which sets forth the science agenda for 2013-2022. The section after that addresses the various assets, resources, and strategies needed to advance AIM science most productively and presents a prioritized program for doing so. 8.3  SIGNIFICANT ACCOMPLISHMENTS OF THE PREVIOUS DECADE Understanding of atmosphere-ionosphere-magnetosphere (AIM) interactions has advanced through a number of vigorous programs, ranging from national, international, and multiagency programs to smaller- scale programs. Examples of programs that have helped shape the research landscape over the past decade are NASA’s Living with a Star (LWS) and Heliophysics Geospace Science programs, the NASA TIMED Solar- Terrestrial Probe, the NASA IMAGE Mid-size Explorer (MIDEX) mission, the NASA FAST Small Explorer (SMEX) mission, the NASA THEMIS MIDEX mission, the NASA AIM SMEX mission, and the U.S. Air Force (USAF) C/NOFS mission; the NASA Sounding Rocket Program; the National Space Weather Program; the NSF-sponsored SHINE, GEM, CEDAR, and small-satellite programs and their international counterparts; the NSF major research initiative (MRI) and science and technology centers (STCs); numerous DOD activi- ties; international satellite programs, such as CHAMP, GRACE, and COSMIC; and international science programs, such as CAWSES. These various programs have supported satellite and ground-based instru- ments and the related data analysis, theory, and modeling efforts. Research models and data assimilation schemes have advanced operational space weather prediction and created new models of the Sun-Earth system using a systemic and holistic perspective: Center for Integrated Space Weather Modeling (CISM), Community Coordinated Modeling Center (CCMC), NCAR Whole Atmosphere Community Climate Model (WACCM) development, and solar wind/magnetosphere models coupled with ionosphere/thermosphere global circulation models. Through these targeted programs and the critically important base programs funded by NSF, NASA, NOAA, and DOD, important scientific progress has been made, helping us to clarify needs and identify priorities that form the basis of this panel report. 2  Emergent behavior results from the interaction of a large number of system components that could not have been anticipated on the basis of the properties of components acting individually.

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156 SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY New supporting technologies, not specifically targeted for AIM research, have also significantly con- tributed to the field’s advancement in the past decade. These include cyberinfrastructure, advanced com- munications, improved sensors, networking technology, increases in computing power, precision naviga- tion systems, and small satellites. Complementing this technology growth were planned developments in space-borne and ground-based missions, major research instrumentation and facilities development, data assimilation schemes, and whole-atmosphere model development. These technological advancements help accelerate scientific endeavors and enable new science areas to be investigated and understood. The emergence of relocatable incoherent scatter radars (ISRs) based on electronically steerable antenna arrays is an excellent example. These NSF-supported advanced modular ISRs (AMISRs) can be steered on a pulse-to-pulse basis, allowing the simultaneous acquisition of information from multiple directions. The rapid steering capabilities of AMISR-class ISRs provide a unique capability for supporting AIM science objectives. For instance, these instruments can be used to construct three-dimensional views of the evolv- ing plasma state within a volume traversed by a satellite or rocket. Model development has been facilitated by major advances in instrumentation and measurement techniques, experimental facilities, and observing networks, which are starting to provide unprecedented volumes of data on processes operating across AIM. Together with concurrent progress in computational techniques, these advances have enabled the development of ever more sophisticated, multidimensional models of geospace. These models, along with data assimilation schemes, offer the promise of greater insights into the physical processes at work and improved ability to forecast disruptive events and their potential impacts. Development of numerical models that extend from Earth’s surface to the thermosphere/ionosphere has made significant breakthroughs during the past decade. These whole-atmosphere models are able to generate atmospheric disturbances, such as sudden stratospheric warming and quasi-biennial oscillation internally without having to impose artificial forcing, and to investigate their dynamical and electrodynami- cal coupling to the upper atmosphere in a self-consistent manner. Models that couple the magnetosphere and the ionosphere/thermosphere have reached the maturity to include feedback interaction between thermospheric neutrals and magnetospheric plasmas, as well as mass and momentum exchanges within geospace. In addition, physics-based data assimilation models of the global ionosphere have been devel- oped that are capable of assimilating multiple data types, for example, to reconstruct the electron density configuration during storms. These models are now running routinely in a test-operational mode for space weather specification. The adoption and implementation of a systems approach are more realizable today with the rapid expansion of multidimensional databases, increasing computational capabilities and sophistication of numerical tools, and emergence of new sensor technologies. Complementing these technological advance- ments have been new scientific discoveries that are rooted in a systems perspective of AIM science. What has emerged from this past research is the recognition that many of the natural coupling processes within AIM are linked through system complexity processes of feedback, nonlinearity, instability, preconditioning, and emergent behavior. The following examples of significant accomplishments of the previous decade reflect this overarching recognition. 8.3.1  Magnetosphere-Ionosphere Coupling A recent discovery in AIM science comes from a fortuitous combination of new measurement capabili- ties. The explosive increase in the global distribution of GPS receivers both on the ground and in space and the flight of the NASA IMAGE mission to image Earth’s magnetosphere-ionosphere (MI) showed a com- pletely new view of ionospheric/magnetospheric coupling during storms. Global GPS maps of ionospheric

