Abstract
Abstract. Major geomagnetic storms are caused by unusually intense solar wind southward magnetic fields that impinge upon the Earth's magnetosphere (Dungey, 1961). How can we predict the occurrence of future interplanetary events? Do we currently know enough of the underlying physics and do we have sufficient observations of solar wind phenomena that will impinge upon the Earth's magnetosphere? We view this as the most important challenge in space weather. We discuss the case for magnetic clouds (MCs), interplanetary sheaths upstream of interplanetary coronal mass ejections (ICMEs), corotating interaction regions (CIRs) and solar wind high-speed streams (HSSs). The sheath- and CIR-related magnetic storms will be difficult to predict and will require better knowledge of the slow solar wind and modeling to solve. For interplanetary space weather, there are challenges for understanding the fluences and spectra of solar energetic particles (SEPs). This will require better knowledge of interplanetary shock properties as they propagate and evolve going from the Sun to 1 AU (and beyond), the upstream slow solar wind and energetic “seed” particles. Dayside aurora, triggering of nightside substorms, and formation of new radiation belts can all be caused by shock and interplanetary ram pressure impingements onto the Earth's magnetosphere. The acceleration and loss of relativistic magnetospheric “killer” electrons and prompt penetrating electric fields in terms of causing positive and negative ionospheric storms are reasonably well understood, but refinements are still needed. The forecasting of extreme events (extreme shocks, extreme solar energetic particle events, and extreme geomagnetic storms (Carrington events or greater)) are also discussed. Energetic particle precipitation into the atmosphere and ozone destruction are briefly discussed. For many of the studies, the Parker Solar Probe, Solar Orbiter, Magnetospheric Multiscale Mission (MMS), Arase, and SWARM data will be useful.
Highlights
1.1 Some comments on the history of the physics of space weather/solar-terrestrial physicsSpace weather is a new term for a topic/science that began over a century and a half ago
Since this event has been used as an example of extreme space weather and events of this type are a problem for U.S Homeland Security, we felt that there should be a separate section on this topic, Sect
If there are two high-speed streams (HSSs), one from the South Pole and another from the North Pole so that Earth’s magnetosphere is bathed in HSSs for years, as happened during 1973–1975 (Sheeley et al, 1976, 1977; Gosling et al, 1976; Tsurutani et al, 1995), will the energies go above ∼ 10 MeV? What will physically limit the energy range? This answer is important for keeping Earth-orbiting satellites safe during such events
Summary
1.1 Some comments on the history of the physics of space weather/solar-terrestrial physics. Prior to the space age (where we have satellites orbiting the Earth, probing interplanetary space and viewing the Sun at UV, EUV and X-ray wavelengths), it was clearly realized that solar phenomena caused geomagnetic activity at the Earth. After Carrington (1959) published his seminal paper, Hale (1931), Newton (1943) and others showed that magnetic storms were delayed by several days from intense solar flares These types of magnetic storms are known to be caused by either their associated interplanetary coronal mass ejections (ICMEs) or their upstream sheaths. Phenomena associated with the declining phase of the solar cycle will be addressed These include corotating interaction regions (CIRs) and HSSs, which cause high-intensity long-duration continuous AE activity (HILDCAA) events and the acceleration and loss of magnetospheric relativistic electrons. The present authors are active researchers in the field and will attempt to introduce new viewpoints and topics not covered in the above works
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