A Quick Method for Estimating the Propagation Direction of Coronal Mass Ejections Using STEREO-COR1 Images

Mierla, M.; Davila, J. M.; Thompson, W. T.; Inhester, B.; Srivastava, Nandita; Kramar, Maxim; Cyr, O. C. St.; Stenborg, G.; Howard, R. A.

doi:10.1007/s11207-008-9267-8

Cited by 83 publications

(96 citation statements)

References 19 publications

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“…The event is connected to a GOES-class B6 flare and partial halo coronal mass ejection (CME) event in active region 10956 on 20 May 2007 (Mierla et al, 2008;Kilpua et al, 2009). Thus, our event is at the lower end of the importance classification of solar eruptions as observed during solar minimum.…”

Section: Introductionmentioning

confidence: 84%

“…The corresponding CME event on 20 May 2007 has been discussed by Mierla et al (2008) using data from Inner Coronagraph (COR1) of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) experiment from two view-points, inferring the CME direction and de-projected velocity. Kilpua et al (2009) showed that this de-projected velocity matches much better the transit time of the MC than the projected velocity.…”

Section: Discussionmentioning

confidence: 99%

“…Kilpua et al (2009) showed that this de-projected velocity matches much better the transit time of the MC than the projected velocity. Additionally, Mierla et al (2008) were able to estimate the CME propagation direction as 2 degrees east of the Sun -Earth line between 2.4 to 6 R , and the latitude as −30 degree to the ecliptic. At Earth, the MC axis passes west of Earth by approximately 3 degrees (see Figure 2, and Figures 1 and 7 in Kilpua et al, 2009) but seems to have its apex indeed below the ecliptic.…”

Section: Discussionmentioning

confidence: 99%

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Optimized Grad – Shafranov Reconstruction of a Magnetic Cloud Using STEREO-Wind Observations

et al. 2009

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We present results on the geometry of a magnetic cloud (MC) on 23 May 2007 from a comprehensive analysis of Wind and STEREO observations. We first apply a GradShafranov reconstruction to the STEREO-A plasma and magnetic field data, delivered by the PLASTIC and IMPACT instruments. We then optimize the resulting field map with the aid of observations by Wind, which were made at the very outer boundary of the cloud, at a spacecraft angular separation of 6°. For the correct choice of reconstruction parameters such as axis orientation, interval and grid size, we find both a very good match between the predicted magnetic field at the position of Wind and the actual observations as well as consistent timing. We argue that the reconstruction captures almost the full extent of the cross-section of the cloud. The resulting shape transverse to the invariant axis consists of distorted ellipses and is slightly flattened in the direction of motion. The MC axis is inclined at −58°to the ecliptic with an axial field strength of 12 nT. We derive integrated axial fluxes and currents with increased precision, which we contrast with the results from linear force- free fitting. The helical geometry of the MC with almost constant twist (≈1.5 turns AU −1 ) is not consistent with the linear force-free Lundquist model. We also find that the cloud is non-force-free (|J ⊥ |/|J | > 0.3) in about a quarter of the cloud cross sectional area, particularly in the back part which is interacting with the trailing high speed stream. Based on the optimized reconstruction we put forward preliminary guidelines for the improved use of single-spacecraft Grad -Shafranov reconstruction. The results also give us the opportunity to compare the CME direction inferred from STEREO/SECCHI observations by Mierla et al. (Solar Phys. 252, 385, 2008) with the three-dimensional configuration of the MC at 1 AU. This yields an almost radial CME propagation from the Sun to the Earth.

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Section: Introductionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Optimized Grad – Shafranov Reconstruction of a Magnetic Cloud Using STEREO-Wind Observations

et al. 2009

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“…Along with an assortment of in-situ, radio, and EUV imaging instruments, both STEREO carry two coronagraphs (COR1 and COR2) and two heliospheric imagers (HI-1 and HI-2), aligned such that their fields of view cover the angular (elongation) range from the Sun to 90°. Following the first attempts of triangulation using COR1 and COR2 observations by Mierla et al (2008) and Howard & Tappin (2008), respectively, a large number of 3-D reconstruction techniques using the coronagraphs has emerged in the literature. The earlier reconstruction techniques are reviewed by Mierla et al (2010) but the number of different techniques continues to grow.…”

