Location of Repository

Excitation of twin-vortex flow in the nightside high-latitude ionosphere during an isolated substorm

By A. Grocott, S.W.H. Cowley, J.B. Sigwarth, J.F. Watermann and T.K. Yeoman


We present SuperDARN radar observations of the ionospheric flow during a well-observed high-latitude substorm which occurred during steady northward IMF conditions on 2 December 1999. These data clearly demonstrate the excitation of large-scale flow associated with the substorm expansion phase, with enhanced equatorward flows being observed in the pre-midnight local time sector of the expansion phase auroral bulge and westward electrojet, and enhanced return sunward flows being present at local times on either side, extending into the dayside sector. The flow pattern excited was thus of twin-vortex form, with foci located at either end of the substorm auroral bulge, as imaged by the Polar VIS UV imager. Estimated total transpolar voltages were ~40 kV prior to expansion phase onset, grew to ~80 kV over a ~15 min interval during the expansion phase, and then decayed to ~35 kV over ~10 min during recovery. The excitation of the large-scale flow pattern resulted in the development of magnetic disturbances which extended well outside of the region directly disturbed by the substorm, depending upon the change in the flow and the local ionospheric conductivity. It is estimated that the nightside reconnection rate averaged over the 24-min interval of the substorm was ~65– 75 kV, compared with continuing dayside reconnection rates of ~30–45 kV. The net closure of open flux during the sub-storm was thus ~0.4–0.6 × 108 Wb, representing ~15–20% of the open flux present at onset, and corresponding to an overall contraction of the open-closed field line boundary by ~1° latitude

Year: 2002
DOI identifier: 10.5194/angeo-20-1577-2002
OAI identifier: oai:eprints.lancs.ac.uk:35421
Provided by: Lancaster E-Prints

