scholarly journals Clustering of Fast Coronal Mass Ejections during Solar Cycles 23 and 24 and Implications for CME–CME Interactions

2021 ◽  
Author(s):  
Jenny Marcela Rodriguez Gomez ◽  
Tatiana Podlachikova ◽  
Astrid Veronig ◽  
Alexander Ruzmaikin ◽  
Joan Feynman ◽  
...  
Keyword(s):  
Space Weather ◽  
Coronal Mass Ejections ◽  
Solar Minimum ◽  
Geomagnetic Storms ◽  
Active Regions ◽  
Solar Cycles ◽  
Characteristic Energy ◽  
Time Index ◽  
Threshold Time ◽  
Large Flare

<p>Coronal Mass Ejections (CMEs) and their interplanetary counterparts (ICMEs) are the major sources for strong space weather disturbances. We present a study of statistical properties of fast CMEs (v≥1000 km/s) that occurred during solar cycles 23 and 24. We apply the Max Spectrum and the declustering threshold time methods. The Max Spectrum can detect the predominant clusters, and the declustering threshold time method provides details on the typical clustering properties and timescales. Our analysis shows that during the different phases of solar cycles 23 and 24, fast CMEs preferentially occur as isolated events and in clusters with, on average, two members. However, clusters with more members appear, particularly during the maximum phases of the solar cycles. During different solar cycle phases, the typical declustering timescales of fast CMEs are τ<sub>c</sub> =28-32 hrs, irrespective of the very different occurrence frequencies of CMEs during a solar minimum and maximum. These findings suggest that  τ<sub>c</sub>   for extreme events may reflect the characteristic energy build-up time for large flare and CME-prolific active regions. Statistically associating the clustering properties of fast CMEs with the disturbance storm time index at Earth suggests that fast CMEs occurring in clusters tend to produce larger geomagnetic storms than isolated fast CMEs. Our results highlight the importance of CME-CME interaction and their impact on Space Weather.</p>

scholarly journals Extreme Space-Weather Events and the Solar Cycle

Solar Physics ◽  
2021 ◽  
Vol 296 (5) ◽  
Author(s):  
Mathew J. Owens ◽  
Mike Lockwood ◽  
Luke A. Barnard ◽  
Chris J. Scott ◽  
Carl Haines ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Space Weather ◽  
Extreme Events ◽  
Solar Minimum ◽  
Geomagnetic Storms ◽  
Extreme Event ◽  
Solar Maximum ◽  
Solar Cycles ◽  
Event Occurrence

AbstractSpace weather has long been known to approximately follow the solar cycle, with geomagnetic storms occurring more frequently at solar maximum than solar minimum. There is much debate, however, about whether the most hazardous events follow the same pattern. Extreme events – by definition – occur infrequently, and thus establishing their occurrence behaviour is difficult even with very long space-weather records. Here we use the 150-year $aa_{H}$ a a H record of global geomagnetic activity with a number of probabilistic models of geomagnetic-storm occurrence to test a range of hypotheses. We find that storms of all magnitudes occur more frequently during an active phase, centred on solar maximum, than during the quiet phase around solar minimum. We also show that the available observations are consistent with the most extreme events occurring more frequently during large solar cycles than small cycles. Finally, we report on the difference in extreme-event occurrence during odd- and even-numbered solar cycles, with events clustering earlier in even cycles and later in odd cycles. Despite the relatively few events available for study, we demonstrate that this is inconsistent with random occurrence. We interpret this finding in terms of the overlying coronal magnetic field and enhanced magnetic-field strengths in the heliosphere, which act to increase the geoeffectiveness of sheath regions ahead of extreme coronal mass ejections. Putting the three “rules” together allows the probability of extreme event occurrence for Solar Cycle 25 to be estimated, if the magnitude and length of the coming cycle can be predicted. This highlights both the feasibility and importance of solar-cycle prediction for planning and scheduling of activities and systems that are affected by extreme space weather.

