부산대학교 도서관

Equatorial Pc pulsations, having periods from 30 to 100sec and amplitude up to several nT, were studied by making use of the fluxgate magnetometer data obtained at Huancayo (0.8°N, 335.6°E in geomagnetic coordinates), Peru during the period from December 5, 1985 to January 5, 1986. Diurnal change of polarization parameters (orientation angle of the major axis and ellipticity) in the H-D plane were investigated. The following results were obtained.1) Pulsations are linearly polarized. The ellipticities lie between +0.3 and -0.3.2) orientation angle of the principal axis of variation vectors shows a diurnal variation. It deviates westward from the north for the local time 6-7h. The deviation angle of the major axis from the north occasionally amounts to 60 degrees. A small eastward deviation is also seen in the local time 15-17h. Around 17h a westward turning tendency is noted. During the other time of day, it remains in the north-south direction.It is suggested that the changes in the D component which bring about the deviation of the orientation angle from the north could locally be produced through an east-west non-uniformity of the ionospheric conductivity distribution.