Investigating plasma motion of magnetic clouds at 1 AU through a velocity-modified cylindrical force-free flux rope model

Abstract

Magnetic clouds (MCs) are the interplanetary counterparts of coronal mass ejections (CMEs), and usually modeled by a flux rope. By assuming the quasi-steady evolution and self-similar expansion, we introduce three types of global motion into a cylindrical force-free flux rope model, and developed a new velocity-modified model for MCs. The three types of the global motion are the linear propagating motion away from the Sun, the expanding and the poloidal motion with respect to the axis of the MC. The model is applied to 72 MCs observed by Wind spacecraft to investigate the properties of the plasma motion of MCs. First, we find that some MCs had a significant propagation velocity perpendicular to the radial direction, suggesting the direct evidence of the CME's deflected propagation and/or rotation in interplanetary space. Second, we confirm the previous results that the expansion speed is correlated with the radial propagation speed and most MCs did not expand self-similarly at 1 AU. In our statistics, about 62\%/17\% of MCs underwent a under/over-expansion at 1 AU and the expansion rate is about 0.6 on average. Third, most interestingly, we find that a significant poloidal motion did exist in some MCs. Three speculations about the cause of the poloidal motion are therefore proposed. These findings advance our understanding of the MC's properties at 1 AU as well as the dynamic evolution of CMEs from the Sun to interplanetary space.

accepted by JGR

References in corpus (10)

• Non-linear Least Squares Fitting in IDL with MPFIT
• Progressive transformation of a flux rope to an ICME
• Global and local expansion of magnetic clouds in the inner heliosphere
• Deflected propagation of a coronal mass ejection from the corona to interplanetary space
• Accuracy and Limitations of Fitting and Stereoscopic Methods to Determine the Direction of Coronal Mass Ejections from Heliospheric Imagers Observations
• Linking two consecutive nonmerging magnetic clouds with their solar sources
• Relationship between EIT Post Eruption Arcades, Coronal Mass Ejections, Coronal Neutral Line and Magnetic Clouds
• Three-dimensional evolution of erupted flux ropes from the Sun (2-20 Rs) to 1 AU
• Magnetohydrodynamic simulation of the interaction between two interplanetary magnetic clouds and its consequent geoeffectiveness
• Magnetohydrodynamic Simulation of the Interaction between Interplanetary Strong Shock and Magnetic Cloud and its Consequent Geoeffectiveness 2: Oblique Collision

Cited by in corpus (6)

• On the twists of interplanetary magnetic flux ropes observed at 1 AU
• On the Propagation of a Geoeffective Coronal Mass Ejection during March 15 -- 17, 2015
• Assessing the collision nature of coronal mass ejections in the inner heliosphere
• Untwisting Jets Related to Magnetic Flux Cancellation
• Downward catastrophe of solar magnetic flux ropes
• Upward and downward catastrophes of coronal magnetic flux ropes in quadrupolar magnetic fields