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Polar, Cluster and SuperDARN evidence for high-latitude merging during southward IMF: temporal/spatial evolution

By N. C. Maynard, D. M. Ober, W. J. Burke, J. D. Scudder, M. Lester, M. W. Dunlop, J. A. Wild, Adrian Grocott, C. J. Farrugia, E. J. Lund, C. T. Russell, D. R. Weimer, K. D. Siebert, A. Balogh, M. André and H. Rème


This paper was published as Annales Geophysicae, 2003, 21 (12), pp. 2233-2258. It is also available from http://www.ann-geophys.net/21/2233/2003/angeo-21-2233-2003.htmlMagnetic merging on the dayside magnetopause often occurs at high latitudes. Polar measured fluxes of accelerated ions and wave Poynting vectors while skimming the subsolar magnetopause. The measurements indicate that their source was located to the north of the spacecraft, well removed from expected component merging sites. This represents the first use of wave Poynting flux as a merging discriminator at the magnetopause. We argue that wave Poynting vectors, like accelerated particle fluxes and the Walén tests, are necessary, but not sufficient, conditions for identifying merging events. The Polar data are complemented with nearly simultaneous measurements from Cluster in the northern cusp, with correlated observations from the Super-DARN radar, to show that the locations and rates of merging vary. Magnetohydrodynamic (MHD) simulations are used to place the measurements into a global context. The MHD simulations confirm the existence of a high-latitude merging site and suggest that Polar and SuperDARN observed effects are attributable to both exhaust regions of a temporally varying X-line. A survey of 13 merging events places the location at high latitudes whenever the interplanetary magnetic field (IMF) clock angle is less than ~150°. While inferred high-latitude merging sites favor the antiparallel merging hypothesis, our data alone cannot exclude the possible existence of a guide field. Merging can even move away from equatorial latitudes when the IMF has a strong southward component. MHD simulations suggest that this happens when the dipole ilt angle increases or when IMF BX increases the effective dipole tilt

Publisher: European Geosciences Union (EGU)
Year: 2003
DOI identifier: 10.5194/angeo-21-2233-2003
OAI identifier: oai:lra.le.ac.uk:2381/7905

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  1. (1974). A quantitative model for the potential resulting from reconnection with arbitrary interplanetary magnetic field, doi
  2. (2001). A reconnection layer associated with a magnetic cloud, doi
  3. (1979). A unified kinetic model of tangential magnetopause structure, doi
  4. Aerodynamic aspects of magnetospheric flow, doi
  5. (2002). Ambipolar electric fields parallel and perpendicular to the local magnetic field: Magnetopause and depletion layers, SM21C-04, Fall meeting of the AGU,
  6. (1974). An ionospheric convection signature of antiparallel reconnection, doi
  7. (1983). Cluster and SuperDARN evidence for high-latitude merging during southward IMF: temporal/spatial evolution doi
  8. (1989). Dayside merging and cusp geometry, doi
  9. (1976). Depletion of solar wind plasma near a planetary boundary, doi
  10. (1996). Dynamics of the inner magnetosphere near times of substorm onsets, doi
  11. (2002). Evidence for component merging near the subsolar magnetopause: Geotail observations, doi
  12. (1981). Evidence for magnetic reconnection at the earth’s magnetopause, doi
  13. (2002). Evidence of Diffusion Regions at a Subsolar Magnetopause Crossing, doi
  14. (1992). Excitation and decay of solar wind driven flows in the magnetosphere-ionosphere system, doi
  15. (2000). Extended magnetic reconnection at the Earth’s magnetopause from detection of bi-directional jets, doi
  16. Fingerprints of collisionless reconnection at the separator: I, Ambipolar-Hall signatures, doi
  17. (2001). Fluid and particle signatures of dayside reconnection, doi
  18. (1984). Fluid signatures of rotational discontinuities, doi
  19. (2002). Four-point Cluster application of magnetic field analysis tools: The curlometer, doi
  20. (1999). Generalized Wale´n tests through Alfve´n waves and rotational discontinuities using electron velocities, doi
  21. Hill model of transpolar potential saturation: doi
  22. (1997). How wide in magnetic local time N. C. Maynard et al.: High-latitude merging 2257 is the cusp?: An event study, doi
  23. (1995). Hydra: A three dimensional electron and ion instrument for the polar spacecraft of the GGS mission, doi
  24. (1961). Interplanetary magnetic field and the auroral zones, doi
  25. (1991). Ion reflection and transmission during reconnection at the Earth’s subsolar magnetopause, doi
  26. (1998). Large-scale imaging of highlatitude convection with Super Dual Aurora Radar network HF radar observations, doi
  27. (1950). Magnetohydrodynamic shocks,
  28. (1974). Magnetopause rotational forms, doi
  29. (1996). Magnetosphere-ionosphere coupling during substorm onset, doi
  30. (1992). Mechanism by which merging at X-lines causes discrete auroral arcs, doi
  31. MHD properties of magnetosheath flow, doi
  32. (2001). MHD simulation of magnetospheric transport at the mesoscale, in: Space Weather, doi
  33. Observation of the magnetospheric ”sash” and its implications relative to solar-wind/magnetospheric coupling: A multisatellite event analysis, doi
  34. (1984). Observations of plasma decelleration at a rotational magnetopause discontinuity, doi
  35. Observations of simultaneous effects of merging in both hemispheres, doi
  36. (2003). Observed and simulated depletion layers with southward IMF, submitted to Annales Geophysicae, doi
  37. (1979). Plasma acceleration at the earth’s magnetopause: Evidence for reconnection, doi
  38. (1997). Reconnection event at the dayside magnetopause on doi
  39. Responses of the open-closed field line boundary in the evening sector to IMF changes: A source mechanism for Sun-aligned arcs,
  40. (1992). Reverse convection, doi
  41. (1992). Slow mode transition in the frontside magnetosheath, doi
  42. (1983). Solar system magnetohydrodynamics, in: Solar Terrestrial Physics, edited by doi
  43. (1998). Solar wind electron, proton, and alpha monitor (SWEPAM) on the Advanced Composition Explorer, Space Sci. doi
  44. (2000). Some comments on transient and steady-state reconnection at the dayside magnetopause, doi
  45. (1996). Statistical patterns of high-latitude convection obtained from Goose Bay HF radar observations, doi
  46. (1987). Structure of reconnection boundary layers in incompressible doi
  47. (1995). SuperDARN: A global view of high-latitude convection, doi
  48. (1995). SWE: A comprehensive plasma instrument for the wind spacecraft: Space Sci. doi
  49. The causes of convection in the Earth’s magnetosphere: A review of developments during the IMS, doi
  50. (1997). The Cluster ion spectrometry (CIS) experiment, doi
  51. (2001). The Cluster magnetic field investigation: overview of in-flight performance and initial results, doi
  52. (2002). The dayside reconnection X-line, doi
  53. (1997). The electric field and wave experiment for the Cluster mission, doi
  54. (1995). The electric field instrument on the Polar satellite, doi
  55. (1995). The GGS/polar magnetic field investigation, doi
  56. (1990). The magnetopause for high magnetic shear: Analysis of convection electric fields from AMPTE/IRM, doi
  57. (1986). The magnetopause for large magnetic shear: doi
  58. (1976). The magnetospheric boundary layer: Site of plasma, momentum and energy transfer from the magnetosheath into the magnetosphere, doi
  59. (1987). The partial donor cell method, doi
  60. (1995). The Wind magnetic field Investigation, Space Sci. doi
  61. (2002). Variable time delays in the propagation of the interplanetary magnetic field, doi

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