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8 Report of the Panel on Atmosphere-Ionosphere-Magnetosphere Interactions
8 Report of the Panel on Atmosphere-Ionosphere-Magnetosphere Interactions
Pages 149-208
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From page 149... ...
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: A IMI Science Priority 1.
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From page 150... ...
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 atmosphere.
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From page 151... ...
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 instruments to measure the critical energy inputs to the AIM system from the spectrum of waves entering from below.
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From page 152... ...
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.
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From page 153... ...
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.
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From page 154... ...
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.
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From page 155... ...
These various programs have supported satellite and ground-based instruments 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)
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From page 156... ...
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.
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From page 157... ...
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)
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From page 158... ...
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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From page 159... ...
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.
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From page 160... ...
Nerem, Rotating solar coronal holes and periodic modulation of the upper atmosphere, Geophysical Research Letters 35:L10109, doi:10.1029/2008GL033875, 2008. Copyright 2008 American Geophysical Union, reproduced by permission of American Geophysical Union.
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From page 161... ...
An effect predicted in the 1980s, this change is thought to arise largely in response to the increase in atmospheric CO2 that acts as a radiative cooler in the upper atmosphere, diametric to its role in the lower atmosphere. This is not itself an effect of the change in climate in the lower atmosphere, but rather a human-influenced change in the upper.
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From page 162... ...
Gradual changes in solar activity, solar wind, EUV radiation, and Earth's magnetic field each play a significant role in defining the longer-term variation in the geospace environment. For instance, long-term changes in Earth's magnetic field are occurring and producing measurable changes in the ionosphere.
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From page 163... ...
Achieving the above level of understanding is a multidecade task. The AIMI panel has, however, narrowed the scope of aspirations to five AIMI science goals that have the potential to be comprehensively addressed with current technologies or those under development, and within the 2013-2022 decade.
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From page 164... ...
FIGURE 8.6 Five AIMI science goals for the 2013-2022 decade and how they map into the decadal survey's key science goals 1-4. Figure 8-6 8.4.1 AIMI Science Goal 1.
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From page 165... ...
Differences in ionospheric conductivity play an important role in the closure of magnetospheric currents and may have a profound influence on magnetospheric current closure, as the ionosphere and magnetosphere interact to regulate the response of geospace to solar wind input. SOURCE: Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE)
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From page 166... ...
This picture varies considerably from day to day, but is available only at a single local time on any given day. Without coincident global measurements of neutral winds, temperature, and total mass density and some measure of localized heating, the causes and consequences of this composition variability cannot be ascertained.
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From page 167... ...
A similar effect can occur at middle latitudes when equatorward winds push the plasma up magnetic field lines, lessening the drag on the zonal winds. Large redistributions of plasma occur as the result of subauroral electric fields that couple the inner magnetosphere and plasmasphere to the mid-latitude ionosphere (Figure 8.9)
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From page 168... ...
. The interactions and feedbacks that occur between energy deposition, dynamics, radiative cooling, energetic particles, electric fields, and plasma and neutral constituents and temperatures are how the global IT system regulates its response to magnetospheric forcing, and how it also regulates the response of the magnetosphere to solar wind forcing.
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From page 169... ...
Figure 8-10 carried by the waves can redistribute ionospheric plasma, either through the electric fields generated via the dynamo mechanism, or directly by moving plasma along magnetic field lines (Figure 8.11)
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From page 170... ...
and By what mechanisms are electric fields and plasma drifts generated in the dynamo region at PW periods? As one example, recent measurements reveal the fascinating result that stratospheric warmings significantly alter the state of the IT system: a prevailing theory is that enhanced quasi-stationary PWs common to these dynamical events interact nonlinearly with existing tides to produce secondary tides that propagate globally and generate dynamo electric fields in the ionosphere.
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From page 171... ...
In addition, first-principles modeling predicts a thermospheric warming in response to the stratospheric warmings, and resulting changes in thermospheric winds and density that impact satellite drag. The above wave-plasma interactions focus on electric fields generated by the dynamo mechanism, but one must ask: What other processes compete with dynamo electric fields to modify and redistribute plasma in the F region (~200-600 km)
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From page 172... ...
The AIMI panel concluded that a major goal of the coming decade is to understand how tropospheric weather drives space weather. 8.4.3 AIMI Science Goal 3.
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From page 173... ...
