Validation and interpretation of three-dimensional configuration of a magnetic cloud flux rope

TL;DR

This study validates a 3D magnetic flux rope model of a magnetic cloud using in situ measurements from Wind and Venus Express spacecraft, revealing the flux rope's complex structure and reconnection processes reducing its magnetic flux.

Contribution

It introduces a comprehensive 3D flux rope model validated by multi-spacecraft data, linking solar reconnection processes to magnetic cloud structure.

Findings

The magnetic cloud's 3D configuration explains spatial magnetic field variations.

Reconnection during the solar flare reduces the flux rope’s axial magnetic flux by about 50%.

Multi-spacecraft data confirms the 3D flux rope model accuracy.

Abstract

One "strong" magnetic cloud (MC) with the magnetic field magnitude reaching $\sim$ 40 nT at 1 au during 2012 June 16-17 is examined in association with a pre-existing magnetic flux rope (MFR) identified on the Sun. The MC is characterized by a quasi-three dimensional (3D) flux rope model based on in situ measurements from the Wind spacecraft. The magnetic flux contents and other parameters are quantified. In addition, a correlative study with the corresponding measurements of the same structure crossed by the Venus Express (VEX) spacecraft at a heliocentric distance 0.7 au and with an angular separation $\sim 6^\circ$ in longitude is performed to validate the MC modeling results. The spatial variation between the Wind and VEX magnetic field measurements is attributed to the 3D configuration of the structure as featured by a knotted bundle of flux. The comparison of the magnetic flux contents between the MC and the source region on the Sun indicates that the 3D reconnection process accompanying an M1.9 flare may correspond to the magnetic reconnection between the field lines of the pre-existing MFR rooted in the opposite polarity footpoints. Such a process reduces the amount of the axial magnetic flux in the erupted flux rope, by approximately 50\%, in this case.