MAGNETIC CLOUDS: A SUBJECT OF SPACE WEATHER PREDICTION

2005 ◽  
Vol 20 (29) ◽  
pp. 6650-6653
Author(s):  
A. GERANIOS ◽  
M. VANDAS ◽  
E. ANTONIADOU ◽  
O. ZACHAROPOULOU
Keyword(s):  
Space Weather ◽  
Coronal Mass Ejections ◽  
Strong Influence ◽  
Geomagnetic Storms ◽  
Interplanetary Medium ◽  
Weather Prediction ◽  
Magnetic Clouds ◽  
The Sun ◽  
Time Intervals ◽  
The Earth

Magnetic clouds are ideal objects for solar-terrestrial studies because of their simplicity and their extended time intervals of southward and northward magnetic fields. Magnetic clouds constitute a significant subset of coronal mass ejections with remarkable characteristics in the interplanetary medium and a strong influence on the Earth's magnetosphere, giving rise to geomagnetic storms. The evolution of such a cloud from the neighborhood of the Sun up to the Earth is numerically simulated for two cases, without and with a presence of a faster moving shock front. Its influence on the magnetosphere can be seen by the triggered geomagnetic storm. Therefore, magnetic clouds are an important subject for space weather predictions.

scholarly journals The spatial relationship between active regions and coronal holes and the occurrence of intense geomagnetic storms throughout the solar activity cycle

1998 ◽  
Vol 16 (1) ◽  
pp. 49-54 ◽  
Author(s):  
S. Bravo ◽  
J. A. L. Cruz-Abeyro ◽  
D. Rojas
Keyword(s):  
Solar Activity ◽  
Coronal Mass Ejections ◽  
Geomagnetic Storms ◽  
Coronal Holes ◽  
Spatial Relationship ◽  
Active Regions ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Frequency Of Occurrence ◽  
Sunspot Maximum

Abstract. We study the annual frequency of occurrence of intense geomagnetic storms (Dst < –100 nT) throughout the solar activity cycle for the last three cycles and find that it shows different structures. In cycles 20 and 22 it peaks during the ascending phase, near sunspot maximum. During cycle 21, however, there is one peak in the ascending phase and a second, higher, peak in the descending phase separated by a minimum of storm occurrence during 1980, the sunspot maximum. We compare the solar cycle distribution of storms with the corresponding evolution of coronal mass ejections and flares. We find that, as the frequency of occurrence of coronal mass ejections seems to follow very closely the evolution of the sunspot number, it does not reproduce the storm profiles. The temporal distribution of flares varies from that of sunspots and is more in agreement with the distribution of intense geomagnetic storms, but flares show a maximum at every sunspot maximum and cannot then explain the small number of intense storms in 1980. In a previous study we demonstrated that, in most cases, the occurrence of intense geomagnetic storms is associated with a flaring event in an active region located near a coronal hole. In this work we study the spatial relationship between active regions and coronal holes for solar cycles 21 and 22 and find that it also shows different temporal evolution in each cycle in accordance with the occurrence of strong geomagnetic storms; although there were many active regions during 1980, most of the time they were far from coronal holes. We analyse in detail the situation for the intense geomagnetic storms in 1980 and show that, in every case, they were associated with a flare in one of the few active regions adjacent to a coronal hole.

scholarly journals Carrington Longitudinal and Solar Cycle Distribution of the Super Active Regions From 1976 to 2018

2021 ◽  
Author(s):  
MIng-Xian Zhao ◽  
Guiming Le ◽  
Yonghua Liu ◽  
Tian Mao
Keyword(s):  
Solar Cycle ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Solar Maximum ◽  
Active Regions ◽  
Ground Level ◽  
Weather Events ◽  
Flare Index ◽  
Statistical Results ◽  
Extreme Space Weather Events

Abstract We studied the Carrington longitudinal and solar cycle distribution of the super active regions (SARs) from 1976to 2018. There were 51 SARs during this period. We divided the SARs into SARs1 and SARs2. SARs1 refers tothe SARs that produced extreme space weather events including ≥X5.0 flares, ground level events (GLEs) andsuper geomagnetic storms (SGSs: Dst≤ −250 nT), while SARs2 did not produce extreme space weather events.The total number of SARs1 and SARs2 are 32 and 19, respectively. The statistical results show that 34.4%, 65.6%and 78.1% of the SARs1 appeared in the ascending phase, descending phase and in the period from two yearsbefore to the three years after the solar maximum, respectively, while 52.6%, 47.4% and 100% of the SARs2appeared in the ascending phase, descending phase and in the period from two years before to the three years aftersolar maximum, respectively. The Carrington longitude distribution of the SARs1 shows that SARs1 in thelongitudinal scope of [0,150°] produced ≥X5.0 flares and GLEs, while only the SARs1 in the longitude range of[150°,360°] not only produced ≥X5.0 flares and GLEs, but also produced SGSs. The total number of SARsduring a SC has a good correlation with the SC size. However, the largest flare index of a SAR within a SC has apoor correlation with the SC size, implying that the number of SARs in a weak SC will be small. However, aweak SC may have a SAR that can produce very strong solar flare activities.

