Seasonal and Annual Variations of Solar Quiet of the Horizontal Magnetic Field along the African Geomagnetic Equator during the Ascending Phase of Solar Cycle 24

Abstract

The seasonal and annual variation of the solar quiet of the horizontal magnetic field along the African geomagnetic equator during the ascending phase of solar cycle 24 has been investigated. This has been done using magnetic field measurements obtained from International Real-time Magnetic Observatory Network (INTERMAGNET) stations in Ethiopia, Addis Ababa (AAE) and Mbour (MBO) in Senegal and African Meridian B-field Education and Research (AMBER) arrays data at Yaoundé (CMRN), Cameroon and Adigrat (ETHI), Ethiopia for the duration from January 2009 to December 2014. The results showed that in the African equatorial region, the equinoctial peaks of solar quiet of Horizontal component of the magnetic field (SqH) were generally higher than the peaks during the December solstice (D) and June solstice (J) seasons. The largest seasonal SqH values were observed during the March equinox and December equinox in the year 2014 while the largest annual values were observed in the year 2014. There was a solar activity and a dependence on the local time for the annual geomagnetic field variation in SqH. The SqH magnitude increased with increasing activity of the sun, with the highest attained amplitudes in the years 2012 and 2014 which were high solar activity years. The daily peaks were seen at around local noon for all the stations under this study. The results on the seasonal and annual variations of the solar quiet of the horizontal magnetic field are essential in ensuring reliability and accuracy for systems that depend on the Earth’s magnetic field.