Full halo coronal mass ejections: Do we need to correct the projection effect in terms of velocity?

Shen, Chenglong; Wang, Yuming; Pan, Zihan; Zhang, Min; Ye, Pinzhong; Wang, S.

doi:10.1002/2013ja018872

Cited by 45 publications

(64 citation statements)

References 76 publications

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“…Our results are almost similar to Michalek (2010), who evaluated an average width for 69 halo CMEs from 2001 and 2002 by applying an asymmetric cone model to SOHO/ LASCO data. The mean value (100°) of the 3D widths for the full halo CMEs is quite similar to Shen et al (2013), who showed that the average value of the 3D widths from the GCS model is 103°. Figure 4 shows the yearly variation of CME speed together with the yearly sunspot number, indicating solar activities.…”

Section: Methodssupporting

confidence: 82%

“…This indicates that most CMEs propagate radially to some extent, although some CMEs are noticeably deflected. Furthermore, we compare our findings with those of Shen et al (2013) using 34 overlapping events in Figure 8. All parameters are similar to each other, with higher correlation (0.75).…”

Section: Resultsmentioning

confidence: 94%

“…Comparison between the 2D and 3D CME parameters: speed (a), width (b), latitude (c), and longitude (d). The dashed line corresponds to the case in which the 3D parameters are consistent with those of Shen et al (2013).…”

Section: Resultsmentioning

confidence: 99%

“…Following Shen et al (2013), who estimated that the error is about 0.2 Rs (about a 4 pixel uncertainty in SOHO/ LASCO C3 images), the mean value of the relative error in 2D speed is assumed to about 10%. We also estimated an~10% error in 3D speed, which is determined as a mean value of 10 times the trials of measurements.…”

Section: Resultsmentioning

confidence: 99%

“…Bosman et al (2012) estimated the locations and angular widths of 51 wellidentified STEREO CMEs from 2007 to 2010 using the GCS model. Shen et al (2013) analyzed 86 full halo CMEs from 2007 March to 2012 May by applying the GCS model and estimated the projection effect by examining the ratio of 3D and 2D speeds as a function of deviation angle, which is defined as an angle between the propagation direction and the Sun-Earth line. Mierla et al (2010) compared several different techniques in terms of velocity and location using 5 events in 2007.…”

Section: Introductionmentioning

confidence: 99%

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COMPARISON BETWEEN 2D AND 3D PARAMETERS OF 306 FRONT-SIDE HALO CMEs FROM 2009 TO 2013

Jang

Moon

Kim

et al. 2016

ApJ

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We investigate 306 LASCO front-side halo (partial and full) CMEs from 2009 to 2013, which are well-observed by both the Solar and Heliospheric Observatory (SOHO) and the Solar TErrestrial RElations Observatory (STEREO). These CMEs have two-dimensional (2D) parameters, such as speed, angular width, and propagation direction, from a single spacecraft (SOHO), as well as three-dimensional (3D) parameters from a multi-spacecraft (STEREO). These 2D CME parameters, which are based on plane-of-sky observations, are taken from the SOHO LASCO CME catalog and the NGDC flare catalog. We have determined their 3D CME parameters using the Stereoscopic CME analysis tool (StereoCAT) provided by the Community Coordinated Modeling Center at NASA. We compare 2D and 3D CME parameters, making this the most comprehensive statistical study on CME 3D parameters. As a result, we find that 2D speeds underestimate the 3D speed by about 20%. The 3D width ranges from 30°to 158°, values which are much smaller than the 2D widths with a mean value of 225°. We also find that the ratio between the 2D and 3D widths decreases with central meridian distance. The 3D propagation directions are similar to the flare locations, with a mean absolute difference of about 13°. The width-speed relationship in 3D is much stronger than that in 2D.

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Section: Methodssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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COMPARISON BETWEEN 2D AND 3D PARAMETERS OF 306 FRONT-SIDE HALO CMEs FROM 2009 TO 2013

Jang

Moon

Kim

et al. 2016

ApJ

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Full‐halo coronal mass ejections: Arrival at the Earth

et al. 2014

Self Cite

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A geomagnetic storm is mainly caused by a frontside coronal mass ejection (CME) hitting the Earth and then interacting with the magnetosphere. However, not all frontside CMEs can hit the Earth. Thus, which CMEs hit the Earth and when they do so are important issues in the study and forecasting of space weather. In our previous work, the deprojected parameters of the full-halo coronal mass ejections (FHCMEs) that occurred from 1 March 2007 to 31 May 2012 were estimated, and there are 39 frontside events that could be fitted by the Graduated Cylindrical Shell model. In this work, we continue to study whether and when these frontside FHCMEs (FFHCMEs) hit the Earth. It is found that 59% of these FFHCMEs hit the Earth, and for central events, whose deviation angles , which are the angles between the propagation direction and the Sun-Earth line, are smaller than 45• , the fraction increases to 75%. After checking the deprojected angular widths of the CMEs, we found that all of the Earth-encountered CMEs satisfy a simple criterion that the angular width ( ) is larger than twice the deviation angle ( ). This result suggests that some simple criteria can be used to forecast whether a CME could hit the Earth. Furthermore, for Earth-encountered CMEs, the transit time is found to be roughly anticorrelated with the deprojected velocity, but some events significantly deviate from the linearity. For CMEs with similar velocities, the differences of their transit times can be up to several days. Such deviation is further demonstrated to be mainly caused by the CME geometry and propagation direction, which are essential in the forecasting of CME arrival.

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What flare and CME parameters control the occurrence of solar proton events?

Park

Moon

2014

JGR Space Physics

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In this study we examine the occurrence probabilities of solar proton events (SPEs) and their peak fluxes depending on both flare and coronal mass ejection (CME) parameters: flare peak flux, longitude, impulsive time, CME linear speed, and angular width. For this we use the NOAA SPEs, their associated X-ray flares, and CME from 1997 to 2011. We divide the data into 16 subgroups according to the flare and CME parameters and estimate the SPE probabilities for the subgroups. The three highest probabilities are found for the following subgroups: (1) fast full halo (55.3%) and fast partial halo (42.9%) CMEs associated with strong flares from the western region and (2) slow full halo CMEs associated with strong flares from the western region (31.6%). It is noted that the events whose SPE probabilities are nearly 0% belong to the following subgroups: (1) slow and fast partial halo CMEs from the eastern region, (2) slow partial halo CMEs from the western region, and (3) slow full halo CMEs from the eastern region. These results show that important parameters to control SPE occurrences are CME linear speed, angular width, and source longitude, which can be understood by the piston-driven shock formation of fast CMEs and magnetic field connectivity from the source site to the Earth. It is also shown that when the subgroups are separately considered by flare impulsive time and source longitude, the correlation coefficients between the observed and the predicted SPE peak fluxes are greatly improved.

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Full halo coronal mass ejections: Do we need to correct the projection effect in terms of velocity?

Cited by 45 publications

References 76 publications

COMPARISON BETWEEN 2D AND 3D PARAMETERS OF 306 FRONT-SIDE HALO CMEs FROM 2009 TO 2013

COMPARISON BETWEEN 2D AND 3D PARAMETERS OF 306 FRONT-SIDE HALO CMEs FROM 2009 TO 2013

Full‐halo coronal mass ejections: Arrival at the Earth

What flare and CME parameters control the occurrence of solar proton events?

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