关键词: S_q变化形态;谐波项;地磁扰动;等效电流矢量;仲冬月

Abstract:

In this paper an analysis is made on the winter characteristics of Sq variation of geomagnetic field in the region of the Chinese Great Wall Station, Antarctica, using geomagnetic data from the geomagnetic observatory of The Chinese Great Wall Station (CGWS) during April-September, 1987. It is shown that (1) The morphology of Sq variation in early winter (Apr.) and late winter (Sep.) at CGWS is similar to that at Beijing Geomagnetic Observatory (BJO) at middle latitude of the Northern Hemisphere and may be controlled by the midlatitude dynamo currents. Amplitude of Sq variation is very small, and the variation is maily the harmonics of 8 hours or shorter periods in midwinter (June and July) because of the decreasing effect of the solar ultraviolet radiation and the dominating disturbance at high latitude. (2) The equivalent current vectors of Sq in the daytime are about five times larger than that at night. The vector directions are clockwise in the daytime (8-15h) and counter-clockwise at night in early winter and late winter. The vector either in the daytime or at night are very small because of the relatively decreasing effect of the current intensity in the ionosphere in midwinter. The equivalent current vector directions of Sq in early winter and late winter are different from that in midwinter at CGWS. That may be affected by ionospheric current or field-aligned current in the polar region.