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Ann. Geophys., 22, 4397-4406, 2004
www.ann-geophys.net/22/4397/2004/
© European Geosciences Union 2004
Non-radial solar wind flows induced by the motion of interplanetary coronal mass ejections
M. Owens1,* and P. Cargill1
1Space and Atmospheric Physics, The Blackett Laboratory Imperial College, London SW7 2BW, UK
*now at: Center for Space Physics Boston University, Boston MA 02215,
Abstract. A survey of the non-radial flows (NRFs) during nearly five years of
interplanetary observations revealed the average non-radial speed of
the solar wind flows to be ~30km/s, with approximately one-half of the large (>100km/s)
NRFs associated with ICMEs. Conversely, the average non-radial flow
speed upstream of all ICMEs is ~100km/s, with just over one-third
preceded by large NRFs. These upstream flow deflections are analysed in the
context of the large-scale structure of the driving ICME. We chose 5
magnetic clouds with relatively uncomplicated upstream flow deflections.
Using variance analysis it was possible to infer 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.
Key words. Interplanetary physics (flare and stream dynamics;
interplanetary magnetic fields; interplanetary shocks)
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