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REPORT OF THE PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS 157 density showed, for the first time, large-scale dense plumes of plasma extending from middle latitudes to the auroral zone at the onset of magnetic storms (Figure 8.2). During such events, plasmaspheric imaging of He+ ions by IMAGE showed corresponding structures in the inner magnetosphere, where plasma was sheared away from the plasmasphere and advected toward the magnetopause. The plasmaspheric structure was never expected to appear in the ionosphere, and the discovery points to a process critical to enhanc- ing auroral ion outflow during storms. Further research results from NASA’s FAST and IMAGE satellites revealed that storm-enhanced ionosphere plasma feeds outflows of ionospheric ions into a tornado-like cusp funnel, powered by Alfvén waves generated by the solar wind-magnetosphere interaction. Evidence is accumulating that energy in these small-scale Alfvénic current filaments is deposited over a range of spatial and temporal scales and is converted to heat and momentum through ion-neutral interactions. These findings highlight the importance of feedback through the AIM system where magnetospheri- cally imposed electric fields redistribute ionospheric plasma, fueling the flux of outflowing ions to the magnetosphere. The outflows, especially heavy-ion outflows, can overwhelm reconnection mass loss in the plasma sheet and, effectively, reduce the cross-polar-cap potential and the concomitant ionospheric electric fields. In some instances, emergent behavior results whereby ~3-hour planetary-scale (sawtooth) FIGURE 8.2  Storm-enhanced plasma density signatures in total electron content (TEC) observed on March 31, 2001. These are believed to be connected to plasmashere erosion and driven by subauroral electric fields from the inner magnetosphere. SOURCE: J.C. Foster, P.J. Erickson, A.J. Coster, J. Goldstein, and F.J. Rich, Ionospheric signatures of plasmaspheric tails, Geophysi- cal Research Letters 29(13):1-1, doi:10.1029/2002GL015067, 2002. Copyright 2002 American Geophysical Union, reproduced by permission of American Geophysical Union. Figure 8-2

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158 SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY oscillations in the magnetosphere are observed. These occur when the MI system is strongly driven by a steady solar wind and seem to rely on superfluent nightside outflows of ionospheric O+. 8.3.2  Solar-AIM Coupling The past decade marked the 23rd solar cycle on modern record. Notable events included a number of powerful geomagnetic storms, two separate sunspot maxima, and a very deep solar minimum. With obser- vations from an array of space- and ground-based instruments unprecedented in their capabilities, solar cycle 23 is the first cycle since the initial detection of coronal mass ejections (CMEs) in the early 1970s in which a complete record of CMEs, coronal hole distributions, and solar wind data are all available over the whole cycle. The availability of simultaneous space- and ground-based data covering the Sun-Earth space has made solar cycle 23 solar storms and geomagnetic activity one of the best sets of events to analyze. It has been possible to assemble atmospheric, ionospheric, magnetospheric, interplanetary, and solar data on 88 CME storms during solar cycle 23. Many more events of enhanced geomagnetic activity were observed during this cycle associated with corotating interaction regions (CIRs)/high-speed solar wind streams (HSS) related to low-heliolatitude distributions of persistent coronal holes. A few of the CME storms were considered “great” storms that led to unexpected or emergent behavior in the AIM system. Ionosphere observations indicated the emergence of a daytime super-fountain effect lifting the ionosphere to new heights and increasing its total electron content by as much as 250 percent. Also observed were very large amplitude traveling ionospheric disturbances (Figure 8.3), new ionosphere layers, and very different behavior in equatorial plasma irregularities. The atmosphere responded with dramatic changes in neutral composition, winds, temperature, and mass density. Thermosphere mass density at 400 km increased by over 400 percent during these great storms while experiencing exceptionally fast recovery times, indicating a unique overcooling effect. The CIR/HSS storms were predominant during the declining and minimum phase of the solar cycle, producing an entirely different response in the AIM system. Where CME storms lasted a few days and were episodic, CIR/HSS storms lasted for more than a week and recurred for many solar rotations—in some instances sustaining common periodicities for an entire year. This has led to the discovery in atmosphere and iono- sphere data sets of pervasive periodicities at subharmonics of the ~27-day solar rotation period during solar cycle 23 (Figure 8.4). Unfortunately, although CHAMP, COSMIC, and ground-based platforms provided new discoveries in terms of total neutral and plasma density responses of the AIM system to the various solar disturbances noted above, only sparse measurements were made of the key parameters (e.g., winds, plasma drifts, neutral and ion composition) needed to understand these responses. It is a high-priority goal of the next decade to gain this understanding. 8.3.3  Meteorology-AIM Coupling One of the most exciting developments in recent years has been a new realization of the direct and strong impact of tropospheric weather and climate on the upper atmosphere and ionosphere. The connec- tion has been elicited, first, from measurements of the ionospheric density near the equator by NASA IMAGE and TIMED satellites, showing large changes in the structure of the ionosphere on seasonal timescales. This signature has subsequently been observed in upper-thermospheric composition and temperature. The clear correspondence demonstrated in this confluence of efforts has energized the study of atmospheric wave coupling to space plasma. Other observations and model studies have unequivocally revealed that Earth’s IT system owes a considerable amount of its longitudinal, local time, seasonal-latitudinal, and day-to-day variability to atmospheric waves that begin near Earth’s surface and propagate into the upper atmosphere.

