Interplanetary coronal mass ejections during the descending cycle 23: Sheath and ejecta properties comparison

Mitsakou, E.; Babasidis, G.; Moussas, X.

doi:10.1016/j.asr.2008.08.003

Cited by 7 publications

(6 citation statements)

References 22 publications

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“…Consistently with Mitsakou et al () and Janvier et al (; both of which studied the sheath as a single entity), we found a strong correlation between the ejecta LE speed and the speed in the sheath. We further demonstrated that this high correlations exists throughout the sheath by investigating correlations separately for three sheath subregions.…”

Section: Summary and Discussionsupporting

confidence: 92%

“…Despite their evident importance in regard to geomagnetic impact, sheaths are relatively little studied when compared to ejecta. Previous studies of general sheath properties have indicated that, due to their compressed nature, sheaths commonly have much higher values of solar wind plasma parameters than the ejecta (Guo et al, ; Kilpua, Koskinen et al, ; Kilpua, Balogh et al, ; Mitsakou et al, ; Myllys et al, ) and higher levels of turbulence (Kilpua et al, ; Kilpua, Koskinen et al ). In consequence, sheaths also have higher Alfvén Mach numbers and dynamic pressures (Kilpua, Koskinen et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…This is because information on CME properties, and in particular CME speed, is continuously available from white‐light remote‐sensing observations and related reconstruction techniques in the corona and heliosphere (e.g., Mierla et al, ; Thernisien et al, ; Yashiro et al, ). For example, Mitsakou et al () studied and compared the properties of 67 sheaths and ejecta during 2003–2006. The authors found a strong (0.801) correlation between the mean speeds in sheaths and ejecta.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Solar Wind Properties and Geospace Impact of Coronal Mass Ejection‐Driven Sheath Regions: Variation and Driver Dependence

et al. 2019

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We present a statistical study of interplanetary conditions and geospace response to 89 coronal mass ejection-driven sheaths observed during Solar Cycles 23 and 24. We investigate in particular the dependencies on the driver properties and variations across the sheath. We find that the ejecta speed principally controls the sheath geoeffectiveness and shows the highest correlations with sheath parameters, in particular in the region closest to the shock. Sheaths of fast ejecta have on average high solar wind speeds, magnetic (B) field magnitudes, and fluctuations, and they generate efficiently strong out-of-ecliptic fields. Slow-ejecta sheaths are considerably slower and have weaker fields and field fluctuations, and therefore they cause primarily moderate geospace activity. Sheaths of weak and strong B field ejecta have distinct properties, but differences in their geoeffectiveness are less drastic. Sheaths of fast and strong ejecta push the subsolar magnetopause significantly earthward, often even beyond geostationary orbit. Slow-ejecta sheaths also compress the magnetopause significantly due to their large densities that are likely a result of their relatively long propagation times and source near the streamer belt. We find the regions near the shock and ejecta leading edge to be the most geoeffective parts of the sheath. These regions are also associated with the largest B field magnitudes, out-of-ecliptic fields, and field fluctuations as well as largest speeds and densities. The variations, however, depend on driver properties. Forecasting sheath properties is challenging due to their variable nature, but the dependence on ejecta properties determined in this work could help to estimate sheath geoeffectiveness through remote-sensing coronal mass ejection observations.

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Section: Summary and Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Solar Wind Properties and Geospace Impact of Coronal Mass Ejection‐Driven Sheath Regions: Variation and Driver Dependence

et al. 2019

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“… Mitsakou et al [2009] examined the correlation between the mean characteristic properties of the ICMEs and sheaths during the descending phase of cycle 23 and found that there is a strong correlation between the sheath and ICME speeds and a medium correlation between the sheath and the ICME magnetic field strength, the proton density, the length scale, and the passage time, while there appears to be no correlation between their temperatures and plasma beta parameters. The strong correlation between the sheath and ICME speeds implies that the shock and ICME are tightly coupled at 1 AU, and the shock is not running away from the ICME, which was first discussed by Gopalswamy [2004].…”

