Development of a Full Ice-cream Cone Model for Halo Coronal Mass Ejections

Abstract

It is essential to determine three-dimensional parameters (e.g., radial speed, angular width, and source location) of coronal mass ejections (CMEs) for the space weather forecast. In this study, we investigate which cone type represents a halo CME morphology using 29 CMEs (12 Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) halo CMEs and 17 Solar Terrestrial Relations Observatory (STEREO)/Sun–Earth Connection Coronal and Heliospheric Investigation COR2 halo CMEs) from 2010 December to 2011 June. These CMEs are identified as halo CMEs by one spacecraft (SOHO or one of STEREO A and B) and limb ones by the other spacecraft (One of STEREO A and B or SOHO). From cone shape parameters of these CMEs, such as their front curvature, we find that the CME observational structures are much closer to a full ice-cream cone type than a shallow ice-cream cone type. Thus, we develop a full ice-cream cone model based on a new methodology that the full ice-cream cone consists of many flat cones with different heights and angular widths to estimate the three-dimensional parameters of the halo CMEs. This model is constructed by carrying out the following steps: (1) construct a cone for a given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, and (4) minimize the difference between the estimated projection speeds with the observed ones. By applying this model to 12 SOHO/LASCO halo CMEs, we find that 3D parameters from our method are similar to those from other stereoscopic methods (i.e., a triangulation method and a Graduated Cylindrical Shell model).

Implementation and validation of the FRi3D flux rope model in EUHFORIA

“…• Cone: In the "full ice-cream cone model", the CME is a hydrodynamic cloud of plasma without any intrinsic magnetic field (see, e.g. Xue et al, 2005;Gopalswamy et al, 2009;Na et al, 2017). A spherical blob is self-similarly expanded, conserving the angular width, propagation direction, and speed, before being launched into the heliospheric domain.…”

Tracing the ICME plasma with a MHD simulation

“…Accordingly, we chose to describe an ejected cloud with no internal magnetic flux rope that is embed in the ambient magnetic field (non-MC ICME, Kilpua et al 2017) and to assume that in the early phase the angular width and the velocity of the perturbation remain constant. The initial ICME can then be described by an ice-cream cone model (e.g., Zhao et al 2002;Xie et al 2004;Xue et al 2005;Gopalswamy et al 2009;Na et al 2017): a homogeneous plasma cloud, isotropic in expansion and with radial bulk velocity. The small number of input parameters needed by CME cone models make them particularly convenient for routine applications in space weather forecasting (Scolini et al 2018) despite the drawback of not including an internal magnetic field.…”

Effect of the Initial Shape of Coronal Mass Ejections on 3‐D MHD Simulations and Geoeffectiveness Predictions

“…In EUHFORIA we initialize the CME body at the height corresponding to the heliospheric inner boundary, that is, at 0.1 AU, and we use the angular width determined from observations to determine the CME radius at the inner boundary. Since the CME is initialized as having a spherical or quasi‐spherical shape in EUHFORIA, the cone model used in this work is similar to the “full ice cream cone model” described in previous works (see, e.g., Gopalswamy et al, ; Na et al, ; Xue et al, ). The spherical CME shape is obtained by slicing the CME body as it passes through the heliospheric inner boundary, that is, stacking the slices in time.…”