Effects on the upper atmosphere and ionosphere of transient electric fields, electromagnetic waves, and high-energy electrons produced by these events remain unknown. SOURCE: Reprinted by permission from Macmillan Publishers Ltd: Nature, V.P.
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From page 174... ...
Elphic, Factors controlling ionospheric outflows as observed at intermediate altitudes, Journal of Geophysical Research 110:A03221, doi:10.1029/2004JA01082, 2005. Copyright 2005 American Geophysical Union.
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From page 175... ...
The AIMI panel concluded that an additional major goal of the coming decade is to understand how the IT and magnetosphere interact to regulate their coupled response to solar wind forcing. 8.4.4 AIMI Science Goal 4.
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From page 176... ...
Forbes, Longitudinal and geomagnetic activity modulation of the equatorial thermosphere anomaly, Journal of Geophysical Research 115:A08311, doi:10.1029/2009JA015177, 2010. Copyright 2010 American Geophysical Union.
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From page 177... ...
It is hypothesized that the southwestward directionality of the waves, at least at nighttime, is aligned in the direction of weakest Joule damping as predicted by the Perkins instability. This hypothesis is supported by measurements that indicate the existence of electric fields within the wave structures, which are FIGURE 8.16 Two-dimensional distribution of total electron content (TEC)
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From page 178... ...
Breakthroughs in the next decade in understanding the dynamic interaction between the magnetosphere and the IT system must therefore confront the question, How do activities in neutral and ionized gases and electromagnetic fields interact to produce observed magnetic field-aligned structure and motions of the thermosphere and ionosphere? The AIMI panel concluded that a major goal of the 2013-2022 decade is to understand the plasmaneutral coupling processes that give rise to local, regional, and global-scale structures in the AIM system, particularly those relevant to society.
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From page 179... ...
Köhler, Global distribution of the thermospheric total mass density derived from CHAMP, Journal of Geophysical Research 110:A04301, Figure 8-17 doi:10.1029/2004JA010741, 2005. Copyright 2005 American Geophysical Union.
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From page 180... ...
mission to understand how geospace is influenced by the lower atmosphere. One of the urgent, unresolved heliophysics questions is how feedback processes in the Earth system amplify the effects of small changes in solar energy output, leading to disproportionately large changes in atmospheric parameters.
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From page 181... ...
Perturbations to these three entities are intertwined and can trigger nonlocal changes, e.g., by perturbing propagation of waves to the upper atmosphere or weather and climate in the lower atmosphere. Thus EPP-NOx-induced perturbations in O3 are communicated via effects on temperature and circulation upward to the MLT and potentially downward to the troposphere, thereby triggering the redistribution of particle energy throughout the atmosphere.
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From page 182... ...
8.5 IMPLEMENTATION STRATEGIES AND ENABLING CAPABILITIES The following section focuses on strategies and enabling capabilities to address the AIMI science goals outlined in the previous section, with particular emphasis on the three science priorities just enumerated. The AIMI panel's four imperatives as summarized in Section 8.1 fall under the categories of spaceflight
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From page 183... ...
that, by their very nature, respond at all local times to the interconnected processes that define the AIM system. On the other hand, a constellation of identical, multiple satellites in low Earth orbit, such as proposed here as the Geospace Dynamics Constellation, would provide the necessary global, simultaneous observations covering all latitudes and local times while orbiting Earth in
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From page 184... ...
GDC Science Objectives GDC Scientific Merit GDC Space Weather Relevance Understand the dynamic, energy/ Will determine how the global IT system Enable prediction of how highmomentum exchange between ionized/ participates as an active element in the latitude structures in the ionosphere neutral gases at high latitudes and evolution of storms. and thermosphere are driven by their coupling and feedback to the magnetosphere input and then magnetosphere and solar wind.
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From page 185... ...
The satellites will nominally have an inclination of 80°, in order to use precession to help separate the local time planes, while maintaining adequate coverage of the high-latitude region. Three main orbital configurations were considered by the AIMI panel: 1.
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From page 186... ...
Figure 4-10 and 8-20 highly elliptical orbits that will gather data that will address important science questions under AIMI science goals 2, 3, and 4, in addition to science goal 1, thus cutting across all three AIMI science priorities for the 2013-2022 decade. Baseline Mission and Possible Descope The GDC baseline mission can fully meet its science objectives with a complement of six satellites as discussed above.
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From page 187... ...
breakthroughs in understanding of feedbacks between field-aligned currents, ion drifts (electric fields) , conductivities, neutral densities, and winds that result from the interaction between the atmosphereionosphere and the magnetosphere; (2)
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From page 188... ...
