HR: 10:40h
AN: SH41D-02    [PDF]
TI: Large-Scale Magnetic Field Inversions at Sector Boundaries and Their Relation to Coronal Mass Ejections
AU: * Crooker, N U
EM: crooker@bu.edu
AF: Boston University, Center for Space Physics, Boston, MA 02215 United States
AU: Kahler, S W
EM: Stephen.Kahler@hanscom.af.mil
AF: Air Force Research Laboratory, 29 Randolph Road, Hanscom Air Force Ba, MA 01731 United States
AU: Larson, D E
EM: davin@ssl.berkeley.edu
AF: University of California, Space Sciences Laboratory, Berkeley, CA 94720 United States
AB: During the declining phase of the last solar cycle, the Wind spacecraft observed a quasi-recurrent pattern of mismatches between sector boundaries identified in suprathermal electron pitch angle spectrograms and in magnetic field data alone. Intervals of mismatch imply the presence of magnetic fields that are locally inverted or turned back on themselves in a way that is intrinsic to the sector boundary. We analyze 8 cases of inversion during 9 successive solar rotations in 1994-1995. These range in duration from 15 to 53 hours. In most the inversions are incomplete in a systematic way: Rather than pointing opposite to its true polarity along the Parker spiral, the magnetic field hovers at an orientation more nearly orthogonal to it, always in the sense of decreasing azimuth angle. The inversion pattern is consistent with passage through coronal streamer belt loops in which the polarity of the two legs of each loop matches the sector structure and where one leg has been released from the Sun through interchange reconnection. There are four possible variations of this pattern, depending upon the sense of polarity change across the sector boundary and whether the leading or trailing leg has been released. The latter determines whether the sector boundary or the local field reversal passes first. Three of the 4 variations are represented in the 8 cases. Plasma parameters in the inversions are typical of the slow wind. While a some cases display signatures of interplanetary coronal mass ejections, many do not. Thus the inversions may represent the quiet, quasi-steady end of a spectrum of large-scale transient outflows.
DE: 2111 Ejecta, driver gases, and magnetic clouds
DE: 2134 Interplanetary magnetic fields
DE: 2169 Sources of the solar wind
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting