FR2.3 – Integrating theory, lab, and observations of geospace
Challenge: Because the near-Earth space environment is a complex, dynamic region filled with LTP, energetic particles, and charged dust, as well as hosting a vast fleet of orbital systems that provide communications, navigation, and national security, it is critical to have a fundamental and predictive understanding of the space environment.
FR2.3(a) Wave generation in space plasmas
Background: The Van Allen Probes mission greatly improved our understanding of ultra-low frequency wave processes, but the global aspects of radiation belt dynamics associated with electromagnetic ion cyclotron (EMIC) waves as well as their role in the loss of relativistic (MeV) electrons are still poorly understood.
Proposed research: To use cross-correlated global simulations, multipoint space observations, and laboratory experiments to understand and forecast, under various solar wind and interplanetary magnetic field (IMF) conditions: 1) the processes that control the generation and structure of EMIC waves in the inner magnetosphere, and 2) the contribution of EMIC waves in radiation belt electron losses. Global simulations will be performed using hybrid models combined with test-particle simulations and a diffusion model. The models include an inner magnetospheric hybrid model in dipole geometry and the Auburn global hybrid code in 3D (ANGIE3D)26 based on the self-consistent solar wind-magnetosphere interaction. Innovative laboratory experiments will focus on the linear and nonlinear physics of EMIC waves in multispecies plasmas, and the results will be validated by in-situ observations of magnetospheric EMIC waves and be simulated (with hybrid code) for a laboratory geometry. The timing of the energization and loss of relativistic electrons will be modeled using a low-dimensional space weather prediction model of the magnetosphere (WINDMI)27, driven by solar wind velocity, IMF, and solar wind particle density.
Specific research tasks include:
- Research Task 1 — Understand the internal (by local ion injection) or external (by solar wind compression) processes controlling the generation and global structure of EMIC waves in the inner magnetosphere.
- Research Task 2 — Understand the linear and nonlinear properties of EMIC waves through theory/simulation, space observation, and lab experiment.
- Research Task 3 — Understand the wave-particle interaction, including transport coefficients of energetic electrons and electron scattering, in EMIC waves by combined simulation, observation, and experiment.
- Research Task 4 — Develop the prediction capability of the radiation belt electron loss.
- Research Task 5 — Analyze the relationship between plasmaspheric notches and kilometric continuum (KC).
- Research Task 6 — Correlate ring-current/radiation belt losses to presence of KC.
- Research Task 7 — Correlate plasmapause density structures with lightning-generated whistlers observed outside the plasmasphere.
- Research Task 8 — Correlate lightning-generated whistlers observed outside the plasmasphere with ring-current/radiation belt losses.
FR2.3(b) Dynamics of the plasmasphere
Background: The plasmasphere is a weakly ionized LTP that extends from the top of the ionosphere to 3- 5 Earth radii. Electric and magnetic fields cause it to co-rotate with the Earth but with some slippage that 47 leads to a decoupling of Earth and plasmasphere rotation while its shape is correlated with geomagnetic activity in the magnetosphere. However, the physics of the plasmasphere and its co-rotation mechanism are still poorly understood. Besides being an important spatial region surrounding the Earth, it is an excellent laboratory to study the LTP kinetics due to its large size.
Proposed research: We will investigate the slippage in co-rotation and the dynamical causes behind the large-scale shape variations of the Earth’s plasmasphere using modeling and analyzing the extensive, available satellite datasets.
Specific research tasks include:
- Research Task 1 — Develop an online introductory class on Earth’s Plasmasphere, accepting students from all EPSCoR participating institutions/universities.
- Research Task 2 — Implement online introductory class on Earth’s Plasmasphere.
- Research Task 3 — Probe the interaction physics resulting from the interaction between the LTPs of the plasmasphere and the energetic plasmas of the ring current and radiation belts using in-situ and remote observations.
- Research Task 4 — Develop a next-generation model of the plasmasphere density distribution and dynamics based on 1st principles and constrained by in-situ and remote observations of the plasmasphere.
- Research Task 5 — Incorporate results from Yrs. 3 & 4 into ANGIE3D-CIMI model.
- Research Task 6 — Analyze/correlate statistics on occurrence of plasmaspheric plumes with solar wind drivers.
- Research Task 7 — Characterize and quantify plasmaspheric plume density turbulence.
- Research Task 8 — Analyze/correlate statistics on occurrence of corotating low-density channels and deep plasmaspheric notches with solar wind drivers.
- Research Task 9 — Conduct statistical analysis of occurrence of plasmaspheric “standingwave”/ wave-like density features with solar wind drivers.
- Research Task 10 — Correlate statistical plasmaspheric conditions with radiation belt/ring current conditions/states.
Integration with Transformational Technology: This work will support TT5 by providing the validated plasma parameter models (based on simulations and observations) that will be used as inputs for space weather algorithms.
Impact: Our understanding of geospace will be advanced by developing new tools that can forecast space weather events, particularly with respect to particle energization by waves and the formation of large-scale plasma structures. Validation: using ANGIE3D and WINDMI, EMIC wave generation and structure will be studied using hybrid models to obtain both the growth rates of waves and scattering rates of relativistic electrons in EMIC waves. These will be validated against modeling and simulations in (FR1 and TT5). Scaling: We will use the ALEXIS device, which has already demonstrated plasma wave generation in rotating plasmas under scaled ionospheric28,29 and radiation belt conditions,30,31 to investigate the spontaneous and driven generation of EMIC waves (TT5). Measurement: Lab experiments will use simulation results to guide studies of rotating plasmas and spontaneously generated EMIC waves. Lab observations will be benchmarked against multipoint satellite observations made by near-equatorial (e.g., Van Allen Probes, MMS, GOES) and low altitude (POES/MetOp, CubeSats) spacecraft in the magnetosphere as well as BARREL balloons in the polar atmosphere.