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Read Full Article (file size: 2214482 bytes) Cited by
JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 112,
A12219,
doi:10.1029/2007JA012293,
2007
Interaction of the bow shock with a tangential discontinuity and solar wind density decrease: Observations of predicted fast
mode waves and magnetosheath merging
N. C. Maynard
Space Science Center, University of New Hampshire, Durham, New Hampshire, USA
W. J. Burke
Air Force Research Laboratory, Hanscom AFB, Massachusetts, USA Institute for Scientific Research, Boston College, Chestnut Hill, Massachusetts, USA
D. M. Ober
Institute for Scientific Research, Boston College, Chestnut Hill, Massachusetts, USA
C. J. Farrugia
Space Science Center, University of New Hampshire, Durham, New Hampshire, USA
H. Kucharek
Space Science Center, University of New Hampshire, Durham, New Hampshire, USA
M. Lester
Department of Physics and Astronomy, University of Leicester, Leicester, UK
F. S. Mozer
Space Science Laboratory, University of California at Berkeley, Berkeley, California, USA
C. T. Russell
Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA
K. D. Siebert
SPARTA Inc., Nashua, New Hampshire, USA
Abstract
Shortly after 0600 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-2
decrease in the plasma density. About 50 min later, Polar encountered more complex manifestations of the discontinuity near
noon in the magnetosheath outside the Northern Hemisphere cusp. On the basis of 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 antiparallel 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 antiparallel 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, bidirectional 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.
Received 24
January
2007;
accepted 17
July
2007;
published 27
December
2007.
Keywords: magnetosheath;
magnetic merging (reconnection);
ion acceleration;
fast mode waves;
slow mode waves;
solar wind/magnetosphere coupling.
Index Terms: 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2728 Magnetospheric Physics: Magnetosheath; 2723 Magnetospheric Physics: Magnetic reconnection (7526, 7835); 2752 Magnetospheric Physics: MHD waves and instabilities (2149, 6050, 7836); 2736 Magnetospheric Physics: Magnetosphere/ionosphere interactions (2431).
Read Full Article (file size: 2214482 bytes) Cited by
Citation: Maynard, N. C., W. J. Burke, D. M. Ober, C. J. Farrugia, H. Kucharek, M. Lester, F. S. Mozer, C. T. Russell, and K. D. Siebert
(2007),
Interaction of the bow shock with a tangential discontinuity and solar wind density decrease: Observations of predicted fast
mode waves and magnetosheath merging,
J. Geophys. Res.,
112,
A12219,
doi:10.1029/2007JA012293.
Copyright 2007 by the American Geophysical Union.
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