Non-radial solar wind flows induced by the motion of interplanetary coronal mass ejections

摘要

A survey of the non-radial flows (NRFs) duringudnearly five years of interplanetary observations revealedudthe average non-radial speed of the solar wind flows toudbe �30 km/s, with approximately one-half of the largeud(>100 km/s) NRFs associated with ICMEs. Conversely, theudaverage non-radial flow speed upstream of all ICMEs isud�100 km/s, with just over one-third preceded by large NRFs.udThese upstream flow deflections are analysed in the contextudof the large-scale structure of the driving ICME. We choseud5 magnetic clouds with relatively uncomplicated upstreamudflow deflections. Using variance analysis it was possible toudinfer the local axis orientation, and to qualitatively estimate the point of interception of the spacecraft with the ICME. For all 5 events the observed upstream flows were in agreement with the point of interception predicted by variance analysis. Thus we conclude that the upstream flow deflections in these events are in accord with the current concept of the large scale structure of an ICME: a curved axial loop connected to the Sun, bounded by a curved (though not necessarily circular)cross section.