Signatures of mode conversion and kinetic Alfvén waves at the magnetopause

Jay R. Johnson, C. Z. Cheng, P. Song

Research output: Contribution to journalArticlepeer-review

66 Citations (Scopus)


It has been suggested that resonant mode conversion of compressional MHD waves into kinetic Alfvén waves at the magnetopause can explain the abrupt transition in wave polarization from compressional to transverse commonly observed during magnetopause crossings [Johnson and Cheng, 1997b]. We analyze magnetic field data for magnetopause crossings as a function of magnetic shear angle (defined as the angle between the magnetic fields in the magnetosheath and magnetosphere) and compare with the theory of resonant mode conversion. The data suggest that amplification in the transverse magnetic field component at the magnetopause is not significant up to a threshold magnetic shear angle. Above the threshold angle significant amplification results but with weak dependence on magnetic shear angle. Waves with higher frequency are less amplified and have a higher threshold angle. These observations are qualitatively consistent with theoretical results obtained from the kinetic-fluid wave equations.

Original languageEnglish
Pages (from-to)227-230
Number of pages4
JournalGeophysical Research Letters
Issue number2
Publication statusPublished - 2001 Jan 15

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)


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