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

We present the first quantitative comparison between the total magnetic reconnection flux in the low corona in the wake of coronal mass ejections (CMEs) and the magnetic flux in magnetic clouds (MCs) that reach 1 AU 2-3 days after CME onset. The total reconnection flux is measured from flare ribbons, and the MC flux is computed using in situ observations at 1 AU, all ranging from 10 20 to 10 22 Mx. It is found that for the nine studied events in which the association between flares, CMEs, and MCs is identified, the MC flux is correlated with the total reconnection flux Φ r . Further, the poloidal (azimuthal) MC flux Φ p is comparable with the reconnection flux Φ r , and the toroidal (axial) MC flux Φ t is a fraction of Φ r . Events associated with filament eruption do not exhibit a different Φ t , p -Φ r relation from events not accompanied by erupting filaments. The relations revealed between these independently measured physical quantities suggest that for the studied samples, the magnetic flux and twist of interplanetary magnetic flux ropes, reflected by MCs, are highly relevant to low-corona magnetic reconnection during the eruption. We discuss the implications of this result for the formation mechanism of twisted magnetic flux ropes, namely, whether the helical structure of the magnetic flux rope is largely pre-existing or formed in situ by low-corona magnetic reconnection. We also measure magnetic flux encompassed in coronal dimming regions (Φ d ) and discuss its relation to the reconnection flux inferred from flare ribbons and MC flux.