Previous abstract Next abstract

Session 2 - Everything Else.
Display session, Friday, June 27
Ballroom C, Chair: Richard Canfield

[2.69] Topology of a magnetic cloud in the context of the topology surrounding its solar source

N. U. Crooker (Boston University), A. H. McAllister (Helio Research), R. J. Fitzenreiter, K. W. Ogilvie, A. Szabo, R. P. Lepping (Goddard Space Flight Center), J. T. Steinberg, A. J. Lazarus (Massachusetts Institute of Technology)

A magnetic cloud observed by the Wind spacecraft on February 8, 1995, appeared to occur in the middle of an away sector. The electron heat flux data, however, indicate that the cloud brought the sector boundary. The magnetic elevation angle in the day-long cloud and the following two-day interval together show the arch pattern characteristic of clouds at sector boundaries, suggesting that the cloud was the leading edge of a larger transient structure. The larger structure, bounded on its trailing edge by a stream interface, appears to fill the streamer belt. A comparison with the source surface model prediction for sector boundary location suggests that the coronal mass ejection that gave birth to this transient structure created a substantial occlusion in the heliospheric current sheet (HCS). The leading magnetic field in the cloud pointed southward, consistent with the solar cycle pattern identified by Bothmer and Rust [1997], and the cloud's helicity was left-handed, suggesting a northern-hemisphere solar source. Yohkoh x-ray data on February 4 show a CME signature that is a likely source for the transient structure. It has the form of an eruptive event along a neutral line through an active region just south of the solar equator and was observed as a long-duration x-ray event at GOES. A filament disappearance just north of the equator may also have been associated with this event. The relationships between the skew of the arcades over the neutral line at the eruptive sites, the neutral line orientation at the photospheric and source surface levels, the field configuration in the transient structure, and the topology of the HCS will be presented.

Program listing for Friday