HR: 15:25h
AN: SM33C-07    [Abstracts]
TI: Interaction of the Bow Shock with a Tangential Discontinuity and Solar-Wind Density Decrease: Observations of Predicted Fast Mode Waves and Magnetosheath Merging
AU: Maynard, N C
EM: nelson.maynard@unh.edu
AF: Space Science Center, University of New Hampshire, Morse Hall College Road, Durham, NH 03824, United States
AU: Burke, W J
EM: william.burke2@hanscom.af.mil
AF: Air Force Research Laboratory, Space Vehicles Directorate 29 Randolph Road, Hanscom AFB, MA 01731, United States
AU: * Ober, D M
EM: daniel.ober@hanscom.af.mil
AF: Air Force Research Laboratory, Space Vehicles Directorate 29 Randolph Road, Hanscom AFB, MA 01731, United States
AU: Farrugia, C J
EM: charlie.farrugia@unh.edu
AF: Space Science Center, University of New Hampshire, Morse Hall College Road, Durham, NH 03824, United States
AU: Kucharek, H
EM: harald.kucharek@unh.edu
AF: Space Science Center, University of New Hampshire, Morse Hall College Road, Durham, NH 03824, United States
AU: Lester, M
EM: mle@ion.le.ac.uk
AF: University of Leicester, Dept Physics & Astronomy University Road, Leicester, LE17RH, United Kingdom
AU: Mozer, F S
EM: fmozer@cluster2.ssl.berkeley.edu
AF: Space Science Laboratory, UCB, Grizzly Peak Road, Berkeley, CA 94720, United States
AU: Russell, C T
EM: ctrussell@igpp.ucla.edu
AF: Inbstitute of Geophysics, UCLA, 405 Hilgard Ave, Los Angeles, CA 90095, United States
AU: Siebert, K D
EM: keith.siebert@sparta.com
AF: SPARTA, 39 Simon St, Nashua, NH 03060, United States
AB: Shortly after 06:00 UT on 7 April 2000 a tangential discontinuity (TD) in the solar wind passed the Advanced Composition Explorer satellite (ACE). It was characterized by a rotation of the interplanetary magnetic field (IMF) by ~145° and more than a factor-of-two decrease in the plasma density. About 50 minutes later Polar encountered more complex manifestations of the discontinuity near noon in the magnetosheath outside the northern hemisphere cusp. Based on Polar observations, theoretical modeling, and MHD simulations we interpret the event as demonstrating that: (1) a fast-mode rarefaction wave was generated during the TD–bow shock interaction, (2) the fast wave carried a significant fraction of the density change to the magnetopause while the remainder stayed with the transmitted discontinuity, and (3) magnetic merging occurred between IMF field lines within the magnetosheath on opposite sides of the discontinuity's surface as it approached the magnetopause. Before the discontinuity passed the spacecraft, Polar detected ions accelerated anti-parallel to B in the fast wave and perpendicular to B in a weak slow-mode structure located adjacent to and just downstream of the fast wave. The anti-parallel accelerated ions in the fast wave had no measurable ion-velocity dispersion signature, placing their source a few R_E equatorward of Polar. Simulation results, a Walén test, detections of wave Poynting flux parallel to B, bi-directional electron heat flux, and ion velocity enhancements all indicate that the three ion bursts associated with the passage of the discontinuity were signatures of time- dependent, magnetic merging events within the magnetosheath.
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2728 Magnetosheath
DE: 2740 Magnetospheric configuration and dynamics
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting