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Towards a synthesis of substorm electrodynamics: HF radar and auroral observations

By Adrian Grocott, Mark Lester, M. L. Parkinson, Tim K. Yeoman, P. L. Dyson, J. C. Devlin and H. U. Frey


At 08:35 UT on 21 November 2004, the onset of an interval of substorm activity was captured in the southern hemisphere by the Far UltraViolet (FUV) instrument on board the IMAGE spacecraft. This was accompanied by the onset of Pi2 activity and subsequent magnetic bays, evident in ground magnetic data from both hemispheres. Further intensifications were then observed in both the auroral and ground magnetic data over the following ~3 h. During this interval the fields-of-view of the two southern hemisphere Tasman International Geospace Enviroment Radars (TIGER) moved through the evening sector towards midnight. Whilst initially low, the amount of backscatter from TIGER increased considerably during the early stages of the expansion phase such that by ~09:20 UT an enhanced dusk flow cell was clearly evident. During the expansion phase the equatorward portion of this flow cell developed into a narrow high-speed flow channel, indicative of the auroral and sub-auroral flows identified in previous studies (e.g. Freeman et al., 1992; Parkinson et al., 2003). At the same time, higher latitude transient flow features were observed and as the interval progressed the flow reversal region and Harang discontinuity became very well defined. Overall, this study has enabled the spatial and temporal development of many different elements of the substorm process to be resolved and placed within a simple conceptual framework of magnetospheric convection. Specifically, the detailed observations of ionospheric flows have illustrated the complex interplay between substorm electric fields and associated auroral dynamics. They have helped define the distinct nature of different substorm current systems such as the traditional substorm current wedge and the more equatorward currents associated with polarisation electric fields. Additionally, they have revealed a radar signature of nightside reconnection which provides the promise of quantifying nightside reconnection in a way which has already proved extremely successful in studies of the dayside magnetosphere

Publisher: Copernicus Publications on behalf of the European Geosciences Union (EGU)
Year: 2006
DOI identifier: 10.5194/angeo-24-3365-2006
OAI identifier: oai:lra.le.ac.uk:2381/7876