Section: -D Reconstruction Techniquesmentioning

confidence: 99%

Regarding the detectability and measurement of coronal mass ejections

Howard

2015

J. Space Weather Space Clim.

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In this review I discuss the problems associated with the detection and measurement of coronal mass ejections (CMEs). CMEs are important phenomena both scientifically, as they play a crucial role in the evolution of the solar corona, and technologically, as their impact with the Earth leads to severe space weather activity in the form of magnetic storms. I focus on the observation of CMEs using visible white light imagers (coronagraphs and heliospheric imagers), as they may be regarded as the binding agents between different datasets and different models that are used to reconstruct them. Our ability to accurately measure CMEs observed by these imagers is hampered by many factors, from instrumental to geometrical to physical. Following a brief review of the history of CME observation and measurement, I explore the impediments to our ability to measure them and describe possible means for which we may be able to mitigate those impediments. I conclude with a discussion of the claim that we have reached the limit of the information that we can extract from the current generation of white light imagers, and discuss possible ways forward regarding future instrument capabilities.

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“…The propagation parameters extracted from a single point of view (i.e., one spacecraft) do not give reliable information on the actual CME propagation path. Extraction of the parameters from two vantage points (i.e., both spacecraft), however, makes reconstruction of a true CME propagation path in 3D space possible (Howard & Tappin 2008;Mierla et al 2008Mierla et al , 2010Boursier et al 2009;Colaninno & Vourlidas 2009;de Koning et al 2009; de Koning & Pizzo 2011). The reconstruction can be accomplished using a technique of geometric triangulation, such as that proposed by Liu et al (2010) and Mays et al (2015).…”

Section: Introductionmentioning

confidence: 99%

Combining STEREO SECCHI COR2 and HI1 images for automatic CME front edge tracking

Kirnosov

Chang

Pulkkinen

2016

J. Space Weather Space Clim.

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COR2 coronagraph images are the most commonly used data for coronal mass ejection (CME) analysis among the various types of data provided by the STEREO (Solar Terrestrial Relations Observatory) SECCHI (Sun-Earth Connection Coronal and Heliospheric Investigation) suite of instruments. The field of view (FOV) in COR2 images covers 2-15 solar radii (Rs) that allow for tracking the front edge of a CME in its initial stage to forecast the lead-time of a CME and its chances of reaching the Earth. However, estimating the lead-time of a CME using COR2 images gives a larger lead-time, which may be associated with greater uncertainty. To reduce this uncertainty, CME front edge tracking should be continued beyond the FOV of COR2 images. Therefore, heliospheric imager (HI1) data that covers 15-90 Rs FOV must be included. In this paper, we propose a novel automatic method that takes both COR2 and HI1 images into account and combine the results to track the front edges of a CME continuously. The method consists of two modules: pre-processing and tracking. The pre-processing module produces a set of segmented images, which contain the signature of a CME, for both COR2 and HI1 separately. In addition, the HI1 images are resized and padded, so that the center of the Sun is the central coordinate of the resized HI1 images. The resulting COR2 and HI1 image set is then fed into the tracking module to estimate the position angle (PA) and track the front edge of a CME. The detected front edge is then used to produce a height-time profile that is used to estimate the speed of a CME. The method was validated using 15 CME events observed in the period from January 1, 2008 to August 31, 2009. The results demonstrate that the proposed method is effective for CME front edge tracking in both COR2 and HI1 images. Using this method, the CME front edge can now be tracked automatically and continuously in a much larger range, i.e., from 2 to 90 Rs, for the first time. These improvements can greatly help in making the quantitative CME analysis more accurate and have the potential to assist in space weather forecasting.

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A Quick Method for Estimating the Propagation Direction of Coronal Mass Ejections Using STEREO-COR1 Images

Cited by 83 publications

References 19 publications

Optimized Grad – Shafranov Reconstruction of a Magnetic Cloud Using STEREO-Wind Observations

Optimized Grad – Shafranov Reconstruction of a Magnetic Cloud Using STEREO-Wind Observations

Regarding the detectability and measurement of coronal mass ejections

Combining STEREO SECCHI COR2 and HI1 images for automatic CME front edge tracking

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