Understanding the Origins of Problem Geomagnetic Storms Associated with “Stealth” Coronal Mass Ejections

Abstract

Geomagnetic storms are an important aspect of space weather and can result in significant impacts on space- and ground-based assets. The majority of strong storms are associated with the passage of interplanetary coronal mass ejections (ICMEs) in the near-Earth environment. In many cases, these ICMEs can be traced back unambiguously to a specific coronal mass ejection (CME) and solar activity on the frontside of the Sun. Hence, predicting the arrival of ICMEs at Earth from routine observations of CMEs and solar activity currently makes a major contribution to the forecasting of geomagnetic storms. However, it is clear that some ICMEs, which may also cause enhanced geomagnetic activity, cannot be traced back to an observed CME, or, if the CME is identified, its origin may be elusive or ambiguous in coronal images. Such CMEs have been termed “stealth CMEs”. In this review, we focus on these “problem” geomagnetic storms in the sense that the solar/CME precursors are enigmatic and stealthy. We start by reviewing evidence for stealth CMEs discussed in past studies. We then identify several moderate to strong geomagnetic storms (minimum Dst $< -50$ < − 50 nT) in solar cycle 24 for which the related solar sources and/or CMEs are unclear and apparently stealthy. We discuss the solar and in situ circumstances of these events and identify several scenarios that may account for their elusive solar signatures. These range from observational limitations (e.g., a coronagraph near Earth may not detect an incoming CME if it is diffuse and not wide enough) to the possibility that there is a class of mass ejections from the Sun that have only weak or hard-to-observe coronal signatures. In particular, some of these sources are only clearly revealed by considering the evolution of coronal structures over longer time intervals than is usually considered. We also review a variety of numerical modelling approaches that attempt to advance our understanding of the origins and consequences of stealthy solar eruptions with geoeffective potential. Specifically, we discuss magnetofrictional modelling of the energisation of stealth CME source regions and magnetohydrodynamic modelling of the physical processes that generate stealth CME or CME-like eruptions, typically from higher altitudes in the solar corona than CMEs from active regions or extended filament channels.

Eruption and Interplanetary Evolution of a Stealthy Streamer-Blowout CME Observed by PSP at ${\sim}$0.5~AU

“…This results in a type of base-difference image sequence where the (averaged) difference Ĩproc is above the intensity minimum values over a temporal interval rather than from the intensity at an initial time. In general, base-difference processing has demonstrated an advantage in the identification of larger-scale, slowly-varying signatures of eruptive transients, such as the EUV dimmings and/or brightenings, associated with stealth or stealthy CME eruptions (e.g., Palmerio et al, 2021b;Nitta et al, 2021).…”

“…Recent high-resolution, multi-wavelength, and multi-viewpoint coronal observations have revealed weak low-coronal dynamics associated with stealth CMEs, in some cases enabling study of their formation and lift-off (Korreck et al, 2020;O'Kane et al, 2021;Palmerio et al, 2021b). Stealth CMEs may also cause significant magnetic storms at Earth that are problematic for space weather forecasting (Nitta et al, 2021).…”

Interaction of coronal mass ejections and the solar wind. A force analysis

“…Robbrecht et al (2009b) concluded that one reason why these ejections do not present clear source signatures is their large lift-off heights, usually above 1.4 solar radii (R ). Even though their sources are dif-ficult to locate, stealth CMEs can be unexpectedly geoeffective (Kilpua et al 2014;Liu et al 2016;Nitta et al 2021). One reason is that the magnetic fields of slow and stealth CMEs may be enhanced by interactions with the background solar wind through which they are propagating, resulting in surprisingly strong geomagnetic storms (He et al 2018;Chen et al 2019).…”

The Space and Terrestrial Weather Variations as Possible Factors for Ischemia Events in Saint Petersburg

“…The mutual connections of the environmental processes are well-known. They have been carefully investigated in the past and are under investigation now [31][32][33][34][35][36][37][38][39][40][41][42]. It is well-known that the particle fluxes behavior in the inter-planet space, and particularly in Earth's vicinity, named the near-Earth space or Geospace [31,32] in the radiation belts, is governed by solar wind [31].…”

“…As the result, the density and speed of different particles in the radiation belts vary in a wide range that affects the magnetosphere and ionosphere status. Additionally, the separate events-solar coronal mass ejection (CME)-can affect the magnetosphere [33]. The magnetosphere-ionosphere interactions [34,35] give additional complexity to the cosmic impact on the Earth.…”