Influence of the Deformation of Coronal Mass Ejections on Their In-Situ Fitting with Circular-Cross-Section Flux Rope Models

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Main Authors: Zhuang, Bin, Lugaz, Noé, Al-Haddad, Nada, Farrugia, Charles J., Amerstorfer, Ute, Davies, Emma E., Temmer, Manuela, Rüdisser, Hannah T., Yu, Wenyuan, Gou, Tingyu, Winslow, Réka M.
Format: Preprint
Published: 2025
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author Zhuang, Bin
Lugaz, Noé
Al-Haddad, Nada
Farrugia, Charles J.
Amerstorfer, Ute
Davies, Emma E.
Temmer, Manuela
Rüdisser, Hannah T.
Yu, Wenyuan
Gou, Tingyu
Winslow, Réka M.
author_facet Zhuang, Bin
Lugaz, Noé
Al-Haddad, Nada
Farrugia, Charles J.
Amerstorfer, Ute
Davies, Emma E.
Temmer, Manuela
Rüdisser, Hannah T.
Yu, Wenyuan
Gou, Tingyu
Winslow, Réka M.
contents Understanding the properties, especially the magnetohydrodynamic (MHD) invariants, of coronal mass ejections (CMEs) measured in-situ is key to bridging the CME properties from the Sun to interplanetary space. In order to investigate CMEs from the in-situ measurements that provide a one-dimensional (1-D) cut of the CME parameters over the spacecraft trajectory, various magnetic flux rope (MFR) models have been developed, among which the models with a circular cross-section are the most popular and widely used. CMEs are found to be deformed during their propagation in interplanetary space, in which the cross-section may be flattened in the direction of propagation, i.e., to develop an elliptical or even pancake-like shape. We use numerical MHD simulations in 2.5-D to investigate the influence of the CME deformation on the in-situ fitting using two linear force-free MFR models with a circular cross-section, and we focus on the axial and poloidal magnetic fluxes, which are conserved in the ideal MHD frame and simulations. We quantitatively compare the fitted axial and poloidal fluxes with those in simulations. We find that both models underestimate the axial flux compared to that in simulations, and such underestimation depends on the CME deformation. However, the fitting of the poloidal flux is independent of the deformation. We discuss the reasons for the axial flux underestimation and the implication of the CME deformation for the CME in-situ fitting.
format Preprint
id arxiv_https___arxiv_org_abs_2503_00166
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Influence of the Deformation of Coronal Mass Ejections on Their In-Situ Fitting with Circular-Cross-Section Flux Rope Models
Zhuang, Bin
Lugaz, Noé
Al-Haddad, Nada
Farrugia, Charles J.
Amerstorfer, Ute
Davies, Emma E.
Temmer, Manuela
Rüdisser, Hannah T.
Yu, Wenyuan
Gou, Tingyu
Winslow, Réka M.
Space Physics
Solar and Stellar Astrophysics
Understanding the properties, especially the magnetohydrodynamic (MHD) invariants, of coronal mass ejections (CMEs) measured in-situ is key to bridging the CME properties from the Sun to interplanetary space. In order to investigate CMEs from the in-situ measurements that provide a one-dimensional (1-D) cut of the CME parameters over the spacecraft trajectory, various magnetic flux rope (MFR) models have been developed, among which the models with a circular cross-section are the most popular and widely used. CMEs are found to be deformed during their propagation in interplanetary space, in which the cross-section may be flattened in the direction of propagation, i.e., to develop an elliptical or even pancake-like shape. We use numerical MHD simulations in 2.5-D to investigate the influence of the CME deformation on the in-situ fitting using two linear force-free MFR models with a circular cross-section, and we focus on the axial and poloidal magnetic fluxes, which are conserved in the ideal MHD frame and simulations. We quantitatively compare the fitted axial and poloidal fluxes with those in simulations. We find that both models underestimate the axial flux compared to that in simulations, and such underestimation depends on the CME deformation. However, the fitting of the poloidal flux is independent of the deformation. We discuss the reasons for the axial flux underestimation and the implication of the CME deformation for the CME in-situ fitting.
title Influence of the Deformation of Coronal Mass Ejections on Their In-Situ Fitting with Circular-Cross-Section Flux Rope Models
topic Space Physics
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2503.00166