The Ionosphere extends about 90-2 000 km above the Earth and is composed of free-flowing electrically charged particles, constituting a space plasma. The ionosphere affects all radio signals propagating through it and, amongst others, cause errors in GPS position fixes. By exploiting the refraction-induced error on GPS radio signals, measurements of the ionospheric plasma density can be made along the signal path and used to investigate space plasma structure and dynamics.
The HMO has developed a mathematical model to image the plasma density in the ionosphere over Southern Africa by using signals from a network of geodetic-grade dual frequency GPS receivers. Several techniques exist to accomplish this and a new technique using Kriging is proposed. Kriging, a fundamental interpolation technique named in honour of a South African mining engineer, is well suited for extracting fine structure information from irregularly-spaced two-dimensional data points.
The objective of this project is to use existing Matlab code to apply a relevant kriging technique to bias-corrected plasma measurements spaced at irregular geographic coordinates (Figure 1) to derive a 2D plasma image. It is anticipated that kriging will reveal finer structure in the plasma than possible with existing methods.