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Cluster magnetotail observations of a tailward-travelling plasmoid at substorm expansion phase onset and field aligned currents in the plasma sheet boundary layer

By N. C. Draper, Mark Lester, S. W. H. Cowley, J. A. Wild, Steve E. Milan, Gabrielle P. Provan, Adrian Grocott, A. N. Fazakerley, A. D. Lahiff, J. A. Davies, J-M. Bosqued, J. P. Dewhurst, R. Nakamura, C. J. Owen, J. F. Watermann, M. G. Henderson, H. J. Singer and E. Donovan

Abstract

We present data from both ground- and space-based instruments for a substorm event which occurred on 5 October 2002, with an expansion phase onset time of 02:50 UT determined from the ground magnetometer data. During this substorm, the Cluster spacecraft were located around 15 RE downtail, 8 RE from midnight in the pre-midnight sector and just 2 RE above the equatorial plane (in GSM coordinates). At expansion phase onset the Cluster spacecraft were located in the plasma sheet, tailward of a near-Earth neutral line and detected a significant time delay of 6 min between the tail field Bz component becoming negative and the subsequent detection of Earthward flows. This is explained by the formation of a tailward-directed travelling compression region initially Earthward of the spacecraft; 7 min later the Cluster spacecraft entered the plasma sheet boundary layer; they remained in and close to the plasma sheet boundary layer for around 15 min before exiting to the lobe. The spacecraft then re-entered the plasma sheet 30 min after onset. Earthward then tailward directed currents detected in the plasma sheet boundary layer after onset indicate that the Cluster spacecraft encountered the dawnward and duskward portions of the reconnection flow associated current system with Region 1 sense, respectively. The reconnection site and current system were initially skewed towards the pre-midnight sector, consistent with previous observations that found the majority of substorm onsets located in this sector. At later times the reconnection site and current system had moved towards dawn, to be located more centrally in the midnight sector

Publisher: Copernicus Publications on behalf of the European Geosciences Union (EGU)
Year: 2005
DOI identifier: 10.5194/angeo-23-3667-2005
OAI identifier: oai:lra.le.ac.uk:2381/7893
Journal:

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Citations

  1. (1988). Average ion moments in the plasma sheet boundary layer, doi
  2. (1995). CANOPUS-A ground based instrument array for remote sensing the high latitude ionosphere during the ISTP/CGS program, doi
  3. (2005). Cluster observations of traveling compression regions in the near-tail, doi
  4. (1996). Current disruption in the Earth’s magnetosphere: Observations and models, doi
  5. (1995). Darn/SuperDARN: a global view of the dynamics of highlatitude convection Space Sci. doi
  6. (1996). Details of current disruption and diversion in simulations of magnetotail dynamics, doi
  7. (2003). Geotail observations of magnetic flux ropes in the plasma sheet,
  8. (1978). Highresolution energetic particle measurements at 6.6RE : 2 highenergy proton drift echoes, doi
  9. (1985). Interplanetary magnetic field control of high-latitude electric fields and currents determined from Greenland magnetometer data, doi
  10. (1998). Large-scale imaging of highlatitude convection with Super Dual Auroral Radar Network HF radar observations, doi
  11. (1996). Neutral line model of substorms: Past results and present view,
  12. (1997). Observations of the response time of high-latitude ionospheric convection to variations in the interplanetary magnetic field using EISCAT and IMP-8 data, doi
  13. Observed magnetic substorm signatures at synchronous altitude, doi
  14. (1968). Satellite studies of magnetospheric substorms on doi
  15. (1998). Solar Wind Electron Proton Alpha Monitor (SWEPAM) for the Advanced Composition Explorer, Space Sci. doi
  16. (1998). Statistical analysis of the plasmoid evolution with Geotail observations, doi
  17. (1998). Structure and dynamics of magnetic reconnection for substorm onsets with Geotail observations, doi
  18. (1984). Structure of the magnetotail at 220 RE and its response to geomagnetic activity, doi
  19. (1998). Temporal relationship between midtail traveling compression regions and substorm onset: Evidence for near-Earth neutral line formation in the late growth phase, doi
  20. (1998). The ACE Magnetic Fields Experiment, Space Sci. doi
  21. (1998). The Advanced Composition Explorer, Space Sci. doi
  22. (1997). The Cluster Ion Spectrometry (CIS) Experiment, Space Sci. doi
  23. (1997). The Cluster magnetic fields investigation Space Sci. doi
  24. (1997). The Imaging Energetic Particle Spectrometer on Cluster, Space Sci. doi
  25. (1983). The origins of Birkeland currents, doi

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