Journal of geomagnetism and geoelectricity

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The obtained sheath capacity data of the spherical impedance probe with a radius of 6cm, installed on the TAIYO satellite, indicate periodic oscillations corresponding to wavy patterns, for the electron density distribution in the region of the ionosphere. The wave patterns can be identified with the substorm type geomagnetic disturbance within a possible delay time of 2 hours 30min to 6 hours from the onset time of the substorms. There were spread F echoes indicated in ISIS-2 data in the region of the South Atlantic anomaly coinciding with the time of the occurrence of the wavy pattern of the electron density profile detected by TAIYO in which the solar X-ray detector is also installed; the detector of the solar X-ray can be operated for the monitor of the energetic particle precipitation during night time conditions when no solar X-ray is injected to the detector. The occurrence of the spread F echoes is associated with the enhancement of energetic particle precipitations. The most likely process that can provide a consistent interpretation of these observed evidences is the TID effect that is triggered as additional effects of the enhanced particle precipitation of the high energetic particles from the radiation belt caused by the arrival of the TID in the region of the F-2 layer. The possible TID is inferred to be caused by the auroral break up in a form of the acoustic gravity wave which propagates through the F layer with group velocity ranging from 250m/sec to 760m/sec, period of about 10³sec and the wavelength of about 500km.

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Intensity and directions of natural remanent magnetization and their stability against alternating field demagnetization as well as thermomagnetic behavior, opaque mineralogy and chemical composition of constituent ferromagnetic minerals have been extensively investigated with pillow and dyke basalts, dolerites, gabbros and ultramafic rocks composing the Hayama-Mineoka and Setogawa ophiolite complexes.
It has been demonstrated by the present work that degree of alteration of most basalts in these ophiolite complexes is low and comparable to that of the oceanic basalts. Titanomagnetite is subjected to low-temperature oxidation mostly owing to bleaching of ferrous ions but directions of the original TRM appear to be unaffected by the oxidation, although its intensity may be reduced and additional CRM may be acquired. Hydrothermal alteration recognized in a restricted area substantially reduces intensity of NRM and causes scatter in directions. Ultramafic rocks have stable and relatively large NRM, which is carried by fine magnetite particles precipitated along margins of olivine crystals.

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