Characteristics of Pc 3 magnetic pulsations in conjugate area around L=1.3-2.1

In order to establish both our theoretical and experimental researches on low-latitude Pc 3 magnetic pulsations, we carried out the Japan-Australia magnetic conjugate observations at Asahikawa (ASH; λ=142.2°, φ=43.93°, L=1.55), Onagawa (ONW; 141.48°, 38.43°, 1.30) in Japan and Birdsville (BSV; 139.3°, -25.83°, 1.55), i. e., the conjugate point of ASH, Dalby (DAL; 151.2°, -27.18°, 1.56) and St. Kilda (SKD; 138.5°, -34.7°, 2.11) in Australia during the period from 20 July to 16 September 1986. From the analysis of these conjugate-station data, occurrence and polarization characteristics of low-latitude Pc 3 pulsations are found as follows; (1) The average amplitudes at SKD (L=2.1) is about 2.5 times of that at BSV (1.55). (2) The H-component amplitude at BSV in the winter hemisphere is larger than that at ASH in the summer hemisphere. (3) The polarizations at all northern (soushern) stations switch statistically from left- (right-) handed in the morning to right- (left-) handed in the afternoon. Where polarization senses are given by a view looking down onto the earth in each hemisphere. (4) However, the switch from L-H (R-H) to R-H (L-H) polarization at the conjugate northern (southern) stations (L=1.55) is found not to be always occurring near local noon, and sometimes occur at ～5 and ～17h local time. (5) The abrupt changes of major axis orientations of Pc 3 polarization ellipses appear to coincide with the E-layer ionization enhancement and depression, associated with local sunrise and sunset, respectively