Solar Cycle Variation of Axial Orientations and Favorable Locations of Eruptive MFRs

TL;DR

This study analyzes the variation of magnetic flux rope orientations in coronal mass ejections across three solar cycles, revealing cycle-dependent patterns and their implications for space weather prediction.

Contribution

It provides new insights into the solar cycle dependence of MFR axial orientations and their occurrence near Hale sector boundaries, based on multi-viewpoint observations.

Findings

MFR axes in cycle 25 are predominantly northward.

Most MFRs occur near Hale sector boundaries.

MC axial fields show cycle-dependent north-south orientation.

Abstract

Using multi-viewpoint observations from STEREO and SOHO during three solar cycles from 23 to 25, we study the magnetic flux rope (MFR) structures of coronal mass ejections (CMEs) near the Sun and magnetic clouds (MCs) at 1au. The study aims to investigate two phenomena: 1) the occurrence rate of CMEs near Hale sector boundaries (HBs) and 2) solar-cycle variation of MFR axial orientations in CMEs and MCs. Our preliminary results include: 1) the axes of MFRs in cycle 25 present a systematic northward orientation, which is the same as in cycle 23 but opposite to cycle 24; 2) the majority of the MFRs occurred near HBs (within 30 degrees) and some exceptional events occurred at non-HBs; 3) the axial fields in MCs present a similar north-south orientation, which changes from cycle to cycle. We discuss the implication of solar cycle variations of MFR axial orientations for space weather forecasts.