Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.490 IF 1.490
  • IF 5-year value: 1.445 IF 5-year
    1.445
  • CiteScore value: 2.9 CiteScore
    2.9
  • SNIP value: 0.789 SNIP 0.789
  • IPP value: 1.48 IPP 1.48
  • SJR value: 0.74 SJR 0.74
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 88 Scimago H
    index 88
  • h5-index value: 21 h5-index 21
Volume 21, issue 2
Ann. Geophys., 21, 457–472, 2003
https://doi.org/10.5194/angeo-21-457-2003
© Author(s) 2003. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 21, 457–472, 2003
https://doi.org/10.5194/angeo-21-457-2003
© Author(s) 2003. This work is distributed under
the Creative Commons Attribution 3.0 License.

  28 Feb 2003

28 Feb 2003

Evidence for impulsive solar wind plasma penetration through the dayside magnetopause

R. Lundin2,1, J.-A. Sauvaud1, H. Rème1, A. Balogh3, I. Dandouras1, J. M. Bosqued1, C. Carlson4, G. K. Parks4, E. Möbius5, L. M. Kistler5, B. Klecker6, E. Amata7, V. Formisano7, M. Dunlop3, L. Eliasson2, A. Korth8, B. Lavraud1, and M. McCarthy9 R. Lundin et al.
  • 1CESR, Toulouse, France
  • 2Swedish Institute of Space Physics, Kiruna, Sweden
  • 3Imperial College, London, UK
  • 4Space Sciences Laboratory, University of California Berkeley, USA
  • 5EOS, University of New Hampshire, Durham, NH, USA
  • 6MPI für extraterrestrische Physik, Garching, Germany
  • 7IFSI, Rome, Italy
  • 8MPI für Aeronomie, Katlenburg-Lindau, Germany
  • 9Space Program, University of Washington, USA

Abstract. This paper presents in situ observational evidence from the Cluster Ion Spectrometer (CIS) on Cluster of injected solar wind "plasma clouds" protruding into the day-side high-latitude magnetopause. The plasma clouds, presumably injected by a transient process through the day-side magnetopause, show characteristics implying a generation mechanism denoted impulsive penetration (Lemaire and Roth, 1978).

The injected plasma clouds, hereafter termed "plasma transfer events", (PTEs), (Woch and Lundin, 1991), are temporal in nature and relatively limited in size. They are initially moving inward with a high velocity and a magnetic signature that makes them essentially indistinguishable from regular magnetosheath encounters. Once inside the magnetosphere, however, PTEs are more easily distinguished from magnetopause encounters. The PTEs may still be moving while embedded in an isotropic background of energetic trapped particles but, once inside the magnetosphere, they expand along magnetic field lines. However, they frequently have a significant transverse drift component as well. The drift is localised, thus constituting an excess momentum/motional emf generating electric fields and currents. The induced emf also acts locally, accelerating a pre-existing cold plasma (e.g. Sauvaud et al., 2001). Observations of PTE-signatures range from "active" (strong transverse flow, magnetic turbulence, electric current, local plasma acceleration) to "evanescent" (weak flow, weak current signature).

PTEs appear to occur independently of Interplanetary Magnetic Field (IMF) Bz in the vicinity of the polar cusp region, which is consistent with observations of transient plasma injections observed with mid- and high-altitude satellites (e.g. Woch and Lundin, 1992; Stenuit et al., 2001). However the characteristics of PTEs in the magnetosphere boundary layer differ for southward and northward IMF. The Cluster data available up to now indicate that PTEs penetrate deeper into the magnetosphere for northward IMF than for southward IMF. This may or may not mark a difference in nature between PTEs observed for southward and northward IMF. Considering that flux transfer events (FTEs), (Russell and Elphic, 1979), are observed for southward IMF or when the IMF is oriented such that antiparallel merging may occur, it seems likely that PTEs observed for southward IMF are related to FTEs.

Key words. Magnetospheric physics (magnetopause, cusp, and boundary layers; magnetosphere-ionosphere interactions; solar-wind magnetosphere interactions)

Publications Copernicus
Download
Citation