FR1.3: SPACE WEATHER MODELS

FR1.3: Space weather mODELS

Goal: To incorporate energetic particles and extreme events into physics-based models of the geospace radiation environment.

Challenges: A better understanding of space weather-related physics and the solar wind-magnetosphericionospheric environment is critical to the development of predictive nowcasting and forecasting space weather models that in turn are critical to the safe and effective operation of many modern technologies.

Background: a) The acceleration of ions and electrons to high energies is a critical but poorly understood element of space weather. Magnetic structures or small-scale flux ropes (SMFRs) are formed in the solar wind through current sheets or turbulent magnetic reconnection and can accelerate suprathermal ions and electrons efficiently. b) Very little is understood about the basic physics of extreme CME-driven shocks and even less about the related solar energetic particles (SEPs) energization. c) Interplanetary disturbances, such as shocks or large changes in the magnetic field direction, colliding with the Earth’s magnetosphere can drive “geomagnetically induced currents” (GICs). GICs driven by space weather can damage critical infrastructure (e.g., power grids, pipelines, and railway systems) and create economic losses. GICs are frequently localized and the processes that control their spatial variability are unknown.

Proposed Research: A) This project will resolve unanswered key issues about SMFRs and their relation to particle acceleration (SMFR generation, the dominant mechanism for electrons versus ions, role of trapping, contribution to the DSA seed particle population). B) To describe extreme CME- shock-driven solar wind SEP events, we will: 1) develop a plasma model that couples thermal and energetic charged particles, magnetic field, and low-frequency turbulence, and determine the shock structure of extreme events for both time-dependent and 2D/3D models; 2) compute the energetic particle distribution due to diffusive shock acceleration at extreme CME-driven shocks, and 3) describe quantitatively the 2D/3D transport of SEPs that escape an energetic particle mediated shock. C) To address the nature of and factors that influence dB/dt associated with GICs (e.g., conditions that initiate and control temporal and spatial evolution, parameterization of solar wind conditions, pre-conditioning) we will use observations from many instruments flown over the last solar cycle. The global network of magnetometers (SuperMAG) will be used to identify and characterize dB/dt. Solar wind conditions will be provided by the ACE, WIND, DSCOVR, and Geotail spacecraft. Magnetospheric processes occurring conjugate to large dB/dt will be probed by THEMIS, MMS, Van Allen Probes, and Cluster. Ionospheric conditions will be monitored by auroral cameras (the THEMIS all-sky imagers), incoherent and coherent scattering radars (PFISR, RISR, SuperDARN), and LEO spacecraft AMPERE and SWARM.

Integration with Transformational Technology: This work will support TT5 by providing improved space weather models and better understanding of magnetospheric response to severe space weather events. Impacts: Critical to space weather is understanding the geospace radiation environment. This work addresses the origin, characteristics and impact of energetic particles in the heliosphere. The impact of space weather on how, when, and why significant geomagnetically induced currents are created by disturbances impinging on the Earth’s magnetosphere will be clarified, which is critical to managing electrical currents flowing in long engineered conductive systems (TT5)

FR1.3b: Model extreme SEP evens

The physics of the shock structures associated with extreme space weather events is governed by a complex coupling of thermal plasma (governed by density, pressure or temperature, velocity, and magnetic field), which transports, drives, is heated by, and responds to low-frequency turbulence (governed by the energy density in “forward” and “backward” propagating fluctuations, cross helicity, residual energy, and correlation lengths). The thermal plasma and low-frequency turbulence collectively act to transport the SEPs as they scatter in pitch-angle, but the SEPs mediate the thermal plasma through their contribution to the heat flux of the thermal plasma and the total pressure, and they generate turbulence as they stream away from the shock at which they are accelerated. Therefore, in order to describe extreme CME- shock-driven solar wind SEP events, we will: 1) develop a plasma model that couples thermal and energetic charged particles, magnetic field, and low-frequency turbulence, and determine the shock structure of extreme events for both time-dependent and 2D/3D models; 2) compute the energetic particle distribution due to diffusive shock acceleration at extreme CME-driven shocks, and 3) describe quantitatively the 2D/3D transport of SEPs.