Section: Summary and Discussionmentioning

confidence: 99%

Statistical properties and geoefficiency of interplanetary coronal mass ejections and their sheaths during intense geomagnetic storms

et al. 2010

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[1] In this paper, we examine and compare the statistical properties of interplanetary coronal mass ejections (ICMEs) and their sheath regions in the near-Earth space, mainly focusing on the distributions of various physical parameters and their geoefficiency. The 53 events studied are a subset of events responsible for intense (Dst ≤ −100 nT) geomagnetic storms during the time period from 1996 to 2005. These events all fall into the single-type category in which each of the geomagnetic storms was caused by a well-isolated single ICME, free of the complexity of the interaction of multiple ICMEs. For both sheaths and ICMEs, we find that the distributions of the magnetic field strength, the solar-wind speed, the density, the proton temperature, the dynamic pressure, the plasma beta, and the Alfvén Mach number are approximately lognormal, while those of the Bz component and the Y component of the electric field are approximately Gaussian. On the average, the magnetic field strengths, the Bz components, the speeds, the densities, the proton temperatures, the dynamic pressures, the plasma betas, and the Mach numbers for the sheaths are 15, 80, 4, 60, 70, 62, 67, and 30% higher than the corresponding values for ICMEs, respectively, whereas the Y component of the electric field for the sheaths is almost 1 s of that for ICMEs. The two structures have almost equal energy transfer efficiency and comparable Newell functions, whereas they show statistically meaningful differences in the dayside reconnection rate, according to the Borovsky function.Citation: Guo, J., X. Feng, J. Zhang, P. Zuo, and C. Xiang (2010), Statistical properties and geoefficiency of interplanetary coronal mass ejections and their sheaths during intense geomagnetic storms,

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“…In addition, studies of such sheaths, associated with shocks, come mostly from simplified numerical simulations (often hydrodynamic) or similarities with Earth's bow shock. Though studies of MEdriven sheaths based on pure measurements have also been carried out, focusing on the generic profile and/or correlation/comparison with the driving ME (Mitsakou et al 2009;Guo et al 2010;Mitsakou & Moussas 2014;Kilpua et al 2017b;Jian et al 2018;Kilpua et al 2019), superposed epoch analysis (Kilpua et al 2013;Masías-Meza et al 2016;Rodriguez et al 2016;Janvier et al 2019), radial evolution (Lugaz et al 2019;Good et al 2020), to the best of our knowledge there has been no specific study of sheaths driven by MEs not driving any shocks. In this study, we examine ME-driven sheath regions measured by the twin STEREO (Solar Terrestrial Relations Observatory; Kaiser 2005) spacecraft from 2007-2016 focusing on all sheath regions, whether or not they are associated with shocks.…”

Section: Introductionmentioning

confidence: 99%

Properties of the Sheath Regions of Coronal Mass Ejections with or without Shocks from STEREO in situ Observations near 1 au

Salman

Lugaz

Farrugia

et al. 2020

ApJ

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We examine 188 coronal mass ejections (CMEs) measured by the twin STEREO spacecraft during 2007-2016 to investigate the generic features of the CME sheath and the magnetic ejecta (ME) and dependencies of average physical parameters of the sheath on the ME. We classify the MEs into three categories, focusing on whether a ME drives both a shock and sheath, or only a sheath, or neither, near 1 AU. We also reevaluate our initial classification through an automated algorithm and visual inspection. We observe that even for leading edge speeds greater than 500 km s −1 , 1 out of 4 MEs do not drive shocks near 1 AU. MEs driving both shocks and sheaths are the fastest and propagate in high magnetosonic solar wind, whereas MEs driving only sheaths are the slowest and propagate in low magnetosonic solar wind.

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Interplanetary coronal mass ejections during the descending cycle 23: Sheath and ejecta properties comparison

Cited by 7 publications

References 22 publications

Solar Wind Properties and Geospace Impact of Coronal Mass Ejection‐Driven Sheath Regions: Variation and Driver Dependence

Solar Wind Properties and Geospace Impact of Coronal Mass Ejection‐Driven Sheath Regions: Variation and Driver Dependence

Statistical properties and geoefficiency of interplanetary coronal mass ejections and their sheaths during intense geomagnetic storms

Properties of the Sheath Regions of Coronal Mass Ejections with or without Shocks from STEREO in situ Observations near 1 au

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