HAL : insu-00360118, version 1

DOI : 10.1016/j.asr.2007.10.013

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Advances in Space Research 41, 10 (2008) 1619-1629

The plasma sheet and boundary layers under northward IMF: A multi-point and multi-instrument perspective

M. G. Taylor 1, 2, B. Lavraud 3, P. Escoubet 2, S. Milan 4, K. Nykyri 5, 6, M.W. Dunlop 5, 7, J. A. Davies 7, R. H. Friedel 3, H. Frey 8, Y. Bogdanova 1, A. Asnes 2, H. Laakso 2, P. Travnicek 9, 10, Arnaud Masson 2, H. Opgenoorth 2, C. Vallat 2, A. N. Fazakerley 1, A. D. Lahiff 1, C. J. Owen 1, Frederic Pitout 11, 12, Z. Pu 13, C. Shen 14, Q. Zong 15, H. Reme 16, J. D. Scudder 17, T. Zhang 18

(2008)

During conditions of northward interplanetary magnetic field (IMF), the near-tail plasma sheet is known to become denser and cooler, and is described as the cold-dense plasma sheet (CDPS). While its source is likely the solar wind, the prominent penetration mechanisms are less clear. The two main candidates are solar wind direct capture via double high-latitude reconnection on the dayside and Kelvin–Helmholtz/diffusive processes at the flank magnetopause. This paper presents a case study on the formation of the CDPS utilizing a wide variety of space- and ground-based observations, but primarily from the Double Star and Polar spacecraft on December 5th, 2004. The pertinent observations can be summarized as follows: TC-1 observes quasi-periodic (not, vert, similar2 min period) cold-dense boundary layer (compared to a hot-tenuous plasma sheet) signatures interspersed with magnetosheath plasma at the dusk flank magnetopause near the dawn-dusk terminator. Analysis of this region suggests the boundary to be Kelvin–Helmholtz unstable and that plasma transport is ongoing across the boundary. At the same time, IMAGE spacecraft and ground based SuperDARN measurements provide evidence of high-latitude reconnection in both hemispheres. The Polar spacecraft, located in the southern hemisphere afternoon sector, sunward of TC-1, observes a persistent boundary layer with no obvious signature of boundary waves. The plasma is of a similar appearance to that observed by TC-1 inside the boundary layer further down the dusk flank, and by TC-2 in the near-Earth magnetotail. We present comparisons of electron phase space distributions between the spacecraft. Although the dayside boundary layer at Polar is most likely formed via double high-altitude reconnection, and is somewhat comparable to the flank boundary layer at Double Star, some differences argue in favour of additional transport that augment solar wind plasma entry into the tail regions.

1 :	Mullard Space science laboratory
	University College of London (UCL)
2 :	ESA European Space Agency, ESTEC
	ESA ESTEC
3 :	Space Science and Applications
	Los Alamos National Laboratory
4 :	Department of Physics and Astronomy [Leicester]
	University of Leicester
5 :	The Blackett Laboratory
	Imperial College London
6 :	Embry-Riddle Aeronautical University
	Embry-Riddle Aeronautical University
7 :	Space Science and Technology Department (Ral Space)
	STFC Rutherford Appleton Laboratory
8 :	Space Sciences Laboratory (SSL)
	Space Sciences Laboratory (SSL)
9 :	Astronomical Institute
	Academy of Sciences of the Czech Republic
10 :	Institute of Atmospheric Physics
	Academy of Sciences of the Czech Republic
11 :	Laboratoire de Planétologie de Grenoble (LPG)
	CNRS : UMR5109 – OSUG – INSU – Université Joseph Fourier - Grenoble I
12 :	Max Planck Institut für Aeronomie
	Max Planck Institut für Aeronomie
13 :	School of Earth and Space Sciences
	Peking University / Beijing
14 :	Centre for Space Science and Applied Research
	Chinese Academy of Sciences
15 :	Center for Atmospheric Research
	University of Massachussetts Lowell
16 :	Centre d'étude spatiale des rayonnements (CESR)
	CNRS : UMR5187 – Observatoire Midi-Pyrénées – INSU – Université Paul Sabatier [UPS] - Toulouse III
17 :	Department of Physics and Astronomy
	University of Iowa
18 :	Institut fur Weltraumforschung (IWF) (IWF)
	Austrian Academy of Sciences

mots-clés : Plasma sheet – Magnetopshere – Cold dense plasma sheet – Cluster – Double star

insu-00360118, version 1

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Contributeur : Béatrice Pibaret-Bourdon <>

Soumis le : Mardi 10 Février 2009, 12:29:25

Dernière modification le : Mardi 10 Février 2009, 12:29:25