Authors: Yakub Olufadi (UNH), Nada AlHadda (UNH), Florian Regnault(UNH), Noe Lugaz(UNH)
Coronal Mass Ejections (CMEs) are violent events corresponding to strong magnetic structures erupting from the outermost part of the Sun: the corona. CMEs observed in the interplanetary medium have been cataloged in the Helio4Cast catalog which covers more than 2 decades of in situ measurements (1995-2024) and includes measurements made by many interplanetary probes.
Starting from over 1000 CMEs, we use the statistical approach known as the superposed epoch analysis to determine the mean and median in situ profiles of CMEs emitted during the active phase (AP) and the quiet phase (QP) of the solar cycle. We define the quiet and the active phase of the solar cycle by using certain threshold on the sunspot number (60 SSN) . The active phase CMEs events result in a greater enhancement in magnetic field strength, and other plasma parameters as compared with the CMEs emitted during the quiet phase. We found that the AP CMEs are faster with enhancements in Bmag, Vp, Tp but reduction in the Np for the ME and Wake substructures as compared with the QP CMEs.
We compute the distortion parameter for both the AP mean and median DiPs and for QP the mean and median DiPs respectively. The result suggests that the ME during AP is less symmetric than during the QP. The ME expansion
speed during AP for the mean and median profiles are twice as much as during QP which implies that the AP CMEs expand more during their propagation.
Furthermore, this large catalog of CMEs allows us to study the influence of the distance from the Sun on CME mean and median properties. We are currently investigating and conducting the minimum variance analysis on each bin to understand the distance-variation in the axial and azimulthal magnetic field component in the bins.