What is Unusual about the Third Largest Geomagnetic Storm of Solar Cycle 24?

Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.; Mäkelä, P.; Fok, M.‐C.; Ferradas, C.

doi:10.1002/essoar.10510553.1

Cited by 3 publications

(6 citation statements)

References 98 publications

(127 reference statements)

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“…What are the conditions for producing a SEP3 event? Gopalswamy et al (2022) asked an important question: "Can type-III radio storms be a source of seed particles to shock acceleration?" These authors identify a large shock event that follows from the same active region as a storm of type-III bursts.…”

Section: Conditions For Sep3 Eventsmentioning

confidence: 99%

“…Perhaps, some shocks are driven in the direction of the impulsive seeds, while others are driven away from them, but we do not know for sure. The answer to the question posed by Gopalswamy et al (2022) is not yet clear; impulsive seed ions are inadequate, or there may be other required conditions. However, the association of 3 He with the type-III emission remains strong.…”

Section: Conditions For Sep3 Eventsmentioning

confidence: 99%

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Element abundance and the physics of solar energetic particles

Reames

2024

Front. Astron. Space Sci.

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The acceleration and transport of solar energetic particles (SEPs) cause their abundance, measured at a constant velocity, to be enhanced or suppressed as a function of the magnetic rigidity of each ion, and hence, of its atomic mass-to-charge ratio of A/Q. Ion charges, in turn, depend upon the source electron temperature. In small “impulsive” SEP events, arising from solar jets, acceleration during magnetic reconnection causes steep power-law abundance enhancements. These impulsive SEP events can have 1,000-fold enhancements of heavy elements from sources at ∼2.5 MK and similar enhancements of 3He/4He and of streaming electrons that drive type-III radio bursts. Gamma-ray lines show that solar flares also accelerate 3He-rich ions, but their electrons and ions remain trapped in magnetic loops, so they dissipate their energy as X-rays, γ-rays, heat, and light. “Gradual” SEPs accelerated at shock waves, driven by fast coronal mass ejections (CMEs), can show power-law abundance enhancements or depressions, even with seed ions from the ambient solar corona. In addition, shocks can reaccelerate seed particles from residual impulsive SEPs with their pre-existing signature heavy-ion enhancements. Different patterns of abundance often show that heavy elements are dominated by a source different from that of H and He. Nevertheless, the SEP abundance, averaged over many large events, defines the abundance of the corona itself, which differs from the solar photosphere as a function of the first ionization potential (FIP) since ions, with FIP <10 eV, are driven upward by forces of electromagnetic waves, which neutral atoms, with FIP >10 eV, cannot feel. Thus, SEPs provide a measurement of element abundance in the solar corona, distinct from solar wind, and may even better define the photosphere for some elements.

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Section: Conditions For Sep3 Eventsmentioning

confidence: 99%

Section: Conditions For Sep3 Eventsmentioning

confidence: 99%

Element abundance and the physics of solar energetic particles

Reames

2024

Front. Astron. Space Sci.

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“…The storm strength is measured by an index such as Dst, which is an average deviation of Earth's horizontal magnetic field measured at four low-latitude magnetometer stations [84] (https://wdc.kugi.kyoto-u.ac.jp/dstdir/dst2/onDstindex.html). While the southward magnetic field is necessary for a storm, the storm strength is determined by additional solar wind parameters such as the speed and dynamic pressure [85][86][87][88][89][90][91].…”

Section: Solar Connection To Geomagnetic Stormsmentioning

confidence: 99%

“…In reality, the cross-section can be elliptical or heavily deformed due to interaction with the ambient solar wind. When the back of MCs contain high-density material due to filaments [36,91] or when compressed by a CIR [125], the geoeffectiveness can be enhanced. Examples of a double-dip storm and a sheath storm are shown in Figure 12.…”

Section: Cmes and Geomagnetic Stormsmentioning

confidence: 99%

The Sun and Space Weather

Gopalswamy

2022

Atmosphere

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The explosion of space weather research since the early 1990s has been partly fueled by the unprecedented, uniform, and extended observations of solar disturbances from space- and ground-based instruments. Coronal mass ejections (CMEs) from closed magnetic field regions and high-speed streams (HSS) from open-field regions on the Sun account for most of the disturbances relevant to space weather. The main consequences of CMEs and HSS are their ability to cause geomagnetic storms and accelerate particles. Particles accelerated by CME-driven shocks can pose danger to humans and their technological structures in space. Geomagnetic storms produced by CMEs and HSS-related stream interaction regions also result in particle energization inside the magnetosphere that can have severe impact on satellites operating in the magnetosphere. Solar flares are another aspect of solar magnetic energy release, mostly characterized by the sudden enhancement in electromagnetic emission at various wavelengths—from radio waves to gamma-rays. Flares are responsible for the sudden ionospheric disturbances and prompt perturbation of Earth’s magnetic field known as magnetic crochet. Nonthermal electrons accelerated during flares can emit intense microwave radiation that can drown spacecraft and radar signals. This review article summarizes major milestones in understanding the connection between solar variability and space weather.

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“…In order to tackle this issue, we present in this article a detailed analysis of a sequence of solar transients during the second half of August 2018 (i.e., during the late declining phase of Solar Cycle 24) between Earth and Mars, which were separated by ∼8° in longitude, ∼2° in latitude, and ∼0.4 AU in radial distance. Some aspects of these events were addressed by a number of studies (e.g., Abunin et al., 2020; Akala et al., 2021; Chen et al., 2019; Cherniak & Zakharenkova, 2022; Gopalswamy et al., 2022; Mishra & Srivastava, 2019; Moro et al., 2022; Nitta et al., 2021; Piersanti et al., 2020; Thampi et al., 2021; Younas et al., 2020; Zhang et al., 2020), and our goal here is to provide a holistic Sun‐to‐Mars investigation of their evolution from the Sun through the inner heliosphere and their effects at the two planets. Accordingly, we first present remote‐sensing observations of the eruptive events.…”

Section: Introductionmentioning

confidence: 99%

CME Evolution in the Structured Heliosphere and Effects at Earth and Mars During Solar Minimum

et al. 2022

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The activity of the Sun alternates between a solar minimum and a solar maximum, the former corresponding to a period of “quieter” status of the heliosphere. During solar minimum, it is in principle more straightforward to follow eruptive events and solar wind structures from their birth at the Sun throughout their interplanetary journey. In this paper, we report analysis of the origin, evolution, and heliospheric impact of a series of solar transient events that took place during the second half of August 2018, that is, in the midst of the late declining phase of Solar Cycle 24. In particular, we focus on two successive coronal mass ejections (CMEs) and a following high‐speed stream (HSS) on their way toward Earth and Mars. We find that the first CME impacted both planets, whilst the second caused a strong magnetic storm at Earth and went on to miss Mars, which nevertheless experienced space weather effects from the stream interacting region preceding the HSS. Analysis of remote‐sensing and in‐situ data supported by heliospheric modeling suggests that CME–HSS interaction resulted in the second CME rotating and deflecting in interplanetary space, highlighting that accurately reproducing the ambient solar wind is crucial even during “simpler” solar minimum periods. Lastly, we discuss the upstream solar wind conditions and transient structures responsible for driving space weather effects at Earth and Mars.

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What is Unusual about the Third Largest Geomagnetic Storm of Solar Cycle 24?

Cited by 3 publications

References 98 publications

Element abundance and the physics of solar energetic particles

Element abundance and the physics of solar energetic particles

The Sun and Space Weather

CME Evolution in the Structured Heliosphere and Effects at Earth and Mars During Solar Minimum

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