Radiowave Scintillation over Ethiopia using Scinda GPS Stations
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Date
2007-09
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Addis Ababa University
Abstract
The low latitude and equatorial ionosphere TEC and S4 index variability are investigated
using observational data. Two GPS stations namely Addis Ababa located at geographic
latitude 9°.034 N and longitude 38°.67 E and Bahrdar station geographic latitude 11°.37
N and longitude 37°.10 E are analyzed for the ascending period of solar cycle 24. During
the period of observation (January 2008 to December 2014), the variation of scintillations
with diurnal, seasonal, magnetic activity, low and high solar activity are presented in this
thesis. Due to geographical location in
uence there were a time shift of peak VTEC and S4
at both Addis Ababa and Bahir Dar. The occurrence of scintillation is found to be hourly
mean maximum in E-season and minimum in D-season. The suppression or enhancement
of pre-midnight scintillations during magnetic disturbed and quiet periods is found to be a
local time dependent. When the occurrence of geomagnetic storm was observed either to
inhibit or to trigger scintillation occurence. Enhanced scintillation appeared during main
and recovery phase of geomagnetic storm. Scintillation was maximum during high sunspot
number (2011-2014) and was minimum at low sunspot number (2008-2010). Post-sunset
scintillation was found to be maximum in E-season whereas it is minimum in D-season.
The elevation angle of PRN satellites have an in
uence on scintillation occurence. Pre-
reversal enhancement of VTEC is a cause to maximum scintillation ascending during
post-sunset.
Keywords: GPS-SCINDA; VTEC, S4 index, Dst, elevation angle, Geomagnetic
storm, low solar activity period, high solar activity period
Description
Keywords
GPS-SCINDA, VTEC, S4 index, Dst, Elevation Angle, , Geomagnetic Storm, Low Solar Activity Period, High Solar Activity Period