Authors: M. Ala-Lahti (University of Michigan), T. I. Pulkkinen (University of Michigan), J. Ruohotie (University of Helsinki), M. Akhavan-Tafti (University of Michigan), S. W. Good (University of Helsinki), E. K. J. Kilpua (University of Helsinki)
An interplanetary coronal mass ejection (ICME) front boundary, which separates the confined ejecta from the mixed, interacted sheath-ejecta plasma upstream, is analyzed in a multi-point study. Magnetic reconnection with a bifurcated current sheet and two-sided jet were observed at the boundary, which implies multiple (patchy) reconnection sites associated with the ICME erosion. The boundary hosted localized structures, which were measured only by individual Cluster spacecraft with the inter-spacecraft separation of 0.4 − 1.6 Re . The mixed plasma upstream the boundary with a precursor at 0.8 AU lacked coherency at 1 AU and exhibited substantial variations of southward magnetic fields over radial (transverse) distances of 41 – 237 Re (114 Re ). This incoherence demonstrates the need for continuous (sub)second resolution plasma and field measurements at multiple locations in the solar wind to adequately address the spatio-temporal structure of ICMEs and to produce accurate space weather predictions.