On the Magnetic Flux Budget in Low‐Corona Magnetic Reconnection and Interplanetary Coronal Mass Ejections

Abstract

We present the first quantitative comparison between the total magneticreconnection flux in the low corona in the wake of coronal massejections (CMEs) and the magnetic flux in magnetic clouds (MCs) thatreach 1 AU 2-3 days after CME onset. The total reconnection flux ismeasured from flare ribbons, and the MC flux is computed using in situobservations at 1 AU, all ranging from 1020 to1022 Mx. It is found that for the nine studied events inwhich the association between flares, CMEs, and MCs is identified, theMC flux is correlated with the total reconnection fluxΦr. Further, the poloidal (azimuthal) MC fluxΦp is comparable with the reconnection fluxΦr, and the toroidal (axial) MC flux Φt isa fraction of Φr. Events associated with filamenteruption do not exhibit a differentΦt,p-Φr relation from events notaccompanied by erupting filaments. The relations revealed between theseindependently measured physical quantities suggest that for the studiedsamples, the magnetic flux and twist of interplanetary magnetic fluxropes, reflected by MCs, are highly relevant to low-corona magneticreconnection during the eruption. We discuss the implications of thisresult for the formation mechanism of twisted magnetic flux ropes,namely, whether the helical structure of the magnetic flux rope islargely pre-existing or formed in situ by low-corona magneticreconnection. We also measure magnetic flux encompassed in coronaldimming regions (Φd) and discuss its relation to thereconnection flux inferred from flare ribbons and MC flux.