scholarly journals The source and engine of coronal mass ejections

2019 ◽  
Vol 377 (2148) ◽  
pp. 20180094 ◽  
Author(s):  
Manolis K. Georgoulis ◽  
Alexander Nindos ◽  
Hongqi Zhang
Keyword(s):  
Space Weather ◽  
Coronal Mass Ejections ◽  
Large Scale ◽  
Magnetic Energy ◽  
Active Regions ◽  
Magnetic Polarity ◽  
X Rays ◽  
Polarity Inversion ◽  
Magnetic Flux Ropes ◽  
Causal Sequence

Coronal mass ejections (CMEs) are large-scale expulsions of coronal plasma and magnetic field propagating through the heliosphere. Because CMEs are observed by white-light coronagraphs which, by design, occult the solar disc, supporting disc observations (e.g. in EUV, soft X-rays, Halpha and radio) must be employed for the study of their source regions and early development phases. We review the key properties of CME sources and highlight a certain causal sequence of effects that may occur whenever a strong (flux-massive and sheared) magnetic polarity inversion line develops in the coronal base of eruptive active regions (ARs). Storing non-potential magnetic energy and helicity in a much more efficient way than ARs lacking strong polarity inversion lines, eruptive regions engage in an irreversible course, making eruptions inevitable and triggered when certain thresholds of free energy and helicity are crossed. This evolution favours the formation of pre-eruption magnetic flux ropes. We describe the steps of this plausible path to sketch a picture of the pre-eruptive phase of CMEs that may apply to most events, particularly the ones populating the high end of the energy/helicity distribution, that also tend to have the strongest space-weather implications. This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

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

2021 ◽  
Vol 217 (8) ◽  
Author(s):  
Nariaki V. Nitta ◽  
Tamitha Mulligan ◽  
Emilia K. J. Kilpua ◽  
Benjamin J. Lynch ◽  
Marilena Mierla ◽  
...  
Keyword(s):  
Solar Activity ◽  
Coronal Mass Ejections ◽  
Geomagnetic Storms ◽  
Active Regions ◽  
The Sun ◽  
Interplanetary Coronal Mass Ejections ◽  
Source Regions ◽  
Solar Eruptions ◽  
Cycle 24 ◽  
Mass Ejection

AbstractGeomagnetic 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.

scholarly journals Extreme space weather events caused by super active regions during solar cycles 21-24

2021 ◽  
Vol 21 (5) ◽  
pp. 130
Author(s):  
Gui-Ming Le ◽  
Gui-Ang Liu ◽  
Ming-Xian Zhao ◽  
Tian Mao ◽  
Ping-Guo Xu
Keyword(s):  
Space Weather ◽  
Active Regions ◽  
Solar Cycles ◽  
Weather Events ◽  
Extreme Space Weather Events

scholarly journals Source Regions of Coronal Mass Ejections

2001 ◽  
Vol 203 ◽  
pp. 362-373
Author(s):  
K. P. Dere ◽  
P. Subramanian
Keyword(s):  
Active Region ◽  
Coronal Mass Ejections ◽  
Solar Minimum ◽  
Active Regions ◽  
The Other ◽  
Small Scale ◽  
Minimum Phase ◽  
Michelson Doppler Imager ◽  
Doppler Imager ◽  
Source Regions

Observations of the solar corona with the LASCO and EIT instruments on SOHO provide an unprecedented opportunity to study coronal mass ejections (CMEs) from their initiation through their evolution out to 30 R⊙. The objective of this study is to gain an understanding of the source regions from which the CMEs emanate. To this end, we have developed a list of 32 CMEs whose source regions are located on the solar disk and are well observed in EIT 195 Å data during the solar minimum phase of January 1996-May 1998. We compare the EIT source regions with photospheric magnetograms from the Michelson Doppler Imager (MDI) instrument on SOHO and the NSO/Kitt Peak Observatory and also with Hα data from various sources. The overall results of our study show that 59% of the CME related transients observed in EIT 195 Å images are associated with active regions without prominences, 22% are associated with eruptions of prominences embedded in active regions and 19% are associated with eruptions of quiescent prominences. We describe 3 especially well observed events, one from each of these 3 categories. These case studies suggest that active region CMEs are associated with active regions with lifetimes between 11-80 days. They are also often associated with small scale emerging or cancelling flux over timescales of 6-7 hours. CMEs associated with active region prominence eruptions, on the other hand, are typically associated with old active regions with lifetimes ~ 6-7 months.

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