Detailed Analysis of Auroral Zone WADGPS Ionospheric Grid Accuracies during Magnetospheric Substorm Event

S. Skone, M.E. Cannon

Abstract:	By using a number of reference stations, each equipped with a dual frequency receiver, it is possible to estimate values of vertical ionospheric delay (or, equivalently, total electron content) at a set of designated grid points. This type of ionosphere delay modelling is employed in Wide Area Differential GPS (WADGPS) Networks, where vertical TEC values at grid points are determined in an adjustment incorporating all receiver-satellite line-of- sight observations. These models can suffer degraded performance in regions, such as the auroral zone, where large variations in total electron content (TEC) occur during geomagnetic disturbances. The auroral zone is characterized by magnetospheric substorms and similar transient phenomena, in which localised enhancements and depletions of electron density occur. Such events are often associated with small-scale variations in TEC, which are difficult to model. The auroral oval is located at high latitudes, and can extend several degrees southward under significantly disturbed levels of activity. TEC variations in the auroral zone are therefore significant concerns for WADGPS systems operating in Canada, Northern Europe, and Alaska. In this paper, wide area ionospheric grid accuracies are investigated in the auroral zone during a well-defined magnetospheric substorm event. This storm took place in April 1997, in the North American local time sector, and is representative of storm-time conditions anticipated during the next solar maximum (=year 2000). Detailed analysis of this substorm is conducted, in order to identifj both the magnitude and extent of geomagnetic disturbances, using a variety of space-borne instruments. In this way, a clear picture of the substorm development will be presented, and grid accuracies assessed during different phases of substorm development. GPS observations from the Natural Resources Canada (NRCan) wide area network are used in the grid adjustment.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	701 - 710
Cite this article:	Skone, S., Cannon, M.E., "Detailed Analysis of Auroral Zone WADGPS Ionospheric Grid Accuracies during Magnetospheric Substorm Event," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 701-710.
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