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Pulsed flows observed during an interval of prolonged northward IMF

By G. P. Provan, M. Lester, Adrian Grocott and S. W. H. Cowley

Abstract

This paper was published as Annales Geophysicae, 2005, 23 (4), pp. 1207-1225. It is also available from http://www.ann-geophys.net/23/1207/2005/angeo-23-1207-2005.htmlOn the 22 December 2002 the interplanetary magnetic field (IMF) was directed northwards for more than 12h. The Northern and Southern Hemisphere SuperDARN radars were used to study global high-latitude convection during this interval, complemented by data from the ACE and DMSP F13 spacecraft. The relative magnitudes of the IMF Bγ and Bz components varied during this period. When the magnitude of the Bγ component was comparable with or dominated the Bz component, signatures of simultaneous low-latitude and lobe reconnection were observed. Specifically two "standard" merging cells were observed in both hemispheres. In the Northern Hemisphere a high-latitude lobe cell was observed within the dusk merging cell, and there was also evidence of a narrow viscous cell located equatorward of this lobe cell. We observed the ionospheric signatures of flux transfer events (FTEs) in both the Northern and Southern Hemispheres, occurring with a periodicity of ~15min. In the Northern Hemisphere the FTEs were associated with a stepwise equatorward progression of the equatorward boundary of radar backscatter on the dayside. When the IMF Bz component was predominantly greater than the IMF Bγ component, we observed a four-cell convection pattern in the Northern Hemisphere, with pulses of reverse reconnection and an associated stepwise poleward retraction of the equatorward boundary of radar backscatter occurring every ~25min. These observations are consistent with pulsed lobe reconnection occurring in both hemispheres, closing open flux and adding closed flux to the dayside magnetopause. So, during this northward IMF interval the location of the sites of reconnection between the IMF and the Earth's magnetosphere, and thus the form of reconnection process, varied with changing IMF conditions. However, the reconnection remained pulsed, with lobe-only reconnection having a significantly longer periodicity compared with simultaneous lobe and low-latitude reconnection

Publisher: Copernicus Publications on behalf of the European Geosciences Union (EGU)
Year: 2005
DOI identifier: 10.5194/angeo-23-1207-2005
OAI identifier: oai:lra.le.ac.uk:2381/7900
Journal:

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Citations

  1. (2000). A statistical survey of dayside pulsed ionospheric flows as seen by the CUTLASS Finland HF radar, doi
  2. (1984). A survey of dayside flux transfer events using doi
  3. (1990). Auroral and plasma flow transients at magnetic noon, doi
  4. (1985). By -dependent dayside plasma flow and Birkeland currents in the dayside magnetosphere, 2, A global model for northward and southward IMF, doi
  5. (1984). By dependent convection patterns during northwards interplanetary magnetic field, doi
  6. (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
  7. (1998). CUTLASS Finland radar observations of the ionospheric signatures of flux transfer events and the resulting plasma flows, doi
  8. (2000). Dynamic cusp aurora and associated pulsed reverse convection during northward interplanetary magnetic field, doi
  9. (1987). Empirical high-latitude electric field models, doi
  10. (1988). et al.: Ionospheric convection response to slow, strong variations in a northward interplanetary magnetic field: A case study for 14 doi
  11. (1992). Excitation and decay of solar wind-driven flows in the magnetosphere-ionosphere, doi
  12. (1994). Four cells or two? Are four convection cells really necessary? doi
  13. (1995). High spatial and temporal resolution observations of the ionospheric cusp, doi
  14. (1985). IMF By -dependent plasma flow and Birkeland currents in the dayside magnetosphere, 1, Dynamic Explorer observations, doi
  15. (1978). Initial ISEE magnetometer results: Magnetopause observations, doi
  16. (1972). Interplanetary magnetic field direction and high-latitude ionospheric currents. doi
  17. (1983). Interpretation of observed relations between solar-wind characteristics and effects at ionospheric altitudes, doi
  18. (1991). Ionospheric convection response to changing IMF direction, doi
  19. (2003). Ionospheric flows during extended intervals of northward but By -dominated IMF, doi
  20. (1979). ISEE observations of flux transfer events at the dayside magnetopause, doi
  21. (1979). J.:Polar cap electric field structures with a northward interplanetary magnetic field, doi
  22. (1998). Large-scale imaging of highlatitude convection with Super Dual Auroral Radar Network HF radar observations, doi
  23. (2002). Lobe cell convection and fieldaligned currents poleward of the region1 current system, doi
  24. (2003). Lobe cell convection and polar-cap precipitation, doi
  25. (1993). Lobe cell convection as a summer phenomenon, doi
  26. (1981). Magnetospheric and ionospheric flow and the interplanetary magnetic field.
  27. (1999). Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study, doi
  28. (1989). Midday auroral breakup, doi
  29. (1991). Observations of reconnection of interplanetary and lobe magnetic field lines at the high-latitude magnetopause, doi
  30. (1984). Precipitating electron and ion detectors (SSJ/4) for the block 5-D/flights 6–10 DMSP satellites: Calibration and data presentation, Rep. AFGL-TR-84-0317, Air Force Geophys. Lab, Hanscom Air Force Base,
  31. (2003). Proton aurora in the cusp during southward IMF, doi
  32. (1996). Pulsed flows observed during an interval of prolonged northward IMF 1225 doi
  33. (1999). Reconfiguration and closure of lobe flux by reconnection during northward IMF: possible evidence for signatures in cusp/cleft auroral emissions, doi
  34. (1988). Response of the ionospheric convection pattern to a rotation of the interplanetary magnetic field on 14 doi
  35. (1992). Reverse convection, doi
  36. (1990). Signatures of flux transfer events at the dayside magnetopause and in the ionosphere: Combined ISEE, EISCAT and optical observations, doi
  37. (1995). Simultneous optical and HF radar observations of the ionospheric cusp, doi
  38. (2000). Some comments on transient and steady-state reconnection at the dayside magnetopause, doi
  39. (1996). Statistical patterns of high-latitude convection obtained from Goose Bay HF radar observations, doi
  40. (1995). Super dual auroral radar network radar imaging of dayside high-latitude convection under northward interplanetary magnetic field: Toward resolving a distorted twocell versus multicell controversy, doi
  41. (2002). Synoptic maps of polar caps for stable interplanetary magnetic field intervals during doi
  42. (1999). The ACE magnetic field experiment, doi
  43. (1972). The configuration of the magnetosphere, in Critical Problems of Magnetospheric Physics, edited by:
  44. (1998). The dayside auroral zone as a hard target for coherent HF radars, doi
  45. (1978). The frontside boundary layer of the magnetopause and the problem of reconnection, doi
  46. (1997). The ionospheric response to flux transfer events: the first few minutes, doi
  47. (1987). The response of the large-scale ionospheric convection pattern to changes
  48. (1963). The structure of the exosphere, or adventures in velocity space, in Geophysics: The Earth’s Environment, edited by:
  49. (2000). Wind observations of mixed magnetosheath-plasma like ions deep inside the magnetosphere, doi

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