HR: 1330h
AN: SM23B-13    [Abstracts]
TI: Current Structure and Motion of a Northward IMF X-Line
AU: * Wendel, D E
EM: dwendel@rice.edu
AF: Rice University, P. O. Box 1892 MS-108, Houston, TX 77251 United States
AU: Reiff, P H
EM: reiff@rice.edu
AF: Rice University, P. O. Box 1892 MS-108, Houston, TX 77251 United States
AU: Han, T
EM: ph_hth@stu.ust.hk
AF: Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
AU: Fazakerley, A
EM: anf@mssl.ucl.ac.uk
AF: Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Sur RH5 6NT United Kingdom
AU: Schwartz, S
EM: steve.schwartz@qmul.ac.uk
AF: Imperial College London, South Kensington, London, SW7 2AZ United Kingdom
AU: Mende, S
EM: mende@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California at Berkeley, Berkeley, CA 94720 United States
AU: Winningham, J D
EM: dwinningham@swri.edu
AF: Southwest Research Institute, 6220 Culabra Rd, San Antonio, TX 78228 United States
AU: Goldstein, M
EM: melvyn.goldstein@gsfc.nasa.gov
AF: Goddard Space Science Laboratory, Code 632, Greenbelt, MD 20771 United States
AB: On March 18, 2002, between 14:50 and 15:03 UT, Cluster passed from the tail lobe northward and sunward into the magnetosheath. The IMAGE FUV instrument observed a proton emission, northward of the auroral zone, that endured for a period of hours, including the time of the Cluster crossing. Some researchers mapped the location of cluster during its magnetopause crossing to the location of the ionospheric footprint observed by IMAGE. We argue from Cluster PEACE electron and magnetic field data that the Cluster spacecraft pass to within at least 5 km of an active x-line, the spacecraft actually entering the Hall zone where ions demagnetize. We map the position of the x-line at the points of closest approach to each spacecraft through inversion of a low-order expansion for the magnetic field near the x-line, allowing us to infer the current structure, velocity, orientation, and size of the x-line. The functional fit to the data also gives an estimate of the thickness of the current sheet. The x-line earth and IMF fields form a large angle from the GSE x-direction and while undergoing enhancement in the GSE y-direction, consistent with anti-parallel reconnection, but with a twist in the x-y plane. We propose that the x-line, though it does waver across the spacecraft several times, is largely stable over the times of Cluster observations.
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2728 Magnetosheath
DE: 2730 Magnetosphere--inner
DE: 2744 Magnetotail
DE: 7835 Magnetic reconnection
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly