The physics of space weather/solar-terrestrial physics (STP): what we know now and what the current and future challenges are

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.

Lower‐Band “Monochromatic” Chorus Riser Subelement/Wave Packet Observations

“…The overall scenario for the generation of these waves is thus southward interplanetary magnetic fields (IMFs) lead to reconnection with the Earth's dayside magnetopause fields and resultant nightside reconnection of magnetotail magnetic fields (Dungey, 1961) creates substorms (Akasofu, 1964;Tsurutani & Meng, 1972). This reconnection process is the prime mechanism of solar wind energy transfer to the Earth's magnetosphere (Tsurutani et al, 2006(Tsurutani et al, , 2020. The magnetotail reconnection during substorms leads to the energization of~100 eV to 1 keV plasma sheet plasma to energies of~10 to 100 keV (DeForest & McIlwain, 1971) by compression, as the inner edge of the plasma sheet is injected into the nightside magnetosphere to distances as close as L = 4 (Soraas et al, 2004).…”

Geomagnetically Induced Currents

“…A GIC event is generated by the high-frequency changes in geomagnetic fields due to space weather events. Geomagnetic storms, substorms, supersubstorms, magnetic pulsations, and sudden impulses (SI + ) are the major drivers for the generation of GICs (Pulkkinen et al 2005;Viljanen et al 2006;Ngwira et al 2014;Tsurutani et al 2020). In fact, a GIC event is essentially the ground manifestation of the complex spaceweather chain starting from the solar eruptions, extending to the interplanetary space, and then to the surface of the Earth and below.…”

“…There has been tremendous progress in understanding the space weather processes and generation of GICs during the past two decades. An exhaustive review on the current status and future challenges of space-weather physics and solarterrestrial physics (STP) is given by Tsurutani et al (2020).…”

Study of Ionospheric Variability During Super Substorms

“…Many studies on storm, substorm has conducted for ionospheric parameters in different latitudes however no result for the SSSs on ionospheric parameters have been reported up to now. The list of researchers carried research on other area of SSSs are Tsurutani [1]; Hajra [13]; Adhikari [14][15][16]; Despirak [17,18]; Tsurutani [19]. In this paper, we report for the first time the ionospheric responses during the 24 August 2005 and 7 and 8 September 2017 super substorm using ionosonde data measured at Boulder, Colorado, USA (40.0° N, 105.0° W).…”