摘要：The quiet daily variations of the geomagnetic field ( S q) have been studied by using the geomagnetic data of the 10 International Quietest Days.Geomagnetic data from MAGDAS I and II stations—ten stations were selected around the 96° magnetic meridian (MM)—over Africa have been analyzed from September 2008 to August 2009.The analysis of this unique data set clarifies the characteristics of the S q variations over the African sector for the first time by observational geomagnetic data.In this paper, we found that S q( H ) and S q( D ) show a predominantly annual variation.The most interesting result, and a new finding in the African sector, is the appearance of two vortices in the day lit southern hemisphere during spring.Further data analysis also revealed many other interesting characteristics for the S q over the African sector.
关键词：S q ;northward current ;ionospheric currents ;ground-based magnetometers
