Global features of Pi 2 pulsations obtained by independent component analysis

Terumasa Tokunaga, Hiroko Kohta, Akimasa Yoshikawa, Teiji Uozumi, Kiyohumi Yumoto

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12 Citations (Scopus)


Ground Pi 2 pulsations are mixtures of several components reflecting (1) propagations of fast and shear Alfvén wave, (2) resonances of plasmaspheric/magnetospheric cavity and magnetic field lines, and (3) tansformations to ionospheric current systems. However, it has been unclear how they coupled with each other and how their signals are distributed at different latitudes. The present work is intended to pilot the future possibilities whether we can identify the global system of Pi 2 pulsations by Independent Component Analysis (ICA). We have successfully decomposed an isolated Pi 2 event on a quiet day observed at the CPMN stations into two components. One was the global oscillation that occurs from nightside high to equatorial latitudes with the common waveform and has an amplitude maximum at nightside high latitude. Another component was localized at nightside high latitudes. Its amplitudes were quite weak at low latitudes, but were enhanced near dayside dip equator.

Original languageEnglish
Article numberL14106
JournalGeophysical Research Letters
Issue number14
Publication statusPublished - Jul 28 2007

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences


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