摘要：This study investigated the magnetospheric and ionospheric sources of geomagnetic field variation using the data set that consists of the hourly values of the geomagnetic element: horizontal intensity H, recorded at the geomagnetic observatory of the Department of physics, university of Ilorin, Ilorin (Long 4.670 and Lat. 8.50, dip 4.1 oS) Nigeria for the months of august, October and December in the year 2008. The study attributed the daytime variation to the ionospheric sources while various reasons were given to explain these night-time variations, which include convective drift currents in the magnetosphere and the asymmetric rings currents in the magnetospheric currents; this variation due to disturbances indicates possible non-ionospheric origin and a partial ring current in the night side magnetosphere. The mean monthly hourly variation showed seasonal variation with the Sq(H) maximizes in equinox with least variation in June solstice. Moreover, the mean ration of seasonal contributions of magnetospheric to ionospheric sources revealed that the E season has more contributions from both magnetospheric and ionospheric sources than other seasons with the least occurring during the J season.
关键词：Sq(H)Geomagnetic ObservatoryMagnetospheric and Ionospheric SourcesGeomagnetic Field Variation and Asymmetric Rings Currents
