STUDY OF 2 mHz, LONG WAVE-TRAIN Pc5 WAVES ON THE DAYSIDE AT AN EQUATORIAL STATION

Abstract:

Although long-period Pc5 waves (~ 2 mHz) are ubiquitous, their appearance on the dayside at low latitudes is not well understood. In order to gain an improved understanding of the processes involved in their propagation and occurrence at equatorial latitudes, their general properties at Ilorin (Geographic: 4.53°E, 8.50°N; Dip latitude -1.82°) were investigated. Geomagnetic field data, obtained from a magnetometer at Ilorin (ILR), from January 2007 – December 2009 was analyzed. A summary of the diurnal characteristics, dependence on seasons and on level of magnetic activity of these waves is presented. A general classification of Pc5 wave activity at ILR based on observed frequencies and time of occurrence is also provided. Preliminary results from detailed analysis of a case study event show a clear response of the event to an increase in solar wind flow pressure and proton density. Analysis of geomagnetic field data from higher latitudes revealed activity at similar frequency but at a higher power level than at ILR and with decreasing phase difference equator wards.