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REPORT OF THE PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS 159 Density 80 (g cm-3) 60 8.10–15 40 Latitude (deg) 20 6.10–15 0 –20 –40 4.10–15 –60 –80 2.10–15 1 3 5 7 9 11 13 15 Orbit Number FIGURE 8.3  Illustration of traveling atmospheric disturbances seen in densities near 400 km near local noon measured by the accelerometer on the Challenging Mini-Satellite Payload (CHAMP) satellite, in connection with a geomagnetic distur- bance on day 308 of 2003. The data are obtained at nearly constant longitudes about every 1.5 hours, i.e., the time between consecutive “passes” or “orbits” of the satellite. The disturbance was initiated between pass 6 and 7 and took roughly 4.5 hours to reach the equator from both polar/auroral regions. The southward-propagating disturbance appears to pass into the Southern Hemisphere. Researchers do not know the behaviors of these disturbances in other local time sectors, or how Figure 8-3 dissipation of this disturbance has modified the mean state of the ionosphere-thermosphere system. SOURCE: Courtesy of Sean Bruinsma, Centre National d’Études Spatiales. Waves propagating upward from the lower atmosphere contribute about equally to the energy transfer in the IT system as direct solar energy in the form of EUV and UV radiation and reprocessed solar energy in the form of particles and fields from the magnetosphere. This unexpected and new realization is important for the space weather of the IT system. It is becoming increasingly clear that understanding wave driving from below is critical for predicting large- and small-scale structures in the IT system, such as ionospheric scintillations important to communication and navigation, and for testing and improving models for orbit propagation and collision warnings. 8.3.4  AIM Coupling and Global Change Earth is changing, and there are compelling and urgent needs for society to expand and develop basic science research to assess and answer society’s concerns in the area of climate change. There is sufficient evidence to believe that any climate change connected to changes in solar activity may involve chemical and dynamical pathways through the upper and middle atmosphere. Furthermore, long-term evolution-

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198 SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY propagation characteristics. All of these processes are subgrid processes in general circulation models of the AIM system, and their macroscopic effects need to be parameterized in such models before the influ- ences on the mean state can be determined. A significant impediment to further progress has been the lack of adequate observations. However, measurements of neutral gas properties from the lower atmosphere to the mid-thermosphere are within the current reach of lidar technologies. The combination of Rayleigh and resonance lidars is currently able to observe winds and temperatures from the ground to 105 km, albeit with signal-to-noise ratio (SNR) that is marginal for advancing the state of knowledge. Large-aperture telescopes and more powerful lasers are the natural remedy for limited SNR in lidar. Previous campaigns using resonance lidar techniques have demon- strated the scientific utility of using large telescope apertures of 3.5 meters at Starfire Optical Range, New Mexico, and the Air Force facility on Haleakala, Hawaii, with correlative passive optics, meteor radars, and rocket payloads to achieve desired resolutions to advance mesosphere and lower thermosphere science. A further demonstration of possibilities using large-aperture telescopes is shown in Figure 8.23, provided by a resonance lidar team working on sodium guide star studies. A 6-meter, zenith-pointing telescope com- prising a spinning mercury mirror was coupled to a sodium lidar system and revealed amazing detail in MLT instability structures, identified as Kelvin-Helmholtz billows evident at the base of the sodium layer, at a temporal resolution of 60 milliseconds and a spatial resolution of 15 meters. The available laser power has also increased exponentially over the years and, when combined with a large-aperture telescope, enables retrieval of winds and temperatures well into the thermosphere using the proven Rayleigh lidar technique. A lidar simulation based on a laser transmitter of 325 watts at 750 pulses per second and an 8-meter telescope can retrieve neutral temperatures at 200 km with 10 percent error at a range resolution of 5 km with 1-hour integration. Obviously the temporal and spatial resolution improves exponentially as altitude decreases, leading to unprecedented measurements of neutral gas properties in 99.4 40 35 98.2 30 Height above MSL [km] 97.0 25 95.8 20 15 94.6 10 93.4 5 92.2 0 0:26:7.968 0:33:28.826 0:40:49.684 0:48:10.542 local time [h:min:sec.ms] FIGURE 8.23  Large-aperture Na atomic density lidar measurements at 60-millisecond and 15-meter resolution showing detailed Kelvin-Helmholtz structures at the base of the layer. SOURCE: T. Pfrommer, P. Hickson, and C.-Y. She, A large-aperture sodium fluorescence lidar with very high resolution for mesopause dynamics and adaptive optics studies, Geophysical Research Letters 36:L15831, doi:10.1029/2009GL038802, 2009. Copyright 2009 American Geophysical Union. Reproduced by permission of American Geophysical Union. Figure 2-12 and 8-23

