|
Read Full Article (file size: 1316059 bytes) Cited by
JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
A05211,
doi:10.1029/2005JA011266,
2006
Evidence for newly closed magnetosheath field lines at the dayside magnetopause under northward IMF
B. Lavraud
Space Science and Applications, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
M. F. Thomsen
Space Science and Applications, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
B. Lefebvre
Blackett Laboratory, Imperial College, London, UK
S. J. Schwartz
Blackett Laboratory, Imperial College, London, UK
K. Seki
Solar-Terrestrial Environment Laboratory, University of Nagoya, Aichi, Japan
T. D. Phan
Space Sciences Laboratory, University of California, Berkeley, Berkeley, California, USA
Y. L. Wang
Space Science and Applications, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
A. Fazakerley
Mullard Space Science Laboratory, Surrey, UK
H. Rème
Centre d'Etude Spatiale des Rayonnements, Toulouse, France
A. Balogh
Blackett Laboratory, Imperial College, London, UK
Abstract
We analyze the structure of the high-latitude magnetopause under steady interplanetary magnetic field (IMF). We use 56 magnetopause
encounters of Cluster spacecraft from 2001 to 2003 to explore the statistical properties of the magnetosheath electron boundary
layer, observed outside the high-latitude dayside magnetopause. We focus on the occurrence of low absolute parallel heat flux
in this layer and its dependence on the magnetic field clock angle simultaneously measured by Cluster. The low absolute parallel
heat fluxes result from the presence of bidirectional heated electrons in the magnetosheath electron boundary layer and are
primarily observed when the local magnetic field is northward. The bidirectional heated electrons are interpreted as the signature
of newly closed magnetosheath field lines that have reconnected at the high-latitude magnetopause, tailward of the cusp, in
both hemispheres. This study strongly suggests that double high-latitude reconnection is a tenable mechanism for the formation
of the low-latitude boundary layer and potentially of the cold, dense plasma sheet under northward IMF. Although the efficiency
(in terms of mass and energy transfer) of this mechanism is still to be investigated, it is an obvious way of capturing solar
wind plasma under northward IMF.
Received 13
June
2005;
accepted 1
February
2006;
published 26
May
2006.
Keywords: boundary layer;
magnetopause structure.
Index Terms: 2724 Magnetospheric Physics: Magnetopause and boundary layers; 2723 Magnetospheric Physics: Magnetic reconnection (7526, 7835); 2706 Magnetospheric Physics: Cusp; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions.
Read Full Article (file size: 1316059 bytes) Cited by
Citation: Lavraud, B., M. F. Thomsen, B. Lefebvre, S. J. Schwartz, K. Seki, T. D. Phan, Y. L. Wang, A. Fazakerley, H. Rème, and A. Balogh
(2006),
Evidence for newly closed magnetosheath field lines at the dayside magnetopause under northward IMF,
J. Geophys. Res.,
111,
A05211,
doi:10.1029/2005JA011266.
Copyright 2006 by the American Geophysical Union.
|