Observations and Analytic Modeling of ULF Pc5 Wave Propagation through the Equatorial Ionosphere

Olugbon, Busola

Observations and Analytic Modeling of ULF Pc5 Wave Propagation through the Equatorial Ionosphere

Tuesday, 11 July 2017

Furong Room (Cynn Hotel)

Busola Olugbon¹, Fred William Menk², Colin L Waters³, Elijah Oyedola Oyeyemi¹, Anton Kashcheyev⁴ and Adebowale Adeloye¹, (1)University of Lagos, Lagos, Nigeria, (2)University of Newcastle, School of Mathematical and Physical Sciences, Callaghan, Australia, (3)University of Newcastle, Department of Physical and Mathematical Sciences, Callaghan, Australia, (4)National Academy of Sciences of Ukraine, Institute of Radio Astronomy, Kiev, Ukraine

Abstract:

Geomagnetic field data available from Ilorin (4.53°E, 8.50°N geographic, dip latitude -1.82°) during January 2007 – December 2009 were analyzed for Pc5 wave activity. From a total of 148 Pc5 events, 8 were selected for detailed analysis. Data from a high latitude location were also analyzed in order to investigate similarities (or otherwise) in the properties of the equatorial and high latitude Pc5 waves. In order to understand the propagation mechanisms of the Pc5 waves to ground, especially at Ilorin (ILR), observational results were compared with outputs from a 1-D analytic model. The results from two case study events which occurred at different local times and under different solar wind and magnetic conditions are presented. In particular, the solar wind proton density was elevated during both events (15 N/cm³ and 55 N/cm³). The azimuthal wave numbers for both events were low (m < 3.5) and wave properties on the ground for the high latitude cases closely matched a modeled incident wave at the top boundary of the magnetosphere comprising 80% shear Alfven and 20% fast mode. Model results showed that the ionosphere did not have a significant effect on the amplitude and phase properties of the Pc5 waves in both the equatorial and high latitude cases.