RECONSTRUCTING CORONAL MASS EJECTIONS WITH COORDINATED IMAGING AND IN SITU OBSERVATIONS: GLOBAL STRUCTURE, KINEMATICS, AND IMPLICATIONS FOR SPACE WEATHER FORECASTING

By Ying Liu, A. Thernisien, Jan Luhmann, A. Vourlidas, J. Davies, R. Lin, S. Bale. 2010

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We reconstruct the global structure and kinematics of coronal mass ejections (CMEs) using coordinated imaging and in situ observations from multiple vantage points. A forward modeling technique, which assumes a rope-like morphology for CMEs, is used to determine the global structure (including orientation and propagation direction) from coronagraph observations. We reconstruct the corresponding structure from in situ measurements at 1 AU with the Grad–Shafranov method, which gives the flux-rope orientation, cross section, and a rough knowledge of the propagation direction. CME kinematics (propagation direction and radial distance) during the transit from the Sun to 1 AU are studied with a geometric triangulation technique, which provides an unambiguous association between solar observations and in situ signatures; a track fitting approach is invoked when data are available from only one spacecraft. We show how the results obtained from imaging and in situ data can be compared by applying these methods to the 2007 November 14–16 and 2008 December 12 CMEs. This merged imaging and in situ study shows important consequences and implications for CME research as well as space weather forecasting: (1) CME propagation directions can be determined to a relatively good precision as shown by the consistency between different methods; (2) the geometric triangulation technique shows a promising capability to link solar observations with corresponding in situ signatures at 1 AU and to predict CME arrival at the Earth; (3) the flux rope within CMEs, which has the most hazardous southward magnetic field, cannot be imaged at large distances due to expansion; (4) the flux-rope orientation derived from in situ measurements at 1 AU may have a large deviation from that determined by coronagraph image modeling; and (5) we find, for the first time, that CMEs undergo a westward migration with respect to the Sun–Earth line at their acceleration phase, which we suggest is a universal feature produced by the magnetic field connecting the Sun and ejecta. The importance of having dedicated spacecraft at L4 and L5, which are well situated for the triangulation concept, is also discussed based on the results.

Subfields: Astronomy and Astrophysics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/bd7f2fde876e714c6186a391047d2cf4c51aab2a

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Citations in the corpus

IMPLEMENTATION OF THE GRADUATED CYLINDRICAL SHELL MODEL FOR THE THREE-DIMENSIONAL RECONSTRUCTION OF CORONAL MASS EJECTIONS (2011, methodology): “They also showed that the model can be used to obtain estimations of parameters such as CME position, direction, three-dimensional extent, true speed, and even, but with a smaller confidence, its orientation (see Thernisien et al. 2009; Liu et al. 2010).”
CONNECTING SPEEDS, DIRECTIONS AND ARRIVAL TIMES OF 22 CORONAL MASS EJECTIONS FROM THE SUN TO 1 AU (2014, methodology): “There is an error associated with manual measurements of CME fronts in J-maps, which is on the order of ±0.5◦ in elongation angle ǫ(t) (Williams et al. 2009; Liu et al. 2010a; Möstl et al. 2011).”
THE DEFLECTION OF THE TWO INTERACTING CORONAL MASS EJECTIONS OF 2010 MAY 23–24 AS REVEALED BY COMBINED IN SITU MEASUREMENTS AND HELIOSPHERIC IMAGING (2012, methodology): “For these reasons, we rely on stereoscopic methods: triangulation (see Liu et al. 2010a), which is based on the Fixed-Φ (FΦ) geometry; and tangent-to-a-sphere method (see Lugaz et al. 2010), which is based on the Harmonic Mean (HM) geometry.”
ON SUN-TO-EARTH PROPAGATION OF CORONAL MASS EJECTIONS (2013, methodology): “In conjunction with imaging observations, it provides a larger spatial perspective of ICMEs than one-dimensional in situ measurements (Liu et al. 2010b).”
The Physical Processes of CME/ICME Evolution (2017, methodology): “…largely intact, and careful examination suggests that they can be connected to the magnetic structures observed at 1 AU (e.g., Yurchyshyn et al. 2007; Démoulin 2008; Möstl et al. 2008; Davis et al. 2009; Liu et al. 2010a,b, 2011; Howard and DeForest 2012; Manchester et al. 2014a; Hu et al. 2016).”