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REPORT OF THE PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS 199 the thermosphere and mesosphere. Recent lidar developments are also providing new possibilities for observations in the thermosphere. A helium resonance lidar is under development to probe the resonance structure of metastable helium in the upper atmosphere. If the lidar demonstrated, wind and temperatures would be derivable from altitudes well above 200 km. The technological advances expected with this pro- gram will also help lead to future developments of a lidar system in space for upper-atmosphere research. AIMI Priority: Create and operate a lidar observatory capable of measuring gravity waves, tides, wave- wave and wave-mean flow interactions, and wave dissipation and vertical coupling processes from the stratosphere to 200 km. Collocation with a research facility such as an incoherent scatter radar (ISR) instal- lation would enable study of a number of local-scale plasma-neutral interactions relevant to space weather. 8.5.3.3  Southern Hemisphere Expansion of Incoherent Scatter Radar (ISR) Network ISR is an extraordinarily powerful AIMI diagnostic, able to remotely sense the fundamental state parameters of the ionospheric plasma (Ne, Te, Ti, Vi) as a function of range and time. Through the use of ancillary models, higher-order parameters can also be resolved, including conductance, ion composition, Joule heating, electric current systems, and neutral wind fields. The emergence of electronically steerable ISRs in the previous decade has provided a major step forward in AIMI science. The Advanced Modular ISR (AMISR) facilities have demonstrated enormous capabilities to study the ionosphere with unprecedented resolution and precision. One example is provided in Figure 8.22, illustrating the capability of the Poker Flat AMISR (PFISR) to observe the ionospheric signatures of gravity waves in the critical 100- to 300-km- altitude region. A second example is provided in Figure 8.24, illustrating the capability of an AMISR to measure ionospheric flow fields and ion temperatures over small spatial and temporal scales. FIGURE 8.24  Composite image showing auroral forms, F-region ion temperature, and F-region ion flows, illustrating the local reduction in electric field in the vicinity of an auroral activation—a consequence of the polarization response of the ionosphere to the increased conductivity produced by the auroral precipitation. SOURCE: J. Semeter, T. W. Butler, M. Z ­ ettergren, C.J. Heinselman, and M.J. Nicolls, Composite imaging of auroral forms and convective flows during a substorm cycle, Journal of Geophysical Research 115:A08308, doi:10.1029/2009JA014931, 2010. Copyright 2010 American Geophysical Union. Reproduced by permission of American Geophysical Union. Figure 8-24

