Investigation of energetic particle environments in the plasmasphere

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This research project aims to investigate variations of energetic particle environments and atmospheric conditions in the upper atmosphere, associated with solar activities.1) L F whistler-mode signals were measured in the conjugate area of the transmitter around Birdsville (L=1.55), Australia. The intensity increase of the LF signals appeared with the time delays behind enhanced AE activities, due to the wave growth caused by cyclotron resonance interactions with trapped electrons more than 30 ke V.The frequency of enhanced LF whistler-mode signals shifted, which is caused by the drift of whistler ducts due to the magnetospheric electric fields penetrating into the low-latitude magnetosphere. Otherwise, VLF/ELF emissions generated in the plasmapause-latitude magnetosphere and observed at low- latitude ground- based stations occurred almost simultaneously with enhanced AB activities. So, the penetration of energetic electrons deep into the magnetosphere may be deduced from ground-based … More measurements of resonant waves at low latitudes.2) The altitude, temperature, and pressure of the tropopause and the total ozone content over Syowa Station, Antarctica were investigated in association with the solar flare activities. The temporal variations of the above quantities were found to be correlated with the energetic protons and enhanced X ray intensities associated with the bigger solar flares.3) Geomagnetic pulsations of Pi2 (period : 40-150 sec) usually occur during nighttime in association with magnetic storms. By using the Pi2 geomagnetic data based on the 210 MM magnetic observations, the relation between seismic activities and geromagnetic pulsation activities was investigates. The geomagnetic fields during a large earthquake (Ms=7.1) at Guam on 8 August 1993 were enhanced in the induced Z components, due to the electrical conductivity increase around the earthquake source region.Also, step-like changes appear occasionally mainly on the Z fields at Guam, which may be caused by electric fields, related to the precursor activity. Less