Characterisation Of The Ionosphere Over The South Atlantic Anomaly By Using A Ship Based Dual Frequency Gps Receiver

Characterisation of the Ionosphere Over the South Atlantic Anomaly by Using a Ship-based Dual-frequency GPS Receiver

The ionosphere is a layer of ionised gas in the upper layers of the atmosphere around the Earth that plays a critical role in satellite communication, military communication and space science. The influence that the ionosphere has on communication systems can be quantified if the distribution of the electron density within the ionosphere is known. Several methods and instruments to determine the distribution of electron density are currently being used: satellites, ionosondes, incoherent scatter radars and computerised ionospheric tomography based on dual-frequency GPS signals. The present study investigates a novel way of using GPS receivers on mobile platforms to achieve near real-time ionospheric characterisation over locations beyond the reach of land-based ionospheric characterisation methods. GPS observations were collected, pre-processed and inverted by means of tomography to generate three-dimensional electron density maps. These electron density maps were analysed and verified. The viability of using observations from a mobile GPS receiver for ionospheric tomography was investigated. The algorithms were verified by means of a model ionosphere and a simulated GPS receiver. Furthermore, electron density maps generated from GPS observables from a mobile receiver were verified against ionosonde-derived electron density profiles, static land-based GPS receivers and known high-frequency propagation paths using propagation path prediction. The results were evaluated and the conclusion was that, although some aspects still have to be addressed, a dual-frequency GPS receiver on a ship can provide useful ionospheric characterisation in areas which are otherwise poorly or not covered by land-based receivers.

Characterization of the Ionosphere Over the South Atlantic Ocean by Means of Ionospheric Tomography Using Dual Frequency GPS Signals Received On Board a Research Ship

This paper reports a novel approach to extend the coverage of terrestrial ionospheric measurements over a poorly characterized region of the South Atlantic Ocean, including the South Atlantic Anomaly, by using dual frequency GPS signals received on board the South African polar research ship SA Agulhas. The routes of the SA Agulhas to the South Atlantic Islands, Gough (40 deg 17 sec S, 9 deg 58 sec W, Mag lat 42 deg S) and Marion (46 deg 52 sec S, 37 deg 5 sec E, Mag lat 51 deg S) and the South African Antarctic base SANAE IV (71 deg 40 sec S, 2 deg 51 sec W, Mag lat 61 deg S) present unique locations for investigating the variability of the upper atmosphere in the high latitudes in the vicinity of the South Atlantic Anomaly and its link with the near-Earth space environment.

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