Suggested articles



  1. (1992). A class of high-m pulsations and its auroral radar signature, doi
  2. (1999). A flux transfer event observed at the magnetopause by the Equator-S spacecraft and in the ionosphere by the CUTLASS HF radar, doi
  3. (1992). A multipoint study of a substorm occurring on 7 doi
  4. (1989). A new magnetic coordinate system for conjugate studies at high latitudes, doi
  5. (1998). A statistical study of the ionsopheric convection response to changing interplanetary magnetic field conditions using the assimilative mapping of ionospheric electrodynamics technique, doi
  6. (2000). A survey of magnetopause FTEs and associated flow bursts in the polar ionosphere, doi
  7. (1600). A. Grocott et al.: Excitation of ionospheric flow during substorms doi
  8. (1989). A.: A magnetospheric magnetic field model with a warped tail current sheet, doi
  9. (1991). A.: Numerical tracing of energetic particle drifts in a model magnetosphere, doi
  10. (1998). Are northsouth aligned auroral structures an ionospheric manifestation of bursty bulk flows?, doi
  11. (1999). Association between Geotail plasma flows and auroral poleward boundary intensifications observed by CANOPUS photometers, doi
  12. (1992). Bursty bulk flows in the central plasma sheet, doi
  13. (1990). Characteristics of high-speed flows in the plasma sheet, doi
  14. (2000). Combined CUTLASS, EISCAT and ESR observations of ionospheric plasma flows at the onset of an isolated substorm, doi
  15. (2000). Comparison of ionospheric electric currents and plasma convection patterns observed during substorms,
  16. (2000). Convection and auroral response to a southward turning of the IMF: Polar UVI, CUTLASS, and IMAGE signatures of transient magnetic flux transfer at the magnetopause, doi
  17. (1996). Current disruption in the Earth’s magnetosphere: Observations and models, doi
  18. (1998). CUTLASS Finland radar observations of the ionospheric signatures of flux transfer events and the resulting plasma flows, doi
  19. (1997). CUTLASS/IMAGE observations of high-latitude convection features during substorms, doi
  20. (1999). Development of auroral streamers in association with localized impulsive injections to the inner magnetotail, doi
  21. (1978). Development of the auroral electrojets on
  22. (2001). Dynamics of the substorm expansion phase, doi
  23. (2000). Electrostatic potential patterns in the high-latitude ionosphere constrained by SuperDARN measurements, doi
  24. (2000). Electrostatic potential patternsinthehigh-latitudeionosphereconstrainedby SuperDARN measurements, doi
  25. (1995). Events of enhanced convection and related dayside auroral activity, doi
  26. (1992). Excitation and decay of flows in the magnetosphere-ionosphere system due to magnetic reconnection at the dayside magnetopause and in the geomagnetic tail,
  27. (1992). Excitation and decay of flows in the magnetosphere-ionosphere system due to magnetic reconnection atthedaysidemagnetopauseandinthegeomagnetictail, in‘Substorms 1’,
  28. (1992). Excitation and decay of solar wind-driven flows in the magnetosphere-ionosphere system, doi
  29. (1997). Excitation of flow in the Earth’s magnetosphereionosphere system: observations by incoherent-scatter radar, in ‘Polar Cap Boundary Phenomena’ edited by doi
  30. (2000). Findings concerning the positions ofsubstormonsetswithauroralimagesfromthePolarspacecraft, doi
  31. (2001). First simultaneous observations of flux transfer events at the high-latitude magnetopause by the Cluster spacecraft and pulsed radar signatures in the conjugate ionosphere by the CUTLASS and EISCAT radars, doi
  32. (1990). Flux transfer events at the magnetopause and in the ionosphere, doi
  33. (1999). Geotail observations of flow velocity and north-south magnetic field variations in the near and middistant tail associated with substorm onsets, doi
  34. (1998). Grocott et al.: Excitation of ionospheric flow during substorms 1601 Two spacecraft observations of a reconnection pulse during an auroral breakup, doi
  35. (1997). H.: CUTLASS/IMAGE observations of high-latitude convection features during substorms, doi
  36. (1988). H.: Response time of the high-latitude dayside ionosphere to sudden changes in the north-south component of the IMF, doi
  37. (1988). H.: The dependence of high-latitude dayside ionospheric flows on the north-south component of the IMF: a high-time resolution correlation analysis using doi
  38. (1995). High temporal and spatial observations of the ionospheric cusp, doi
  39. (1989). HighZ energetic particles at geostationary orbit during the great solar proton event series of doi
  40. (1993). Interplanetary field control of dayside auroral activity and the transfer of momentum across the dayside magnetopause, doi
  41. (1985). Interplanetary magnetic field control of high-latitude electric fields and currents determined from Greenland magnetometer data, doi
  42. (1988). Ionospheric conductivities, electric fields and currents associated with auroral substorms measured by the EISCAT radar, doi
  43. (1998). Large-scale imaging of highlatitude convection with Super Dual Auroral Radar Network HF radar observations, doi
  44. (1998). Localised activation of the distant tail neutral line just prior to substorm onsets, doi
  45. (1998). Magnetic reconnection in the near-earth magnetotail, in ‘New Perspectives on the Earth’s Magnetotail’ edited by doi
  46. (1996). Measurements of the magnetotail reconnection rate, doi
  47. (1996). Monitoring space weather with GOES Magnetometers, doi
  48. (2000). Multiple spacecraft observation of a narrow transient plasma jet in the Earth’s plasma sheet, doi
  49. (1996). Neutral line model of substorms: Past results and present view, doi
  50. (1990). Non-substorm transient injection events in the ionosphere and magnetosphere, doi
  51. (1991). Numerical tracing of energetic particle drifts in a model magnetosphere, doi
  52. (1993). Observations of an enhanced convection channel in the cusp ionosphere, doi
  53. (1999). Observations of the response time of high latitude ionospheric convection to variations in the interplanetary magnetic field using EISCAT and IMP-8 data, doi
  54. (2001). Observations of two complete substorm cycles during the Cassini Earth swing-by: Cassini magnetometer data in a global context, doi
  55. (1996). Occurrence frequency of substorm field and plasma signatures observed near-Earth by ISEE-1/2, in
  56. (1996). Plasma flow in the coupled magnetosphere- ionosphere system and its relationship to the substorm cycle, doi
  57. (1985). Polar cap inflation and deflation, doi
  58. (2001). Polar Ultraviolet Imager observations of global auroral power as a function of polar cap size and magnetotail stretching, doi
  59. (1994). Quiet-time intensifications along the poleward boundary near midnight, doi
  60. (1995). Radar observations of auroral zone flows during a multiple-onset substorm, doi
  61. (1988). Response time of the high-latitude dayside ionosphere to sudden changes in the north-south component of the IMF, doi
  62. (1998). Simultaneous ionospheric and magnetospheric observations of azimuthally propagating transient features during substorms, doi
  63. (2001). Solar wind effects on ionospheric convection: A review, doi
  64. (1998). Solar Wind Electron Proton Alpha Monitor (SWEPAM) for the Advanced Composition Explorer, Space Sci. doi
  65. (1991). Sondrestrom radar measurements of the reconnection electric field, doi
  66. (1996). Statistical patterns of high-latitude convection obtained from Goose Bay HF radar observations, doi
  67. (1998). Structure and dynamics of magnetic reconnection for substorm onsets with Geotail observations, doi
  68. (1996). Substorm correlated absorption on a 3200 km trans-auroral HF propagation path, doi
  69. (1996). Substorm correlated absorption on a 3200km trans-auroral HF propagation path, doi
  70. (1999). Substorm influence on the ionospheric electric potentials and currents, doi
  71. (1999). The ACE Magnetic Field Experiment, Space Sci. doi
  72. (1998). The Advanced Composition Explorer, Space Sci. doi
  73. (1993). The response of the high-latitude dayside ionosphere to a sudden southward IMF turning,
  74. (1995). The Visible Imaging System (VIS) for the Polar spacecraft, doi
  75. (1979). Transient phenomena in the magnetotail and their relation to substorms, doi
  76. (1998). Westward moving dynamic substorm features observed with the IMAGE magnetometer network and other ground-based instruments, doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.