Authors: Wenyuan Yu (University of New Hampshire), Nada A. Al-Haddad (University of New Hampshire), Charles J. Farrugia (University of New Hampshire), Noé Lugaz (University of New Hampshire), Bin Zhuang (University of New Hampshire), Florian Regnault (University of New Hampshire), Antoinette Galvin (University of New Hampshire)

The aim of this study is to use multi-spacecraft measurements of interplanetary coronal mass ejections (ICMEs) to better constrain and understand the effect of expansion on them. We propose an additional parameter (γ) derived from the magnetic fields obtained from multiple spacecraft using the minimum variance analysis technique. Our goal is to determine whether a magnetic cloud exhibits self-similar expansion and, if so, whether this expansion is predominantly radial or isotropic. Through our analysis of data from multiple spacecraft, we observe a notable consistency in the values of this parameter across the examples examined. We find that the overall expansion of these magnetic clouds tends to be isotropic, while the local expansion shows anisotropic behavior, particularly when there is a short time interval between the observations from the two spacecraft. This discovery offers valuable insights for refining flux rope models and advancing our comprehension of the expansion processes associated with ICMEs.