|
|
 |
|
|
Ann. Geophys., 19, 1567-1578, 2001
www.ann-geophys.net/19/1567/2001/
© European Geosciences Union 2001
Four point measurements of electrons using PEACE in the high-altitude cusp
M. G. G. T. Taylor1, A. Fazakerley1, I. C. Krauklis1, C. J. Owen1, P. Travnicek1,2, M. Dunlop3, P. Carter1, A. J. Coates1, S. Szita1, G. Watson1, and R. J. Wilson1
1Mullard Space Science Laboratory, University College London, UK
2Institute of Atmospheric Physics, The Academy of Sciences of the Czech Republic
3Imperial College of Science Technology and Medicine, UK
Abstract. We present examples of
electron measurements from the PEACE instruments on the Cluster spacecraft in
the high-latitude, high-altitude region of the Earth’s magnetosphere. Using
electron density and energy spectra measurements, we examine two cases where
the orbit of the Cluster tetrahedron is outbound over the northern hemisphere,
in the afternoon sector approaching the magnetopause. Data from the
magnetometer is also used to pinpoint the position of the spacecraft with
respect to magnetospheric boundaries. This preliminary work specifically
highlights the benefit of the multipoint measurement capability of the Cluster
mission. In the first case, we observe a small-scale spatial structure within
the magnetopause boundary layer. The Cluster spacecraft initially straddle a
boundary, characterised by a discontinuous change in the plasma population,
with a pair of spacecraft on either side. This is followed by a complete
crossing of the boundary by all four spacecraft. In the second case, Cluster
encounters an isolated region of higher energy electrons within the cusp. The
characteristics of this region are consistent with a trapped boundary layer
plasma sheet population on closed magnetospheric field lines. However, a
boundary motion study indicates that this region convects past Cluster, a
characteristic more consistent with open field lines. An interpretation of this
event in terms of the motion of the cusp boundary region is presented.
Key words. Magnetospheric physics
(magnetopause, cusp and boundary layers; solar wind-magnetosphere interactions)
Full Article in PDF (1507 KB) |
|
|
