Intercycle and Intracycle Variation of Halo CME Rate Obtained from SOHO/LASCO Observations

Dagnew, Fithanegest Kassa; Gopalswamy, N.; Tessema, Solomon Belay; Akiyama, S.; Yashiro, S.; Tesfu, Tesfay Yemane

doi:10.3847/1538-4357/abb887

Cited by 10 publications

(11 citation statements)

References 25 publications

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“…All of them were marked as "poor" events, and for many of them estimating associated mass and kinetic energy was impossible. No halo-CME was observed during this period (Dagnew et al, 2020). Thus the number of events in our simulation ( 19) appears comparable with the number of recorded CMEs.…”

Section: Concluding Discussionsupporting

confidence: 74%

Two Classes of Eruptive Events During Solar Minimum

Bhowmik

Yeates

2021

Sol Phys

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During solar minimum, the Sun is relatively inactive with few sunspots observed on the solar surface. Consequently, we observe a smaller number of highly energetic events such as solar flares or coronal mass ejections (CMEs), which are often associated with active regions on the photosphere. Nonetheless, our magnetofrictional simulations during the minimum period suggest that the solar corona is still dynamically evolving in response to the large-scale shearing velocities on the solar surface. The non-potential evolution of the corona leads to the accumulation of magnetic free energy and helicity, which is periodically shed in eruptive events. We find that these events fall into two distinct classes: One set of events are caused by eruption and ejection of low-lying coronal flux ropes, and they could explain the origin of occasional CMEs during solar minimum. The other set of events are not driven by destabilisation of low-lying structures but rather by eruption of overlying sheared arcades. These could be associated with streamer blowouts or stealth CMEs. The two classes differ significantly in the amount of magnetic flux and helicity shed through the outer coronal boundary. We additionally explore how other measurables such as current, open magnetic flux, free energy, coronal holes, and the horizontal component of the magnetic field on the outer model boundary vary during the two classes of event. This study emphasises the importance and necessity of understanding the dynamics of the coronal magnetic field during solar minimum.

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Section: Concluding Discussionsupporting

confidence: 74%

Two Classes of Eruptive Events During Solar Minimum

Bhowmik

Yeates

2021

Sol Phys

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“…However, CMEs vary in their occurrence rate as well as in their characteristics over different solar cycles. While flare rates and their properties have not changed much over the past solar cycles, the CME properties for solar cycle 24 are significantly different as given in recent statistics (Lamy et al 2019;Dagnew et al 2020b). CMEs were found to be more numerous Fig.…”

Section: General Characteristicsmentioning

confidence: 97%

Space weather: the solar perspective

Temmer

2021

Living Rev Sol Phys

183

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The Sun, as an active star, is the driver of energetic phenomena that structure interplanetary space and affect planetary atmospheres. The effects of Space Weather on Earth and the solar system is of increasing importance as human spaceflight is preparing for lunar and Mars missions. This review is focusing on the solar perspective of the Space Weather relevant phenomena, coronal mass ejections (CMEs), flares, solar energetic particles (SEPs), and solar wind stream interaction regions (SIR). With the advent of the STEREO mission (launched in 2006), literally, new perspectives were provided that enabled for the first time to study coronal structures and the evolution of activity phenomena in three dimensions. New imaging capabilities, covering the entire Sun-Earth distance range, allowed to seamlessly connect CMEs and their interplanetary counterparts measured in-situ (so called ICMEs). This vastly increased our knowledge and understanding of the dynamics of interplanetary space due to solar activity and fostered the development of Space Weather forecasting models. Moreover, we are facing challenging times gathering new data from two extraordinary missions, NASA’s Parker Solar Probe (launched in 2018) and ESA’s Solar Orbiter (launched in 2020), that will in the near future provide more detailed insight into the solar wind evolution and image CMEs from view points never approached before. The current review builds upon the Living Reviews article by Schwenn from 2006, updating on the Space Weather relevant CME-flare-SEP phenomena from the solar perspective, as observed from multiple viewpoints and their concomitant solar surface signatures.

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“…It can be found that the two periods, 1.3 years and 1.7 years, are mainly focused on the parameters of various types of solar radiation and plasma in an interplanetary environment, which are usually considered to be related to the energy released from the Sun. Therefore, it may suggest the important role of halo CMEs in the interplanetary environment and space weather (Gopalswamy et al 2015;Dagnew et al 2020).…”

Section: Discussionmentioning

confidence: 99%

Quasiperiodic Variations of Coronal Mass Ejections with Different Angular Widths

Deng

Wang

et al. 2023

ApJS

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Coronal mass ejections (CMEs) are energetic expulsions of organized magnetic features from the Sun. The study of CME quasiperiodicity helps establish a possible relationship between CMEs, solar flares, and geomagnetic disturbances. We used the angular width of CMEs as a criterion for classifying the CMEs in the study. Based on 25 yr of observational data, we systematically analyzed the quasiperiodic variations corresponding to the CME occurrence rate of different angular widths in the northern and southern hemispheres, using frequency and time–frequency analysis methods. There are various periods for CMEs of different angular widths: 9 months, 1.7 yr, and 3.3–4.3 yr. Compared with previous studies based on the occurrence rate of CMEs, we obtained the same periods of 1.2 (±0.01), 3.1 (±0.04), and ≈6.1 (±0.4) months, and 1.2 (±0.1) and 2.4 (±0.4) yr. We also found additional periods of all CMEs that appear only in one hemisphere or during a specific solar cycle. For example, 7.1 (±0.2) months and 4.1 (±0.2) yr in the northern hemisphere, 1 (±0.004) and 5.9 (±0.2) months and 1 (±0.1), 1.4 (±0.1), and 2.4 (±0.4) yr in the southern hemisphere, 6.1 (±0.4) months in solar cycle 23, and 6.1 (±0.4) months and 1.2 (±0.1) and 3.7 (±0.2) yr in solar cycle 24. The analysis shows that quasiperiodic variations of the CMEs are a link among oscillations in coronal magnetic activity, solar flare eruptions, and interplanetary space.

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Intercycle and Intracycle Variation of Halo CME Rate Obtained from SOHO/LASCO Observations

Cited by 10 publications

References 25 publications

Two Classes of Eruptive Events During Solar Minimum

Two Classes of Eruptive Events During Solar Minimum

Space weather: the solar perspective

Quasiperiodic Variations of Coronal Mass Ejections with Different Angular Widths

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