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200 SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY In addition to boasting low operation and maintenance costs, low power requirements, and a highly robust architecture, the AMISR facilities offer an extraordinary degree of experimental flexibility that has not yet been fully realized. For instance, during the 2009 International Polar Year, the PFISR facility was configured to record a vertical profile every 15 minutes for the entire year. This low-duty cycle mode was interleaved seamlessly with other experiments. Figure 8.25 shows an epoch analysis of ionospheric effects caused by corotating interaction regions extracted from these data. AMISR facilities deployed in the Southern Hemisphere and in the southern polar regions will contrib- ute significantly to understanding of inter-hemispheric variability that serves as the focus of the longitu- dinal sensor network proposed above. Collocation of the proposed whole-atmosphere lidar with such a deployment will lead to further advances in AIMI science by elucidating wave-plasma and plasma-neutral interactions over a range of scales, as well as contributing to understanding of the spatial and temporal evolution of Joule heating. Thus, with successful AMISR deployments at Poker Flat (PFISR) and at Resolute Bay (RISR), and planned deployments in Argentina and Antarctica, attention over the next decade should turn to developing technologies and strategies to fully exploit the emerging ISR network to address AIMI panel science priorities. AIMI Priority: Develop and deploy phased-array ISR facilities in the Southern Hemisphere including Antarctica, and develop the technologies and strategies to enable autonomous, extended, and coordinated operation of these facilities. AIMI Priority: Create a medium-scale research facility program at NSF. The above facilities are can- didates for support by the NSF Geospace program and would require that a medium-scale (~$40 million to $50 million) research facility funding program be instituted at NSF to fill the gap between the Major Research Instrumentation (MRI; <$4 million) and Major Research Equipment and Facilities Construction (MREFC; >$100 million) programs. FIGURE 8.25  Epoch analysis of ion temperature affected by the arrival of corotating interaction regions over the course of a year, extracted from AMISR low-duty-cycle measurements. SOURCE: J.J. Sojka, R.L. McPherron, A.P. van Eyken, M.J. Nicolls, C.J. Heinselman, and J.D. Kelly, Observations of ionospheric heating during the passage of solar coronal hole fast streams, Geophysical Research Letters 36:L19105, doi:10.1029/2009GL039064, 2009. Copyright 2009 American Geophysical Union. Reproduced by permission of American Geophysical Union. Figure 8-25

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REPORT OF THE PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS 201 8.5.3.4  Ionospheric Modification Facilities Ionospheric modification using high-frequency (HF) radio transmitters, or “heaters,” provides a pow- erful tool for exploring the physics of the upper atmosphere from the ground. Heating facilities treat the ionosphere as a “laboratory without walls,” providing insight into complicated plasma physics processes that occur elsewhere in the cosmos but that are difficult or impossible to explore in the laboratory. Iono- spheric heaters affect the propagation of radio signals; they generate airglow and radio emissions that can be observed from the ground; they create plasma density irregularities that can be studied using small coherent scatter radars; they provide access to chemical rate constants that are otherwise hard to quantify; they accelerate electrons, mimicking auroral processes; and finally, they modify plasma density and electron and ion temperatures and enhance the plasma and ion lines observed by incoherent scatter. The DOD operates and maintains the world’s largest ionospheric modification facility, HAARP, near Gakona, Alaska. HAARP is not collocated with an incoherent scatter radar, and so its full potential has not been realized since the phenomena it creates cannot be fully diagnosed. Figure 8.26 shows an image of an artificial aurora created at the HAARP facility. Another ionospheric modification facility is under construction at the Arecibo Radio Observatory. While this facility will be modest in power compared to HAARP, its collocation with Arecibo, the world’s most sensitive incoherent scatter radar, raises the prospect of discovery science in the areas of artificial and naturally occurring ionospheric phenomena. The Arecibo heater came about through close collaboration between DOD and NSF. The AIMI panel regards this kind of interagency cooperation as a model to be followed for the utilization of existing iono- spheric modification facilities as well as the planning and development of new ones. AIMI Priority: Fully realize the potential of ionospheric modification techniques through collocation of modern heating facilities with a full complement of diagnostic instruments including incoherent scatter radars. This effort requires coordination between NSF and DOD agencies in the planning and operation of existing and future ionospheric modification facilities. FIGURE 8.26  Artificial aurora induced by high-power HF radiation from the HAARP heater facility. The rayed structures are about 100 meters in width and are aligned with the geomagnetic field. SOURCE: E. Kendall, R. Marshall, R.T. Parris, A. Bhatt, A. Coster, T. Pedersen, P. Bernhardt, and C. Selcher, Decameter structure in heater-induced airglow at the High-frequency Active Auroral Research Program facility, Journal of Geophysical Research 115:A08306, doi:10.1029/2009JA015043, 2010. Copyright 2010 American Geophysical Union. Reproduced by permission of American Geophysical Union. Figure 8-26

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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, tur- bulence, 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., instabili- ties 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 global- scale 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 two- way 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 real- time 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 fore- casts 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 trans- form 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,