Measurement of winds, plasma drifts, and plasma densities at high latitudes will lead to estimates of Joule heating, as well as to estimates of a number of other plasma-neutral interactions at high and low latitudes. In addition, the simultaneous measurement of lower-thermosphere winds and plasma drifts at higher altitudes (or, equivalently, electric fields)
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From page 189... ...
winds and electric fields combine to drive ionosphere variability. What is the role of gravity waves in Cross-scale plasma-neutral processes Develop the basis for forecasting "seeding" equatorial Rayleigh-Taylor in the equatorial ionosphere are ionospheric scintillations.
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From page 190... ...
By combining two-point ESCAPE measurements with solar wind and interplanetary magnetic field measurements; ground-based radar, lidar, imaging, and TEC measurements; and global geospace simulations, the ESCAPE mission can also address two related, global questions directly aligned with AIMI panel science priorities 1 and 3: How do interplanetary and AIM conditions control outflows, their distributions, and fluxes? How does the AIM system respond to ionospheric outflows?
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From page 191... ...
is in the topside ionosphere. When one spacecraft is at higher altitude, it measures electromagnetic and precipitating particle energy inputs and properties of outflowing ions, while the magnetically aligned low-altitude spacecraft measures the properties of the ion and neutral gas source region and physical attributes of the energy conversion process.
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From page 192... ...
Changes in the neutral atmosphere dynamics and conductance also change the internally generated electric fields and the coupling processes to the magnetosphere. Thus the ability to specify the energy input and view the dynamic state of a large volume at middle and high latitudes over time periods ranging from less than 1 minute to many tens of minutes is necessary to determine how magnetosphereatmosphere coupling processes affect the behavior of both regions.
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From page 193... ...
and Aeronomy of Ice in the Mesosphere have provided system-level information on the behavior of the magnetosphere effective in the upper atmosphere and ionosphere, and the conditions at the boundary between the atmosphere and space, respectively. These notable achievements could be followed by an Explorer mission that investigates the coupling of energy between the regions or the development of large-scale structures and emergent behavior in the system.
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From page 194... ...
The AIMI panel supports an enhancement of the Heliophysics Explorer budget line to accomplish a broad range of science missions that can address important AIMI science challenges. The 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.
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From page 195... ...
Thus, the physics and evolutionary aspects of waves, electric fields, and plasma structures can be explored over much shorter timescales than from space. Ground-based remote sensing techniques and suborbital platforms are also capable of accessing regions of the atmosphere and space that are not easily probed by orbital vehicles.
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From page 196... ...
Saito, Medium-scale traveling ionospheric disturbances detected with dense and wide TEC maps over North America, Geophysical Research Letters 34:L22101, doi:10.1029/2007GL031663, 2007. Copyright 2007 American Geophysical Union.
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From page 197... ...
How gravity waves are dissipated and drive the mean circulation and thermal structure of the thermosphere remains unclear. In addition, gravity waves interact with longer-period tides and planetary waves and modify their vertical FIGURE 8.22 Gravity wave vertical structures seen in electron densities by the Poker Flat Incoherent Scatter Radar (PFISR)
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From page 198... ...
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]
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From page 199... ...
The technological advances expected with this program 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, wavewave and wave-mean flow interactions, and wave dissipation and vertical coupling processes from the stratosphere to 200 km.
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From page 200... ...
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.
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From page 201... ...
The AIMI panel regards this kind of interagency cooperation as a model to be followed for the utilization of existing ionospheric 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.
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From page 202... ...
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.
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From page 203... ...
8.5.5.2 Theory, Modeling, and Data Exploitation Programmatic Support High-priority AIMI science described throughout this chapter focuses on multiscale coupling, emergence, nonlinear dynamics, and system-level behaviors. This focus sets new requirements for research programs, computational technologies, and data analysis needs.
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From page 204... ...
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.
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From page 205... ...
AIMI Priority: Develop a data environment that preserves important elements of the current heliophysics 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 information from multiple data sets into new knowledge about the AIM system.
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From page 206... ...
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 investment and are vital for the system science goals of the AIM program.
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From page 207... ...
It is widely recognized that space environment data provided by NOAA and DOD operational satellites for almost four decades are essential to AIMI science. Data from these satellites are of fundamental importance for space weather forecasting.
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From page 208... ...
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.
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