Location of Repository

Intermediate-m ULF waves generated by substorm injection: a case study

By Tim K. Yeoman, D. Yu. Klimushkin and P.N. Mager

Abstract

A case study of SuperDARN observations of Pc5 Alfvén ULF wave activity generated in the immediate aftermath of a modest-intensity substorm expansion phase onset is presented. Observations from the Hankasalmi radar reveal that the wave had a period of 580 s and was characterized by an intermediate azimuthal wave number (m=13), with an eastwards phase propagation. It had a significant poloidal component and a rapid equatorward phase propagation (~62° per degree of latitude). The total equatorward phase variation over the wave signatures visible in the radar field-of-view exceeded the 180° associated with field line resonances. The wave activity is interpreted as being stimulated by recently-injected energetic particles. Specifically the wave is thought to arise from an eastward drifting cloud of energetic electrons in a similar fashion to recent theoretical suggestions (Mager and Klimushkin, 2008; Zolotukhina et al., 2008; Mager et al., 2009). The azimuthal wave number m is determined by the wave eigenfrequency and the drift velocity of the source particle population. To create such an intermediate-m wave, the injected particles must have rather high energies for a given L-shell, in comparison to previous observations of wave events with equatorward polarization. The wave period is somewhat longer than previous observations of equatorward-propagating events. This may well be a consequence of the wave occurring very shortly after the substorm expansion, on stretched near-midnight field lines characterised by longer eigenfrequencies than those involved in previous observations

Publisher: Copernicus Publications on behalf of the European Geosciences Union (EGU)
Year: 2010
DOI identifier: 10.5194/angeo-28-1499-2010
OAI identifier: oai:lra.le.ac.uk:2381/8368
Journal:

Suggested articles

Preview

Citations

  1. (1979). A compressional Pc4 pulsation observed by three satellites in geostationary orbit near local midnight, doi
  2. (2007). A decade of the Super Dual Auroral Radar Network (SuperDARN): scientific achievements, new techniques and future directions, doi
  3. (1976). A general approach to low-frequency instability in the ring current plasma, doi
  4. (1996). A possible driving source for transient field line oscillations in the postmidnight sector at geosynchronous altitudes, doi
  5. (1999). A statistical study of Pc 3-Pc 5 magnetic pulsations observed by the AMPTE/Ion Release Module satellite, doi
  6. (1992). A study of Pc5 hydromagnetic waves with equatorward phase propagation, doi
  7. (1983). A theory of long period magnetic pulsations. 3. Local field line oscillations, doi
  8. (1990). A.: A statistical study of Pc 3-5 pulsations observed by the AMPTE/CCE magnetic fields experiment. 1. Occurrence distributions, doi
  9. (1976). Adiabatic plasma convection in a dipole field: Proton forbidden-zone effects for a simple electric field model, doi
  10. (2008). Alfvén ship waves: highm ULF pulsations in the magnetosphere generated by a moving plasma inhomogeneity, doi
  11. (1978). Alfvén waves generated by an inverted plasma energy distribution, doi
  12. (1985). Azimuthal propagation and frequency characteristic of compressional Pc5 waves observed at geostationary orbit, doi
  13. (1983). BARS – a dual bistatic auroral radar system for the study of electric fields in the Canadian sector of the auroral zone, doi
  14. (2008). Bistatic observations of large and small scale ULF waves in SPEAR-induced HF coherent backscatter, doi
  15. (1969). Bounce resonant interactions between pulsations and trapped particles, doi
  16. (2006). Cluster satellite observations of mHz pulsations in the dayside magnetosphere, doi
  17. (1999). Concerning the generation of geomagnetic giant pulsations by drift-bounce resonance ring current instabilities, doi
  18. (1995). DARN/SUPERDARN A global view of the dynamics of highlatitude convection, doi
  19. (1970). Dynamics of geomagnetically trapped radiation, doi
  20. (1992). Excitation of Pc 5 pulsations in the morning sector by a local injection of particles in the magnetosphere, doi
  21. Far ultraviolet imaging from the IMAGE spacecraft. 2. Wideband FUV imaging, doi
  22. (1983). First results of micropulsation activity observed by SABRE, doi
  23. HF doppler sounder measurements of the ionospheric signatures of small scale ULF waves, doi
  24. (2000). High-latitude observations of ULF waves with large azimuthal wavenumbers, doi
  25. (1997). Highlatitude HF Doppler observations of ULF waves. 1. Waves with large spatial scale sizes, doi
  26. (1990). Ion flux oscillations associated with a radially polarised transverse Pc5 magnetic pulsation, doi
  27. (1997). Long-period magnetic activity during the May 15, doi
  28. (1980). Low frequency pulsation generation by energetic particles, doi
  29. Magnetospheric field line resonance: a comparative approach, doi
  30. (2001). Modeling the properties of high m Alfvén waves driven by the drift-bounce resonance mechanism, doi
  31. On the coupling between unstable magnetospheric particle populations and resonant high m ULF wave signatures in the ionosphere, doi
  32. (2009). On the equatorward phase propagation of high-m ULF pulsations observed by radars, doi
  33. (2008). Pc5 waves generated by substorm injection: a case study, doi
  34. Relationship between auroral electrojet and Pc5 ULF waves, doi
  35. (2001). S.: A theory of field line resonance in a dipolelike axisymmetric magnetosphere, doi
  36. (1983). SABRE – new radar-auroral backscatter experiment, doi
  37. (2007). Spatial and temporal characteristics of poloidal waves in the terrestrial plasmasphere: a CLUSTER case study, doi
  38. (2005). Spatial localization and azimuthal wave numbers of Alfvén waves generated by driftbounce resonance in the magnetosphere, doi
  39. (2008). Spatio-temporal structure of a poloidal Alfvén wave detected by Cluster adjacent to the dayside plasmapause, doi
  40. (1998). Standing Alfvén waves with m 1 in an axisymmetric magnetosphere excited by a non-stationary source, doi
  41. (1978). STARE: A new radar auroral backscatter experiment in northern Scandinavia, doi
  42. (1985). Statistical characteristics of Pc5 waves at geostationary orbit, doi
  43. (1991). Statistical studies of giant pulsations (Pgs): harmonic mode, doi
  44. (1991). Statistics of Pc5 pulsation events observed by SABRE, doi
  45. (2004). Substorm onset observations by IMAGE-FUV, doi
  46. (2009). Surface waves and field line resonances: A THEMIS case study, doi
  47. System design,
  48. (1994). The IMAGE magnetometer network,
  49. (2000). The propagation of high-m Alfvén waves in the Earth’s magnetosphere and their interaction with high-energy particles, doi
  50. (1992). The spatial extent of radial magnetic pulsation events observed in the dayside near synchronous orbit, doi
  51. (2004). The spatio-temporal structure of impulse-generated azimuthalsmall-scale Alfvén waves interacting with high-energy chargedparticles in the magnetosphere, doi
  52. (2001). ULF waves with drift resonance and drift-bounce resonance energy sources as observed in artificially-induced HF radar backscatter, doi
  53. (2010). Yeoman et al.: Intermediate-m ULF waves generated by substorm injection doi
  54. (2010). Yeoman et al.: Intermediate-m ULF waves generated by substorm injection 1509

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