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REPORT OF THE PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS 203 and data exploitation; research to operations and operations to research; and education and workforce, and are detailed below. 8.5.5.1  Innovations: Technology, Instruments, and Data Systems Key Instrument Development Principal among the challenges presented to AIM science is a description of the neutral wind over the altitude range from 90 km to 300 km where a transition from a collision-dominated to a magnetized atmosphere occurs. Neutral-wind instrument development for space is a high priority for AIM science. The panel notes that reductions in mass, power, and volume of AIM space sensors would increase the effectiveness of small-satellite missions. Similarly, early action in instrument and technology development reduces the risk of unanticipated cost growth. Performed alongside a revitalized Explorer program, a new heliophysics instrument and technology development program would thus be highly complementary and support rapid scientific advancement. AIMI Priority: An expanded instrument development program to enable new observational advances that can reduce cost risk and threats when implemented as part of satellite missions. Data Access The AIM community uses a wide variety of heterogeneous data sets that sample regions throughout the geospace system and are collected by space- and ground-based instruments, some of them in networks or arrays. The synthesis of data sets within arrays, with other data sets, and with global and regional models to explore frontier science issues is a major challenge for the future. The Solar and Space Physics Information System (SSPIS) was created to enable access to, and digital searching of, the many distributed data resources managed or utilized by NASA. It currently consists of a set of VxOs providing access to distributed data sets with space data model descriptors. New search-and-analysis technologies that make use of these core capabilities are now possible with a potential for significantly enhancing AIM research. In the near future SSPIS will face major challenges in providing data services for manipulation, visualization, and storage of terabyte data sets and model outputs. The development and the implementation of new capabilities are extremely slow given the minimal funding levels of the program (only 1 percent of the NASA heliophysics budget). VxOs have developed to the point that software tools can now be built by end users to support scientific studies that could not conceivably have been performed before. For geospace regions that are populated by heterogeneous sensors, this is an important capability for revealing the processes that drive the development of structure and change in the AIM system. AIMI Priority: Create enhanced VxOs and interactive data access for system-level understanding. 8.5.5.2  Theory, Modeling, and Data Exploitation Programmatic Support High-priority AIMI science described throughout this chapter focuses on multiscale coupling, emer- gence, nonlinear dynamics, and system-level behaviors. This focus sets new requirements for research pro- grams, computational technologies, and data analysis needs. Discovery science in all these areas requires a means of understanding global connections, sometimes across vast distances or very disparate spatial or temporal scales, while at the same time developing a deep understanding of the individual regions and

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204 SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY processes that are elements of these connections. Coupling within the AIM system and with other ele- ments in the Sun-Earth system spans timescales from seconds to centuries and serves to refocus efforts in understanding global change and the role of solar variability in climate. Tackling planetary change and space climate issues is dependent on the availability of historical data sets and continuity in observations of key AIM parameters like atmospheric temperatures, composition and cooling rates, and solar inputs like spectral irradiance and interplanetary magnetic field. Finally, the future of assimilative modeling in space weather prediction rests on a continuing supply of near-real-time observations of the AIM system that provide information on large-scale features like the auroral zone and equatorial electrojet as well as small-scale gradients relevant to the triggering of ionospheric instabilities. Advances in computer power and speed have reached the point that self-consistent simulations of multiscale coupling in the AIM system are already possible. Existing peta-scale computers have reached 300,000 cores, and powerful mega-core computers are expected in the next decade to provide the com- putational equivalent of 1 million to 10 million CPU cores. These computational advances will drive a revolution in the realism of simulations and the ability to reproduce the self-consistent global signatures of small-scale processes. These advances in modeling in a very real sense parallel the innovations in obser- vational programs that are high-priority targets in this chapter. An investment in a range of technological capabilities is needed to take full advantage of these powerful computational resources, including new multiscale, multiphysics algorithms (such as adaptive mesh refinement), computational frameworks that couple physics across disparate time and spatial scales, innovative ways to mine, visualize, and analyze massive amounts of data produced by the next generation of multiscale simulations, and data assimilation technologies essential to improve space weather forecasting tools. These requirements and technological advances compel the following: AIMI Priority: Establish a re-balanced and expanded Research and Analysis Program with the follow- ing elements: • Solar and space physics (heliophysics) science centers, a new program of interdisciplinary centers (heliophysics scientists with computational experts) that leverages the power of peta-scale computers to create powerful physics-based multiscale models of the AIM system and its coupling to other regions, alongside parallel efforts in data assimilation and data fusion. Similar interdisciplinary theory and modeling efforts in the range of $1.5 million to $5 million per year over 3 to 5 years’ duration but not focused spe- cifically on geospace are funded through NSF through its Frontiers in Earth System Dynamics, and AFOSR through its Multidisciplinary Research Program of the University Research Initiative program. NASA funds smaller-scale modeling efforts within the strategic capabilities category in the Living with a Star Targeted Research and Technology program. Given the large costs of these programs, it may work best if NASA, NSF, and AFOSR coordinate their funding of these multidisciplinary programs in order to avoid duplication and ensure that essential projects are funded. • A strengthened NASA theory program that supports critical-mass groups responding to new theoreti- cal challenges in AIM science using a wide variety of research approaches. • An enhanced data analysis program (attached to satellite missions and ground-based facilities) that provides a level of support needed to convert new and archived AIM observations into knowledge and understanding. • An upgraded R&A program that is a reasonable fraction of the overall AIM budget to make sure that expenditures in the program are converted to major advances in science.

