On Sun-to-Earth Propagation of Coronal Mass Ejections

Abstract

We investigate how coronal mass ejections (CMEs) propagate through, and interact with, the inner heliosphere between the Sun and Earth, a key question in CME research and space weather forecasting. CME Sun-to-Earth kinematics are constrained by combining wide-angle heliospheric imaging observations, interplanetary radio type II bursts and in situ measurements from multiple vantage points. We select three events for this study, the 2012 January 19, 23, and March 7 CMEs. Different from previous event studies, this work attempts to create a general picture for CME Sun-to-Earth propagation and compare different techniques for determining CME interplanetary kinematics. Key results are obtained concerning CME Sun-to-Earth propagation: (1) the Sun-to-Earth propagation of fast CMEs can be approximately formulated into three phases: an impulsive acceleration, then a rapid deceleration, and finally a nearly constant speed propagation (or gradual deceleration); (2) the CMEs studied here are still accelerating even after the flare maximum, so energy must be continuously fed into the CME even after the time of the maximum heating and radiation has elapsed in the corona; (3) the rapid deceleration, presumably due to interactions with the ambient medium, mainly occurs over a relatively short time scale following the acceleration phase; (4) CME-CME interactions seem a common phenomenon close to solar maximum. Our comparison between different techniques (and data sets) has important implications for CME observations and their interpretations: (1) for the current cases, triangulation assuming a compact CME -2geometry is more reliable than triangulation assuming a spherical front attached to the Sun for distances below 50-70 solar radii from the Sun, but beyond about 100 solar radii we would trust the latter more; (2) a proper treatment of CME geometry must be performed in determining CME Sun-to-Earth kinematics, especially when the CME propagation direction is far away from the observer; (3) our approach to comparing wide-angle heliospheric imaging observations with interplanetary radio type II bursts provides a novel tool in investigating CME propagation characteristics. Future CME observations and space weather forecasting are discussed based on these results.

Sheath-accumulating Propagation of Interplanetary Coronal Mass Ejection

“…In that case, the ICME arrives at 1 au with almost the same speed as the background solar wind. This behavior is consistent with the two-phased deceleration characteristics of ICMEs reported by Liu et al (2013). When the CME is as heavy as =Ḿ 3 10 0 16 g (thick lines), the ICME arrives at 1 au, with a larger speed compared to the =Ḿ 3 10 0 15 g cases.…”

“…They have studied with the use of global MHD simulations in 3D (Manchester et al 2004;Lugaz & Roussev 2011;Shiota & Kataoka 2016). Liu et al (2013) reported the first detailed examination of the Sun-to-Earth propagation characteristics of three fast CMEs and an associated shock front using the combination of wideangle heliospheric imaging observations by STEREO, interplanetary Type II radio bursts, and in situ observations of solar wind parameters at multiple points. They reported that CME Sun-to-Earth propagation can be approximately formulated into three phases: (1) an impulsive acceleration near the Sun (up tõ 0.1 au), (2) rapid deceleration up to the distance of 0.2 0.4 au -, and (3) nearly constant speed propagation or gradual deceleration afterward.…”

Interplanetary and Geomagnetic Consequences of Interacting CMEs of 13 – 14 June 2012

“…On the basis of earlier studies regarding the relative performance of the reconstruction methods (Lugaz, 2010;Liu et al, 2013;Mishra, Srivastava, and Davies, 2014), we applied the stereoscopic self-similar expansion (SSSE) method to the J-maps of the interacting CMEs in the present study. The SSSE method is expected to yield better results as the CMEs were observed in HI field of view of both STEREO-A and B.…”

“…After the launch of twin Solar TErrestrial Relations Observatory spacecraft (STEREO: Kaiser et al 2008), the data from the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI: Howard et al 2008) have enabled us to continuously image CMEs from their lift-off in the corona up to the Earth and beyond Harrison et al, 2012;Liu et al, 2013;Möstl et al, 2015;Vemareddy and Mishra, 2015). These observations have also revealed direct evidence of CME-CME interaction when they are launched in close succession in the same direction Lugaz et al, 2012;Shen et al, 2012;Mishra, Srivastava, and Chakrabarty, 2015).…”

Assessing the Effect of Spacecraft Motion on Single-Spacecraft Solar Wind Tracking Techniques

“…Wood, Howard, and Socker, 2010;Liu et al, 2013). These techniques are usually used to determine the motion of transients travelling in the ecliptic plane, although can be applied out of the ecliptic.…”