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Monitoring cusp/cleft topology using Pc5 ULF waves
Author(s) -
Ables S. T.,
Fraser B. J.,
Waters C. L.,
Neudegg D. A.,
Morris R. J.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/98gl00848
Subject(s) - magnetosphere , field line , physics , ionosphere , earth's magnetic field , geophysics , noon , magnetometer , context (archaeology) , geodesy , azimuth , magnetic field , geology , topology (electrical circuits) , atmospheric sciences , optics , paleontology , mathematics , quantum mechanics , combinatorics
Induction magnetometer data recorded at three closely spaced sites (∼120 Km) in Antarctica (mlat ∼ −75°) have been examined for ionospheric signatures of the cusp/cleft region of the magnetosphere. Crossphase analysis of the 1–10 mHz band, using pure‐state filtering techniques reveal diurnally varying field line resonances embedded in the spectra, while interstation phase lag measurements indicate azimuthal propagation of waves away from local magnetic noon. Using the T89 external field model crossphase measurements are put in the context of diurnally changing field line topology due to compression at the subsolar region and stretching along the dawn and dusk flanks. On six of the eight days of this study we have identify a consistent two dimensional phase pattern projected in the dayside ionosphere, indicating closed field lines thread these sites during periods of low to moderate geomagnetic activity (Kp<3).