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REPORT OF THE PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS 205 AIM Data Environment The innovative observational and modeling programs described in this chapter will provide essential new information about how the AIM system works. However, this information will be embedded in the relationships between data sets as well as within the individual data sets themselves. It will be buried in petabytes of simulation data and in large volumes of heterogeneous data from new and ongoing space missions, from major new ground-based facilities, from suborbital platforms, and from arrays of ground- based all-sky cameras, lidars, radars, magnetometers, GPS receivers, ionosondes, imagers, and other instru- ments. There must be a parallel effort to develop the tools needed to convert the volumes of data into new knowledge about the AIM system. The challenge is to combine these heterogeneous data sources, housed in archives distributed around the world, into new browse summaries and new data products that contain information about AIM system behaviors in addition to the regional and process information contained in the individual data sets themselves. In turn, this global view will provide needed context for the interpreta- tion of small-scale features and local observations. Because of these requirements, new efforts in data exploitation and data synthesis are essential ingredients for the future of the AIM research environment. As data sources grow in size and complexity, exploiting the data requires being able to (1) locate specific pieces of information within a large distributed set of worldwide data archives, (2) manipulate and visualize the data while retaining knowledge of ver- sion information and all supporting analysis programs, and (3) combine data sources to create new data products while maintaining linkages back to the original data sources. This is where the development of data synthesis capabilities is essential. In the face of constrained budgets, much of this effort can be accom- plished by using robust and sustainable commercial off-the-shelf (COTS) technologies that keep pace with new developments. To make heliophysics data “findable” by these commercial technologies requires the development of standard text-based metadata descriptors. Much of the groundwork for this capability has taken place in the last few years with the creation of an array of virtual observatories and the continuing development and implementation of the international Space Physics Archive Search and Extract (SPASE) data model. The full and complete implementation of SPASE opens the way for the development of an array of shared software tools for essential capabilities in data mining, pattern recognition, statistical analyses, data visualization, and so on, both on the client side and on the server side in the case of large data vol- umes. Virtual observatories also enable the development of tools that require detailed information about instruments not easily obtained by individual investigators. One example is the calculation of common volumes in which in situ and remote-sensing measurements are made or in which space- and ground- based observations intersect. AIMI Priority: Develop a data environment that preserves important elements of the current helio- physics data environment, while expanding the capabilities in directions that enhance data exploitation to maximize the scientific value of the data sets. Data Synthesis Essential to many of the AIM science frontiers identified in this chapter is the ability to synthesize infor- mation from multiple data sets into new knowledge about the AIM system. This includes, for example, map- ping between geospace data sets using magnetic fields from continuously running magnetohydrodynamic simulations, browse products that superpose observations along satellite tracks onto global patterns from constellations or imagers, maps that combine information from a large number of individual ground-based instruments into global views, and combinations of ground- and space-based observations that address space-time ambiguities, among others.

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206 SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY AIMI Priority: Explore new data synthesis technologies to leverage the many types of AIM data into new knowledge of the AIM system required for accelerating progress on AIM system science frontiers. Heterogeneous Data Sets To accomplish AIM goals in the coming decade, a data environment is needed that draws together new and archived satellite and ground-based geospace data sets from U.S. agencies as well as international partners. This effort is needed to obtain the best possible coverage of the geospace system and describe its evolution over time. This data environment should also provide access to operational space weather data sets, climatological data sets, archived simulation outputs, and the latest technological advances in digital searching, storage, and retrieval and in data mining, fusion, and assimilation, as well as client-side and server-side data manipulation and visualization. These ground and space assets represent a large invest- ment and are vital for the system science goals of the AIM program. The full value of that investment will be realized only if adequate funding is provided. The present Solar and Space Physics Information System (SSPIS) could naturally form the core of this program. The valuable multiagency and international efforts to unify standards and increase interoperability through agreements on data and metadata formats and communication protocols started under the SSPIS program must be an essential component of this effort. AIMI Priority: Increase investment in the acquisition, archiving, and ease of use of geospace data sets. Long-Term Data Sets NASA and NSF should identify essential long-term data sets and pursue maintenance and preservation through funding within the heliophysics data environment activities and related NSF data archives. Some of this data, not in digital formats yet, is in danger of being irretrievably lost. A larger problem is the continuity of key long-term data sets, for example, solar spectral irradiance and 30 years of particle precipitation on operational satellites. Mechanisms do not yet exist to continue such data sets except by competing against new satellite missions. New mechanisms must be established to add instrumentation where possible on rides of opportunity and to partner with other agencies to re-establish space environment monitors on key operational satellite payloads. AIMI Priority: Establish mechanisms for maintenance and continuity of essential long-term data sets. Laboratory Experiments Modeling planetary atmospheres and interpreting information in airglow and auroral emissions from Earth’s atmosphere, planetary bodies, and comets requires detailed knowledge of differential cross sections and of reaction rates. The extraction of information about planetary environments from these emissions and the design of new and innovative remote-sensing instrumentation are dependent on accurate cross-section information. Laboratory experiments are a primary source of this information and have a long history of advancing the discovery of fundamental processes in all of these environments. Critical information on rates and cross sections for key atomic and molecular processes is still lacking. One particular example where cross-section information is highly uncertain and has impeded progress is oxygen ion precipitation and backsplash during extreme space weather events. AIMI Priority: Establish a program of laboratory experiments joint between NSF, NASA, and DOE that includes measurements of key cross sections and reaction rates.

