Study of Second and third Order Ionospheric Effect on Global Positioning System (GPS) Signals Along The Equatorial Regions
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Date
2013-04
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Addis Ababa University
Abstract
Ionosphere is the major source of error for geodetic applications despite the fact that it’s possible to remove
most of the effect using its dispersive nature. However, it’s only the first order of the ionospheric effect that
can be removed using dual frequencies signal observations. The second and third order ionosphere effect
cannot be removed though we can model their effects on geodetic applications such as their effects on Global
Positioning System (GPS) signals. The study mainly focuses on the assessment of higher order (second and
third) ionosphere effects on GPS for accurate positioning along the equatorial regions. Some stations at higher
latitudes were also included in our GPS data processing for comparison purposes. GAMIT/GLOBK software
was used to process the GPS data including a suite of other ancillary information.
The time series of the residuals from the final GAMIT/GLOBK result were compared with the geomagnetic
field effects and solar cycle (sunspot activities). High ionopheric effects on the GPS signals from stations
along the equator were observed relative to stations at higher latitudes due to the fact that total electron
content density is high along the equator. In addition to this, the contribution of Equatorial Electrojet (EEJ) to
ionospheric disturbances is higher along the equator. Higher total electron content was also observed for the
stations from the equatorial region in particular on years 2002 and 2012 as these are the years where solar
activity were at maximum.
Keywords: GPS, Higher order ionosphereic effects, Total electron contents density, Geomagnetic field
Description
Keywords
GPS; Higher Order Ionosphereic Effects;Total Electron Contents Density; Geomagnetic Field