ANALYSIS AND RESEARCH OF SqFOCUS POSITION OF THE MID-LOW LATITUDES IN CHINA
Xiong Xianbao, Qian Jiadong(Earthquake Research Institute of Lanzhou, SSB, China) Xu Wenyao(Institute of Geophysics, Academia Sinica, Beijing, China)
Using the geomagnetic data of several great solar activities from Mar. 1988 to Mal. 1989 of 9 stations in China, and the equivalent ionosphere current systems of infinite plate current, we analysed the variation features of S_qfocus position of the mid-low latitudes in China and obtained reasonable explanation of S_qfocus variability corresponding to K_p, D_st, A_pindexes. It is showed that 1) In different K_pindex intervals, S_qfocus has different regularities. When K_p4, S_qfocus moves to high latitudes as K_pindex is increased; When 4K_p6, S_qfocus moves to low latitudes as K_pindex is increased; when K_p6, S_qfocus is indistinct as K_pindex is increased.2) S_qfocus variation along latitude direction was mainly caused by ring currents, but variation along longitudinal direction was mainly affected by IMF sector effect.