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REPORT OF THE PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS 207 8.5.5.3  Research to Operations and Operations to Research Research is the foundation for future improvements in space weather services. Ionospheric models are just now beginning to reach maturity at a level that can benefit space weather customers. But at the same time, there is a major decline in support for the development and improvement of models, which are critical to operational entities. Furthermore, model development aimed at improving forecasts requires a dedicated effort focused on validation and verification. Also, in order to quantify a model’s performance, there is a need to establish a standard set of metrics for space weather products. Under NASA, NSF, NOAA, and AFOSR sponsorship, a standard set of metrics and a skill score most appropriate for a given space weather application need to be selected that would reflect operational needs. Metrics and skill score should also be used to quantify progress with each new model version. To reduce “the valley of death” that separates research models and operational systems, the AIMI panel suggests that operational and research agencies fund open-source models. Open-source operational models have the potential to minimize the cost of transitioning research models to operations and of maintaining the models. AIMI Priority: Improve the effectiveness and level of support for model development, validation, and transition to operation. Existing and planned assets that are routinely used for purposes other than space weather often have capabilities that could be utilized to return valuable space science measurements. With minimal investment, important data can be obtained from these instruments. One very-low-cost example includes tasking on a daily basis the Altair radar at Kwajalein to measure ionospheric parameters (electron density and plasma irregularities). This can easily be done during short periods interlaced between scheduled radar target acquisitions. These measurements would also benefit the users of the Altair system by providing a method to detect and forecast possible scintillation problems that could affect the radar data. AIMI Priority: Seek high-leverage opportunities for acquiring new measurements. It is widely recognized that space environment data provided by NOAA and DOD operational satel- lites for almost four decades are essential to AIMI science. Data from these satellites are of fundamental importance for space weather forecasting. They are among the most often used data sets for space science research on ionosphere/magnetosphere coupling. In addition, they are essential for studying long-term climatic changes in geospace. The following three-part imperative follows: AIMI Priority: Leverage national investments in operational satellite data for scientific progress: (1) NOAA and DOD should maintain the space environment sensing capability that has provided data for almost four decades and should continue to acquire observations from low-Earth-orbit satellites of particle precipitation, ion drifts, ion density, and magnetic perturbations similar to those measured from POES and DMSP. (2) Open data policies should be negotiated with DOD, DOE, and other agencies (that also safeguard national security concerns). (3) DOD, NOAA, and NASA should coordinate the archiving of these data sets, making data accessible and creating tools that provide for ease of use. The present Solar and Space Physics Information System could naturally form the core of this program.

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208 SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY 8.5.5.4  Education and Workforce The AIM community recognizes the increasing need to promote education and training in all aspects of space science and space technology. At the same time, few educational institutions have the breadth within their faculty, or the student numbers within a department, to facilitate a complete AIM curriculum. Thus it is important to afford the opportunity for students and faculty to participate in programs that bring together varying expertise from different institutions in intensive training sessions in order to fill this pedagogical gap. NSF, NASA, and DOD should continue to support the development and execution of summer schools and workshops to provide a full spectrum of instruction in geospace science and technology. This effort is considered essential to the proper development of the next generation of space scientists and engineers. NSF should continue its Faculty Development in Space Sciences program, which provides an incentive for universities to hire faculty in geospace research. The federal government should revise export control policies to exempt basic space research from government restrictions such as those mandated under ITAR. AIMI Priority: As described above, expand and promote education and training opportunities to develop the future generation of AIM scientists and engineers.