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  1. (2006). 3380 A. Grocott et al.: Towards a synthesis of substorm electrodynamics doi
  2. (2001). A case study of HF radar spectra and 630.0 nm auroral emission in the premidnight sector, doi
  3. (1958). A fresh perspective of the substorm current system and its dynamo, doi
  4. (1964). A model of the auroral electrojets, doi
  5. (1992). A multipoint study of a substorm occurring on 7 doi
  6. (2002). A new categorization for subauroral electric fields, doi
  7. (1989). A new magnetic coordinate system for conjugate studies at high latitudes, doi
  8. (1993). A proposed production model of rapid subauroral ion drifts and their relationship to substorm evolution, doi
  9. (1969). A study of polar magnetic substorms, 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. (2002). Average characteristics and activity dependence of the subauroral polarisation stream, doi
  13. (1992). Bursty bulk flows in the central plasma sheet, doi
  14. (1990). Characteristics of high-speed flows in the plasma sheet, doi
  15. (2000). Combined CUTLASS, EISCAT and ESR observations of ionospheric plasma flows at the onset of an isolated substorm, doi
  16. (2000). Comparison of ionospheric electric currents and plasma convection patterns observed during substorms, in:
  17. (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
  18. (1997). CUTLASS/IMAGE observations of high-latitude convection features during substorms, doi
  19. (1995). DARN/SuperDARN: A global view of the dynamics of high-latitude convection, doi
  20. (2006). Dayside and nightside reconnection rates inferred from IMAGE-FUV and SuperDARN data, doi
  21. (1978). Development of the auroral electrojets on
  22. (1995). Direct determination of large-scale magnetospheric field-aligned currents with SuperDARN, doi
  23. (1973). Direct measurements of ion drift velocity in the upper ionosphere during a magnetic storm, 2. Results of measurements during the November 3, 1967, magnetic storm, Cosmic Res.
  24. (1992). Excitation and decay of solar wind-driven flows in the magnetosphere-ionosphere system, doi
  25. (1998). Excitation of flow in the Earth’s magnetosphereionosphere system: observations by incoherent-scatter radar, in: Polar Cap Boundary Phenomena, edited by: doi
  26. Far ultraviolet imaging from the IMAGE spacecraft, 1. System design, doi
  27. Far ultraviolet imaging from the IMAGE spacecraft, 2. Wideband FUV imaging , doi
  28. (2006). First observations of the temporal/spatial variation of the sub-auroral polarization stream from the SuperDARN Wallops HF radar, doi
  29. (1994). Ground-based studies of ionospheric convection associated with substorm expansion, doi
  30. (1970). Growth phase of magnetospheric substorms, doi
  31. (2000). HF coherent scatter radar observations of ionospheric convection during magnetospheric substorms, Adv. Polar Upper Atmos.
  32. (1977). I.: Physics of magnetospheric substorms, doi
  33. (2005). Interhemispheric observations of the ionospheric signature of tail reconnection during IMF-northward non-substorm intervals, doi
  34. (1988). Ionospheric conductivities, electric fields and currents associated with auroral substorms measured by the EISCAT radar, doi
  35. (2003). J.-P.: Substorm associated changes in the highlatitude ionospheric convection, doi
  36. (1998). Large-scale imaging of highlatitude convection with Super Dual Auroral Radar Network HF radar observations, doi
  37. (1998). Localised activation of the distant tail neutral line just prior to substorm onsets, doi
  38. (2005). Localized fast flow disturbance observed in the plasma sheet and in the ionosphere, doi
  39. (1988). Measurement of field-aligned currents by the SABRE coherent scatter radar, in: doi
  40. (1996). Measurements of the magnetotail reconnection rate, doi
  41. (2005). Mesoscale ionospheric electrodynamics of omega bands determined from ground-based electromagnetic and satellite optical observations, doi
  42. (2004). Multi-instrument observations of the ionospheric counterpart to a bursty bulk flow in the nearEarth plasma sheet, doi
  43. (2001). Observations of two complete substorm cycles during the Cassini Earth swing-by: Cassini magnetometer data in a global context, doi
  44. (2003). On the lifetime and extent of an auroral westward flow channel observed during a magnetospheric substorm, doi
  45. (1016). On the occurrence of auroral westward flow channels and substorm phase, Adv. Space Res., doi
  46. (1991). Physical processes producing magnetospheric substorms and magnetic storms, in: doi
  47. (1968). Polar and magnetospheric substorms, doi
  48. (1985). Polar cap inflation and deflation, doi
  49. (2006). Postmidnight convection dynamics during substorm expansion phase, doi
  50. (1994). Quiet-time intensifications along the poleward boundary near midnight, doi
  51. (1995). Radar observations of auroral zone flows during a multiple-onset substorm, doi
  52. (1995). Radar observations of magnetosphere-ionosphere coupling at mid and high latitudes, doi
  53. (2001). Rapid flux transport and plasma sheet reconfiguration, doi
  54. (1972). Rapid flux transport in the central plasma sheet,
  55. (1968). Satellite studies of magnetospheric substorms on doi
  56. (1998). Simultaneous ionospheric and magnetospheric observations of azimuthally propagating transient features during substorms, doi
  57. (1998). Solar Wind Electron Proton Alpha Monitor (SWEPAM) for the Advanced Composition Explorer, Space Sci. doi
  58. (1996). Statistical patterns of high-latitude convection obtained from Goose Bay HF radar observations, doi
  59. (2004). Statistical study of high-latitude plasma flow during magnetospheric substorms, doi
  60. (1998). Substorm associated radar auroral surges: a statistical study and possible generation model, doi
  61. (2001). Substorm convection patterns observed by the Super Dual Auroral Radar Network, doi
  62. (1999). Substorm influence on the ionospheric electric potentials and currents, doi
  63. (1992). Substorm-associated radar auroral surges, doi
  64. (1984). Substorms in the magnetosphere, in Solar Terrestrial Physics: Present and Future, NASA reference publication 1120,
  65. (1998). The Advanced Composition Explorer, Space Sci. doi
  66. (2001). The dayside ultraviolet aurora and convection responses to a southward turning of the interplanetary magnetic field, doi
  67. (1963). The dynamical morphology of the auroral polaris, doi
  68. (1965). The polar electrojet, doi
  69. (2000). The Tasman International Geospace Envirenoment Radar,
  70. (1979). Transient phenomena in the magnetotail and their relation to substorms, doi
  71. (1996). What is a global auroral substorm?, doi
  72. (2006). www.ann-geophys.net/24/3365/2006/ A. Grocott et al.: Towards a synthesis of substorm electrodynamics 3381 doi

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